Modules API reference
Reference for the Redis Modules API
Sections
- Heap allocation raw functions
- Commands API
- Module information and time measurement
- Automatic memory management for modules
- String objects APIs
- Reply APIs
- Commands replication API
- DB and Key APIs – Generic API
- Key API for String type
- Key API for List type
- Key API for Sorted Set type
- Key API for Sorted Set iterator
- Key API for Hash type
- Key API for Stream type
- Calling Redis commands from modules
- Modules data types
- RDB loading and saving functions
- Key digest API (DEBUG DIGEST interface for modules types)
- AOF API for modules data types
- IO context handling
- Logging
- Blocking clients from modules
- Thread Safe Contexts
- Module Keyspace Notifications API
- Modules Cluster API
- Modules Timers API
- Modules EventLoop API
- Modules ACL API
- Modules Dictionary API
- Modules Info fields
- Modules utility APIs
- Modules API exporting / importing
- Module Command Filter API
- Scanning keyspace and hashes
- Module fork API
- Server hooks implementation
- Module Configurations API
- RDB load/save API
- Key eviction API
- Miscellaneous APIs
- Defrag API
- Function index
Heap allocation raw functions
Memory allocated with these functions are taken into account by Redis key eviction algorithms and are reported in Redis memory usage information.
RedisModule_Alloc
void *RedisModule_Alloc(size_t bytes);
Available since: 4.0.0
Use like malloc()
. Memory allocated with this function is reported in
Redis INFO memory, used for keys eviction according to maxmemory settings
and in general is taken into account as memory allocated by Redis.
You should avoid using malloc()
.
This function panics if unable to allocate enough memory.
RedisModule_TryAlloc
void *RedisModule_TryAlloc(size_t bytes);
Available since: 7.0.0
Similar to RedisModule_Alloc
, but returns NULL in case of allocation failure, instead
of panicking.
RedisModule_Calloc
void *RedisModule_Calloc(size_t nmemb, size_t size);
Available since: 4.0.0
Use like calloc()
. Memory allocated with this function is reported in
Redis INFO memory, used for keys eviction according to maxmemory settings
and in general is taken into account as memory allocated by Redis.
You should avoid using calloc()
directly.
RedisModule_Realloc
void* RedisModule_Realloc(void *ptr, size_t bytes);
Available since: 4.0.0
Use like realloc()
for memory obtained with RedisModule_Alloc()
.
RedisModule_Free
void RedisModule_Free(void *ptr);
Available since: 4.0.0
Use like free()
for memory obtained by RedisModule_Alloc()
and
RedisModule_Realloc()
. However you should never try to free with
RedisModule_Free()
memory allocated with malloc()
inside your module.
RedisModule_Strdup
char *RedisModule_Strdup(const char *str);
Available since: 4.0.0
Like strdup()
but returns memory allocated with RedisModule_Alloc()
.
RedisModule_PoolAlloc
void *RedisModule_PoolAlloc(RedisModuleCtx *ctx, size_t bytes);
Available since: 4.0.0
Return heap allocated memory that will be freed automatically when the module callback function returns. Mostly suitable for small allocations that are short living and must be released when the callback returns anyway. The returned memory is aligned to the architecture word size if at least word size bytes are requested, otherwise it is just aligned to the next power of two, so for example a 3 bytes request is 4 bytes aligned while a 2 bytes request is 2 bytes aligned.
There is no realloc style function since when this is needed to use the pool allocator is not a good idea.
The function returns NULL if bytes
is 0.
Commands API
These functions are used to implement custom Redis commands.
For examples, see https://redis.io/topics/modules-intro.
RedisModule_IsKeysPositionRequest
int RedisModule_IsKeysPositionRequest(RedisModuleCtx *ctx);
Available since: 4.0.0
Return non-zero if a module command, that was declared with the flag "getkeys-api", is called in a special way to get the keys positions and not to get executed. Otherwise zero is returned.
RedisModule_KeyAtPosWithFlags
void RedisModule_KeyAtPosWithFlags(RedisModuleCtx *ctx, int pos, int flags);
Available since: 7.0.0
When a module command is called in order to obtain the position of
keys, since it was flagged as "getkeys-api" during the registration,
the command implementation checks for this special call using the
RedisModule_IsKeysPositionRequest()
API and uses this function in
order to report keys.
The supported flags are the ones used by RedisModule_SetCommandInfo
, see REDISMODULE_CMD_KEY_
*.
The following is an example of how it could be used:
if (RedisModule_IsKeysPositionRequest(ctx)) {
RedisModule_KeyAtPosWithFlags(ctx, 2, REDISMODULE_CMD_KEY_RO | REDISMODULE_CMD_KEY_ACCESS);
RedisModule_KeyAtPosWithFlags(ctx, 1, REDISMODULE_CMD_KEY_RW | REDISMODULE_CMD_KEY_UPDATE | REDISMODULE_CMD_KEY_ACCESS);
}
Note: in the example above the get keys API could have been handled by key-specs (preferred). Implementing the getkeys-api is required only when is it not possible to declare key-specs that cover all keys.
RedisModule_KeyAtPos
void RedisModule_KeyAtPos(RedisModuleCtx *ctx, int pos);
Available since: 4.0.0
This API existed before RedisModule_KeyAtPosWithFlags
was added, now deprecated and
can be used for compatibility with older versions, before key-specs and flags
were introduced.
RedisModule_IsChannelsPositionRequest
int RedisModule_IsChannelsPositionRequest(RedisModuleCtx *ctx);
Available since: 7.0.0
Return non-zero if a module command, that was declared with the flag "getchannels-api", is called in a special way to get the channel positions and not to get executed. Otherwise zero is returned.
RedisModule_ChannelAtPosWithFlags
void RedisModule_ChannelAtPosWithFlags(RedisModuleCtx *ctx,
int pos,
int flags);
Available since: 7.0.0
When a module command is called in order to obtain the position of
channels, since it was flagged as "getchannels-api" during the
registration, the command implementation checks for this special call
using the RedisModule_IsChannelsPositionRequest()
API and uses this
function in order to report the channels.
The supported flags are:
REDISMODULE_CMD_CHANNEL_SUBSCRIBE
: This command will subscribe to the channel.REDISMODULE_CMD_CHANNEL_UNSUBSCRIBE
: This command will unsubscribe from this channel.REDISMODULE_CMD_CHANNEL_PUBLISH
: This command will publish to this channel.REDISMODULE_CMD_CHANNEL_PATTERN
: Instead of acting on a specific channel, will act on any channel specified by the pattern. This is the same access used by the PSUBSCRIBE and PUNSUBSCRIBE commands available in Redis. Not intended to be used with PUBLISH permissions.
The following is an example of how it could be used:
if (RedisModule_IsChannelsPositionRequest(ctx)) {
RedisModule_ChannelAtPosWithFlags(ctx, 1, REDISMODULE_CMD_CHANNEL_SUBSCRIBE | REDISMODULE_CMD_CHANNEL_PATTERN);
RedisModule_ChannelAtPosWithFlags(ctx, 1, REDISMODULE_CMD_CHANNEL_PUBLISH);
}
Note: One usage of declaring channels is for evaluating ACL permissions. In this context,
unsubscribing is always allowed, so commands will only be checked against subscribe and
publish permissions. This is preferred over using RedisModule_ACLCheckChannelPermissions
, since
it allows the ACLs to be checked before the command is executed.
RedisModule_CreateCommand
int RedisModule_CreateCommand(RedisModuleCtx *ctx,
const char *name,
RedisModuleCmdFunc cmdfunc,
const char *strflags,
int firstkey,
int lastkey,
int keystep);
Available since: 4.0.0
Register a new command in the Redis server, that will be handled by calling the function pointer 'cmdfunc' using the RedisModule calling convention.
The function returns REDISMODULE_ERR
in these cases:
- If creation of module command is called outside the
RedisModule_OnLoad
. - The specified command is already busy.
- The command name contains some chars that are not allowed.
- A set of invalid flags were passed.
Otherwise REDISMODULE_OK
is returned and the new command is registered.
This function must be called during the initialization of the module
inside the RedisModule_OnLoad()
function. Calling this function outside
of the initialization function is not defined.
The command function type is the following:
int MyCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc);
And is supposed to always return REDISMODULE_OK
.
The set of flags 'strflags' specify the behavior of the command, and should be passed as a C string composed of space separated words, like for example "write deny-oom". The set of flags are:
- "write": The command may modify the data set (it may also read from it).
- "readonly": The command returns data from keys but never writes.
- "admin": The command is an administrative command (may change replication or perform similar tasks).
- "deny-oom": The command may use additional memory and should be denied during out of memory conditions.
- "deny-script": Don't allow this command in Lua scripts.
- "allow-loading": Allow this command while the server is loading data. Only commands not interacting with the data set should be allowed to run in this mode. If not sure don't use this flag.
- "pubsub": The command publishes things on Pub/Sub channels.
- "random": The command may have different outputs even starting from the same input arguments and key values. Starting from Redis 7.0 this flag has been deprecated. Declaring a command as "random" can be done using command tips, see https://redis.io/topics/command-tips.
- "allow-stale": The command is allowed to run on slaves that don't serve stale data. Don't use if you don't know what this means.
- "no-monitor": Don't propagate the command on monitor. Use this if the command has sensitive data among the arguments.
- "no-slowlog": Don't log this command in the slowlog. Use this if the command has sensitive data among the arguments.
- "fast": The command time complexity is not greater than O(log(N)) where N is the size of the collection or anything else representing the normal scalability issue with the command.
- "getkeys-api": The command implements the interface to return the arguments that are keys. Used when start/stop/step is not enough because of the command syntax.
- "no-cluster": The command should not register in Redis Cluster since is not designed to work with it because, for example, is unable to report the position of the keys, programmatically creates key names, or any other reason.
- "no-auth": This command can be run by an un-authenticated client. Normally this is used by a command that is used to authenticate a client.
- "may-replicate": This command may generate replication traffic, even though it's not a write command.
- "no-mandatory-keys": All the keys this command may take are optional
- "blocking": The command has the potential to block the client.
- "allow-busy": Permit the command while the server is blocked either by a script or by a slow module command, see RedisModule_Yield.
- "getchannels-api": The command implements the interface to return the arguments that are channels.
The last three parameters specify which arguments of the new command are Redis keys. See https://redis.io/commands/command for more information.
firstkey
: One-based index of the first argument that's a key. Position 0 is always the command name itself. 0 for commands with no keys.lastkey
: One-based index of the last argument that's a key. Negative numbers refer to counting backwards from the last argument (-1 means the last argument provided) 0 for commands with no keys.keystep
: Step between first and last key indexes. 0 for commands with no keys.
This information is used by ACL, Cluster and the COMMAND
command.
NOTE: The scheme described above serves a limited purpose and can
only be used to find keys that exist at constant indices.
For non-trivial key arguments, you may pass 0,0,0 and use
RedisModule_SetCommandInfo
to set key specs using a more advanced scheme and use
RedisModule_SetCommandACLCategories
to set Redis ACL categories of the commands.
RedisModule_GetCommand
RedisModuleCommand *RedisModule_GetCommand(RedisModuleCtx *ctx,
const char *name);
Available since: 7.0.0
Get an opaque structure, representing a module command, by command name. This structure is used in some of the command-related APIs.
NULL is returned in case of the following errors:
- Command not found
- The command is not a module command
- The command doesn't belong to the calling module
RedisModule_CreateSubcommand
int RedisModule_CreateSubcommand(RedisModuleCommand *parent,
const char *name,
RedisModuleCmdFunc cmdfunc,
const char *strflags,
int firstkey,
int lastkey,
int keystep);
Available since: 7.0.0
Very similar to RedisModule_CreateCommand
except that it is used to create
a subcommand, associated with another, container, command.
Example: If a module has a configuration command, MODULE.CONFIG, then
GET and SET should be individual subcommands, while MODULE.CONFIG is
a command, but should not be registered with a valid funcptr
:
if (RedisModule_CreateCommand(ctx,"module.config",NULL,"",0,0,0) == REDISMODULE_ERR)
return REDISMODULE_ERR;
RedisModuleCommand *parent = RedisModule_GetCommand(ctx,,"module.config");
if (RedisModule_CreateSubcommand(parent,"set",cmd_config_set,"",0,0,0) == REDISMODULE_ERR)
return REDISMODULE_ERR;
if (RedisModule_CreateSubcommand(parent,"get",cmd_config_get,"",0,0,0) == REDISMODULE_ERR)
return REDISMODULE_ERR;
Returns REDISMODULE_OK
on success and REDISMODULE_ERR
in case of the following errors:
- Error while parsing
strflags
- Command is marked as
no-cluster
but cluster mode is enabled parent
is already a subcommand (we do not allow more than one level of command nesting)parent
is a command with an implementation (RedisModuleCmdFunc
) (A parent command should be a pure container of subcommands)parent
already has a subcommand calledname
- Creating a subcommand is called outside of
RedisModule_OnLoad
.
RedisModule_SetCommandACLCategories
int RedisModule_SetCommandACLCategories(RedisModuleCommand *command,
const char *aclflags);
Available since: 7.2.0
RedisModule_SetCommandACLCategories
can be used to set ACL categories to module
commands and subcommands. The set of ACL categories should be passed as
a space separated C string 'aclflags'.
Example, the acl flags 'write slow' marks the command as part of the write and slow ACL categories.
On success REDISMODULE_OK
is returned. On error REDISMODULE_ERR
is returned.
This function can only be called during the RedisModule_OnLoad
function. If called
outside of this function, an error is returned.
RedisModule_SetCommandInfo
int RedisModule_SetCommandInfo(RedisModuleCommand *command,
const RedisModuleCommandInfo *info);
Available since: 7.0.0
Set additional command information.
Affects the output of COMMAND
, COMMAND INFO
and COMMAND DOCS
, Cluster,
ACL and is used to filter commands with the wrong number of arguments before
the call reaches the module code.
This function can be called after creating a command using RedisModule_CreateCommand
and fetching the command pointer using RedisModule_GetCommand
. The information can
only be set once for each command and has the following structure:
typedef struct RedisModuleCommandInfo {
const RedisModuleCommandInfoVersion *version;
const char *summary;
const char *complexity;
const char *since;
RedisModuleCommandHistoryEntry *history;
const char *tips;
int arity;
RedisModuleCommandKeySpec *key_specs;
RedisModuleCommandArg *args;
} RedisModuleCommandInfo;
All fields except version
are optional. Explanation of the fields:
-
version
: This field enables compatibility with different Redis versions. Always set this field toREDISMODULE_COMMAND_INFO_VERSION
. -
summary
: A short description of the command (optional). -
complexity
: Complexity description (optional). -
since
: The version where the command was introduced (optional). Note: The version specified should be the module's, not Redis version. -
history
: An array ofRedisModuleCommandHistoryEntry
(optional), which is a struct with the following fields:const char *since; const char *changes;
since
is a version string andchanges
is a string describing the changes. The array is terminated by a zeroed entry, i.e. an entry with both strings set to NULL. -
tips
: A string of space-separated tips regarding this command, meant for clients and proxies. See https://redis.io/topics/command-tips. -
arity
: Number of arguments, including the command name itself. A positive number specifies an exact number of arguments and a negative number specifies a minimum number of arguments, so use -N to say >= N. Redis validates a call before passing it to a module, so this can replace an arity check inside the module command implementation. A value of 0 (or an omitted arity field) is equivalent to -2 if the command has sub commands and -1 otherwise. -
key_specs
: An array ofRedisModuleCommandKeySpec
, terminated by an element memset to zero. This is a scheme that tries to describe the positions of key arguments better than the oldRedisModule_CreateCommand
argumentsfirstkey
,lastkey
,keystep
and is needed if those three are not enough to describe the key positions. There are two steps to retrieve key positions: begin search (BS) in which index should find the first key and find keys (FK) which, relative to the output of BS, describes how can we will which arguments are keys. Additionally, there are key specific flags.Key-specs cause the triplet (firstkey, lastkey, keystep) given in RedisModule_CreateCommand to be recomputed, but it is still useful to provide these three parameters in RedisModule_CreateCommand, to better support old Redis versions where RedisModule_SetCommandInfo is not available.
Note that key-specs don't fully replace the "getkeys-api" (see RedisModule_CreateCommand, RedisModule_IsKeysPositionRequest and RedisModule_KeyAtPosWithFlags) so it may be a good idea to supply both key-specs and implement the getkeys-api.
A key-spec has the following structure:
typedef struct RedisModuleCommandKeySpec { const char *notes; uint64_t flags; RedisModuleKeySpecBeginSearchType begin_search_type; union { struct { int pos; } index; struct { const char *keyword; int startfrom; } keyword; } bs; RedisModuleKeySpecFindKeysType find_keys_type; union { struct { int lastkey; int keystep; int limit; } range; struct { int keynumidx; int firstkey; int keystep; } keynum; } fk; } RedisModuleCommandKeySpec;
Explanation of the fields of RedisModuleCommandKeySpec:
-
notes
: Optional notes or clarifications about this key spec. -
flags
: A bitwise or of key-spec flags described below. -
begin_search_type
: This describes how the first key is discovered. There are two ways to determine the first key:REDISMODULE_KSPEC_BS_UNKNOWN
: There is no way to tell where the key args start.REDISMODULE_KSPEC_BS_INDEX
: Key args start at a constant index.REDISMODULE_KSPEC_BS_KEYWORD
: Key args start just after a specific keyword.
-
bs
: This is a union in which theindex
orkeyword
branch is used depending on the value of thebegin_search_type
field.-
bs.index.pos
: The index from which we start the search for keys. (REDISMODULE_KSPEC_BS_INDEX
only.) -
bs.keyword.keyword
: The keyword (string) that indicates the beginning of key arguments. (REDISMODULE_KSPEC_BS_KEYWORD
only.) -
bs.keyword.startfrom
: An index in argv from which to start searching. Can be negative, which means start search from the end, in reverse. Example: -2 means to start in reverse from the penultimate argument. (REDISMODULE_KSPEC_BS_KEYWORD
only.)
-
-
find_keys_type
: After the "begin search", this describes which arguments are keys. The strategies are:REDISMODULE_KSPEC_BS_UNKNOWN
: There is no way to tell where the key args are located.REDISMODULE_KSPEC_FK_RANGE
: Keys end at a specific index (or relative to the last argument).REDISMODULE_KSPEC_FK_KEYNUM
: There's an argument that contains the number of key args somewhere before the keys themselves.
find_keys_type
andfk
can be omitted if this keyspec describes exactly one key. -
fk
: This is a union in which therange
orkeynum
branch is used depending on the value of thefind_keys_type
field.-
fk.range
(forREDISMODULE_KSPEC_FK_RANGE
): A struct with the following fields:-
lastkey
: Index of the last key relative to the result of the begin search step. Can be negative, in which case it's not relative. -1 indicates the last argument, -2 one before the last and so on. -
keystep
: How many arguments should we skip after finding a key, in order to find the next one? -
limit
: Iflastkey
is -1, we uselimit
to stop the search by a factor. 0 and 1 mean no limit. 2 means 1/2 of the remaining args, 3 means 1/3, and so on.
-
-
fk.keynum
(forREDISMODULE_KSPEC_FK_KEYNUM
): A struct with the following fields:-
keynumidx
: Index of the argument containing the number of keys to come, relative to the result of the begin search step. -
firstkey
: Index of the fist key relative to the result of the begin search step. (Usually it's just afterkeynumidx
, in which case it should be set tokeynumidx + 1
.) -
keystep
: How many arguments should we skip after finding a key, in order to find the next one?
-
-
Key-spec flags:
The first four refer to what the command actually does with the value or metadata of the key, and not necessarily the user data or how it affects it. Each key-spec may must have exactly one of these. Any operation that's not distinctly deletion, overwrite or read-only would be marked as RW.
-
REDISMODULE_CMD_KEY_RO
: Read-Only. Reads the value of the key, but doesn't necessarily return it. -
REDISMODULE_CMD_KEY_RW
: Read-Write. Modifies the data stored in the value of the key or its metadata. -
REDISMODULE_CMD_KEY_OW
: Overwrite. Overwrites the data stored in the value of the key. -
REDISMODULE_CMD_KEY_RM
: Deletes the key.
The next four refer to user data inside the value of the key, not the metadata like LRU, type, cardinality. It refers to the logical operation on the user's data (actual input strings or TTL), being used/returned/copied/changed. It doesn't refer to modification or returning of metadata (like type, count, presence of data). ACCESS can be combined with one of the write operations INSERT, DELETE or UPDATE. Any write that's not an INSERT or a DELETE would be UPDATE.
-
REDISMODULE_CMD_KEY_ACCESS
: Returns, copies or uses the user data from the value of the key. -
REDISMODULE_CMD_KEY_UPDATE
: Updates data to the value, new value may depend on the old value. -
REDISMODULE_CMD_KEY_INSERT
: Adds data to the value with no chance of modification or deletion of existing data. -
REDISMODULE_CMD_KEY_DELETE
: Explicitly deletes some content from the value of the key.
Other flags:
-
REDISMODULE_CMD_KEY_NOT_KEY
: The key is not actually a key, but should be routed in cluster mode as if it was a key. -
REDISMODULE_CMD_KEY_INCOMPLETE
: The keyspec might not point out all the keys it should cover. -
REDISMODULE_CMD_KEY_VARIABLE_FLAGS
: Some keys might have different flags depending on arguments.
-
-
args
: An array ofRedisModuleCommandArg
, terminated by an element memset to zero.RedisModuleCommandArg
is a structure with at the fields described below.typedef struct RedisModuleCommandArg { const char *name; RedisModuleCommandArgType type; int key_spec_index; const char *token; const char *summary; const char *since; int flags; struct RedisModuleCommandArg *subargs; } RedisModuleCommandArg;
Explanation of the fields:
-
name
: Name of the argument. -
type
: The type of the argument. See below for details. The typesREDISMODULE_ARG_TYPE_ONEOF
andREDISMODULE_ARG_TYPE_BLOCK
require an argument to have sub-arguments, i.e.subargs
. -
key_spec_index
: If thetype
isREDISMODULE_ARG_TYPE_KEY
you must provide the index of the key-spec associated with this argument. Seekey_specs
above. If the argument is not a key, you may specify -1. -
token
: The token preceding the argument (optional). Example: the argumentseconds
inSET
has a tokenEX
. If the argument consists of only a token (for exampleNX
inSET
) the type should beREDISMODULE_ARG_TYPE_PURE_TOKEN
andvalue
should be NULL. -
summary
: A short description of the argument (optional). -
since
: The first version which included this argument (optional). -
flags
: A bitwise or of the macrosREDISMODULE_CMD_ARG_*
. See below. -
value
: The display-value of the argument. This string is what should be displayed when creating the command syntax from the output ofCOMMAND
. Iftoken
is not NULL, it should also be displayed.
Explanation of
RedisModuleCommandArgType
:REDISMODULE_ARG_TYPE_STRING
: String argument.REDISMODULE_ARG_TYPE_INTEGER
: Integer argument.REDISMODULE_ARG_TYPE_DOUBLE
: Double-precision float argument.REDISMODULE_ARG_TYPE_KEY
: String argument representing a keyname.REDISMODULE_ARG_TYPE_PATTERN
: String, but regex pattern.REDISMODULE_ARG_TYPE_UNIX_TIME
: Integer, but Unix timestamp.REDISMODULE_ARG_TYPE_PURE_TOKEN
: Argument doesn't have a placeholder. It's just a token without a value. Example: theKEEPTTL
option of theSET
command.REDISMODULE_ARG_TYPE_ONEOF
: Used when the user can choose only one of a few sub-arguments. Requiressubargs
. Example: theNX
andXX
options ofSET
.REDISMODULE_ARG_TYPE_BLOCK
: Used when one wants to group together several sub-arguments, usually to apply something on all of them, like making the entire group "optional". Requiressubargs
. Example: theLIMIT offset count
parameters inZRANGE
.
Explanation of the command argument flags:
REDISMODULE_CMD_ARG_OPTIONAL
: The argument is optional (like GET in the SET command).REDISMODULE_CMD_ARG_MULTIPLE
: The argument may repeat itself (like key in DEL).REDISMODULE_CMD_ARG_MULTIPLE_TOKEN
: The argument may repeat itself, and so does its token (likeGET pattern
in SORT).
-
On success REDISMODULE_OK
is returned. On error REDISMODULE_ERR
is returned
and errno
is set to EINVAL if invalid info was provided or EEXIST if info
has already been set. If the info is invalid, a warning is logged explaining
which part of the info is invalid and why.
Module information and time measurement
RedisModule_IsModuleNameBusy
int RedisModule_IsModuleNameBusy(const char *name);
Available since: 4.0.3
Return non-zero if the module name is busy. Otherwise zero is returned.
RedisModule_Milliseconds
mstime_t RedisModule_Milliseconds(void);
Available since: 4.0.0
Return the current UNIX time in milliseconds.
RedisModule_MonotonicMicroseconds
uint64_t RedisModule_MonotonicMicroseconds(void);
Available since: 7.0.0
Return counter of micro-seconds relative to an arbitrary point in time.
RedisModule_Microseconds
ustime_t RedisModule_Microseconds(void);
Available since: 7.2.0
Return the current UNIX time in microseconds
RedisModule_CachedMicroseconds
ustime_t RedisModule_CachedMicroseconds(void);
Available since: 7.2.0
Return the cached UNIX time in microseconds.
It is updated in the server cron job and before executing a command.
It is useful for complex call stacks, such as a command causing a
key space notification, causing a module to execute a RedisModule_Call
,
causing another notification, etc.
It makes sense that all this callbacks would use the same clock.
RedisModule_BlockedClientMeasureTimeStart
int RedisModule_BlockedClientMeasureTimeStart(RedisModuleBlockedClient *bc);
Available since: 6.2.0
Mark a point in time that will be used as the start time to calculate
the elapsed execution time when RedisModule_BlockedClientMeasureTimeEnd()
is called.
Within the same command, you can call multiple times
RedisModule_BlockedClientMeasureTimeStart()
and RedisModule_BlockedClientMeasureTimeEnd()
to accumulate independent time intervals to the background duration.
This method always return REDISMODULE_OK
.
RedisModule_BlockedClientMeasureTimeEnd
int RedisModule_BlockedClientMeasureTimeEnd(RedisModuleBlockedClient *bc);
Available since: 6.2.0
Mark a point in time that will be used as the end time
to calculate the elapsed execution time.
On success REDISMODULE_OK
is returned.
This method only returns REDISMODULE_ERR
if no start time was
previously defined ( meaning RedisModule_BlockedClientMeasureTimeStart
was not called ).
RedisModule_Yield
void RedisModule_Yield(RedisModuleCtx *ctx, int flags, const char *busy_reply);
Available since: 7.0.0
This API allows modules to let Redis process background tasks, and some commands during long blocking execution of a module command. The module can call this API periodically. The flags is a bit mask of these:
REDISMODULE_YIELD_FLAG_NONE
: No special flags, can perform some background operations, but not process client commands.REDISMODULE_YIELD_FLAG_CLIENTS
: Redis can also process client commands.
The busy_reply
argument is optional, and can be used to control the verbose
error string after the -BUSY
error code.
When the REDISMODULE_YIELD_FLAG_CLIENTS
is used, Redis will only start
processing client commands after the time defined by the
busy-reply-threshold
config, in which case Redis will start rejecting most
commands with -BUSY
error, but allow the ones marked with the allow-busy
flag to be executed.
This API can also be used in thread safe context (while locked), and during
loading (in the rdb_load
callback, in which case it'll reject commands with
the -LOADING error)
RedisModule_SetModuleOptions
void RedisModule_SetModuleOptions(RedisModuleCtx *ctx, int options);
Available since: 6.0.0
Set flags defining capabilities or behavior bit flags.
REDISMODULE_OPTIONS_HANDLE_IO_ERRORS
:
Generally, modules don't need to bother with this, as the process will just
terminate if a read error happens, however, setting this flag would allow
repl-diskless-load to work if enabled.
The module should use RedisModule_IsIOError
after reads, before using the
data that was read, and in case of error, propagate it upwards, and also be
able to release the partially populated value and all it's allocations.
REDISMODULE_OPTION_NO_IMPLICIT_SIGNAL_MODIFIED
:
See RedisModule_SignalModifiedKey()
.
REDISMODULE_OPTIONS_HANDLE_REPL_ASYNC_LOAD
:
Setting this flag indicates module awareness of diskless async replication (repl-diskless-load=swapdb)
and that redis could be serving reads during replication instead of blocking with LOADING status.
REDISMODULE_OPTIONS_ALLOW_NESTED_KEYSPACE_NOTIFICATIONS
:
Declare that the module wants to get nested key-space notifications.
By default, Redis will not fire key-space notifications that happened inside
a key-space notification callback. This flag allows to change this behavior
and fire nested key-space notifications. Notice: if enabled, the module
should protected itself from infinite recursion.
RedisModule_SignalModifiedKey
int RedisModule_SignalModifiedKey(RedisModuleCtx *ctx,
RedisModuleString *keyname);
Available since: 6.0.0
Signals that the key is modified from user's perspective (i.e. invalidate WATCH and client side caching).
This is done automatically when a key opened for writing is closed, unless
the option REDISMODULE_OPTION_NO_IMPLICIT_SIGNAL_MODIFIED
has been set using
RedisModule_SetModuleOptions()
.
Automatic memory management for modules
RedisModule_AutoMemory
void RedisModule_AutoMemory(RedisModuleCtx *ctx);
Available since: 4.0.0
Enable automatic memory management.
The function must be called as the first function of a command implementation that wants to use automatic memory.
When enabled, automatic memory management tracks and automatically frees keys, call replies and Redis string objects once the command returns. In most cases this eliminates the need of calling the following functions:
These functions can still be used with automatic memory management enabled, to optimize loops that make numerous allocations for example.
String objects APIs
RedisModule_CreateString
RedisModuleString *RedisModule_CreateString(RedisModuleCtx *ctx,
const char *ptr,
size_t len);
Available since: 4.0.0
Create a new module string object. The returned string must be freed
with RedisModule_FreeString()
, unless automatic memory is enabled.
The string is created by copying the len
bytes starting
at ptr
. No reference is retained to the passed buffer.
The module context 'ctx' is optional and may be NULL if you want to create a string out of the context scope. However in that case, the automatic memory management will not be available, and the string memory must be managed manually.
RedisModule_CreateStringPrintf
RedisModuleString *RedisModule_CreateStringPrintf(RedisModuleCtx *ctx,
const char *fmt,
...);
Available since: 4.0.0
Create a new module string object from a printf format and arguments.
The returned string must be freed with RedisModule_FreeString()
, unless
automatic memory is enabled.
The string is created using the sds formatter function sdscatvprintf()
.
The passed context 'ctx' may be NULL if necessary, see the
RedisModule_CreateString()
documentation for more info.
RedisModule_CreateStringFromLongLong
RedisModuleString *RedisModule_CreateStringFromLongLong(RedisModuleCtx *ctx,
long long ll);
Available since: 4.0.0
Like RedisModule_CreateString()
, but creates a string starting from a long long
integer instead of taking a buffer and its length.
The returned string must be released with RedisModule_FreeString()
or by
enabling automatic memory management.
The passed context 'ctx' may be NULL if necessary, see the
RedisModule_CreateString()
documentation for more info.
RedisModule_CreateStringFromULongLong
RedisModuleString *RedisModule_CreateStringFromULongLong(RedisModuleCtx *ctx,
unsigned long long ull);
Available since: 7.0.3
Like RedisModule_CreateString()
, but creates a string starting from a unsigned long long
integer instead of taking a buffer and its length.
The returned string must be released with RedisModule_FreeString()
or by
enabling automatic memory management.
The passed context 'ctx' may be NULL if necessary, see the
RedisModule_CreateString()
documentation for more info.
RedisModule_CreateStringFromDouble
RedisModuleString *RedisModule_CreateStringFromDouble(RedisModuleCtx *ctx,
double d);
Available since: 6.0.0
Like RedisModule_CreateString()
, but creates a string starting from a double
instead of taking a buffer and its length.
The returned string must be released with RedisModule_FreeString()
or by
enabling automatic memory management.
RedisModule_CreateStringFromLongDouble
RedisModuleString *RedisModule_CreateStringFromLongDouble(RedisModuleCtx *ctx,
long double ld,
int humanfriendly);
Available since: 6.0.0
Like RedisModule_CreateString()
, but creates a string starting from a long
double.
The returned string must be released with RedisModule_FreeString()
or by
enabling automatic memory management.
The passed context 'ctx' may be NULL if necessary, see the
RedisModule_CreateString()
documentation for more info.
RedisModule_CreateStringFromString
RedisModuleString *RedisModule_CreateStringFromString(RedisModuleCtx *ctx,
const RedisModuleString *str);
Available since: 4.0.0
Like RedisModule_CreateString()
, but creates a string starting from another
RedisModuleString
.
The returned string must be released with RedisModule_FreeString()
or by
enabling automatic memory management.
The passed context 'ctx' may be NULL if necessary, see the
RedisModule_CreateString()
documentation for more info.
RedisModule_CreateStringFromStreamID
RedisModuleString *RedisModule_CreateStringFromStreamID(RedisModuleCtx *ctx,
const RedisModuleStreamID *id);
Available since: 6.2.0
Creates a string from a stream ID. The returned string must be released with
RedisModule_FreeString()
, unless automatic memory is enabled.
The passed context ctx
may be NULL if necessary. See the
RedisModule_CreateString()
documentation for more info.
RedisModule_FreeString
void RedisModule_FreeString(RedisModuleCtx *ctx, RedisModuleString *str);
Available since: 4.0.0
Free a module string object obtained with one of the Redis modules API calls that return new string objects.
It is possible to call this function even when automatic memory management is enabled. In that case the string will be released ASAP and removed from the pool of string to release at the end.
If the string was created with a NULL context 'ctx', it is also possible to pass ctx as NULL when releasing the string (but passing a context will not create any issue). Strings created with a context should be freed also passing the context, so if you want to free a string out of context later, make sure to create it using a NULL context.
RedisModule_RetainString
void RedisModule_RetainString(RedisModuleCtx *ctx, RedisModuleString *str);
Available since: 4.0.0
Every call to this function, will make the string 'str' requiring
an additional call to RedisModule_FreeString()
in order to really
free the string. Note that the automatic freeing of the string obtained
enabling modules automatic memory management counts for one
RedisModule_FreeString()
call (it is just executed automatically).
Normally you want to call this function when, at the same time the following conditions are true:
- You have automatic memory management enabled.
- You want to create string objects.
- Those string objects you create need to live after the callback function(for example a command implementation) creating them returns.
Usually you want this in order to store the created string object into your own data structure, for example when implementing a new data type.
Note that when memory management is turned off, you don't need any call to RetainString() since creating a string will always result into a string that lives after the callback function returns, if no FreeString() call is performed.
It is possible to call this function with a NULL context.
When strings are going to be retained for an extended duration, it is good
practice to also call RedisModule_TrimStringAllocation()
in order to
optimize memory usage.
Threaded modules that reference retained strings from other threads must explicitly trim the allocation as soon as the string is retained. Not doing so may result with automatic trimming which is not thread safe.
RedisModule_HoldString
RedisModuleString* RedisModule_HoldString(RedisModuleCtx *ctx,
RedisModuleString *str);
Available since: 6.0.7
This function can be used instead of RedisModule_RetainString()
.
The main difference between the two is that this function will always
succeed, whereas RedisModule_RetainString()
may fail because of an
assertion.
The function returns a pointer to RedisModuleString
, which is owned
by the caller. It requires a call to RedisModule_FreeString()
to free
the string when automatic memory management is disabled for the context.
When automatic memory management is enabled, you can either call
RedisModule_FreeString()
or let the automation free it.
This function is more efficient than RedisModule_CreateStringFromString()
because whenever possible, it avoids copying the underlying
RedisModuleString
. The disadvantage of using this function is that it
might not be possible to use RedisModule_StringAppendBuffer()
on the
returned RedisModuleString
.
It is possible to call this function with a NULL context.
When strings are going to be held for an extended duration, it is good
practice to also call RedisModule_TrimStringAllocation()
in order to
optimize memory usage.
Threaded modules that reference held strings from other threads must explicitly trim the allocation as soon as the string is held. Not doing so may result with automatic trimming which is not thread safe.
RedisModule_StringPtrLen
const char *RedisModule_StringPtrLen(const RedisModuleString *str,
size_t *len);
Available since: 4.0.0
Given a string module object, this function returns the string pointer and length of the string. The returned pointer and length should only be used for read only accesses and never modified.
RedisModule_StringToLongLong
int RedisModule_StringToLongLong(const RedisModuleString *str, long long *ll);
Available since: 4.0.0
Convert the string into a long long
integer, storing it at *ll
.
Returns REDISMODULE_OK
on success. If the string can't be parsed
as a valid, strict long long
(no spaces before/after), REDISMODULE_ERR
is returned.
RedisModule_StringToULongLong
int RedisModule_StringToULongLong(const RedisModuleString *str,
unsigned long long *ull);
Available since: 7.0.3
Convert the string into a unsigned long long
integer, storing it at *ull
.
Returns REDISMODULE_OK
on success. If the string can't be parsed
as a valid, strict unsigned long long
(no spaces before/after), REDISMODULE_ERR
is returned.
RedisModule_StringToDouble
int RedisModule_StringToDouble(const RedisModuleString *str, double *d);
Available since: 4.0.0
Convert the string into a double, storing it at *d
.
Returns REDISMODULE_OK
on success or REDISMODULE_ERR
if the string is
not a valid string representation of a double value.
RedisModule_StringToLongDouble
int RedisModule_StringToLongDouble(const RedisModuleString *str,
long double *ld);
Available since: 6.0.0
Convert the string into a long double, storing it at *ld
.
Returns REDISMODULE_OK
on success or REDISMODULE_ERR
if the string is
not a valid string representation of a double value.
RedisModule_StringToStreamID
int RedisModule_StringToStreamID(const RedisModuleString *str,
RedisModuleStreamID *id);
Available since: 6.2.0
Convert the string into a stream ID, storing it at *id
.
Returns REDISMODULE_OK
on success and returns REDISMODULE_ERR
if the string
is not a valid string representation of a stream ID. The special IDs "+" and
"-" are allowed.
RedisModule_StringCompare
int RedisModule_StringCompare(const RedisModuleString *a,
const RedisModuleString *b);
Available since: 4.0.0
Compare two string objects, returning -1, 0 or 1 respectively if a < b, a == b, a > b. Strings are compared byte by byte as two binary blobs without any encoding care / collation attempt.
RedisModule_StringAppendBuffer
int RedisModule_StringAppendBuffer(RedisModuleCtx *ctx,
RedisModuleString *str,
const char *buf,
size_t len);
Available since: 4.0.0
Append the specified buffer to the string 'str'. The string must be a
string created by the user that is referenced only a single time, otherwise
REDISMODULE_ERR
is returned and the operation is not performed.
RedisModule_TrimStringAllocation
void RedisModule_TrimStringAllocation(RedisModuleString *str);
Available since: 7.0.0
Trim possible excess memory allocated for a RedisModuleString
.
Sometimes a RedisModuleString
may have more memory allocated for
it than required, typically for argv arguments that were constructed
from network buffers. This function optimizes such strings by reallocating
their memory, which is useful for strings that are not short lived but
retained for an extended duration.
This operation is not thread safe and should only be called when no concurrent access to the string is guaranteed. Using it for an argv string in a module command before the string is potentially available to other threads is generally safe.
Currently, Redis may also automatically trim retained strings when a module command returns. However, doing this explicitly should still be a preferred option:
- Future versions of Redis may abandon auto-trimming.
- Auto-trimming as currently implemented is not thread safe. A background thread manipulating a recently retained string may end up in a race condition with the auto-trim, which could result with data corruption.
Reply APIs
These functions are used for sending replies to the client.
Most functions always return REDISMODULE_OK
so you can use it with
'return' in order to return from the command implementation with:
if (... some condition ...)
return RedisModule_ReplyWithLongLong(ctx,mycount);
Reply with collection functions
After starting a collection reply, the module must make calls to other
ReplyWith*
style functions in order to emit the elements of the collection.
Collection types include: Array, Map, Set and Attribute.
When producing collections with a number of elements that is not known
beforehand, the function can be called with a special flag
REDISMODULE_POSTPONED_LEN
(REDISMODULE_POSTPONED_ARRAY_LEN
in the past),
and the actual number of elements can be later set with RedisModule_ReplySet
*Length()
call (which will set the latest "open" count if there are multiple ones).
RedisModule_WrongArity
int RedisModule_WrongArity(RedisModuleCtx *ctx);
Available since: 4.0.0
Send an error about the number of arguments given to the command,
citing the command name in the error message. Returns REDISMODULE_OK
.
Example:
if (argc != 3) return RedisModule_WrongArity(ctx);
RedisModule_ReplyWithLongLong
int RedisModule_ReplyWithLongLong(RedisModuleCtx *ctx, long long ll);
Available since: 4.0.0
Send an integer reply to the client, with the specified long long
value.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithError
int RedisModule_ReplyWithError(RedisModuleCtx *ctx, const char *err);
Available since: 4.0.0
Reply with the error 'err'.
Note that 'err' must contain all the error, including the initial error code. The function only provides the initial "-", so the usage is, for example:
RedisModule_ReplyWithError(ctx,"ERR Wrong Type");
and not just:
RedisModule_ReplyWithError(ctx,"Wrong Type");
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithErrorFormat
int RedisModule_ReplyWithErrorFormat(RedisModuleCtx *ctx,
const char *fmt,
...);
Available since: 7.2.0
Reply with the error create from a printf format and arguments.
Note that 'fmt' must contain all the error, including the initial error code. The function only provides the initial "-", so the usage is, for example:
RedisModule_ReplyWithErrorFormat(ctx,"ERR Wrong Type: %s",type);
and not just:
RedisModule_ReplyWithErrorFormat(ctx,"Wrong Type: %s",type);
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithSimpleString
int RedisModule_ReplyWithSimpleString(RedisModuleCtx *ctx, const char *msg);
Available since: 4.0.0
Reply with a simple string (+... \r\n
in RESP protocol). This replies
are suitable only when sending a small non-binary string with small
overhead, like "OK" or similar replies.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithArray
int RedisModule_ReplyWithArray(RedisModuleCtx *ctx, long len);
Available since: 4.0.0
Reply with an array type of 'len' elements.
After starting an array reply, the module must make len
calls to other
ReplyWith*
style functions in order to emit the elements of the array.
See Reply APIs section for more details.
Use RedisModule_ReplySetArrayLength()
to set deferred length.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithMap
int RedisModule_ReplyWithMap(RedisModuleCtx *ctx, long len);
Available since: 7.0.0
Reply with a RESP3 Map type of 'len' pairs. Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
After starting a map reply, the module must make len*2
calls to other
ReplyWith*
style functions in order to emit the elements of the map.
See Reply APIs section for more details.
If the connected client is using RESP2, the reply will be converted to a flat array.
Use RedisModule_ReplySetMapLength()
to set deferred length.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithSet
int RedisModule_ReplyWithSet(RedisModuleCtx *ctx, long len);
Available since: 7.0.0
Reply with a RESP3 Set type of 'len' elements. Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
After starting a set reply, the module must make len
calls to other
ReplyWith*
style functions in order to emit the elements of the set.
See Reply APIs section for more details.
If the connected client is using RESP2, the reply will be converted to an array type.
Use RedisModule_ReplySetSetLength()
to set deferred length.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithAttribute
int RedisModule_ReplyWithAttribute(RedisModuleCtx *ctx, long len);
Available since: 7.0.0
Add attributes (metadata) to the reply. Should be done before adding the actual reply. see https://github.com/antirez/RESP3/blob/master/spec.md#attribute-type
After starting an attribute's reply, the module must make len*2
calls to other
ReplyWith*
style functions in order to emit the elements of the attribute map.
See Reply APIs section for more details.
Use RedisModule_ReplySetAttributeLength()
to set deferred length.
Not supported by RESP2 and will return REDISMODULE_ERR
, otherwise
the function always returns REDISMODULE_OK
.
RedisModule_ReplyWithNullArray
int RedisModule_ReplyWithNullArray(RedisModuleCtx *ctx);
Available since: 6.0.0
Reply to the client with a null array, simply null in RESP3, null array in RESP2.
Note: In RESP3 there's no difference between Null reply and
NullArray reply, so to prevent ambiguity it's better to avoid
using this API and use RedisModule_ReplyWithNull
instead.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithEmptyArray
int RedisModule_ReplyWithEmptyArray(RedisModuleCtx *ctx);
Available since: 6.0.0
Reply to the client with an empty array.
The function always returns REDISMODULE_OK
.
RedisModule_ReplySetArrayLength
void RedisModule_ReplySetArrayLength(RedisModuleCtx *ctx, long len);
Available since: 4.0.0
When RedisModule_ReplyWithArray()
is used with the argument
REDISMODULE_POSTPONED_LEN
, because we don't know beforehand the number
of items we are going to output as elements of the array, this function
will take care to set the array length.
Since it is possible to have multiple array replies pending with unknown length, this function guarantees to always set the latest array length that was created in a postponed way.
For example in order to output an array like [1,[10,20,30]] we could write:
RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
RedisModule_ReplyWithLongLong(ctx,1);
RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
RedisModule_ReplyWithLongLong(ctx,10);
RedisModule_ReplyWithLongLong(ctx,20);
RedisModule_ReplyWithLongLong(ctx,30);
RedisModule_ReplySetArrayLength(ctx,3); // Set len of 10,20,30 array.
RedisModule_ReplySetArrayLength(ctx,2); // Set len of top array
Note that in the above example there is no reason to postpone the array length, since we produce a fixed number of elements, but in the practice the code may use an iterator or other ways of creating the output so that is not easy to calculate in advance the number of elements.
RedisModule_ReplySetMapLength
void RedisModule_ReplySetMapLength(RedisModuleCtx *ctx, long len);
Available since: 7.0.0
Very similar to RedisModule_ReplySetArrayLength
except len
should
exactly half of the number of ReplyWith*
functions called in the
context of the map.
Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
RedisModule_ReplySetSetLength
void RedisModule_ReplySetSetLength(RedisModuleCtx *ctx, long len);
Available since: 7.0.0
Very similar to RedisModule_ReplySetArrayLength
Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
RedisModule_ReplySetAttributeLength
void RedisModule_ReplySetAttributeLength(RedisModuleCtx *ctx, long len);
Available since: 7.0.0
Very similar to RedisModule_ReplySetMapLength
Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
Must not be called if RedisModule_ReplyWithAttribute
returned an error.
RedisModule_ReplyWithStringBuffer
int RedisModule_ReplyWithStringBuffer(RedisModuleCtx *ctx,
const char *buf,
size_t len);
Available since: 4.0.0
Reply with a bulk string, taking in input a C buffer pointer and length.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithCString
int RedisModule_ReplyWithCString(RedisModuleCtx *ctx, const char *buf);
Available since: 5.0.6
Reply with a bulk string, taking in input a C buffer pointer that is assumed to be null-terminated.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithString
int RedisModule_ReplyWithString(RedisModuleCtx *ctx, RedisModuleString *str);
Available since: 4.0.0
Reply with a bulk string, taking in input a RedisModuleString
object.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithEmptyString
int RedisModule_ReplyWithEmptyString(RedisModuleCtx *ctx);
Available since: 6.0.0
Reply with an empty string.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithVerbatimStringType
int RedisModule_ReplyWithVerbatimStringType(RedisModuleCtx *ctx,
const char *buf,
size_t len,
const char *ext);
Available since: 7.0.0
Reply with a binary safe string, which should not be escaped or filtered taking in input a C buffer pointer, length and a 3 character type/extension.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithVerbatimString
int RedisModule_ReplyWithVerbatimString(RedisModuleCtx *ctx,
const char *buf,
size_t len);
Available since: 6.0.0
Reply with a binary safe string, which should not be escaped or filtered taking in input a C buffer pointer and length.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithNull
int RedisModule_ReplyWithNull(RedisModuleCtx *ctx);
Available since: 4.0.0
Reply to the client with a NULL.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithBool
int RedisModule_ReplyWithBool(RedisModuleCtx *ctx, int b);
Available since: 7.0.0
Reply with a RESP3 Boolean type. Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
In RESP3, this is boolean type In RESP2, it's a string response of "1" and "0" for true and false respectively.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithCallReply
int RedisModule_ReplyWithCallReply(RedisModuleCtx *ctx,
RedisModuleCallReply *reply);
Available since: 4.0.0
Reply exactly what a Redis command returned us with RedisModule_Call()
.
This function is useful when we use RedisModule_Call()
in order to
execute some command, as we want to reply to the client exactly the
same reply we obtained by the command.
Return:
REDISMODULE_OK
on success.REDISMODULE_ERR
if the given reply is in RESP3 format but the client expects RESP2. In case of an error, it's the module writer responsibility to translate the reply to RESP2 (or handle it differently by returning an error). Notice that for module writer convenience, it is possible to pass0
as a parameter to the fmt argument ofRedisModule_Call
so that theRedisModuleCallReply
will return in the same protocol (RESP2 or RESP3) as set in the current client's context.
RedisModule_ReplyWithDouble
int RedisModule_ReplyWithDouble(RedisModuleCtx *ctx, double d);
Available since: 4.0.0
Reply with a RESP3 Double type. Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
Send a string reply obtained converting the double 'd' into a bulk string.
This function is basically equivalent to converting a double into
a string into a C buffer, and then calling the function
RedisModule_ReplyWithStringBuffer()
with the buffer and length.
In RESP3 the string is tagged as a double, while in RESP2 it's just a plain string that the user will have to parse.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithBigNumber
int RedisModule_ReplyWithBigNumber(RedisModuleCtx *ctx,
const char *bignum,
size_t len);
Available since: 7.0.0
Reply with a RESP3 BigNumber type. Visit https://github.com/antirez/RESP3/blob/master/spec.md for more info about RESP3.
In RESP3, this is a string of length len
that is tagged as a BigNumber,
however, it's up to the caller to ensure that it's a valid BigNumber.
In RESP2, this is just a plain bulk string response.
The function always returns REDISMODULE_OK
.
RedisModule_ReplyWithLongDouble
int RedisModule_ReplyWithLongDouble(RedisModuleCtx *ctx, long double ld);
Available since: 6.0.0
Send a string reply obtained converting the long double 'ld' into a bulk
string. This function is basically equivalent to converting a long double
into a string into a C buffer, and then calling the function
RedisModule_ReplyWithStringBuffer()
with the buffer and length.
The double string uses human readable formatting (see
addReplyHumanLongDouble
in networking.c).
The function always returns REDISMODULE_OK
.
Commands replication API
RedisModule_Replicate
int RedisModule_Replicate(RedisModuleCtx *ctx,
const char *cmdname,
const char *fmt,
...);
Available since: 4.0.0
Replicate the specified command and arguments to slaves and AOF, as effect of execution of the calling command implementation.
The replicated commands are always wrapped into the MULTI/EXEC that
contains all the commands replicated in a given module command
execution. However the commands replicated with RedisModule_Call()
are the first items, the ones replicated with RedisModule_Replicate()
will all follow before the EXEC.
Modules should try to use one interface or the other.
This command follows exactly the same interface of RedisModule_Call()
,
so a set of format specifiers must be passed, followed by arguments
matching the provided format specifiers.
Please refer to RedisModule_Call()
for more information.
Using the special "A" and "R" modifiers, the caller can exclude either the AOF or the replicas from the propagation of the specified command. Otherwise, by default, the command will be propagated in both channels.
Note about calling this function from a thread safe context:
Normally when you call this function from the callback implementing a module command, or any other callback provided by the Redis Module API, Redis will accumulate all the calls to this function in the context of the callback, and will propagate all the commands wrapped in a MULTI/EXEC transaction. However when calling this function from a threaded safe context that can live an undefined amount of time, and can be locked/unlocked in at will, the behavior is different: MULTI/EXEC wrapper is not emitted and the command specified is inserted in the AOF and replication stream immediately.
Return value
The command returns REDISMODULE_ERR
if the format specifiers are invalid
or the command name does not belong to a known command.
RedisModule_ReplicateVerbatim
int RedisModule_ReplicateVerbatim(RedisModuleCtx *ctx);
Available since: 4.0.0
This function will replicate the command exactly as it was invoked by the client. Note that this function will not wrap the command into a MULTI/EXEC stanza, so it should not be mixed with other replication commands.
Basically this form of replication is useful when you want to propagate the command to the slaves and AOF file exactly as it was called, since the command can just be re-executed to deterministically re-create the new state starting from the old one.
The function always returns REDISMODULE_OK
.
DB and Key APIs – Generic API
RedisModule_GetClientId
unsigned long long RedisModule_GetClientId(RedisModuleCtx *ctx);
Available since: 4.0.0
Return the ID of the current client calling the currently active module command. The returned ID has a few guarantees:
- The ID is different for each different client, so if the same client executes a module command multiple times, it can be recognized as having the same ID, otherwise the ID will be different.
- The ID increases monotonically. Clients connecting to the server later are guaranteed to get IDs greater than any past ID previously seen.
Valid IDs are from 1 to 2^64 - 1. If 0 is returned it means there is no way to fetch the ID in the context the function was currently called.
After obtaining the ID, it is possible to check if the command execution is actually happening in the context of AOF loading, using this macro:
if (RedisModule_IsAOFClient(RedisModule_GetClientId(ctx)) {
// Handle it differently.
}
RedisModule_GetClientUserNameById
RedisModuleString *RedisModule_GetClientUserNameById(RedisModuleCtx *ctx,
uint64_t id);
Available since: 6.2.1
Return the ACL user name used by the client with the specified client ID.
Client ID can be obtained with RedisModule_GetClientId()
API. If the client does not
exist, NULL is returned and errno is set to ENOENT. If the client isn't
using an ACL user, NULL is returned and errno is set to ENOTSUP
RedisModule_GetClientInfoById
int RedisModule_GetClientInfoById(void *ci, uint64_t id);
Available since: 6.0.0
Return information about the client with the specified ID (that was
previously obtained via the RedisModule_GetClientId()
API). If the
client exists, REDISMODULE_OK
is returned, otherwise REDISMODULE_ERR
is returned.
When the client exist and the ci
pointer is not NULL, but points to
a structure of type RedisModuleClientInfoV
1, previously initialized with
the correct REDISMODULE_CLIENTINFO_INITIALIZER_V1
, the structure is populated
with the following fields:
uint64_t flags; // REDISMODULE_CLIENTINFO_FLAG_*
uint64_t id; // Client ID
char addr[46]; // IPv4 or IPv6 address.
uint16_t port; // TCP port.
uint16_t db; // Selected DB.
Note: the client ID is useless in the context of this call, since we already know, however the same structure could be used in other contexts where we don't know the client ID, yet the same structure is returned.
With flags having the following meaning:
REDISMODULE_CLIENTINFO_FLAG_SSL Client using SSL connection.
REDISMODULE_CLIENTINFO_FLAG_PUBSUB Client in Pub/Sub mode.
REDISMODULE_CLIENTINFO_FLAG_BLOCKED Client blocked in command.
REDISMODULE_CLIENTINFO_FLAG_TRACKING Client with keys tracking on.
REDISMODULE_CLIENTINFO_FLAG_UNIXSOCKET Client using unix domain socket.
REDISMODULE_CLIENTINFO_FLAG_MULTI Client in MULTI state.
However passing NULL is a way to just check if the client exists in case we are not interested in any additional information.
This is the correct usage when we want the client info structure returned:
RedisModuleClientInfo ci = REDISMODULE_CLIENTINFO_INITIALIZER;
int retval = RedisModule_GetClientInfoById(&ci,client_id);
if (retval == REDISMODULE_OK) {
printf("Address: %s\n", ci.addr);
}
RedisModule_GetClientNameById
RedisModuleString *RedisModule_GetClientNameById(RedisModuleCtx *ctx,
uint64_t id);
Available since: 7.0.3
Returns the name of the client connection with the given ID.
If the client ID does not exist or if the client has no name associated with it, NULL is returned.
RedisModule_SetClientNameById
int RedisModule_SetClientNameById(uint64_t id, RedisModuleString *name);
Available since: 7.0.3
Sets the name of the client with the given ID. This is equivalent to the client calling
CLIENT SETNAME name
.
Returns REDISMODULE_OK
on success. On failure, REDISMODULE_ERR
is returned
and errno is set as follows:
- ENOENT if the client does not exist
- EINVAL if the name contains invalid characters
RedisModule_PublishMessage
int RedisModule_PublishMessage(RedisModuleCtx *ctx,
RedisModuleString *channel,
RedisModuleString *message);
Available since: 6.0.0
Publish a message to subscribers (see PUBLISH command).
RedisModule_PublishMessageShard
int RedisModule_PublishMessageShard(RedisModuleCtx *ctx,
RedisModuleString *channel,
RedisModuleString *message);
Available since: 7.0.0
Publish a message to shard-subscribers (see SPUBLISH command).
RedisModule_GetSelectedDb
int RedisModule_GetSelectedDb(RedisModuleCtx *ctx);
Available since: 4.0.0
Return the currently selected DB.
RedisModule_GetContextFlags
int RedisModule_GetContextFlags(RedisModuleCtx *ctx);
Available since: 4.0.3
Return the current context's flags. The flags provide information on the current request context (whether the client is a Lua script or in a MULTI), and about the Redis instance in general, i.e replication and persistence.
It is possible to call this function even with a NULL context, however in this case the following flags will not be reported:
- LUA, MULTI, REPLICATED, DIRTY (see below for more info).
Available flags and their meaning:
-
REDISMODULE_CTX_FLAGS_LUA
: The command is running in a Lua script -
REDISMODULE_CTX_FLAGS_MULTI
: The command is running inside a transaction -
REDISMODULE_CTX_FLAGS_REPLICATED
: The command was sent over the replication link by the MASTER -
REDISMODULE_CTX_FLAGS_MASTER
: The Redis instance is a master -
REDISMODULE_CTX_FLAGS_SLAVE
: The Redis instance is a slave -
REDISMODULE_CTX_FLAGS_READONLY
: The Redis instance is read-only -
REDISMODULE_CTX_FLAGS_CLUSTER
: The Redis instance is in cluster mode -
REDISMODULE_CTX_FLAGS_AOF
: The Redis instance has AOF enabled -
REDISMODULE_CTX_FLAGS_RDB
: The instance has RDB enabled -
REDISMODULE_CTX_FLAGS_MAXMEMORY
: The instance has Maxmemory set -
REDISMODULE_CTX_FLAGS_EVICT
: Maxmemory is set and has an eviction policy that may delete keys -
REDISMODULE_CTX_FLAGS_OOM
: Redis is out of memory according to the maxmemory setting. -
REDISMODULE_CTX_FLAGS_OOM_WARNING
: Less than 25% of memory remains before reaching the maxmemory level. -
REDISMODULE_CTX_FLAGS_LOADING
: Server is loading RDB/AOF -
REDISMODULE_CTX_FLAGS_REPLICA_IS_STALE
: No active link with the master. -
REDISMODULE_CTX_FLAGS_REPLICA_IS_CONNECTING
: The replica is trying to connect with the master. -
REDISMODULE_CTX_FLAGS_REPLICA_IS_TRANSFERRING
: Master -> Replica RDB transfer is in progress. -
REDISMODULE_CTX_FLAGS_REPLICA_IS_ONLINE
: The replica has an active link with its master. This is the contrary of STALE state. -
REDISMODULE_CTX_FLAGS_ACTIVE_CHILD
: There is currently some background process active (RDB, AUX or module). -
REDISMODULE_CTX_FLAGS_MULTI_DIRTY
: The next EXEC will fail due to dirty CAS (touched keys). -
REDISMODULE_CTX_FLAGS_IS_CHILD
: Redis is currently running inside background child process. -
REDISMODULE_CTX_FLAGS_RESP3
: Indicate the that client attached to this context is using RESP3. -
REDISMODULE_CTX_FLAGS_SERVER_STARTUP
: The Redis instance is starting
RedisModule_AvoidReplicaTraffic
int RedisModule_AvoidReplicaTraffic(void);
Available since: 6.0.0
Returns true if a client sent the CLIENT PAUSE command to the server or if Redis Cluster does a manual failover, pausing the clients. This is needed when we have a master with replicas, and want to write, without adding further data to the replication channel, that the replicas replication offset, match the one of the master. When this happens, it is safe to failover the master without data loss.
However modules may generate traffic by calling RedisModule_Call()
with
the "!" flag, or by calling RedisModule_Replicate()
, in a context outside
commands execution, for instance in timeout callbacks, threads safe
contexts, and so forth. When modules will generate too much traffic, it
will be hard for the master and replicas offset to match, because there
is more data to send in the replication channel.
So modules may want to try to avoid very heavy background work that has the effect of creating data to the replication channel, when this function returns true. This is mostly useful for modules that have background garbage collection tasks, or that do writes and replicate such writes periodically in timer callbacks or other periodic callbacks.
RedisModule_SelectDb
int RedisModule_SelectDb(RedisModuleCtx *ctx, int newid);
Available since: 4.0.0
Change the currently selected DB. Returns an error if the id is out of range.
Note that the client will retain the currently selected DB even after the Redis command implemented by the module calling this function returns.
If the module command wishes to change something in a different DB and
returns back to the original one, it should call RedisModule_GetSelectedDb()
before in order to restore the old DB number before returning.
RedisModule_KeyExists
int RedisModule_KeyExists(RedisModuleCtx *ctx, robj *keyname);
Available since: 7.0.0
Check if a key exists, without affecting its last access time.
This is equivalent to calling RedisModule_OpenKey
with the mode REDISMODULE_READ
|
REDISMODULE_OPEN_KEY_NOTOUCH
, then checking if NULL was returned and, if not,
calling RedisModule_CloseKey
on the opened key.
RedisModule_OpenKey
RedisModuleKey *RedisModule_OpenKey(RedisModuleCtx *ctx,
robj *keyname,
int mode);
Available since: 4.0.0
Return a handle representing a Redis key, so that it is possible to call other APIs with the key handle as argument to perform operations on the key.
The return value is the handle representing the key, that must be
closed with RedisModule_CloseKey()
.
If the key does not exist and REDISMODULE_WRITE
mode is requested, the handle
is still returned, since it is possible to perform operations on
a yet not existing key (that will be created, for example, after
a list push operation). If the mode is just REDISMODULE_READ
instead, and the
key does not exist, NULL is returned. However it is still safe to
call RedisModule_CloseKey()
and RedisModule_KeyType()
on a NULL
value.
Extra flags that can be pass to the API under the mode argument:
REDISMODULE_OPEN_KEY_NOTOUCH
- Avoid touching the LRU/LFU of the key when opened.REDISMODULE_OPEN_KEY_NONOTIFY
- Don't trigger keyspace event on key misses.REDISMODULE_OPEN_KEY_NOSTATS
- Don't update keyspace hits/misses counters.REDISMODULE_OPEN_KEY_NOEXPIRE
- Avoid deleting lazy expired keys.REDISMODULE_OPEN_KEY_NOEFFECTS
- Avoid any effects from fetching the key.
RedisModule_GetOpenKeyModesAll
int RedisModule_GetOpenKeyModesAll(void);
Available since: 7.2.0
Returns the full OpenKey modes mask, using the return value the module can check if a certain set of OpenKey modes are supported by the redis server version in use. Example:
int supportedMode = RedisModule_GetOpenKeyModesAll();
if (supportedMode & REDISMODULE_OPEN_KEY_NOTOUCH) {
// REDISMODULE_OPEN_KEY_NOTOUCH is supported
} else{
// REDISMODULE_OPEN_KEY_NOTOUCH is not supported
}
RedisModule_CloseKey
void RedisModule_CloseKey(RedisModuleKey *key);
Available since: 4.0.0
Close a key handle.
RedisModule_KeyType
int RedisModule_KeyType(RedisModuleKey *key);
Available since: 4.0.0
Return the type of the key. If the key pointer is NULL then
REDISMODULE_KEYTYPE_EMPTY
is returned.
RedisModule_ValueLength
size_t RedisModule_ValueLength(RedisModuleKey *key);
Available since: 4.0.0
Return the length of the value associated with the key. For strings this is the length of the string. For all the other types is the number of elements (just counting keys for hashes).
If the key pointer is NULL or the key is empty, zero is returned.
RedisModule_DeleteKey
int RedisModule_DeleteKey(RedisModuleKey *key);
Available since: 4.0.0
If the key is open for writing, remove it, and setup the key to
accept new writes as an empty key (that will be created on demand).
On success REDISMODULE_OK
is returned. If the key is not open for
writing REDISMODULE_ERR
is returned.
RedisModule_UnlinkKey
int RedisModule_UnlinkKey(RedisModuleKey *key);
Available since: 4.0.7
If the key is open for writing, unlink it (that is delete it in a
non-blocking way, not reclaiming memory immediately) and setup the key to
accept new writes as an empty key (that will be created on demand).
On success REDISMODULE_OK
is returned. If the key is not open for
writing REDISMODULE_ERR
is returned.
RedisModule_GetExpire
mstime_t RedisModule_GetExpire(RedisModuleKey *key);
Available since: 4.0.0
Return the key expire value, as milliseconds of remaining TTL.
If no TTL is associated with the key or if the key is empty,
REDISMODULE_NO_EXPIRE
is returned.
RedisModule_SetExpire
int RedisModule_SetExpire(RedisModuleKey *key, mstime_t expire);
Available since: 4.0.0
Set a new expire for the key. If the special expire
REDISMODULE_NO_EXPIRE
is set, the expire is cancelled if there was
one (the same as the PERSIST command).
Note that the expire must be provided as a positive integer representing the number of milliseconds of TTL the key should have.
The function returns REDISMODULE_OK
on success or REDISMODULE_ERR
if
the key was not open for writing or is an empty key.
RedisModule_GetAbsExpire
mstime_t RedisModule_GetAbsExpire(RedisModuleKey *key);
Available since: 6.2.2
Return the key expire value, as absolute Unix timestamp.
If no TTL is associated with the key or if the key is empty,
REDISMODULE_NO_EXPIRE
is returned.
RedisModule_SetAbsExpire
int RedisModule_SetAbsExpire(RedisModuleKey *key, mstime_t expire);
Available since: 6.2.2
Set a new expire for the key. If the special expire
REDISMODULE_NO_EXPIRE
is set, the expire is cancelled if there was
one (the same as the PERSIST command).
Note that the expire must be provided as a positive integer representing the absolute Unix timestamp the key should have.
The function returns REDISMODULE_OK
on success or REDISMODULE_ERR
if
the key was not open for writing or is an empty key.
RedisModule_ResetDataset
void RedisModule_ResetDataset(int restart_aof, int async);
Available since: 6.0.0
Performs similar operation to FLUSHALL, and optionally start a new AOF file (if enabled)
If restart_aof
is true, you must make sure the command that triggered this call is not
propagated to the AOF file.
When async is set to true, db contents will be freed by a background thread.
RedisModule_DbSize
unsigned long long RedisModule_DbSize(RedisModuleCtx *ctx);
Available since: 6.0.0
Returns the number of keys in the current db.
RedisModule_RandomKey
RedisModuleString *RedisModule_RandomKey(RedisModuleCtx *ctx);
Available since: 6.0.0
Returns a name of a random key, or NULL if current db is empty.
RedisModule_GetKeyNameFromOptCtx
const RedisModuleString *RedisModule_GetKeyNameFromOptCtx(RedisModuleKeyOptCtx *ctx);
Available since: 7.0.0
Returns the name of the key currently being processed.
RedisModule_GetToKeyNameFromOptCtx
const RedisModuleString *RedisModule_GetToKeyNameFromOptCtx(RedisModuleKeyOptCtx *ctx);
Available since: 7.0.0
Returns the name of the target key currently being processed.
RedisModule_GetDbIdFromOptCtx
int RedisModule_GetDbIdFromOptCtx(RedisModuleKeyOptCtx *ctx);
Available since: 7.0.0
Returns the dbid currently being processed.
RedisModule_GetToDbIdFromOptCtx
int RedisModule_GetToDbIdFromOptCtx(RedisModuleKeyOptCtx *ctx);
Available since: 7.0.0
Returns the target dbid currently being processed.
Key API for String type
See also RedisModule_ValueLength()
, which returns the length of a string.
RedisModule_StringSet
int RedisModule_StringSet(RedisModuleKey *key, RedisModuleString *str);
Available since: 4.0.0
If the key is open for writing, set the specified string 'str' as the
value of the key, deleting the old value if any.
On success REDISMODULE_OK
is returned. If the key is not open for
writing or there is an active iterator, REDISMODULE_ERR
is returned.
RedisModule_StringDMA
char *RedisModule_StringDMA(RedisModuleKey *key, size_t *len, int mode);
Available since: 4.0.0
Prepare the key associated string value for DMA access, and returns a pointer and size (by reference), that the user can use to read or modify the string in-place accessing it directly via pointer.
The 'mode' is composed by bitwise OR-ing the following flags:
REDISMODULE_READ -- Read access
REDISMODULE_WRITE -- Write access
If the DMA is not requested for writing, the pointer returned should only be accessed in a read-only fashion.
On error (wrong type) NULL is returned.
DMA access rules:
-
No other key writing function should be called since the moment the pointer is obtained, for all the time we want to use DMA access to read or modify the string.
-
Each time
RedisModule_StringTruncate()
is called, to continue with the DMA access,RedisModule_StringDMA()
should be called again to re-obtain a new pointer and length. -
If the returned pointer is not NULL, but the length is zero, no byte can be touched (the string is empty, or the key itself is empty) so a
RedisModule_StringTruncate()
call should be used if there is to enlarge the string, and later call StringDMA() again to get the pointer.
RedisModule_StringTruncate
int RedisModule_StringTruncate(RedisModuleKey *key, size_t newlen);
Available since: 4.0.0
If the key is open for writing and is of string type, resize it, padding with zero bytes if the new length is greater than the old one.
After this call, RedisModule_StringDMA()
must be called again to continue
DMA access with the new pointer.
The function returns REDISMODULE_OK
on success, and REDISMODULE_ERR
on
error, that is, the key is not open for writing, is not a string
or resizing for more than 512 MB is requested.
If the key is empty, a string key is created with the new string value unless the new length value requested is zero.
Key API for List type
Many of the list functions access elements by index. Since a list is in essence a doubly-linked list, accessing elements by index is generally an O(N) operation. However, if elements are accessed sequentially or with indices close together, the functions are optimized to seek the index from the previous index, rather than seeking from the ends of the list.
This enables iteration to be done efficiently using a simple for loop:
long n = RedisModule_ValueLength(key);
for (long i = 0; i < n; i++) {
RedisModuleString *elem = RedisModule_ListGet(key, i);
// Do stuff...
}
Note that after modifying a list using RedisModule_ListPop
, RedisModule_ListSet
or
RedisModule_ListInsert
, the internal iterator is invalidated so the next operation
will require a linear seek.
Modifying a list in any another way, for example using RedisModule_Call()
, while a key
is open will confuse the internal iterator and may cause trouble if the key
is used after such modifications. The key must be reopened in this case.
See also RedisModule_ValueLength()
, which returns the length of a list.
RedisModule_ListPush
int RedisModule_ListPush(RedisModuleKey *key,
int where,
RedisModuleString *ele);
Available since: 4.0.0
Push an element into a list, on head or tail depending on 'where' argument
(REDISMODULE_LIST_HEAD
or REDISMODULE_LIST_TAIL
). If the key refers to an
empty key opened for writing, the key is created. On success, REDISMODULE_OK
is returned. On failure, REDISMODULE_ERR
is returned and errno
is set as
follows:
- EINVAL if key or ele is NULL.
- ENOTSUP if the key is of another type than list.
- EBADF if the key is not opened for writing.
Note: Before Redis 7.0, errno
was not set by this function.
RedisModule_ListPop
RedisModuleString *RedisModule_ListPop(RedisModuleKey *key, int where);
Available since: 4.0.0
Pop an element from the list, and returns it as a module string object
that the user should be free with RedisModule_FreeString()
or by enabling
automatic memory. The where
argument specifies if the element should be
popped from the beginning or the end of the list (REDISMODULE_LIST_HEAD
or
REDISMODULE_LIST_TAIL
). On failure, the command returns NULL and sets
errno
as follows:
- EINVAL if key is NULL.
- ENOTSUP if the key is empty or of another type than list.
- EBADF if the key is not opened for writing.
Note: Before Redis 7.0, errno
was not set by this function.
RedisModule_ListGet
RedisModuleString *RedisModule_ListGet(RedisModuleKey *key, long index);
Available since: 7.0.0
Returns the element at index index
in the list stored at key
, like the
LINDEX command. The element should be free'd using RedisModule_FreeString()
or using
automatic memory management.
The index is zero-based, so 0 means the first element, 1 the second element and so on. Negative indices can be used to designate elements starting at the tail of the list. Here, -1 means the last element, -2 means the penultimate and so forth.
When no value is found at the given key and index, NULL is returned and
errno
is set as follows:
- EINVAL if key is NULL.
- ENOTSUP if the key is not a list.
- EBADF if the key is not opened for reading.
- EDOM if the index is not a valid index in the list.
RedisModule_ListSet
int RedisModule_ListSet(RedisModuleKey *key,
long index,
RedisModuleString *value);
Available since: 7.0.0
Replaces the element at index index
in the list stored at key
.
The index is zero-based, so 0 means the first element, 1 the second element and so on. Negative indices can be used to designate elements starting at the tail of the list. Here, -1 means the last element, -2 means the penultimate and so forth.
On success, REDISMODULE_OK
is returned. On failure, REDISMODULE_ERR
is
returned and errno
is set as follows:
- EINVAL if key or value is NULL.
- ENOTSUP if the key is not a list.
- EBADF if the key is not opened for writing.
- EDOM if the index is not a valid index in the list.
RedisModule_ListInsert
int RedisModule_ListInsert(RedisModuleKey *key,
long index,
RedisModuleString *value);
Available since: 7.0.0
Inserts an element at the given index.
The index is zero-based, so 0 means the first element, 1 the second element and so on. Negative indices can be used to designate elements starting at the tail of the list. Here, -1 means the last element, -2 means the penultimate and so forth. The index is the element's index after inserting it.
On success, REDISMODULE_OK
is returned. On failure, REDISMODULE_ERR
is
returned and errno
is set as follows:
- EINVAL if key or value is NULL.
- ENOTSUP if the key of another type than list.
- EBADF if the key is not opened for writing.
- EDOM if the index is not a valid index in the list.
RedisModule_ListDelete
int RedisModule_ListDelete(RedisModuleKey *key, long index);
Available since: 7.0.0
Removes an element at the given index. The index is 0-based. A negative index can also be used, counting from the end of the list.
On success, REDISMODULE_OK
is returned. On failure, REDISMODULE_ERR
is
returned and errno
is set as follows:
- EINVAL if key or value is NULL.
- ENOTSUP if the key is not a list.
- EBADF if the key is not opened for writing.
- EDOM if the index is not a valid index in the list.
Key API for Sorted Set type
See also RedisModule_ValueLength()
, which returns the length of a sorted set.
RedisModule_ZsetAdd
int RedisModule_ZsetAdd(RedisModuleKey *key,
double score,
RedisModuleString *ele,
int *flagsptr);
Available since: 4.0.0
Add a new element into a sorted set, with the specified 'score'. If the element already exists, the score is updated.
A new sorted set is created at value if the key is an empty open key setup for writing.
Additional flags can be passed to the function via a pointer, the flags are both used to receive input and to communicate state when the function returns. 'flagsptr' can be NULL if no special flags are used.
The input flags are:
REDISMODULE_ZADD_XX: Element must already exist. Do nothing otherwise.
REDISMODULE_ZADD_NX: Element must not exist. Do nothing otherwise.
REDISMODULE_ZADD_GT: If element exists, new score must be greater than the current score.
Do nothing otherwise. Can optionally be combined with XX.
REDISMODULE_ZADD_LT: If element exists, new score must be less than the current score.
Do nothing otherwise. Can optionally be combined with XX.
The output flags are:
REDISMODULE_ZADD_ADDED: The new element was added to the sorted set.
REDISMODULE_ZADD_UPDATED: The score of the element was updated.
REDISMODULE_ZADD_NOP: No operation was performed because XX or NX flags.
On success the function returns REDISMODULE_OK
. On the following errors
REDISMODULE_ERR
is returned:
- The key was not opened for writing.
- The key is of the wrong type.
- 'score' double value is not a number (NaN).
RedisModule_ZsetIncrby
int RedisModule_ZsetIncrby(RedisModuleKey *key,
double score,
RedisModuleString *ele,
int *flagsptr,
double *newscore);
Available since: 4.0.0
This function works exactly like RedisModule_ZsetAdd()
, but instead of setting
a new score, the score of the existing element is incremented, or if the
element does not already exist, it is added assuming the old score was
zero.
The input and output flags, and the return value, have the same exact
meaning, with the only difference that this function will return
REDISMODULE_ERR
even when 'score' is a valid double number, but adding it
to the existing score results into a NaN (not a number) condition.
This function has an additional field 'newscore', if not NULL is filled with the new score of the element after the increment, if no error is returned.
RedisModule_ZsetRem
int RedisModule_ZsetRem(RedisModuleKey *key,
RedisModuleString *ele,
int *deleted);
Available since: 4.0.0
Remove the specified element from the sorted set.
The function returns REDISMODULE_OK
on success, and REDISMODULE_ERR
on one of the following conditions:
- The key was not opened for writing.
- The key is of the wrong type.
The return value does NOT indicate the fact the element was really removed (since it existed) or not, just if the function was executed with success.
In order to know if the element was removed, the additional argument 'deleted' must be passed, that populates the integer by reference setting it to 1 or 0 depending on the outcome of the operation. The 'deleted' argument can be NULL if the caller is not interested to know if the element was really removed.
Empty keys will be handled correctly by doing nothing.
RedisModule_ZsetScore
int RedisModule_ZsetScore(RedisModuleKey *key,
RedisModuleString *ele,
double *score);
Available since: 4.0.0
On success retrieve the double score associated at the sorted set element
'ele' and returns REDISMODULE_OK
. Otherwise REDISMODULE_ERR
is returned
to signal one of the following conditions:
- There is no such element 'ele' in the sorted set.
- The key is not a sorted set.
- The key is an open empty key.
Key API for Sorted Set iterator
RedisModule_ZsetRangeStop
void RedisModule_ZsetRangeStop(RedisModuleKey *key);
Available since: 4.0.0
Stop a sorted set iteration.
RedisModule_ZsetRangeEndReached
int RedisModule_ZsetRangeEndReached(RedisModuleKey *key);
Available since: 4.0.0
Return the "End of range" flag value to signal the end of the iteration.
RedisModule_ZsetFirstInScoreRange
int RedisModule_ZsetFirstInScoreRange(RedisModuleKey *key,
double min,
double max,
int minex,
int maxex);
Available since: 4.0.0
Setup a sorted set iterator seeking the first element in the specified
range. Returns REDISMODULE_OK
if the iterator was correctly initialized
otherwise REDISMODULE_ERR
is returned in the following conditions:
- The value stored at key is not a sorted set or the key is empty.
The range is specified according to the two double values 'min' and 'max'. Both can be infinite using the following two macros:
REDISMODULE_POSITIVE_INFINITE
for positive infinite valueREDISMODULE_NEGATIVE_INFINITE
for negative infinite value
'minex' and 'maxex' parameters, if true, respectively setup a range where the min and max value are exclusive (not included) instead of inclusive.
RedisModule_ZsetLastInScoreRange
int RedisModule_ZsetLastInScoreRange(RedisModuleKey *key,
double min,
double max,
int minex,
int maxex);
Available since: 4.0.0
Exactly like RedisModule_ZsetFirstInScoreRange()
but the last element of
the range is selected for the start of the iteration instead.
RedisModule_ZsetFirstInLexRange
int RedisModule_ZsetFirstInLexRange(RedisModuleKey *key,
RedisModuleString *min,
RedisModuleString *max);
Available since: 4.0.0
Setup a sorted set iterator seeking the first element in the specified
lexicographical range. Returns REDISMODULE_OK
if the iterator was correctly
initialized otherwise REDISMODULE_ERR
is returned in the
following conditions:
- The value stored at key is not a sorted set or the key is empty.
- The lexicographical range 'min' and 'max' format is invalid.
'min' and 'max' should be provided as two RedisModuleString
objects
in the same format as the parameters passed to the ZRANGEBYLEX command.
The function does not take ownership of the objects, so they can be released
ASAP after the iterator is setup.
RedisModule_ZsetLastInLexRange
int RedisModule_ZsetLastInLexRange(RedisModuleKey *key,
RedisModuleString *min,
RedisModuleString *max);
Available since: 4.0.0
Exactly like RedisModule_ZsetFirstInLexRange()
but the last element of
the range is selected for the start of the iteration instead.
RedisModule_ZsetRangeCurrentElement
RedisModuleString *RedisModule_ZsetRangeCurrentElement(RedisModuleKey *key,
double *score);
Available since: 4.0.0
Return the current sorted set element of an active sorted set iterator or NULL if the range specified in the iterator does not include any element.
RedisModule_ZsetRangeNext
int RedisModule_ZsetRangeNext(RedisModuleKey *key);
Available since: 4.0.0
Go to the next element of the sorted set iterator. Returns 1 if there was a next element, 0 if we are already at the latest element or the range does not include any item at all.
RedisModule_ZsetRangePrev
int RedisModule_ZsetRangePrev(RedisModuleKey *key);
Available since: 4.0.0
Go to the previous element of the sorted set iterator. Returns 1 if there was a previous element, 0 if we are already at the first element or the range does not include any item at all.
Key API for Hash type
See also RedisModule_ValueLength()
, which returns the number of fields in a hash.
RedisModule_HashSet
int RedisModule_HashSet(RedisModuleKey *key, int flags, ...);
Available since: 4.0.0
Set the field of the specified hash field to the specified value. If the key is an empty key open for writing, it is created with an empty hash value, in order to set the specified field.
The function is variadic and the user must specify pairs of field
names and values, both as RedisModuleString
pointers (unless the
CFIELD option is set, see later). At the end of the field/value-ptr pairs,
NULL must be specified as last argument to signal the end of the arguments
in the variadic function.
Example to set the hash argv[1] to the value argv[2]:
RedisModule_HashSet(key,REDISMODULE_HASH_NONE,argv[1],argv[2],NULL);
The function can also be used in order to delete fields (if they exist)
by setting them to the specified value of REDISMODULE_HASH_DELETE
:
RedisModule_HashSet(key,REDISMODULE_HASH_NONE,argv[1],
REDISMODULE_HASH_DELETE,NULL);
The behavior of the command changes with the specified flags, that can be
set to REDISMODULE_HASH_NONE
if no special behavior is needed.
REDISMODULE_HASH_NX: The operation is performed only if the field was not
already existing in the hash.
REDISMODULE_HASH_XX: The operation is performed only if the field was
already existing, so that a new value could be
associated to an existing filed, but no new fields
are created.
REDISMODULE_HASH_CFIELDS: The field names passed are null terminated C
strings instead of RedisModuleString objects.
REDISMODULE_HASH_COUNT_ALL: Include the number of inserted fields in the
returned number, in addition to the number of
updated and deleted fields. (Added in Redis
6.2.)
Unless NX is specified, the command overwrites the old field value with the new one.
When using REDISMODULE_HASH_CFIELDS
, field names are reported using
normal C strings, so for example to delete the field "foo" the following
code can be used:
RedisModule_HashSet(key,REDISMODULE_HASH_CFIELDS,"foo",
REDISMODULE_HASH_DELETE,NULL);
Return value:
The number of fields existing in the hash prior to the call, which have been
updated (its old value has been replaced by a new value) or deleted. If the
flag REDISMODULE_HASH_COUNT_ALL
is set, inserted fields not previously
existing in the hash are also counted.
If the return value is zero, errno
is set (since Redis 6.2) as follows:
- EINVAL if any unknown flags are set or if key is NULL.
- ENOTSUP if the key is associated with a non Hash value.
- EBADF if the key was not opened for writing.
- ENOENT if no fields were counted as described under Return value above.
This is not actually an error. The return value can be zero if all fields
were just created and the
COUNT_ALL
flag was unset, or if changes were held back due to the NX and XX flags.
NOTICE: The return value semantics of this function are very different between Redis 6.2 and older versions. Modules that use it should determine the Redis version and handle it accordingly.
RedisModule_HashGet
int RedisModule_HashGet(RedisModuleKey *key, int flags, ...);
Available since: 4.0.0
Get fields from a hash value. This function is called using a variable
number of arguments, alternating a field name (as a RedisModuleString
pointer) with a pointer to a RedisModuleString
pointer, that is set to the
value of the field if the field exists, or NULL if the field does not exist.
At the end of the field/value-ptr pairs, NULL must be specified as last
argument to signal the end of the arguments in the variadic function.
This is an example usage:
RedisModuleString *first, *second;
RedisModule_HashGet(mykey,REDISMODULE_HASH_NONE,argv[1],&first,
argv[2],&second,NULL);
As with RedisModule_HashSet()
the behavior of the command can be specified
passing flags different than REDISMODULE_HASH_NONE
:
REDISMODULE_HASH_CFIELDS
: field names as null terminated C strings.
REDISMODULE_HASH_EXISTS
: instead of setting the value of the field
expecting a RedisModuleString
pointer to pointer, the function just
reports if the field exists or not and expects an integer pointer
as the second element of each pair.
Example of REDISMODULE_HASH_CFIELDS
:
RedisModuleString *username, *hashedpass;
RedisModule_HashGet(mykey,REDISMODULE_HASH_CFIELDS,"username",&username,"hp",&hashedpass, NULL);
Example of REDISMODULE_HASH_EXISTS
:
int exists;
RedisModule_HashGet(mykey,REDISMODULE_HASH_EXISTS,argv[1],&exists,NULL);
The function returns REDISMODULE_OK
on success and REDISMODULE_ERR
if
the key is not a hash value.
Memory management:
The returned RedisModuleString
objects should be released with
RedisModule_FreeString()
, or by enabling automatic memory management.
Key API for Stream type
For an introduction to streams, see https://redis.io/topics/streams-intro.
The type RedisModuleStreamID
, which is used in stream functions, is a struct
with two 64-bit fields and is defined as
typedef struct RedisModuleStreamID {
uint64_t ms;
uint64_t seq;
} RedisModuleStreamID;
See also RedisModule_ValueLength()
, which returns the length of a stream, and the
conversion functions RedisModule_StringToStreamID()
and RedisModule_CreateStringFromStreamID()
.
RedisModule_StreamAdd
int RedisModule_StreamAdd(RedisModuleKey *key,
int flags,
RedisModuleStreamID *id,
RedisModuleString **argv,
long numfields);
Available since: 6.2.0
Adds an entry to a stream. Like XADD without trimming.
key
: The key where the stream is (or will be) storedflags
: A bit field ofREDISMODULE_STREAM_ADD_AUTOID
: Assign a stream ID automatically, like*
in the XADD command.
id
: If theAUTOID
flag is set, this is where the assigned ID is returned. Can be NULL ifAUTOID
is set, if you don't care to receive the ID. IfAUTOID
is not set, this is the requested ID.argv
: A pointer to an array of sizenumfields * 2
containing the fields and values.numfields
: The number of field-value pairs inargv
.
Returns REDISMODULE_OK
if an entry has been added. On failure,
REDISMODULE_ERR
is returned and errno
is set as follows:
- EINVAL if called with invalid arguments
- ENOTSUP if the key refers to a value of a type other than stream
- EBADF if the key was not opened for writing
- EDOM if the given ID was 0-0 or not greater than all other IDs in the stream (only if the AUTOID flag is unset)
- EFBIG if the stream has reached the last possible ID
- ERANGE if the elements are too large to be stored.
RedisModule_StreamDelete
int RedisModule_StreamDelete(RedisModuleKey *key, RedisModuleStreamID *id);
Available since: 6.2.0
Deletes an entry from a stream.
key
: A key opened for writing, with no stream iterator started.id
: The stream ID of the entry to delete.
Returns REDISMODULE_OK
on success. On failure, REDISMODULE_ERR
is returned
and errno
is set as follows:
- EINVAL if called with invalid arguments
- ENOTSUP if the key refers to a value of a type other than stream or if the key is empty
- EBADF if the key was not opened for writing or if a stream iterator is associated with the key
- ENOENT if no entry with the given stream ID exists
See also RedisModule_StreamIteratorDelete()
for deleting the current entry while
iterating using a stream iterator.
RedisModule_StreamIteratorStart
int RedisModule_StreamIteratorStart(RedisModuleKey *key,
int flags,
RedisModuleStreamID *start,
RedisModuleStreamID *end);
Available since: 6.2.0
Sets up a stream iterator.
key
: The stream key opened for reading usingRedisModule_OpenKey()
.flags
:REDISMODULE_STREAM_ITERATOR_EXCLUSIVE
: Don't includestart
andend
in the iterated range.REDISMODULE_STREAM_ITERATOR_REVERSE
: Iterate in reverse order, starting from theend
of the range.
start
: The lower bound of the range. Use NULL for the beginning of the stream.end
: The upper bound of the range. Use NULL for the end of the stream.
Returns REDISMODULE_OK
on success. On failure, REDISMODULE_ERR
is returned
and errno
is set as follows:
- EINVAL if called with invalid arguments
- ENOTSUP if the key refers to a value of a type other than stream or if the key is empty
- EBADF if the key was not opened for writing or if a stream iterator is already associated with the key
- EDOM if
start
orend
is outside the valid range
Returns REDISMODULE_OK
on success and REDISMODULE_ERR
if the key doesn't
refer to a stream or if invalid arguments were given.
The stream IDs are retrieved using RedisModule_StreamIteratorNextID()
and
for each stream ID, the fields and values are retrieved using
RedisModule_StreamIteratorNextField()
. The iterator is freed by calling
RedisModule_StreamIteratorStop()
.
Example (error handling omitted):
RedisModule_StreamIteratorStart(key, 0, startid_ptr, endid_ptr);
RedisModuleStreamID id;
long numfields;
while (RedisModule_StreamIteratorNextID(key, &id, &numfields) ==
REDISMODULE_OK) {
RedisModuleString *field, *value;
while (RedisModule_StreamIteratorNextField(key, &field, &value) ==
REDISMODULE_OK) {
//
// ... Do stuff ...
//
RedisModule_FreeString(ctx, field);
RedisModule_FreeString(ctx, value);
}
}
RedisModule_StreamIteratorStop(key);
RedisModule_StreamIteratorStop
int RedisModule_StreamIteratorStop(RedisModuleKey *key);
Available since: 6.2.0
Stops a stream iterator created using RedisModule_StreamIteratorStart()
and
reclaims its memory.
Returns REDISMODULE_OK
on success. On failure, REDISMODULE_ERR
is returned
and errno
is set as follows:
- EINVAL if called with a NULL key
- ENOTSUP if the key refers to a value of a type other than stream or if the key is empty
- EBADF if the key was not opened for writing or if no stream iterator is associated with the key
RedisModule_StreamIteratorNextID
int RedisModule_StreamIteratorNextID(RedisModuleKey *key,
RedisModuleStreamID *id,
long *numfields);
Available since: 6.2.0
Finds the next stream entry and returns its stream ID and the number of fields.
key
: Key for which a stream iterator has been started usingRedisModule_StreamIteratorStart()
.id
: The stream ID returned. NULL if you don't care.numfields
: The number of fields in the found stream entry. NULL if you don't care.
Returns REDISMODULE_OK
and sets *id
and *numfields
if an entry was found.
On failure, REDISMODULE_ERR
is returned and errno
is set as follows:
- EINVAL if called with a NULL key
- ENOTSUP if the key refers to a value of a type other than stream or if the key is empty
- EBADF if no stream iterator is associated with the key
- ENOENT if there are no more entries in the range of the iterator
In practice, if RedisModule_StreamIteratorNextID()
is called after a successful call
to RedisModule_StreamIteratorStart()
and with the same key, it is safe to assume that
an REDISMODULE_ERR
return value means that there are no more entries.
Use RedisModule_StreamIteratorNextField()
to retrieve the fields and values.
See the example at RedisModule_StreamIteratorStart()
.
RedisModule_StreamIteratorNextField
int RedisModule_StreamIteratorNextField(RedisModuleKey *key,
RedisModuleString **field_ptr,
RedisModuleString **value_ptr);
Available since: 6.2.0
Retrieves the next field of the current stream ID and its corresponding value
in a stream iteration. This function should be called repeatedly after calling
RedisModule_StreamIteratorNextID()
to fetch each field-value pair.
key
: Key where a stream iterator has been started.field_ptr
: This is where the field is returned.value_ptr
: This is where the value is returned.
Returns REDISMODULE_OK
and points *field_ptr
and *value_ptr
to freshly
allocated RedisModuleString
objects. The string objects are freed
automatically when the callback finishes if automatic memory is enabled. On
failure, REDISMODULE_ERR
is returned and errno
is set as follows:
- EINVAL if called with a NULL key
- ENOTSUP if the key refers to a value of a type other than stream or if the key is empty
- EBADF if no stream iterator is associated with the key
- ENOENT if there are no more fields in the current stream entry
In practice, if RedisModule_StreamIteratorNextField()
is called after a successful
call to RedisModule_StreamIteratorNextID()
and with the same key, it is safe to assume
that an REDISMODULE_ERR
return value means that there are no more fields.
See the example at RedisModule_StreamIteratorStart()
.
RedisModule_StreamIteratorDelete
int RedisModule_StreamIteratorDelete(RedisModuleKey *key);
Available since: 6.2.0
Deletes the current stream entry while iterating.
This function can be called after RedisModule_StreamIteratorNextID()
or after any
calls to RedisModule_StreamIteratorNextField()
.
Returns REDISMODULE_OK
on success. On failure, REDISMODULE_ERR
is returned
and errno
is set as follows:
- EINVAL if key is NULL
- ENOTSUP if the key is empty or is of another type than stream
- EBADF if the key is not opened for writing, if no iterator has been started
- ENOENT if the iterator has no current stream entry
RedisModule_StreamTrimByLength
long long RedisModule_StreamTrimByLength(RedisModuleKey *key,
int flags,
long long length);
Available since: 6.2.0
Trim a stream by length, similar to XTRIM with MAXLEN.
key
: Key opened for writing.flags
: A bitfield ofREDISMODULE_STREAM_TRIM_APPROX
: Trim less if it improves performance, like XTRIM with~
.
length
: The number of stream entries to keep after trimming.
Returns the number of entries deleted. On failure, a negative value is
returned and errno
is set as follows:
- EINVAL if called with invalid arguments
- ENOTSUP if the key is empty or of a type other than stream
- EBADF if the key is not opened for writing
RedisModule_StreamTrimByID
long long RedisModule_StreamTrimByID(RedisModuleKey *key,
int flags,
RedisModuleStreamID *id);
Available since: 6.2.0
Trim a stream by ID, similar to XTRIM with MINID.
key
: Key opened for writing.flags
: A bitfield ofREDISMODULE_STREAM_TRIM_APPROX
: Trim less if it improves performance, like XTRIM with~
.
id
: The smallest stream ID to keep after trimming.
Returns the number of entries deleted. On failure, a negative value is
returned and errno
is set as follows:
- EINVAL if called with invalid arguments
- ENOTSUP if the key is empty or of a type other than stream
- EBADF if the key is not opened for writing
Calling Redis commands from modules
RedisModule_Call()
sends a command to Redis. The remaining functions handle the reply.
RedisModule_FreeCallReply
void RedisModule_FreeCallReply(RedisModuleCallReply *reply);
Available since: 4.0.0
Free a Call reply and all the nested replies it contains if it's an array.
RedisModule_CallReplyType
int RedisModule_CallReplyType(RedisModuleCallReply *reply);
Available since: 4.0.0
Return the reply type as one of the following:
REDISMODULE_REPLY_UNKNOWN
REDISMODULE_REPLY_STRING
REDISMODULE_REPLY_ERROR
REDISMODULE_REPLY_INTEGER
REDISMODULE_REPLY_ARRAY
REDISMODULE_REPLY_NULL
REDISMODULE_REPLY_MAP
REDISMODULE_REPLY_SET
REDISMODULE_REPLY_BOOL
REDISMODULE_REPLY_DOUBLE
REDISMODULE_REPLY_BIG_NUMBER
REDISMODULE_REPLY_VERBATIM_STRING
REDISMODULE_REPLY_ATTRIBUTE
REDISMODULE_REPLY_PROMISE
RedisModule_CallReplyLength
size_t RedisModule_CallReplyLength(RedisModuleCallReply *reply);
Available since: 4.0.0
Return the reply type length, where applicable.
RedisModule_CallReplyArrayElement
RedisModuleCallReply *RedisModule_CallReplyArrayElement(RedisModuleCallReply *reply,
size_t idx);
Available since: 4.0.0
Return the 'idx'-th nested call reply element of an array reply, or NULL if the reply type is wrong or the index is out of range.
RedisModule_CallReplyInteger
long long RedisModule_CallReplyInteger(RedisModuleCallReply *reply);
Available since: 4.0.0
Return the long long
of an integer reply.
RedisModule_CallReplyDouble
double RedisModule_CallReplyDouble(RedisModuleCallReply *reply);
Available since: 7.0.0
Return the double value of a double reply.
RedisModule_CallReplyBigNumber
const char *RedisModule_CallReplyBigNumber(RedisModuleCallReply *reply,
size_t *len);
Available since: 7.0.0
Return the big number value of a big number reply.
RedisModule_CallReplyVerbatim
const char *RedisModule_CallReplyVerbatim(RedisModuleCallReply *reply,
size_t *len,
const char **format);
Available since: 7.0.0
Return the value of a verbatim string reply, An optional output argument can be given to get verbatim reply format.
RedisModule_CallReplyBool
int RedisModule_CallReplyBool(RedisModuleCallReply *reply);
Available since: 7.0.0
Return the Boolean value of a Boolean reply.
RedisModule_CallReplySetElement
RedisModuleCallReply *RedisModule_CallReplySetElement(RedisModuleCallReply *reply,
size_t idx);
Available since: 7.0.0
Return the 'idx'-th nested call reply element of a set reply, or NULL if the reply type is wrong or the index is out of range.
RedisModule_CallReplyMapElement
int RedisModule_CallReplyMapElement(RedisModuleCallReply *reply,
size_t idx,
RedisModuleCallReply **key,
RedisModuleCallReply **val);
Available since: 7.0.0
Retrieve the 'idx'-th key and value of a map reply.
Returns:
REDISMODULE_OK
on success.REDISMODULE_ERR
if idx out of range or if the reply type is wrong.
The key
and value
arguments are used to return by reference, and may be
NULL if not required.
RedisModule_CallReplyAttribute
RedisModuleCallReply *RedisModule_CallReplyAttribute(RedisModuleCallReply *reply);
Available since: 7.0.0
Return the attribute of the given reply, or NULL if no attribute exists.
RedisModule_CallReplyAttributeElement
int RedisModule_CallReplyAttributeElement(RedisModuleCallReply *reply,
size_t idx,
RedisModuleCallReply **key,
RedisModuleCallReply **val);
Available since: 7.0.0
Retrieve the 'idx'-th key and value of an attribute reply.
Returns:
REDISMODULE_OK
on success.REDISMODULE_ERR
if idx out of range or if the reply type is wrong.
The key
and value
arguments are used to return by reference, and may be
NULL if not required.
RedisModule_CallReplyPromiseSetUnblockHandler
void RedisModule_CallReplyPromiseSetUnblockHandler(RedisModuleCallReply *reply,
RedisModuleOnUnblocked on_unblock,
void *private_data);
Available since: 7.2.0
Set unblock handler (callback and private data) on the given promise RedisModuleCallReply
.
The given reply must be of promise type (REDISMODULE_REPLY_PROMISE
).
RedisModule_CallReplyPromiseAbort
int RedisModule_CallReplyPromiseAbort(RedisModuleCallReply *reply,
void **private_data);
Available since: 7.2.0
Abort the execution of a given promise RedisModuleCallReply
.
return REDMODULE_OK
in case the abort was done successfully and REDISMODULE_ERR
if its not possible to abort the execution (execution already finished).
In case the execution was aborted (REDMODULE_OK
was returned), the private_data
out parameter
will be set with the value of the private data that was given on 'RedisModule_CallReplyPromiseSetUnblockHandler
'
so the caller will be able to release the private data.
If the execution was aborted successfully, it is promised that the unblock handler will not be called. That said, it is possible that the abort operation will successes but the operation will still continue. This can happened if, for example, a module implements some blocking command and does not respect the disconnect callback. For pure Redis commands this can not happened.
RedisModule_CallReplyStringPtr
const char *RedisModule_CallReplyStringPtr(RedisModuleCallReply *reply,
size_t *len);
Available since: 4.0.0
Return the pointer and length of a string or error reply.
RedisModule_CreateStringFromCallReply
RedisModuleString *RedisModule_CreateStringFromCallReply(RedisModuleCallReply *reply);
Available since: 4.0.0
Return a new string object from a call reply of type string, error or integer. Otherwise (wrong reply type) return NULL.
RedisModule_SetContextUser
void RedisModule_SetContextUser(RedisModuleCtx *ctx,
const RedisModuleUser *user);
Available since: 7.0.6
Modifies the user that RedisModule_Call
will use (e.g. for ACL checks)
RedisModule_Call
RedisModuleCallReply *RedisModule_Call(RedisModuleCtx *ctx,
const char *cmdname,
const char *fmt,
...);
Available since: 4.0.0
Exported API to call any Redis command from modules.
-
cmdname: The Redis command to call.
-
fmt: A format specifier string for the command's arguments. Each of the arguments should be specified by a valid type specification. The format specifier can also contain the modifiers
!
,A
,3
andR
which don't have a corresponding argument.-
b
-- The argument is a buffer and is immediately followed by another argument that is the buffer's length. -
c
-- The argument is a pointer to a plain C string (null-terminated). -
l
-- The argument is along long
integer. -
s
-- The argument is a RedisModuleString. -
v
-- The argument(s) is a vector of RedisModuleString. -
!
-- Sends the Redis command and its arguments to replicas and AOF. -
A
-- Suppress AOF propagation, send only to replicas (requires!
). -
R
-- Suppress replicas propagation, send only to AOF (requires!
). -
3
-- Return a RESP3 reply. This will change the command reply. e.g., HGETALL returns a map instead of a flat array. -
0
-- Return the reply in auto mode, i.e. the reply format will be the same as the client attached to the given RedisModuleCtx. This will probably used when you want to pass the reply directly to the client. -
C
-- Run a command as the user attached to the context. User is either attached automatically via the client that directly issued the command and created the context or via RedisModule_SetContextUser. If the context is not directly created by an issued command (such as a background context and no user was set on it via RedisModule_SetContextUser, RedisModule_Call will fail. Checks if the command can be executed according to ACL rules and causes the command to run as the determined user, so that any future user dependent activity, such as ACL checks within scripts will proceed as expected. Otherwise, the command will run as the Redis unrestricted user. -
S
-- Run the command in a script mode, this means that it will raise an error if a command which are not allowed inside a script (flagged with thedeny-script
flag) is invoked (like SHUTDOWN). In addition, on script mode, write commands are not allowed if there are not enough good replicas (as configured withmin-replicas-to-write
) or when the server is unable to persist to the disk. -
W
-- Do not allow to run any write command (flagged with thewrite
flag). -
M
-- Do not allowdeny-oom
flagged commands when over the memory limit. -
E
-- Return error as RedisModuleCallReply. If there is an error before invoking the command, the error is returned using errno mechanism. This flag allows to get the error also as an error CallReply with relevant error message. -
'D' -- A "Dry Run" mode. Return before executing the underlying call(). If everything succeeded, it will return with a NULL, otherwise it will return with a CallReply object denoting the error, as if it was called with the 'E' code.
-
'K' -- Allow running blocking commands. If enabled and the command gets blocked, a special REDISMODULE_REPLY_PROMISE will be returned. This reply type indicates that the command was blocked and the reply will be given asynchronously. The module can use this reply object to set a handler which will be called when the command gets unblocked using RedisModule_CallReplyPromiseSetUnblockHandler. The handler must be set immediately after the command invocation (without releasing the Redis lock in between). If the handler is not set, the blocking command will still continue its execution but the reply will be ignored (fire and forget), notice that this is dangerous in case of role change, as explained below. The module can use RedisModule_CallReplyPromiseAbort to abort the command invocation if it was not yet finished (see RedisModule_CallReplyPromiseAbort documentation for more details). It is also the module's responsibility to abort the execution on role change, either by using server event (to get notified when the instance becomes a replica) or relying on the disconnect callback of the original client. Failing to do so can result in a write operation on a replica. Unlike other call replies, promise call reply must be freed while the Redis GIL is locked. Notice that on unblocking, the only promise is that the unblock handler will be called, If the blocking RedisModule_Call caused the module to also block some real client (using RedisModule_BlockClient), it is the module responsibility to unblock this client on the unblock handler. On the unblock handler it is only allowed to perform the following: * Calling additional Redis commands using RedisModule_Call * Open keys using RedisModule_OpenKey * Replicate data to the replica or AOF
Specifically, it is not allowed to call any Redis module API which are client related such as: * RedisModule_Reply* API's * RedisModule_BlockClient * RedisModule_GetCurrentUserName
-
-
...: The actual arguments to the Redis command.
On success a RedisModuleCallReply
object is returned, otherwise
NULL is returned and errno is set to the following values:
- EBADF: wrong format specifier.
- EINVAL: wrong command arity.
- ENOENT: command does not exist.
- EPERM: operation in Cluster instance with key in non local slot.
- EROFS: operation in Cluster instance when a write command is sent in a readonly state.
- ENETDOWN: operation in Cluster instance when cluster is down.
- ENOTSUP: No ACL user for the specified module context
- EACCES: Command cannot be executed, according to ACL rules
- ENOSPC: Write or deny-oom command is not allowed
- ESPIPE: Command not allowed on script mode
Example code fragment:
reply = RedisModule_Call(ctx,"INCRBY","sc",argv[1],"10");
if (RedisModule_CallReplyType(reply) == REDISMODULE_REPLY_INTEGER) {
long long myval = RedisModule_CallReplyInteger(reply);
// Do something with myval.
}
This API is documented here: https://redis.io/topics/modules-intro
RedisModule_CallReplyProto
const char *RedisModule_CallReplyProto(RedisModuleCallReply *reply,
size_t *len);
Available since: 4.0.0
Return a pointer, and a length, to the protocol returned by the command that returned the reply object.
Modules data types
When String DMA or using existing data structures is not enough, it is possible to create new data types from scratch and export them to Redis. The module must provide a set of callbacks for handling the new values exported (for example in order to provide RDB saving/loading, AOF rewrite, and so forth). In this section we define this API.
RedisModule_CreateDataType
moduleType *RedisModule_CreateDataType(RedisModuleCtx *ctx,
const char *name,
int encver,
void *typemethods_ptr);
Available since: 4.0.0
Register a new data type exported by the module. The parameters are the following. Please for in depth documentation check the modules API documentation, especially https://redis.io/topics/modules-native-types.
-
name: A 9 characters data type name that MUST be unique in the Redis Modules ecosystem. Be creative... and there will be no collisions. Use the charset A-Z a-z 9-0, plus the two "-_" characters. A good idea is to use, for example
<typename>-<vendor>
. For example "tree-AntZ" may mean "Tree data structure by @antirez". To use both lower case and upper case letters helps in order to prevent collisions. -
encver: Encoding version, which is, the version of the serialization that a module used in order to persist data. As long as the "name" matches, the RDB loading will be dispatched to the type callbacks whatever 'encver' is used, however the module can understand if the encoding it must load are of an older version of the module. For example the module "tree-AntZ" initially used encver=0. Later after an upgrade, it started to serialize data in a different format and to register the type with encver=1. However this module may still load old data produced by an older version if the
rdb_load
callback is able to check the encver value and act accordingly. The encver must be a positive value between 0 and 1023. -
typemethods_ptr is a pointer to a
RedisModuleTypeMethods
structure that should be populated with the methods callbacks and structure version, like in the following example:RedisModuleTypeMethods tm = { .version = REDISMODULE_TYPE_METHOD_VERSION, .rdb_load = myType_RDBLoadCallBack, .rdb_save = myType_RDBSaveCallBack, .aof_rewrite = myType_AOFRewriteCallBack, .free = myType_FreeCallBack, // Optional fields .digest = myType_DigestCallBack, .mem_usage = myType_MemUsageCallBack, .aux_load = myType_AuxRDBLoadCallBack, .aux_save = myType_AuxRDBSaveCallBack, .free_effort = myType_FreeEffortCallBack, .unlink = myType_UnlinkCallBack, .copy = myType_CopyCallback, .defrag = myType_DefragCallback // Enhanced optional fields .mem_usage2 = myType_MemUsageCallBack2, .free_effort2 = myType_FreeEffortCallBack2, .unlink2 = myType_UnlinkCallBack2, .copy2 = myType_CopyCallback2, }
-
rdb_load: A callback function pointer that loads data from RDB files.
-
rdb_save: A callback function pointer that saves data to RDB files.
-
aof_rewrite: A callback function pointer that rewrites data as commands.
-
digest: A callback function pointer that is used for
DEBUG DIGEST
. -
free: A callback function pointer that can free a type value.
-
aux_save: A callback function pointer that saves out of keyspace data to RDB files. 'when' argument is either
REDISMODULE_AUX_BEFORE_RDB
orREDISMODULE_AUX_AFTER_RDB
. -
aux_load: A callback function pointer that loads out of keyspace data from RDB files. Similar to
aux_save
, returnsREDISMODULE_OK
on success, and ERR otherwise. -
free_effort: A callback function pointer that used to determine whether the module's memory needs to be lazy reclaimed. The module should return the complexity involved by freeing the value. for example: how many pointers are gonna be freed. Note that if it returns 0, we'll always do an async free.
-
unlink: A callback function pointer that used to notifies the module that the key has been removed from the DB by redis, and may soon be freed by a background thread. Note that it won't be called on FLUSHALL/FLUSHDB (both sync and async), and the module can use the
RedisModuleEvent_FlushDB
to hook into that. -
copy: A callback function pointer that is used to make a copy of the specified key. The module is expected to perform a deep copy of the specified value and return it. In addition, hints about the names of the source and destination keys is provided. A NULL return value is considered an error and the copy operation fails. Note: if the target key exists and is being overwritten, the copy callback will be called first, followed by a free callback to the value that is being replaced.
-
defrag: A callback function pointer that is used to request the module to defrag a key. The module should then iterate pointers and call the relevant
RedisModule_Defrag*()
functions to defragment pointers or complex types. The module should continue iterating as long asRedisModule_DefragShouldStop()
returns a zero value, and return a zero value if finished or non-zero value if more work is left to be done. If more work needs to be done,RedisModule_DefragCursorSet()
andRedisModule_DefragCursorGet()
can be used to track this work across different calls. Normally, the defrag mechanism invokes the callback without a time limit, soRedisModule_DefragShouldStop()
always returns zero. The "late defrag" mechanism which has a time limit and provides cursor support is used only for keys that are determined to have significant internal complexity. To determine this, the defrag mechanism uses thefree_effort
callback and the 'active-defrag-max-scan-fields' config directive. NOTE: The value is passed as avoid**
and the function is expected to update the pointer if the top-level value pointer is defragmented and consequently changes. -
mem_usage2: Similar to
mem_usage
, but provides theRedisModuleKeyOptCtx
parameter so that meta information such as key name and db id can be obtained, and thesample_size
for size estimation (see MEMORY USAGE command). -
free_effort2: Similar to
free_effort
, but provides theRedisModuleKeyOptCtx
parameter so that meta information such as key name and db id can be obtained. -
unlink2: Similar to
unlink
, but provides theRedisModuleKeyOptCtx
parameter so that meta information such as key name and db id can be obtained. -
copy2: Similar to
copy
, but provides theRedisModuleKeyOptCtx
parameter so that meta information such as key names and db ids can be obtained. -
aux_save2: Similar to
aux_save
, but with small semantic change, if the module saves nothing on this callback then no data about this aux field will be written to the RDB and it will be possible to load the RDB even if the module is not loaded.
Note: the module name "AAAAAAAAA" is reserved and produces an error, it happens to be pretty lame as well.
If RedisModule_CreateDataType()
is called outside of RedisModule_OnLoad()
function,
there is already a module registering a type with the same name,
or if the module name or encver is invalid, NULL is returned.
Otherwise the new type is registered into Redis, and a reference of
type RedisModuleType
is returned: the caller of the function should store
this reference into a global variable to make future use of it in the
modules type API, since a single module may register multiple types.
Example code fragment:
static RedisModuleType *BalancedTreeType;
int RedisModule_OnLoad(RedisModuleCtx *ctx) {
// some code here ...
BalancedTreeType = RedisModule_CreateDataType(...);
}
RedisModule_ModuleTypeSetValue
int RedisModule_ModuleTypeSetValue(RedisModuleKey *key,
moduleType *mt,
void *value);
Available since: 4.0.0
If the key is open for writing, set the specified module type object
as the value of the key, deleting the old value if any.
On success REDISMODULE_OK
is returned. If the key is not open for
writing or there is an active iterator, REDISMODULE_ERR
is returned.
RedisModule_ModuleTypeGetType
moduleType *RedisModule_ModuleTypeGetType(RedisModuleKey *key);
Available since: 4.0.0
Assuming RedisModule_KeyType()
returned REDISMODULE_KEYTYPE_MODULE
on
the key, returns the module type pointer of the value stored at key.
If the key is NULL, is not associated with a module type, or is empty, then NULL is returned instead.
RedisModule_ModuleTypeGetValue
void *RedisModule_ModuleTypeGetValue(RedisModuleKey *key);
Available since: 4.0.0
Assuming RedisModule_KeyType()
returned REDISMODULE_KEYTYPE_MODULE
on
the key, returns the module type low-level value stored at key, as
it was set by the user via RedisModule_ModuleTypeSetValue()
.
If the key is NULL, is not associated with a module type, or is empty, then NULL is returned instead.
RDB loading and saving functions
RedisModule_IsIOError
int RedisModule_IsIOError(RedisModuleIO *io);
Available since: 6.0.0
Returns true if any previous IO API failed.
for Load*
APIs the REDISMODULE_OPTIONS_HANDLE_IO_ERRORS
flag must be set with
RedisModule_SetModuleOptions
first.
RedisModule_SaveUnsigned
void RedisModule_SaveUnsigned(RedisModuleIO *io, uint64_t value);
Available since: 4.0.0
Save an unsigned 64 bit value into the RDB file. This function should only
be called in the context of the rdb_save
method of modules implementing new
data types.
RedisModule_LoadUnsigned
uint64_t RedisModule_LoadUnsigned(RedisModuleIO *io);
Available since: 4.0.0
Load an unsigned 64 bit value from the RDB file. This function should only
be called in the context of the rdb_load
method of modules implementing
new data types.
RedisModule_SaveSigned
void RedisModule_SaveSigned(RedisModuleIO *io, int64_t value);
Available since: 4.0.0
Like RedisModule_SaveUnsigned()
but for signed 64 bit values.
RedisModule_LoadSigned
int64_t RedisModule_LoadSigned(RedisModuleIO *io);
Available since: 4.0.0
Like RedisModule_LoadUnsigned()
but for signed 64 bit values.
RedisModule_SaveString
void RedisModule_SaveString(RedisModuleIO *io, RedisModuleString *s);
Available since: 4.0.0
In the context of the rdb_save
method of a module type, saves a
string into the RDB file taking as input a RedisModuleString
.
The string can be later loaded with RedisModule_LoadString()
or
other Load family functions expecting a serialized string inside
the RDB file.
RedisModule_SaveStringBuffer
void RedisModule_SaveStringBuffer(RedisModuleIO *io,
const char *str,
size_t len);
Available since: 4.0.0
Like RedisModule_SaveString()
but takes a raw C pointer and length
as input.
RedisModule_LoadString
RedisModuleString *RedisModule_LoadString(RedisModuleIO *io);
Available since: 4.0.0
In the context of the rdb_load
method of a module data type, loads a string
from the RDB file, that was previously saved with RedisModule_SaveString()
functions family.
The returned string is a newly allocated RedisModuleString
object, and
the user should at some point free it with a call to RedisModule_FreeString()
.
If the data structure does not store strings as RedisModuleString
objects,
the similar function RedisModule_LoadStringBuffer()
could be used instead.
RedisModule_LoadStringBuffer
char *RedisModule_LoadStringBuffer(RedisModuleIO *io, size_t *lenptr);
Available since: 4.0.0
Like RedisModule_LoadString()
but returns a heap allocated string that
was allocated with RedisModule_Alloc()
, and can be resized or freed with
RedisModule_Realloc()
or RedisModule_Free()
.
The size of the string is stored at '*lenptr' if not NULL. The returned string is not automatically NULL terminated, it is loaded exactly as it was stored inside the RDB file.
RedisModule_SaveDouble
void RedisModule_SaveDouble(RedisModuleIO *io, double value);
Available since: 4.0.0
In the context of the rdb_save
method of a module data type, saves a double
value to the RDB file. The double can be a valid number, a NaN or infinity.
It is possible to load back the value with RedisModule_LoadDouble()
.
RedisModule_LoadDouble
double RedisModule_LoadDouble(RedisModuleIO *io);
Available since: 4.0.0
In the context of the rdb_save
method of a module data type, loads back the
double value saved by RedisModule_SaveDouble()
.
RedisModule_SaveFloat
void RedisModule_SaveFloat(RedisModuleIO *io, float value);
Available since: 4.0.0
In the context of the rdb_save
method of a module data type, saves a float
value to the RDB file. The float can be a valid number, a NaN or infinity.
It is possible to load back the value with RedisModule_LoadFloat()
.
RedisModule_LoadFloat
float RedisModule_LoadFloat(RedisModuleIO *io);
Available since: 4.0.0
In the context of the rdb_save
method of a module data type, loads back the
float value saved by RedisModule_SaveFloat()
.
RedisModule_SaveLongDouble
void RedisModule_SaveLongDouble(RedisModuleIO *io, long double value);
Available since: 6.0.0
In the context of the rdb_save
method of a module data type, saves a long double
value to the RDB file. The double can be a valid number, a NaN or infinity.
It is possible to load back the value with RedisModule_LoadLongDouble()
.
RedisModule_LoadLongDouble
long double RedisModule_LoadLongDouble(RedisModuleIO *io);
Available since: 6.0.0
In the context of the rdb_save
method of a module data type, loads back the
long double value saved by RedisModule_SaveLongDouble()
.
Key digest API (DEBUG DIGEST interface for modules types)
RedisModule_DigestAddStringBuffer
void RedisModule_DigestAddStringBuffer(RedisModuleDigest *md,
const char *ele,
size_t len);
Available since: 4.0.0
Add a new element to the digest. This function can be called multiple times
one element after the other, for all the elements that constitute a given
data structure. The function call must be followed by the call to
RedisModule_DigestEndSequence
eventually, when all the elements that are
always in a given order are added. See the Redis Modules data types
documentation for more info. However this is a quick example that uses Redis
data types as an example.
To add a sequence of unordered elements (for example in the case of a Redis Set), the pattern to use is:
foreach element {
AddElement(element);
EndSequence();
}
Because Sets are not ordered, so every element added has a position that does not depend from the other. However if instead our elements are ordered in pairs, like field-value pairs of a Hash, then one should use:
foreach key,value {
AddElement(key);
AddElement(value);
EndSequence();
}
Because the key and value will be always in the above order, while instead the single key-value pairs, can appear in any position into a Redis hash.
A list of ordered elements would be implemented with:
foreach element {
AddElement(element);
}
EndSequence();
RedisModule_DigestAddLongLong
void RedisModule_DigestAddLongLong(RedisModuleDigest *md, long long ll);
Available since: 4.0.0
Like RedisModule_DigestAddStringBuffer()
but takes a long long
as input
that gets converted into a string before adding it to the digest.
RedisModule_DigestEndSequence
void RedisModule_DigestEndSequence(RedisModuleDigest *md);
Available since: 4.0.0
See the documentation for RedisModule_DigestAddElement()
.
RedisModule_LoadDataTypeFromStringEncver
void *RedisModule_LoadDataTypeFromStringEncver(const RedisModuleString *str,
const moduleType *mt,
int encver);
Available since: 7.0.0
Decode a serialized representation of a module data type 'mt', in a specific encoding version 'encver' from string 'str' and return a newly allocated value, or NULL if decoding failed.
This call basically reuses the 'rdb_load
' callback which module data types
implement in order to allow a module to arbitrarily serialize/de-serialize
keys, similar to how the Redis 'DUMP' and 'RESTORE' commands are implemented.
Modules should generally use the REDISMODULE_OPTIONS_HANDLE_IO_ERRORS
flag and
make sure the de-serialization code properly checks and handles IO errors
(freeing allocated buffers and returning a NULL).
If this is NOT done, Redis will handle corrupted (or just truncated) serialized data by producing an error message and terminating the process.
RedisModule_LoadDataTypeFromString
void *RedisModule_LoadDataTypeFromString(const RedisModuleString *str,
const moduleType *mt);
Available since: 6.0.0
Similar to RedisModule_LoadDataTypeFromStringEncver
, original version of the API, kept
for backward compatibility.
RedisModule_SaveDataTypeToString
RedisModuleString *RedisModule_SaveDataTypeToString(RedisModuleCtx *ctx,
void *data,
const moduleType *mt);
Available since: 6.0.0
Encode a module data type 'mt' value 'data' into serialized form, and return it
as a newly allocated RedisModuleString
.
This call basically reuses the 'rdb_save
' callback which module data types
implement in order to allow a module to arbitrarily serialize/de-serialize
keys, similar to how the Redis 'DUMP' and 'RESTORE' commands are implemented.
RedisModule_GetKeyNameFromDigest
const RedisModuleString *RedisModule_GetKeyNameFromDigest(RedisModuleDigest *dig);
Available since: 7.0.0
Returns the name of the key currently being processed.
RedisModule_GetDbIdFromDigest
int RedisModule_GetDbIdFromDigest(RedisModuleDigest *dig);
Available since: 7.0.0
Returns the database id of the key currently being processed.
AOF API for modules data types
RedisModule_EmitAOF
void RedisModule_EmitAOF(RedisModuleIO *io,
const char *cmdname,
const char *fmt,
...);
Available since: 4.0.0
Emits a command into the AOF during the AOF rewriting process. This function
is only called in the context of the aof_rewrite
method of data types exported
by a module. The command works exactly like RedisModule_Call()
in the way
the parameters are passed, but it does not return anything as the error
handling is performed by Redis itself.
IO context handling
RedisModule_GetKeyNameFromIO
const RedisModuleString *RedisModule_GetKeyNameFromIO(RedisModuleIO *io);
Available since: 5.0.5
Returns the name of the key currently being processed. There is no guarantee that the key name is always available, so this may return NULL.
RedisModule_GetKeyNameFromModuleKey
const RedisModuleString *RedisModule_GetKeyNameFromModuleKey(RedisModuleKey *key);
Available since: 6.0.0
Returns a RedisModuleString
with the name of the key from RedisModuleKey
.
RedisModule_GetDbIdFromModuleKey
int RedisModule_GetDbIdFromModuleKey(RedisModuleKey *key);
Available since: 7.0.0
Returns a database id of the key from RedisModuleKey
.
RedisModule_GetDbIdFromIO
int RedisModule_GetDbIdFromIO(RedisModuleIO *io);
Available since: 7.0.0
Returns the database id of the key currently being processed. There is no guarantee that this info is always available, so this may return -1.
Logging
RedisModule_Log
void RedisModule_Log(RedisModuleCtx *ctx,
const char *levelstr,
const char *fmt,
...);
Available since: 4.0.0
Produces a log message to the standard Redis log, the format accepts printf-alike specifiers, while level is a string describing the log level to use when emitting the log, and must be one of the following:
- "debug" (
REDISMODULE_LOGLEVEL_DEBUG
) - "verbose" (
REDISMODULE_LOGLEVEL_VERBOSE
) - "notice" (
REDISMODULE_LOGLEVEL_NOTICE
) - "warning" (
REDISMODULE_LOGLEVEL_WARNING
)
If the specified log level is invalid, verbose is used by default. There is a fixed limit to the length of the log line this function is able to emit, this limit is not specified but is guaranteed to be more than a few lines of text.
The ctx argument may be NULL if cannot be provided in the context of the caller for instance threads or callbacks, in which case a generic "module" will be used instead of the module name.
RedisModule_LogIOError
void RedisModule_LogIOError(RedisModuleIO *io,
const char *levelstr,
const char *fmt,
...);
Available since: 4.0.0
Log errors from RDB / AOF serialization callbacks.
This function should be used when a callback is returning a critical error to the caller since cannot load or save the data for some critical reason.
RedisModule__Assert
void RedisModule__Assert(const char *estr, const char *file, int line);
Available since: 6.0.0
Redis-like assert function.
The macro RedisModule_Assert(expression)
is recommended, rather than
calling this function directly.
A failed assertion will shut down the server and produce logging information that looks identical to information generated by Redis itself.
RedisModule_LatencyAddSample
void RedisModule_LatencyAddSample(const char *event, mstime_t latency);
Available since: 6.0.0
Allows adding event to the latency monitor to be observed by the LATENCY command. The call is skipped if the latency is smaller than the configured latency-monitor-threshold.
Blocking clients from modules
For a guide about blocking commands in modules, see https://redis.io/topics/modules-blocking-ops.
RedisModule_RegisterAuthCallback
void RedisModule_RegisterAuthCallback(RedisModuleCtx *ctx,
RedisModuleAuthCallback cb);
Available since: 7.2.0
This API registers a callback to execute in addition to normal password based authentication.
Multiple callbacks can be registered across different modules. When a Module is unloaded, all the
auth callbacks registered by it are unregistered.
The callbacks are attempted (in the order of most recently registered first) when the AUTH/HELLO
(with AUTH field provided) commands are called.
The callbacks will be called with a module context along with a username and a password, and are
expected to take one of the following actions:
(1) Authenticate - Use the RedisModule_AuthenticateClient
* API and return REDISMODULE_AUTH_HANDLED
.
This will immediately end the auth chain as successful and add the OK reply.
(2) Deny Authentication - Return REDISMODULE_AUTH_HANDLED
without authenticating or blocking the
client. Optionally, err
can be set to a custom error message and err
will be automatically
freed by the server.
This will immediately end the auth chain as unsuccessful and add the ERR reply.
(3) Block a client on authentication - Use the RedisModule_BlockClientOnAuth
API and return
REDISMODULE_AUTH_HANDLED
. Here, the client will be blocked until the RedisModule_UnblockClient
API is used
which will trigger the auth reply callback (provided through the RedisModule_BlockClientOnAuth
).
In this reply callback, the Module should authenticate, deny or skip handling authentication.
(4) Skip handling Authentication - Return REDISMODULE_AUTH_NOT_HANDLED
without blocking the
client. This will allow the engine to attempt the next module auth callback.
If none of the callbacks authenticate or deny auth, then password based auth is attempted and
will authenticate or add failure logs and reply to the clients accordingly.
Note: If a client is disconnected while it was in the middle of blocking module auth, that occurrence of the AUTH or HELLO command will not be tracked in the INFO command stats.
The following is an example of how non-blocking module based authentication can be used:
int auth_cb(RedisModuleCtx *ctx, RedisModuleString *username, RedisModuleString *password, RedisModuleString **err) {
const char *user = RedisModule_StringPtrLen(username, NULL);
const char *pwd = RedisModule_StringPtrLen(password, NULL);
if (!strcmp(user,"foo") && !strcmp(pwd,"valid_password")) {
RedisModule_AuthenticateClientWithACLUser(ctx, "foo", 3, NULL, NULL, NULL);
return REDISMODULE_AUTH_HANDLED;
}
else if (!strcmp(user,"foo") && !strcmp(pwd,"wrong_password")) {
RedisModuleString *log = RedisModule_CreateString(ctx, "Module Auth", 11);
RedisModule_ACLAddLogEntryByUserName(ctx, username, log, REDISMODULE_ACL_LOG_AUTH);
RedisModule_FreeString(ctx, log);
const char *err_msg = "Auth denied by Misc Module.";
*err = RedisModule_CreateString(ctx, err_msg, strlen(err_msg));
return REDISMODULE_AUTH_HANDLED;
}
return REDISMODULE_AUTH_NOT_HANDLED;
}
int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
if (RedisModule_Init(ctx,"authmodule",1,REDISMODULE_APIVER_1)== REDISMODULE_ERR)
return REDISMODULE_ERR;
RedisModule_RegisterAuthCallback(ctx, auth_cb);
return REDISMODULE_OK;
}
RedisModule_BlockClient
RedisModuleBlockedClient *RedisModule_BlockClient(RedisModuleCtx *ctx,
RedisModuleCmdFunc reply_callback,
;
Available since: 4.0.0
Block a client in the context of a blocking command, returning a handle
which will be used, later, in order to unblock the client with a call to
RedisModule_UnblockClient()
. The arguments specify callback functions
and a timeout after which the client is unblocked.
The callbacks are called in the following contexts:
reply_callback: called after a successful RedisModule_UnblockClient()
call in order to reply to the client and unblock it.
timeout_callback: called when the timeout is reached or if [`CLIENT UNBLOCK`](/commands/client-unblock)
is invoked, in order to send an error to the client.
free_privdata: called in order to free the private data that is passed
by RedisModule_UnblockClient() call.
Note: RedisModule_UnblockClient
should be called for every blocked client,
even if client was killed, timed-out or disconnected. Failing to do so
will result in memory leaks.
There are some cases where RedisModule_BlockClient()
cannot be used:
- If the client is a Lua script.
- If the client is executing a MULTI block.
In these cases, a call to RedisModule_BlockClient()
will not block the
client, but instead produce a specific error reply.
A module that registers a timeout_callback
function can also be unblocked
using the CLIENT UNBLOCK
command, which will trigger the timeout callback.
If a callback function is not registered, then the blocked client will be
treated as if it is not in a blocked state and CLIENT UNBLOCK
will return
a zero value.
Measuring background time: By default the time spent in the blocked command
is not account for the total command duration. To include such time you should
use RedisModule_BlockedClientMeasureTimeStart()
and RedisModule_BlockedClientMeasureTimeEnd()
one,
or multiple times within the blocking command background work.
RedisModule_BlockClientOnAuth
RedisModuleBlockedClient *RedisModule_BlockClientOnAuth(RedisModuleCtx *ctx,
RedisModuleAuthCallback reply_callback,
;
Available since: 7.2.0
Block the current client for module authentication in the background. If module auth is not in
progress on the client, the API returns NULL. Otherwise, the client is blocked and the RedisModule_BlockedClient
is returned similar to the RedisModule_BlockClient
API.
Note: Only use this API from the context of a module auth callback.
RedisModule_BlockClientGetPrivateData
void *RedisModule_BlockClientGetPrivateData(RedisModuleBlockedClient *blocked_client);
Available since: 7.2.0
Get the private data that was previusely set on a blocked client
RedisModule_BlockClientSetPrivateData
void RedisModule_BlockClientSetPrivateData(RedisModuleBlockedClient *blocked_client,
void *private_data);
Available since: 7.2.0
Set private data on a blocked client
RedisModule_BlockClientOnKeys
RedisModuleBlockedClient *RedisModule_BlockClientOnKeys(RedisModuleCtx *ctx,
RedisModuleCmdFunc reply_callback,
;
Available since: 6.0.0
This call is similar to RedisModule_BlockClient()
, however in this case we
don't just block the client, but also ask Redis to unblock it automatically
once certain keys become "ready", that is, contain more data.
Basically this is similar to what a typical Redis command usually does, like BLPOP or BZPOPMAX: the client blocks if it cannot be served ASAP, and later when the key receives new data (a list push for instance), the client is unblocked and served.
However in the case of this module API, when the client is unblocked?
- If you block on a key of a type that has blocking operations associated, like a list, a sorted set, a stream, and so forth, the client may be unblocked once the relevant key is targeted by an operation that normally unblocks the native blocking operations for that type. So if we block on a list key, an RPUSH command may unblock our client and so forth.
- If you are implementing your native data type, or if you want to add new
unblocking conditions in addition to "1", you can call the modules API
RedisModule_SignalKeyAsReady()
.
Anyway we can't be sure if the client should be unblocked just because the
key is signaled as ready: for instance a successive operation may change the
key, or a client in queue before this one can be served, modifying the key
as well and making it empty again. So when a client is blocked with
RedisModule_BlockClientOnKeys()
the reply callback is not called after
RedisModule_UnblockClient()
is called, but every time a key is signaled as ready:
if the reply callback can serve the client, it returns REDISMODULE_OK
and the client is unblocked, otherwise it will return REDISMODULE_ERR
and we'll try again later.
The reply callback can access the key that was signaled as ready by
calling the API RedisModule_GetBlockedClientReadyKey()
, that returns
just the string name of the key as a RedisModuleString
object.
Thanks to this system we can setup complex blocking scenarios, like unblocking a client only if a list contains at least 5 items or other more fancy logics.
Note that another difference with RedisModule_BlockClient()
, is that here
we pass the private data directly when blocking the client: it will
be accessible later in the reply callback. Normally when blocking with
RedisModule_BlockClient()
the private data to reply to the client is
passed when calling RedisModule_UnblockClient()
but here the unblocking
is performed by Redis itself, so we need to have some private data before
hand. The private data is used to store any information about the specific
unblocking operation that you are implementing. Such information will be
freed using the free_privdata
callback provided by the user.
However the reply callback will be able to access the argument vector of the command, so the private data is often not needed.
Note: Under normal circumstances RedisModule_UnblockClient
should not be
called for clients that are blocked on keys (Either the key will
become ready or a timeout will occur). If for some reason you do want
to call RedisModule_UnblockClient it is possible: Client will be
handled as if it were timed-out (You must implement the timeout
callback in that case).
RedisModule_BlockClientOnKeysWithFlags
RedisModuleBlockedClient *RedisModule_BlockClientOnKeysWithFlags(RedisModuleCtx *ctx,
RedisModuleCmdFunc reply_callback,
;
Available since: 7.2.0
Same as RedisModule_BlockClientOnKeys
, but can take REDISMODULE_BLOCK_
* flags
Can be either REDISMODULE_BLOCK_UNBLOCK_DEFAULT
, which means default behavior (same
as calling RedisModule_BlockClientOnKeys
)
The flags is a bit mask of these:
REDISMODULE_BLOCK_UNBLOCK_DELETED
: The clients should to be awakened in case any ofkeys
are deleted. Mostly useful for commands that require the key to exist (like XREADGROUP)
RedisModule_SignalKeyAsReady
void RedisModule_SignalKeyAsReady(RedisModuleCtx *ctx, RedisModuleString *key);
Available since: 6.0.0
This function is used in order to potentially unblock a client blocked
on keys with RedisModule_BlockClientOnKeys()
. When this function is called,
all the clients blocked for this key will get their reply_callback
called.
RedisModule_UnblockClient
int RedisModule_UnblockClient(RedisModuleBlockedClient *bc, void *privdata);
Available since: 4.0.0
Unblock a client blocked by RedisModule_BlockedClient
. This will trigger
the reply callbacks to be called in order to reply to the client.
The 'privdata' argument will be accessible by the reply callback, so
the caller of this function can pass any value that is needed in order to
actually reply to the client.
A common usage for 'privdata' is a thread that computes something that needs to be passed to the client, included but not limited some slow to compute reply or some reply obtained via networking.
Note 1: this function can be called from threads spawned by the module.
Note 2: when we unblock a client that is blocked for keys using the API
RedisModule_BlockClientOnKeys()
, the privdata argument here is not used.
Unblocking a client that was blocked for keys using this API will still
require the client to get some reply, so the function will use the
"timeout" handler in order to do so (The privdata provided in
RedisModule_BlockClientOnKeys()
is accessible from the timeout
callback via RedisModule_GetBlockedClientPrivateData
).
RedisModule_AbortBlock
int RedisModule_AbortBlock(RedisModuleBlockedClient *bc);
Available since: 4.0.0
Abort a blocked client blocking operation: the client will be unblocked without firing any callback.
RedisModule_SetDisconnectCallback
void RedisModule_SetDisconnectCallback(RedisModuleBlockedClient *bc,
RedisModuleDisconnectFunc callback);
Available since: 5.0.0
Set a callback that will be called if a blocked client disconnects
before the module has a chance to call RedisModule_UnblockClient()
Usually what you want to do there, is to cleanup your module state
so that you can call RedisModule_UnblockClient()
safely, otherwise
the client will remain blocked forever if the timeout is large.
Notes:
-
It is not safe to call Reply* family functions here, it is also useless since the client is gone.
-
This callback is not called if the client disconnects because of a timeout. In such a case, the client is unblocked automatically and the timeout callback is called.
RedisModule_IsBlockedReplyRequest
int RedisModule_IsBlockedReplyRequest(RedisModuleCtx *ctx);
Available since: 4.0.0
Return non-zero if a module command was called in order to fill the reply for a blocked client.
RedisModule_IsBlockedTimeoutRequest
int RedisModule_IsBlockedTimeoutRequest(RedisModuleCtx *ctx);
Available since: 4.0.0
Return non-zero if a module command was called in order to fill the reply for a blocked client that timed out.
RedisModule_GetBlockedClientPrivateData
void *RedisModule_GetBlockedClientPrivateData(RedisModuleCtx *ctx);
Available since: 4.0.0
Get the private data set by RedisModule_UnblockClient()
RedisModule_GetBlockedClientReadyKey
RedisModuleString *RedisModule_GetBlockedClientReadyKey(RedisModuleCtx *ctx);
Available since: 6.0.0
Get the key that is ready when the reply callback is called in the context
of a client blocked by RedisModule_BlockClientOnKeys()
.
RedisModule_GetBlockedClientHandle
RedisModuleBlockedClient *RedisModule_GetBlockedClientHandle(RedisModuleCtx *ctx);
Available since: 5.0.0
Get the blocked client associated with a given context. This is useful in the reply and timeout callbacks of blocked clients, before sometimes the module has the blocked client handle references around, and wants to cleanup it.
RedisModule_BlockedClientDisconnected
int RedisModule_BlockedClientDisconnected(RedisModuleCtx *ctx);
Available since: 5.0.0
Return true if when the free callback of a blocked client is called, the reason for the client to be unblocked is that it disconnected while it was blocked.
Thread Safe Contexts
RedisModule_GetThreadSafeContext
RedisModuleCtx *RedisModule_GetThreadSafeContext(RedisModuleBlockedClient *bc);
Available since: 4.0.0
Return a context which can be used inside threads to make Redis context
calls with certain modules APIs. If 'bc' is not NULL then the module will
be bound to a blocked client, and it will be possible to use the
RedisModule_Reply*
family of functions to accumulate a reply for when the
client will be unblocked. Otherwise the thread safe context will be
detached by a specific client.
To call non-reply APIs, the thread safe context must be prepared with:
RedisModule_ThreadSafeContextLock(ctx);
... make your call here ...
RedisModule_ThreadSafeContextUnlock(ctx);
This is not needed when using RedisModule_Reply*
functions, assuming
that a blocked client was used when the context was created, otherwise
no RedisModule_Reply
* call should be made at all.
NOTE: If you're creating a detached thread safe context (bc is NULL),
consider using RedisModule_GetDetachedThreadSafeContext
which will also retain
the module ID and thus be more useful for logging.
RedisModule_GetDetachedThreadSafeContext
RedisModuleCtx *RedisModule_GetDetachedThreadSafeContext(RedisModuleCtx *ctx);
Available since: 6.0.9
Return a detached thread safe context that is not associated with any specific blocked client, but is associated with the module's context.
This is useful for modules that wish to hold a global context over a long term, for purposes such as logging.
RedisModule_FreeThreadSafeContext
void RedisModule_FreeThreadSafeContext(RedisModuleCtx *ctx);
Available since: 4.0.0
Release a thread safe context.
RedisModule_ThreadSafeContextLock
void RedisModule_ThreadSafeContextLock(RedisModuleCtx *ctx);
Available since: 4.0.0
Acquire the server lock before executing a thread safe API call.
This is not needed for RedisModule_Reply*
calls when there is
a blocked client connected to the thread safe context.
RedisModule_ThreadSafeContextTryLock
int RedisModule_ThreadSafeContextTryLock(RedisModuleCtx *ctx);
Available since: 6.0.8
Similar to RedisModule_ThreadSafeContextLock
but this function
would not block if the server lock is already acquired.
If successful (lock acquired) REDISMODULE_OK
is returned,
otherwise REDISMODULE_ERR
is returned and errno is set
accordingly.
RedisModule_ThreadSafeContextUnlock
void RedisModule_ThreadSafeContextUnlock(RedisModuleCtx *ctx);
Available since: 4.0.0
Release the server lock after a thread safe API call was executed.
Module Keyspace Notifications API
RedisModule_SubscribeToKeyspaceEvents
int RedisModule_SubscribeToKeyspaceEvents(RedisModuleCtx *ctx,
int types,
RedisModuleNotificationFunc callback);
Available since: 4.0.9
Subscribe to keyspace notifications. This is a low-level version of the keyspace-notifications API. A module can register callbacks to be notified when keyspace events occur.
Notification events are filtered by their type (string events, set events, etc), and the subscriber callback receives only events that match a specific mask of event types.
When subscribing to notifications with RedisModule_SubscribeToKeyspaceEvents
the module must provide an event type-mask, denoting the events the subscriber
is interested in. This can be an ORed mask of any of the following flags:
REDISMODULE_NOTIFY_GENERIC
: Generic commands like DEL, EXPIRE, RENAMEREDISMODULE_NOTIFY_STRING
: String eventsREDISMODULE_NOTIFY_LIST
: List eventsREDISMODULE_NOTIFY_SET
: Set eventsREDISMODULE_NOTIFY_HASH
: Hash eventsREDISMODULE_NOTIFY_ZSET
: Sorted Set eventsREDISMODULE_NOTIFY_EXPIRED
: Expiration eventsREDISMODULE_NOTIFY_EVICTED
: Eviction eventsREDISMODULE_NOTIFY_STREAM
: Stream eventsREDISMODULE_NOTIFY_MODULE
: Module types eventsREDISMODULE_NOTIFY_KEYMISS
: Key-miss events Notice, key-miss event is the only type of event that is fired from within a read command. Performing RedisModule_Call with a write command from within this notification is wrong and discourage. It will cause the read command that trigger the event to be replicated to the AOF/Replica.REDISMODULE_NOTIFY_ALL
: All events (ExcludingREDISMODULE_NOTIFY_KEYMISS
)REDISMODULE_NOTIFY_LOADED
: A special notification available only for modules, indicates that the key was loaded from persistence. Notice, when this event fires, the given key can not be retained, use RedisModule_CreateStringFromString instead.
We do not distinguish between key events and keyspace events, and it is up to the module to filter the actions taken based on the key.
The subscriber signature is:
int (*RedisModuleNotificationFunc) (RedisModuleCtx *ctx, int type,
const char *event,
RedisModuleString *key);
type
is the event type bit, that must match the mask given at registration
time. The event string is the actual command being executed, and key is the
relevant Redis key.
Notification callback gets executed with a redis context that can not be used to send anything to the client, and has the db number where the event occurred as its selected db number.
Notice that it is not necessary to enable notifications in redis.conf for module notifications to work.
Warning: the notification callbacks are performed in a synchronous manner, so notification callbacks must to be fast, or they would slow Redis down. If you need to take long actions, use threads to offload them.
Moreover, the fact that the notification is executed synchronously means
that the notification code will be executed in the middle on Redis logic
(commands logic, eviction, expire). Changing the key space while the logic
runs is dangerous and discouraged. In order to react to key space events with
write actions, please refer to RedisModule_AddPostNotificationJob
.
See https://redis.io/topics/notifications for more information.
RedisModule_AddPostNotificationJob
int RedisModule_AddPostNotificationJob(RedisModuleCtx *ctx,
RedisModulePostNotificationJobFunc callback,
void *privdata,
void (*free_privdata)(void*));
Available since: 7.2.0
When running inside a key space notification callback, it is dangerous and highly discouraged to perform any write
operation (See RedisModule_SubscribeToKeyspaceEvents
). In order to still perform write actions in this scenario,
Redis provides RedisModule_AddPostNotificationJob
API. The API allows to register a job callback which Redis will call
when the following condition are promised to be fulfilled:
- It is safe to perform any write operation.
- The job will be called atomically along side the key space notification.
Notice, one job might trigger key space notifications that will trigger more jobs. This raises a concerns of entering an infinite loops, we consider infinite loops as a logical bug that need to be fixed in the module, an attempt to protect against infinite loops by halting the execution could result in violation of the feature correctness and so Redis will make no attempt to protect the module from infinite loops.
'free_pd
' can be NULL and in such case will not be used.
Return REDISMODULE_OK
on success and REDISMODULE_ERR
if was called while loading data from disk (AOF or RDB) or
if the instance is a readonly replica.
RedisModule_GetNotifyKeyspaceEvents
int RedisModule_GetNotifyKeyspaceEvents(void);
Available since: 6.0.0
Get the configured bitmap of notify-keyspace-events (Could be used
for additional filtering in RedisModuleNotificationFunc
)
RedisModule_NotifyKeyspaceEvent
int RedisModule_NotifyKeyspaceEvent(RedisModuleCtx *ctx,
int type,
const char *event,
RedisModuleString *key);
Available since: 6.0.0
Expose notifyKeyspaceEvent to modules
Modules Cluster API
RedisModule_RegisterClusterMessageReceiver
void RedisModule_RegisterClusterMessageReceiver(RedisModuleCtx *ctx,
uint8_t type,
RedisModuleClusterMessageReceiver callback);
Available since: 5.0.0
Register a callback receiver for cluster messages of type 'type'. If there was already a registered callback, this will replace the callback function with the one provided, otherwise if the callback is set to NULL and there is already a callback for this function, the callback is unregistered (so this API call is also used in order to delete the receiver).
RedisModule_SendClusterMessage
int RedisModule_SendClusterMessage(RedisModuleCtx *ctx,
const char *target_id,
uint8_t type,
const char *msg,
uint32_t len);
Available since: 5.0.0
Send a message to all the nodes in the cluster if target
is NULL, otherwise
at the specified target, which is a REDISMODULE_NODE_ID_LEN
bytes node ID, as
returned by the receiver callback or by the nodes iteration functions.
The function returns REDISMODULE_OK
if the message was successfully sent,
otherwise if the node is not connected or such node ID does not map to any
known cluster node, REDISMODULE_ERR
is returned.
RedisModule_GetClusterNodesList
char **RedisModule_GetClusterNodesList(RedisModuleCtx *ctx, size_t *numnodes);
Available since: 5.0.0
Return an array of string pointers, each string pointer points to a cluster
node ID of exactly REDISMODULE_NODE_ID_LEN
bytes (without any null term).
The number of returned node IDs is stored into *numnodes
.
However if this function is called by a module not running an a Redis
instance with Redis Cluster enabled, NULL is returned instead.
The IDs returned can be used with RedisModule_GetClusterNodeInfo()
in order
to get more information about single node.
The array returned by this function must be freed using the function
RedisModule_FreeClusterNodesList()
.
Example:
size_t count, j;
char **ids = RedisModule_GetClusterNodesList(ctx,&count);
for (j = 0; j < count; j++) {
RedisModule_Log(ctx,"notice","Node %.*s",
REDISMODULE_NODE_ID_LEN,ids[j]);
}
RedisModule_FreeClusterNodesList(ids);
RedisModule_FreeClusterNodesList
void RedisModule_FreeClusterNodesList(char **ids);
Available since: 5.0.0
Free the node list obtained with RedisModule_GetClusterNodesList
.
RedisModule_GetMyClusterID
const char *RedisModule_GetMyClusterID(void);
Available since: 5.0.0
Return this node ID (REDISMODULE_CLUSTER_ID_LEN
bytes) or NULL if the cluster
is disabled.
RedisModule_GetClusterSize
size_t RedisModule_GetClusterSize(void);
Available since: 5.0.0
Return the number of nodes in the cluster, regardless of their state (handshake, noaddress, ...) so that the number of active nodes may actually be smaller, but not greater than this number. If the instance is not in cluster mode, zero is returned.
RedisModule_GetClusterNodeInfo
int RedisModule_GetClusterNodeInfo(RedisModuleCtx *ctx,
const char *id,
char *ip,
char *master_id,
int *port,
int *flags);
Available since: 5.0.0
Populate the specified info for the node having as ID the specified 'id',
then returns REDISMODULE_OK
. Otherwise if the format of node ID is invalid
or the node ID does not exist from the POV of this local node, REDISMODULE_ERR
is returned.
The arguments ip
, master_id
, port
and flags
can be NULL in case we don't
need to populate back certain info. If an ip
and master_id
(only populated
if the instance is a slave) are specified, they point to buffers holding
at least REDISMODULE_NODE_ID_LEN
bytes. The strings written back as ip
and master_id
are not null terminated.
The list of flags reported is the following:
REDISMODULE_NODE_MYSELF
: This nodeREDISMODULE_NODE_MASTER
: The node is a masterREDISMODULE_NODE_SLAVE
: The node is a replicaREDISMODULE_NODE_PFAIL
: We see the node as failingREDISMODULE_NODE_FAIL
: The cluster agrees the node is failingREDISMODULE_NODE_NOFAILOVER
: The slave is configured to never failover
RedisModule_SetClusterFlags
void RedisModule_SetClusterFlags(RedisModuleCtx *ctx, uint64_t flags);
Available since: 5.0.0
Set Redis Cluster flags in order to change the normal behavior of Redis Cluster, especially with the goal of disabling certain functions. This is useful for modules that use the Cluster API in order to create a different distributed system, but still want to use the Redis Cluster message bus. Flags that can be set:
CLUSTER_MODULE_FLAG_NO_FAILOVER
CLUSTER_MODULE_FLAG_NO_REDIRECTION
With the following effects:
-
NO_FAILOVER
: prevent Redis Cluster slaves from failing over a dead master. Also disables the replica migration feature. -
NO_REDIRECTION
: Every node will accept any key, without trying to perform partitioning according to the Redis Cluster algorithm. Slots information will still be propagated across the cluster, but without effect.
Modules Timers API
Module timers are a high precision "green timers" abstraction where every module can register even millions of timers without problems, even if the actual event loop will just have a single timer that is used to awake the module timers subsystem in order to process the next event.
All the timers are stored into a radix tree, ordered by expire time, when the main Redis event loop timer callback is called, we try to process all the timers already expired one after the other. Then we re-enter the event loop registering a timer that will expire when the next to process module timer will expire.
Every time the list of active timers drops to zero, we unregister the main event loop timer, so that there is no overhead when such feature is not used.
RedisModule_CreateTimer
RedisModuleTimerID RedisModule_CreateTimer(RedisModuleCtx *ctx,
mstime_t period,
RedisModuleTimerProc callback,
void *data);
Available since: 5.0.0
Create a new timer that will fire after period
milliseconds, and will call
the specified function using data
as argument. The returned timer ID can be
used to get information from the timer or to stop it before it fires.
Note that for the common use case of a repeating timer (Re-registration
of the timer inside the RedisModuleTimerProc
callback) it matters when
this API is called:
If it is called at the beginning of 'callback' it means
the event will triggered every 'period'.
If it is called at the end of 'callback' it means
there will 'period' milliseconds gaps between events.
(If the time it takes to execute 'callback' is negligible the two
statements above mean the same)
RedisModule_StopTimer
int RedisModule_StopTimer(RedisModuleCtx *ctx,
RedisModuleTimerID id,
void **data);
Available since: 5.0.0
Stop a timer, returns REDISMODULE_OK
if the timer was found, belonged to the
calling module, and was stopped, otherwise REDISMODULE_ERR
is returned.
If not NULL, the data pointer is set to the value of the data argument when
the timer was created.
RedisModule_GetTimerInfo
int RedisModule_GetTimerInfo(RedisModuleCtx *ctx,
RedisModuleTimerID id,
uint64_t *remaining,
void **data);
Available since: 5.0.0
Obtain information about a timer: its remaining time before firing
(in milliseconds), and the private data pointer associated with the timer.
If the timer specified does not exist or belongs to a different module
no information is returned and the function returns REDISMODULE_ERR
, otherwise
REDISMODULE_OK
is returned. The arguments remaining or data can be NULL if
the caller does not need certain information.
Modules EventLoop API
RedisModule_EventLoopAdd
int RedisModule_EventLoopAdd(int fd,
int mask,
RedisModuleEventLoopFunc func,
void *user_data);
Available since: 7.0.0
Add a pipe / socket event to the event loop.
-
mask
must be one of the following values:REDISMODULE_EVENTLOOP_READABLE
REDISMODULE_EVENTLOOP_WRITABLE
REDISMODULE_EVENTLOOP_READABLE | REDISMODULE_EVENTLOOP_WRITABLE
On success REDISMODULE_OK
is returned, otherwise
REDISMODULE_ERR
is returned and errno is set to the following values:
- ERANGE:
fd
is negative or higher thanmaxclients
Redis config. - EINVAL:
callback
is NULL ormask
value is invalid.
errno
might take other values in case of an internal error.
Example:
void onReadable(int fd, void *user_data, int mask) {
char buf[32];
int bytes = read(fd,buf,sizeof(buf));
printf("Read %d bytes \n", bytes);
}
RedisModule_EventLoopAdd(fd, REDISMODULE_EVENTLOOP_READABLE, onReadable, NULL);
RedisModule_EventLoopDel
int RedisModule_EventLoopDel(int fd, int mask);
Available since: 7.0.0
Delete a pipe / socket event from the event loop.
-
mask
must be one of the following values:REDISMODULE_EVENTLOOP_READABLE
REDISMODULE_EVENTLOOP_WRITABLE
REDISMODULE_EVENTLOOP_READABLE | REDISMODULE_EVENTLOOP_WRITABLE
On success REDISMODULE_OK
is returned, otherwise
REDISMODULE_ERR
is returned and errno is set to the following values:
- ERANGE:
fd
is negative or higher thanmaxclients
Redis config. - EINVAL:
mask
value is invalid.
RedisModule_EventLoopAddOneShot
int RedisModule_EventLoopAddOneShot(RedisModuleEventLoopOneShotFunc func,
void *user_data);
Available since: 7.0.0
This function can be called from other threads to trigger callback on Redis
main thread. On success REDISMODULE_OK
is returned. If func
is NULL
REDISMODULE_ERR
is returned and errno is set to EINVAL.
Modules ACL API
Implements a hook into the authentication and authorization within Redis.
RedisModule_CreateModuleUser
RedisModuleUser *RedisModule_CreateModuleUser(const char *name);
Available since: 6.0.0
Creates a Redis ACL user that the module can use to authenticate a client.
After obtaining the user, the module should set what such user can do
using the RedisModule_SetUserACL()
function. Once configured, the user
can be used in order to authenticate a connection, with the specified
ACL rules, using the RedisModule_AuthClientWithUser()
function.
Note that:
- Users created here are not listed by the ACL command.
- Users created here are not checked for duplicated name, so it's up to the module calling this function to take care of not creating users with the same name.
- The created user can be used to authenticate multiple Redis connections.
The caller can later free the user using the function
RedisModule_FreeModuleUser()
. When this function is called, if there are
still clients authenticated with this user, they are disconnected.
The function to free the user should only be used when the caller really
wants to invalidate the user to define a new one with different
capabilities.
RedisModule_FreeModuleUser
int RedisModule_FreeModuleUser(RedisModuleUser *user);
Available since: 6.0.0
Frees a given user and disconnects all of the clients that have been
authenticated with it. See RedisModule_CreateModuleUser
for detailed usage.
RedisModule_SetModuleUserACL
int RedisModule_SetModuleUserACL(RedisModuleUser *user, const char* acl);
Available since: 6.0.0
Sets the permissions of a user created through the redis module
interface. The syntax is the same as ACL SETUSER, so refer to the
documentation in acl.c for more information. See RedisModule_CreateModuleUser
for detailed usage.
Returns REDISMODULE_OK
on success and REDISMODULE_ERR
on failure
and will set an errno describing why the operation failed.
RedisModule_SetModuleUserACLString
int RedisModule_SetModuleUserACLString(RedisModuleCtx *ctx,
RedisModuleUser *user,
const char *acl,
RedisModuleString **error);
Available since: 7.0.6
Sets the permission of a user with a complete ACL string, such as one
would use on the redis ACL SETUSER command line API. This differs from
RedisModule_SetModuleUserACL
, which only takes single ACL operations at a time.
Returns REDISMODULE_OK
on success and REDISMODULE_ERR
on failure
if a RedisModuleString
is provided in error, a string describing the error
will be returned
RedisModule_GetModuleUserACLString
RedisModuleString *RedisModule_GetModuleUserACLString(RedisModuleUser *user);
Available since: 7.0.6
Get the ACL string for a given user
Returns a RedisModuleString
RedisModule_GetCurrentUserName
RedisModuleString *RedisModule_GetCurrentUserName(RedisModuleCtx *ctx);
Available since: 7.0.0
Retrieve the user name of the client connection behind the current context.
The user name can be used later, in order to get a RedisModuleUser
.
See more information in RedisModule_GetModuleUserFromUserName
.
The returned string must be released with RedisModule_FreeString()
or by
enabling automatic memory management.
RedisModule_GetModuleUserFromUserName
RedisModuleUser *RedisModule_GetModuleUserFromUserName(RedisModuleString *name);
Available since: 7.0.0
A RedisModuleUser
can be used to check if command, key or channel can be executed or
accessed according to the ACLs rules associated with that user.
When a Module wants to do ACL checks on a general ACL user (not created by RedisModule_CreateModuleUser
),
it can get the RedisModuleUser
from this API, based on the user name retrieved by RedisModule_GetCurrentUserName
.
Since a general ACL user can be deleted at any time, this RedisModuleUser
should be used only in the context
where this function was called. In order to do ACL checks out of that context, the Module can store the user name,
and call this API at any other context.
Returns NULL if the user is disabled or the user does not exist.
The caller should later free the user using the function RedisModule_FreeModuleUser()
.
RedisModule_ACLCheckCommandPermissions
int RedisModule_ACLCheckCommandPermissions(RedisModuleUser *user,
RedisModuleString **argv,
int argc);
Available since: 7.0.0
Checks if the command can be executed by the user, according to the ACLs associated with it.
On success a REDISMODULE_OK
is returned, otherwise
REDISMODULE_ERR
is returned and errno is set to the following values:
- ENOENT: Specified command does not exist.
- EACCES: Command cannot be executed, according to ACL rules
RedisModule_ACLCheckKeyPermissions
int RedisModule_ACLCheckKeyPermissions(RedisModuleUser *user,
RedisModuleString *key,
int flags);
Available since: 7.0.0
Check if the key can be accessed by the user according to the ACLs attached to the user
and the flags representing the key access. The flags are the same that are used in the
keyspec for logical operations. These flags are documented in RedisModule_SetCommandInfo
as
the REDISMODULE_CMD_KEY_ACCESS
, REDISMODULE_CMD_KEY_UPDATE
, REDISMODULE_CMD_KEY_INSERT
,
and REDISMODULE_CMD_KEY_DELETE
flags.
If no flags are supplied, the user is still required to have some access to the key for this command to return successfully.
If the user is able to access the key then REDISMODULE_OK
is returned, otherwise
REDISMODULE_ERR
is returned and errno is set to one of the following values:
- EINVAL: The provided flags are invalid.
- EACCESS: The user does not have permission to access the key.
RedisModule_ACLCheckChannelPermissions
int RedisModule_ACLCheckChannelPermissions(RedisModuleUser *user,
RedisModuleString *ch,
int flags);
Available since: 7.0.0
Check if the pubsub channel can be accessed by the user based off of the given
access flags. See RedisModule_ChannelAtPosWithFlags
for more information about the
possible flags that can be passed in.
If the user is able to access the pubsub channel then REDISMODULE_OK
is returned, otherwise
REDISMODULE_ERR
is returned and errno is set to one of the following values:
- EINVAL: The provided flags are invalid.
- EACCESS: The user does not have permission to access the pubsub channel.
RedisModule_ACLAddLogEntry
int RedisModule_ACLAddLogEntry(RedisModuleCtx *ctx,
RedisModuleUser *user,
RedisModuleString *object,
RedisModuleACLLogEntryReason reason);
Available since: 7.0.0
Adds a new entry in the ACL log.
Returns REDISMODULE_OK
on success and REDISMODULE_ERR
on error.
For more information about ACL log, please refer to https://redis.io/commands/acl-log
RedisModule_ACLAddLogEntryByUserName
int RedisModule_ACLAddLogEntryByUserName(RedisModuleCtx *ctx,
RedisModuleString *username,
RedisModuleString *object,
RedisModuleACLLogEntryReason reason);
Available since: 7.2.0
Adds a new entry in the ACL log with the username
RedisModuleString
provided.
Returns REDISMODULE_OK
on success and REDISMODULE_ERR
on error.
For more information about ACL log, please refer to https://redis.io/commands/acl-log
RedisModule_AuthenticateClientWithUser
int RedisModule_AuthenticateClientWithUser(RedisModuleCtx *ctx,
RedisModuleUser *module_user,
RedisModuleUserChangedFunc callback,
void *privdata,
uint64_t *client_id);
Available since: 6.0.0
Authenticate the current context's user with the provided redis acl user.
Returns REDISMODULE_ERR
if the user is disabled.
See authenticateClientWithUser for information about callback, client_id
,
and general usage for authentication.
RedisModule_AuthenticateClientWithACLUser
int RedisModule_AuthenticateClientWithACLUser(RedisModuleCtx *ctx,
const char *name,
size_t len,
RedisModuleUserChangedFunc callback,
void *privdata,
uint64_t *client_id);
Available since: 6.0.0
Authenticate the current context's user with the provided redis acl user.
Returns REDISMODULE_ERR
if the user is disabled or the user does not exist.
See authenticateClientWithUser for information about callback, client_id
,
and general usage for authentication.
RedisModule_DeauthenticateAndCloseClient
int RedisModule_DeauthenticateAndCloseClient(RedisModuleCtx *ctx,
uint64_t client_id);
Available since: 6.0.0
Deauthenticate and close the client. The client resources will not be
immediately freed, but will be cleaned up in a background job. This is
the recommended way to deauthenticate a client since most clients can't
handle users becoming deauthenticated. Returns REDISMODULE_ERR
when the
client doesn't exist and REDISMODULE_OK
when the operation was successful.
The client ID is returned from the RedisModule_AuthenticateClientWithUser
and
RedisModule_AuthenticateClientWithACLUser
APIs, but can be obtained through
the CLIENT api or through server events.
This function is not thread safe, and must be executed within the context of a command or thread safe context.
RedisModule_RedactClientCommandArgument
int RedisModule_RedactClientCommandArgument(RedisModuleCtx *ctx, int pos);
Available since: 7.0.0
Redact the client command argument specified at the given position. Redacted arguments are obfuscated in user facing commands such as SLOWLOG or MONITOR, as well as never being written to server logs. This command may be called multiple times on the same position.
Note that the command name, position 0, can not be redacted.
Returns REDISMODULE_OK
if the argument was redacted and REDISMODULE_ERR
if there
was an invalid parameter passed in or the position is outside the client
argument range.
RedisModule_GetClientCertificate
RedisModuleString *RedisModule_GetClientCertificate(RedisModuleCtx *ctx,
uint64_t client_id);
Available since: 6.0.9
Return the X.509 client-side certificate used by the client to authenticate this connection.
The return value is an allocated RedisModuleString
that is a X.509 certificate
encoded in PEM (Base64) format. It should be freed (or auto-freed) by the caller.
A NULL value is returned in the following conditions:
- Connection ID does not exist
- Connection is not a TLS connection
- Connection is a TLS connection but no client certificate was used
Modules Dictionary API
Implements a sorted dictionary (actually backed by a radix tree) with the usual get / set / del / num-items API, together with an iterator capable of going back and forth.
RedisModule_CreateDict
RedisModuleDict *RedisModule_CreateDict(RedisModuleCtx *ctx);
Available since: 5.0.0
Create a new dictionary. The 'ctx' pointer can be the current module context or NULL, depending on what you want. Please follow the following rules:
- Use a NULL context if you plan to retain a reference to this dictionary that will survive the time of the module callback where you created it.
- Use a NULL context if no context is available at the time you are creating the dictionary (of course...).
- However use the current callback context as 'ctx' argument if the dictionary time to live is just limited to the callback scope. In this case, if enabled, you can enjoy the automatic memory management that will reclaim the dictionary memory, as well as the strings returned by the Next / Prev dictionary iterator calls.
RedisModule_FreeDict
void RedisModule_FreeDict(RedisModuleCtx *ctx, RedisModuleDict *d);
Available since: 5.0.0
Free a dictionary created with RedisModule_CreateDict()
. You need to pass the
context pointer 'ctx' only if the dictionary was created using the
context instead of passing NULL.
RedisModule_DictSize
uint64_t RedisModule_DictSize(RedisModuleDict *d);
Available since: 5.0.0
Return the size of the dictionary (number of keys).
RedisModule_DictSetC
int RedisModule_DictSetC(RedisModuleDict *d,
void *key,
size_t keylen,
void *ptr);
Available since: 5.0.0
Store the specified key into the dictionary, setting its value to the
pointer 'ptr'. If the key was added with success, since it did not
already exist, REDISMODULE_OK
is returned. Otherwise if the key already
exists the function returns REDISMODULE_ERR
.
RedisModule_DictReplaceC
int RedisModule_DictReplaceC(RedisModuleDict *d,
void *key,
size_t keylen,
void *ptr);
Available since: 5.0.0
Like RedisModule_DictSetC()
but will replace the key with the new
value if the key already exists.
RedisModule_DictSet
int RedisModule_DictSet(RedisModuleDict *d, RedisModuleString *key, void *ptr);
Available since: 5.0.0
Like RedisModule_DictSetC()
but takes the key as a RedisModuleString
.
RedisModule_DictReplace
int RedisModule_DictReplace(RedisModuleDict *d,
RedisModuleString *key,
void *ptr);
Available since: 5.0.0
Like RedisModule_DictReplaceC()
but takes the key as a RedisModuleString
.
RedisModule_DictGetC
void *RedisModule_DictGetC(RedisModuleDict *d,
void *key,
size_t keylen,
int *nokey);
Available since: 5.0.0
Return the value stored at the specified key. The function returns NULL both in the case the key does not exist, or if you actually stored NULL at key. So, optionally, if the 'nokey' pointer is not NULL, it will be set by reference to 1 if the key does not exist, or to 0 if the key exists.
RedisModule_DictGet
void *RedisModule_DictGet(RedisModuleDict *d,
RedisModuleString *key,
int *nokey);
Available since: 5.0.0
Like RedisModule_DictGetC()
but takes the key as a RedisModuleString
.
RedisModule_DictDelC
int RedisModule_DictDelC(RedisModuleDict *d,
void *key,
size_t keylen,
void *oldval);
Available since: 5.0.0
Remove the specified key from the dictionary, returning REDISMODULE_OK
if
the key was found and deleted, or REDISMODULE_ERR
if instead there was
no such key in the dictionary. When the operation is successful, if
'oldval' is not NULL, then '*oldval' is set to the value stored at the
key before it was deleted. Using this feature it is possible to get
a pointer to the value (for instance in order to release it), without
having to call RedisModule_DictGet()
before deleting the key.
RedisModule_DictDel
int RedisModule_DictDel(RedisModuleDict *d,
RedisModuleString *key,
void *oldval);
Available since: 5.0.0
Like RedisModule_DictDelC()
but gets the key as a RedisModuleString
.
RedisModule_DictIteratorStartC
RedisModuleDictIter *RedisModule_DictIteratorStartC(RedisModuleDict *d,
const char *op,
void *key,
size_t keylen);
Available since: 5.0.0
Return an iterator, setup in order to start iterating from the specified key by applying the operator 'op', which is just a string specifying the comparison operator to use in order to seek the first element. The operators available are:
^
– Seek the first (lexicographically smaller) key.$
– Seek the last (lexicographically bigger) key.>
– Seek the first element greater than the specified key.>=
– Seek the first element greater or equal than the specified key.<
– Seek the first element smaller than the specified key.<=
– Seek the first element smaller or equal than the specified key.==
– Seek the first element matching exactly the specified key.
Note that for ^
and $
the passed key is not used, and the user may
just pass NULL with a length of 0.
If the element to start the iteration cannot be seeked based on the
key and operator passed, RedisModule_DictNext()
/ Prev() will just return
REDISMODULE_ERR
at the first call, otherwise they'll produce elements.
RedisModule_DictIteratorStart
RedisModuleDictIter *RedisModule_DictIteratorStart(RedisModuleDict *d,
const char *op,
RedisModuleString *key);
Available since: 5.0.0
Exactly like RedisModule_DictIteratorStartC
, but the key is passed as a
RedisModuleString
.
RedisModule_DictIteratorStop
void RedisModule_DictIteratorStop(RedisModuleDictIter *di);
Available since: 5.0.0
Release the iterator created with RedisModule_DictIteratorStart()
. This call
is mandatory otherwise a memory leak is introduced in the module.
RedisModule_DictIteratorReseekC
int RedisModule_DictIteratorReseekC(RedisModuleDictIter *di,
const char *op,
void *key,
size_t keylen);
Available since: 5.0.0
After its creation with RedisModule_DictIteratorStart()
, it is possible to
change the currently selected element of the iterator by using this
API call. The result based on the operator and key is exactly like
the function RedisModule_DictIteratorStart()
, however in this case the
return value is just REDISMODULE_OK
in case the seeked element was found,
or REDISMODULE_ERR
in case it was not possible to seek the specified
element. It is possible to reseek an iterator as many times as you want.
RedisModule_DictIteratorReseek
int RedisModule_DictIteratorReseek(RedisModuleDictIter *di,
const char *op,
RedisModuleString *key);
Available since: 5.0.0
Like RedisModule_DictIteratorReseekC()
but takes the key as a
RedisModuleString
.
RedisModule_DictNextC
void *RedisModule_DictNextC(RedisModuleDictIter *di,
size_t *keylen,
void **dataptr);
Available since: 5.0.0
Return the current item of the dictionary iterator di
and steps to the
next element. If the iterator already yield the last element and there
are no other elements to return, NULL is returned, otherwise a pointer
to a string representing the key is provided, and the *keylen
length
is set by reference (if keylen is not NULL). The *dataptr
, if not NULL
is set to the value of the pointer stored at the returned key as auxiliary
data (as set by the RedisModule_DictSet
API).
Usage example:
... create the iterator here ...
char *key;
void *data;
while((key = RedisModule_DictNextC(iter,&keylen,&data)) != NULL) {
printf("%.*s %p\n", (int)keylen, key, data);
}
The returned pointer is of type void because sometimes it makes sense
to cast it to a char*
sometimes to an unsigned char*
depending on the
fact it contains or not binary data, so this API ends being more
comfortable to use.
The validity of the returned pointer is until the next call to the next/prev iterator step. Also the pointer is no longer valid once the iterator is released.
RedisModule_DictPrevC
void *RedisModule_DictPrevC(RedisModuleDictIter *di,
size_t *keylen,
void **dataptr);
Available since: 5.0.0
This function is exactly like RedisModule_DictNext()
but after returning
the currently selected element in the iterator, it selects the previous
element (lexicographically smaller) instead of the next one.
RedisModule_DictNext
RedisModuleString *RedisModule_DictNext(RedisModuleCtx *ctx,
RedisModuleDictIter *di,
void **dataptr);
Available since: 5.0.0
Like RedisModuleNextC()
, but instead of returning an internally allocated
buffer and key length, it returns directly a module string object allocated
in the specified context 'ctx' (that may be NULL exactly like for the main
API RedisModule_CreateString
).
The returned string object should be deallocated after use, either manually or by using a context that has automatic memory management active.
RedisModule_DictPrev
RedisModuleString *RedisModule_DictPrev(RedisModuleCtx *ctx,
RedisModuleDictIter *di,
void **dataptr);
Available since: 5.0.0
Like RedisModule_DictNext()
but after returning the currently selected
element in the iterator, it selects the previous element (lexicographically
smaller) instead of the next one.
RedisModule_DictCompareC
int RedisModule_DictCompareC(RedisModuleDictIter *di,
const char *op,
void *key,
size_t keylen);
Available since: 5.0.0
Compare the element currently pointed by the iterator to the specified
element given by key/keylen, according to the operator 'op' (the set of
valid operators are the same valid for RedisModule_DictIteratorStart
).
If the comparison is successful the command returns REDISMODULE_OK
otherwise REDISMODULE_ERR
is returned.
This is useful when we want to just emit a lexicographical range, so in the loop, as we iterate elements, we can also check if we are still on range.
The function return REDISMODULE_ERR
if the iterator reached the
end of elements condition as well.
RedisModule_DictCompare
int RedisModule_DictCompare(RedisModuleDictIter *di,
const char *op,
RedisModuleString *key);
Available since: 5.0.0
Like RedisModule_DictCompareC
but gets the key to compare with the current
iterator key as a RedisModuleString
.
Modules Info fields
RedisModule_InfoAddSection
int RedisModule_InfoAddSection(RedisModuleInfoCtx *ctx, const char *name);
Available since: 6.0.0
Used to start a new section, before adding any fields. the section name will
be prefixed by <modulename>_
and must only include A-Z,a-z,0-9.
NULL or empty string indicates the default section (only <modulename>
) is used.
When return value is REDISMODULE_ERR
, the section should and will be skipped.
RedisModule_InfoBeginDictField
int RedisModule_InfoBeginDictField(RedisModuleInfoCtx *ctx, const char *name);
Available since: 6.0.0
Starts a dict field, similar to the ones in INFO KEYSPACE. Use normal
RedisModule_InfoAddField
* functions to add the items to this field, and
terminate with RedisModule_InfoEndDictField
.
RedisModule_InfoEndDictField
int RedisModule_InfoEndDictField(RedisModuleInfoCtx *ctx);
Available since: 6.0.0
Ends a dict field, see RedisModule_InfoBeginDictField
RedisModule_InfoAddFieldString
int RedisModule_InfoAddFieldString(RedisModuleInfoCtx *ctx,
const char *field,
RedisModuleString *value);
Available since: 6.0.0
Used by RedisModuleInfoFunc
to add info fields.
Each field will be automatically prefixed by <modulename>_
.
Field names or values must not include \r\n
or :
.
RedisModule_InfoAddFieldCString
int RedisModule_InfoAddFieldCString(RedisModuleInfoCtx *ctx,
const char *field,
const char *value);
Available since: 6.0.0
See RedisModule_InfoAddFieldString()
.
RedisModule_InfoAddFieldDouble
int RedisModule_InfoAddFieldDouble(RedisModuleInfoCtx *ctx,
const char *field,
double value);
Available since: 6.0.0
See RedisModule_InfoAddFieldString()
.
RedisModule_InfoAddFieldLongLong
int RedisModule_InfoAddFieldLongLong(RedisModuleInfoCtx *ctx,
const char *field,
long long value);
Available since: 6.0.0
See RedisModule_InfoAddFieldString()
.
RedisModule_InfoAddFieldULongLong
int RedisModule_InfoAddFieldULongLong(RedisModuleInfoCtx *ctx,
const char *field,
unsigned long long value);
Available since: 6.0.0
See RedisModule_InfoAddFieldString()
.
RedisModule_RegisterInfoFunc
int RedisModule_RegisterInfoFunc(RedisModuleCtx *ctx, RedisModuleInfoFunc cb);
Available since: 6.0.0
Registers callback for the INFO command. The callback should add INFO fields
by calling the RedisModule_InfoAddField*()
functions.
RedisModule_GetServerInfo
RedisModuleServerInfoData *RedisModule_GetServerInfo(RedisModuleCtx *ctx,
const char *section);
Available since: 6.0.0
Get information about the server similar to the one that returns from the
INFO command. This function takes an optional 'section' argument that may
be NULL. The return value holds the output and can be used with
RedisModule_ServerInfoGetField
and alike to get the individual fields.
When done, it needs to be freed with RedisModule_FreeServerInfo
or with the
automatic memory management mechanism if enabled.
RedisModule_FreeServerInfo
void RedisModule_FreeServerInfo(RedisModuleCtx *ctx,
RedisModuleServerInfoData *data);
Available since: 6.0.0
Free data created with RedisModule_GetServerInfo()
. You need to pass the
context pointer 'ctx' only if the dictionary was created using the
context instead of passing NULL.
RedisModule_ServerInfoGetField
RedisModuleString *RedisModule_ServerInfoGetField(RedisModuleCtx *ctx,
RedisModuleServerInfoData *data,
const char* field);
Available since: 6.0.0
Get the value of a field from data collected with RedisModule_GetServerInfo()
. You
need to pass the context pointer 'ctx' only if you want to use auto memory
mechanism to release the returned string. Return value will be NULL if the
field was not found.
RedisModule_ServerInfoGetFieldC
const char *RedisModule_ServerInfoGetFieldC(RedisModuleServerInfoData *data,
const char* field);
Available since: 6.0.0
Similar to RedisModule_ServerInfoGetField
, but returns a char* which should not be freed but the caller.
RedisModule_ServerInfoGetFieldSigned
long long RedisModule_ServerInfoGetFieldSigned(RedisModuleServerInfoData *data,
const char* field,
int *out_err);
Available since: 6.0.0
Get the value of a field from data collected with RedisModule_GetServerInfo()
. If the
field is not found, or is not numerical or out of range, return value will be
0, and the optional out_err
argument will be set to REDISMODULE_ERR
.
RedisModule_ServerInfoGetFieldUnsigned
unsigned long long RedisModule_ServerInfoGetFieldUnsigned(RedisModuleServerInfoData *data,
const char* field,
int *out_err);
Available since: 6.0.0
Get the value of a field from data collected with RedisModule_GetServerInfo()
. If the
field is not found, or is not numerical or out of range, return value will be
0, and the optional out_err
argument will be set to REDISMODULE_ERR
.
RedisModule_ServerInfoGetFieldDouble
double RedisModule_ServerInfoGetFieldDouble(RedisModuleServerInfoData *data,
const char* field,
int *out_err);
Available since: 6.0.0
Get the value of a field from data collected with RedisModule_GetServerInfo()
. If the
field is not found, or is not a double, return value will be 0, and the
optional out_err
argument will be set to REDISMODULE_ERR
.
Modules utility APIs
RedisModule_GetRandomBytes
void RedisModule_GetRandomBytes(unsigned char *dst, size_t len);
Available since: 5.0.0
Return random bytes using SHA1 in counter mode with a /dev/urandom initialized seed. This function is fast so can be used to generate many bytes without any effect on the operating system entropy pool. Currently this function is not thread safe.
RedisModule_GetRandomHexChars
void RedisModule_GetRandomHexChars(char *dst, size_t len);
Available since: 5.0.0
Like RedisModule_GetRandomBytes()
but instead of setting the string to
random bytes the string is set to random characters in the in the
hex charset [0-9a-f].
Modules API exporting / importing
RedisModule_ExportSharedAPI
int RedisModule_ExportSharedAPI(RedisModuleCtx *ctx,
const char *apiname,
void *func);
Available since: 5.0.4
This function is called by a module in order to export some API with a
given name. Other modules will be able to use this API by calling the
symmetrical function RedisModule_GetSharedAPI()
and casting the return value to
the right function pointer.
The function will return REDISMODULE_OK
if the name is not already taken,
otherwise REDISMODULE_ERR
will be returned and no operation will be
performed.
IMPORTANT: the apiname argument should be a string literal with static lifetime. The API relies on the fact that it will always be valid in the future.
RedisModule_GetSharedAPI
void *RedisModule_GetSharedAPI(RedisModuleCtx *ctx, const char *apiname);
Available since: 5.0.4
Request an exported API pointer. The return value is just a void pointer that the caller of this function will be required to cast to the right function pointer, so this is a private contract between modules.
If the requested API is not available then NULL is returned. Because modules can be loaded at different times with different order, this function calls should be put inside some module generic API registering step, that is called every time a module attempts to execute a command that requires external APIs: if some API cannot be resolved, the command should return an error.
Here is an example:
int ... myCommandImplementation(void) {
if (getExternalAPIs() == 0) {
reply with an error here if we cannot have the APIs
}
// Use the API:
myFunctionPointer(foo);
}
And the function registerAPI() is:
int getExternalAPIs(void) {
static int api_loaded = 0;
if (api_loaded != 0) return 1; // APIs already resolved.
myFunctionPointer = RedisModule_GetSharedAPI("...");
if (myFunctionPointer == NULL) return 0;
return 1;
}
Module Command Filter API
RedisModule_RegisterCommandFilter
RedisModuleCommandFilter *RedisModule_RegisterCommandFilter(RedisModuleCtx *ctx,
RedisModuleCommandFilterFunc callback,
int flags);
Available since: 5.0.5
Register a new command filter function.
Command filtering makes it possible for modules to extend Redis by plugging into the execution flow of all commands.
A registered filter gets called before Redis executes any command. This includes both core Redis commands and commands registered by any module. The filter applies in all execution paths including:
- Invocation by a client.
- Invocation through
RedisModule_Call()
by any module. - Invocation through Lua
redis.call()
. - Replication of a command from a master.
The filter executes in a special filter context, which is different and more
limited than a RedisModuleCtx
. Because the filter affects any command, it
must be implemented in a very efficient way to reduce the performance impact
on Redis. All Redis Module API calls that require a valid context (such as
RedisModule_Call()
, RedisModule_OpenKey()
, etc.) are not supported in a
filter context.
The RedisModuleCommandFilterCtx
can be used to inspect or modify the
executed command and its arguments. As the filter executes before Redis
begins processing the command, any change will affect the way the command is
processed. For example, a module can override Redis commands this way:
- Register a
MODULE.SET
command which implements an extended version of the RedisSET
command. - Register a command filter which detects invocation of
SET
on a specific pattern of keys. Once detected, the filter will replace the first argument fromSET
toMODULE.SET
. - When filter execution is complete, Redis considers the new command name and therefore executes the module's own command.
Note that in the above use case, if MODULE.SET
itself uses
RedisModule_Call()
the filter will be applied on that call as well. If
that is not desired, the REDISMODULE_CMDFILTER_NOSELF
flag can be set when
registering the filter.
The REDISMODULE_CMDFILTER_NOSELF
flag prevents execution flows that
originate from the module's own RedisModule_Call()
from reaching the filter. This
flag is effective for all execution flows, including nested ones, as long as
the execution begins from the module's command context or a thread-safe
context that is associated with a blocking command.
Detached thread-safe contexts are not associated with the module and cannot be protected by this flag.
If multiple filters are registered (by the same or different modules), they are executed in the order of registration.
RedisModule_UnregisterCommandFilter
int RedisModule_UnregisterCommandFilter(RedisModuleCtx *ctx,
RedisModuleCommandFilter *filter);
Available since: 5.0.5
Unregister a command filter.
RedisModule_CommandFilterArgsCount
int RedisModule_CommandFilterArgsCount(RedisModuleCommandFilterCtx *fctx);
Available since: 5.0.5
Return the number of arguments a filtered command has. The number of arguments include the command itself.
RedisModule_CommandFilterArgGet
RedisModuleString *RedisModule_CommandFilterArgGet(RedisModuleCommandFilterCtx *fctx,
int pos);
Available since: 5.0.5
Return the specified command argument. The first argument (position 0) is the command itself, and the rest are user-provided args.
RedisModule_CommandFilterArgInsert
int RedisModule_CommandFilterArgInsert(RedisModuleCommandFilterCtx *fctx,
int pos,
RedisModuleString *arg);
Available since: 5.0.5
Modify the filtered command by inserting a new argument at the specified
position. The specified RedisModuleString
argument may be used by Redis
after the filter context is destroyed, so it must not be auto-memory
allocated, freed or used elsewhere.
RedisModule_CommandFilterArgReplace
int RedisModule_CommandFilterArgReplace(RedisModuleCommandFilterCtx *fctx,
int pos,
RedisModuleString *arg);
Available since: 5.0.5
Modify the filtered command by replacing an existing argument with a new one.
The specified RedisModuleString
argument may be used by Redis after the
filter context is destroyed, so it must not be auto-memory allocated, freed
or used elsewhere.
RedisModule_CommandFilterArgDelete
int RedisModule_CommandFilterArgDelete(RedisModuleCommandFilterCtx *fctx,
int pos);
Available since: 5.0.5
Modify the filtered command by deleting an argument at the specified position.
RedisModule_CommandFilterGetClientId
unsigned long long RedisModule_CommandFilterGetClientId(RedisModuleCommandFilterCtx *fctx);
Available since: 7.2.0
Get Client ID for client that issued the command we are filtering
RedisModule_MallocSize
size_t RedisModule_MallocSize(void* ptr);
Available since: 6.0.0
For a given pointer allocated via RedisModule_Alloc()
or
RedisModule_Realloc()
, return the amount of memory allocated for it.
Note that this may be different (larger) than the memory we allocated
with the allocation calls, since sometimes the underlying allocator
will allocate more memory.
RedisModule_MallocUsableSize
size_t RedisModule_MallocUsableSize(void *ptr);
Available since: 7.0.1
Similar to RedisModule_MallocSize
, the difference is that RedisModule_MallocUsableSize
returns the usable size of memory by the module.
RedisModule_MallocSizeString
size_t RedisModule_MallocSizeString(RedisModuleString* str);
Available since: 7.0.0
Same as RedisModule_MallocSize
, except it works on RedisModuleString
pointers.
RedisModule_MallocSizeDict
size_t RedisModule_MallocSizeDict(RedisModuleDict* dict);
Available since: 7.0.0
Same as RedisModule_MallocSize
, except it works on RedisModuleDict
pointers.
Note that the returned value is only the overhead of the underlying structures,
it does not include the allocation size of the keys and values.
RedisModule_GetUsedMemoryRatio
float RedisModule_GetUsedMemoryRatio(void);
Available since: 6.0.0
Return the a number between 0 to 1 indicating the amount of memory currently used, relative to the Redis "maxmemory" configuration.
- 0 - No memory limit configured.
- Between 0 and 1 - The percentage of the memory used normalized in 0-1 range.
- Exactly 1 - Memory limit reached.
- Greater 1 - More memory used than the configured limit.
Scanning keyspace and hashes
RedisModule_ScanCursorCreate
RedisModuleScanCursor *RedisModule_ScanCursorCreate(void);
Available since: 6.0.0
Create a new cursor to be used with RedisModule_Scan
RedisModule_ScanCursorRestart
void RedisModule_ScanCursorRestart(RedisModuleScanCursor *cursor);
Available since: 6.0.0
Restart an existing cursor. The keys will be rescanned.
RedisModule_ScanCursorDestroy
void RedisModule_ScanCursorDestroy(RedisModuleScanCursor *cursor);
Available since: 6.0.0
Destroy the cursor struct.
RedisModule_Scan
int RedisModule_Scan(RedisModuleCtx *ctx,
RedisModuleScanCursor *cursor,
RedisModuleScanCB fn,
void *privdata);
Available since: 6.0.0
Scan API that allows a module to scan all the keys and value in the selected db.
Callback for scan implementation.
void scan_callback(RedisModuleCtx *ctx, RedisModuleString *keyname,
RedisModuleKey *key, void *privdata);
ctx
: the redis module context provided to for the scan.keyname
: owned by the caller and need to be retained if used after this function.key
: holds info on the key and value, it is provided as best effort, in some cases it might be NULL, in which case the user should (can) useRedisModule_OpenKey()
(and CloseKey too). when it is provided, it is owned by the caller and will be free when the callback returns.privdata
: the user data provided toRedisModule_Scan()
.
The way it should be used:
RedisModuleScanCursor *c = RedisModule_ScanCursorCreate();
while(RedisModule_Scan(ctx, c, callback, privateData));
RedisModule_ScanCursorDestroy(c);
It is also possible to use this API from another thread while the lock
is acquired during the actual call to RedisModule_Scan
:
RedisModuleScanCursor *c = RedisModule_ScanCursorCreate();
RedisModule_ThreadSafeContextLock(ctx);
while(RedisModule_Scan(ctx, c, callback, privateData)){
RedisModule_ThreadSafeContextUnlock(ctx);
// do some background job
RedisModule_ThreadSafeContextLock(ctx);
}
RedisModule_ScanCursorDestroy(c);
The function will return 1 if there are more elements to scan and 0 otherwise, possibly setting errno if the call failed.
It is also possible to restart an existing cursor using RedisModule_ScanCursorRestart
.
IMPORTANT: This API is very similar to the Redis SCAN command from the point of view of the guarantees it provides. This means that the API may report duplicated keys, but guarantees to report at least one time every key that was there from the start to the end of the scanning process.
NOTE: If you do database changes within the callback, you should be aware that the internal state of the database may change. For instance it is safe to delete or modify the current key, but may not be safe to delete any other key. Moreover playing with the Redis keyspace while iterating may have the effect of returning more duplicates. A safe pattern is to store the keys names you want to modify elsewhere, and perform the actions on the keys later when the iteration is complete. However this can cost a lot of memory, so it may make sense to just operate on the current key when possible during the iteration, given that this is safe.
RedisModule_ScanKey
int RedisModule_ScanKey(RedisModuleKey *key,
RedisModuleScanCursor *cursor,
RedisModuleScanKeyCB fn,
void *privdata);
Available since: 6.0.0
Scan api that allows a module to scan the elements in a hash, set or sorted set key
Callback for scan implementation.
void scan_callback(RedisModuleKey *key, RedisModuleString* field, RedisModuleString* value, void *privdata);
- key - the redis key context provided to for the scan.
- field - field name, owned by the caller and need to be retained if used after this function.
- value - value string or NULL for set type, owned by the caller and need to be retained if used after this function.
- privdata - the user data provided to
RedisModule_ScanKey
.
The way it should be used:
RedisModuleScanCursor *c = RedisModule_ScanCursorCreate();
RedisModuleKey *key = RedisModule_OpenKey(...)
while(RedisModule_ScanKey(key, c, callback, privateData));
RedisModule_CloseKey(key);
RedisModule_ScanCursorDestroy(c);
It is also possible to use this API from another thread while the lock is acquired during
the actual call to RedisModule_ScanKey
, and re-opening the key each time:
RedisModuleScanCursor *c = RedisModule_ScanCursorCreate();
RedisModule_ThreadSafeContextLock(ctx);
RedisModuleKey *key = RedisModule_OpenKey(...)
while(RedisModule_ScanKey(ctx, c, callback, privateData)){
RedisModule_CloseKey(key);
RedisModule_ThreadSafeContextUnlock(ctx);
// do some background job
RedisModule_ThreadSafeContextLock(ctx);
RedisModuleKey *key = RedisModule_OpenKey(...)
}
RedisModule_CloseKey(key);
RedisModule_ScanCursorDestroy(c);
The function will return 1 if there are more elements to scan and 0 otherwise,
possibly setting errno if the call failed.
It is also possible to restart an existing cursor using RedisModule_ScanCursorRestart
.
NOTE: Certain operations are unsafe while iterating the object. For instance while the API guarantees to return at least one time all the elements that are present in the data structure consistently from the start to the end of the iteration (see HSCAN and similar commands documentation), the more you play with the elements, the more duplicates you may get. In general deleting the current element of the data structure is safe, while removing the key you are iterating is not safe.
Module fork API
RedisModule_Fork
int RedisModule_Fork(RedisModuleForkDoneHandler cb, void *user_data);
Available since: 6.0.0
Create a background child process with the current frozen snapshot of the
main process where you can do some processing in the background without
affecting / freezing the traffic and no need for threads and GIL locking.
Note that Redis allows for only one concurrent fork.
When the child wants to exit, it should call RedisModule_ExitFromChild
.
If the parent wants to kill the child it should call RedisModule_KillForkChild
The done handler callback will be executed on the parent process when the
child existed (but not when killed)
Return: -1 on failure, on success the parent process will get a positive PID
of the child, and the child process will get 0.
RedisModule_SendChildHeartbeat
void RedisModule_SendChildHeartbeat(double progress);
Available since: 6.2.0
The module is advised to call this function from the fork child once in a while,
so that it can report progress and COW memory to the parent which will be
reported in INFO.
The progress
argument should between 0 and 1, or -1 when not available.
RedisModule_ExitFromChild
int RedisModule_ExitFromChild(int retcode);
Available since: 6.0.0
Call from the child process when you want to terminate it. retcode will be provided to the done handler executed on the parent process.
RedisModule_KillForkChild
int RedisModule_KillForkChild(int child_pid);
Available since: 6.0.0
Can be used to kill the forked child process from the parent process.
child_pid
would be the return value of RedisModule_Fork
.
Server hooks implementation
RedisModule_SubscribeToServerEvent
int RedisModule_SubscribeToServerEvent(RedisModuleCtx *ctx,
RedisModuleEvent event,
RedisModuleEventCallback callback);
Available since: 6.0.0
Register to be notified, via a callback, when the specified server event happens. The callback is called with the event as argument, and an additional argument which is a void pointer and should be cased to a specific type that is event-specific (but many events will just use NULL since they do not have additional information to pass to the callback).
If the callback is NULL and there was a previous subscription, the module will be unsubscribed. If there was a previous subscription and the callback is not null, the old callback will be replaced with the new one.
The callback must be of this type:
int (*RedisModuleEventCallback)(RedisModuleCtx *ctx,
RedisModuleEvent eid,
uint64_t subevent,
void *data);
The 'ctx' is a normal Redis module context that the callback can use in order to call other modules APIs. The 'eid' is the event itself, this is only useful in the case the module subscribed to multiple events: using the 'id' field of this structure it is possible to check if the event is one of the events we registered with this callback. The 'subevent' field depends on the event that fired.
Finally the 'data' pointer may be populated, only for certain events, with more relevant data.
Here is a list of events you can use as 'eid' and related sub events:
-
RedisModuleEvent_ReplicationRoleChanged
:This event is called when the instance switches from master to replica or the other way around, however the event is also called when the replica remains a replica but starts to replicate with a different master.
The following sub events are available:
REDISMODULE_SUBEVENT_REPLROLECHANGED_NOW_MASTER
REDISMODULE_SUBEVENT_REPLROLECHANGED_NOW_REPLICA
The 'data' field can be casted by the callback to a
RedisModuleReplicationInfo
structure with the following fields:int master; // true if master, false if replica char *masterhost; // master instance hostname for NOW_REPLICA int masterport; // master instance port for NOW_REPLICA char *replid1; // Main replication ID char *replid2; // Secondary replication ID uint64_t repl1_offset; // Main replication offset uint64_t repl2_offset; // Offset of replid2 validity
-
RedisModuleEvent_Persistence
This event is called when RDB saving or AOF rewriting starts and ends. The following sub events are available:
REDISMODULE_SUBEVENT_PERSISTENCE_RDB_START
REDISMODULE_SUBEVENT_PERSISTENCE_AOF_START
REDISMODULE_SUBEVENT_PERSISTENCE_SYNC_RDB_START
REDISMODULE_SUBEVENT_PERSISTENCE_SYNC_AOF_START
REDISMODULE_SUBEVENT_PERSISTENCE_ENDED
REDISMODULE_SUBEVENT_PERSISTENCE_FAILED
The above events are triggered not just when the user calls the relevant commands like BGSAVE, but also when a saving operation or AOF rewriting occurs because of internal server triggers. The SYNC_RDB_START sub events are happening in the foreground due to SAVE command, FLUSHALL, or server shutdown, and the other RDB and AOF sub events are executed in a background fork child, so any action the module takes can only affect the generated AOF or RDB, but will not be reflected in the parent process and affect connected clients and commands. Also note that the AOF_START sub event may end up saving RDB content in case of an AOF with rdb-preamble.
-
RedisModuleEvent_FlushDB
The FLUSHALL, FLUSHDB or an internal flush (for instance because of replication, after the replica synchronization) happened. The following sub events are available:
REDISMODULE_SUBEVENT_FLUSHDB_START
REDISMODULE_SUBEVENT_FLUSHDB_END
The data pointer can be casted to a RedisModuleFlushInfo structure with the following fields:
int32_t async; // True if the flush is done in a thread. // See for instance FLUSHALL ASYNC. // In this case the END callback is invoked // immediately after the database is put // in the free list of the thread. int32_t dbnum; // Flushed database number, -1 for all the DBs // in the case of the FLUSHALL operation.
The start event is called before the operation is initiated, thus allowing the callback to call DBSIZE or other operation on the yet-to-free keyspace.
-
RedisModuleEvent_Loading
Called on loading operations: at startup when the server is started, but also after a first synchronization when the replica is loading the RDB file from the master. The following sub events are available:
REDISMODULE_SUBEVENT_LOADING_RDB_START
REDISMODULE_SUBEVENT_LOADING_AOF_START
REDISMODULE_SUBEVENT_LOADING_REPL_START
REDISMODULE_SUBEVENT_LOADING_ENDED
REDISMODULE_SUBEVENT_LOADING_FAILED
Note that AOF loading may start with an RDB data in case of rdb-preamble, in which case you'll only receive an AOF_START event.
-
RedisModuleEvent_ClientChange
Called when a client connects or disconnects. The data pointer can be casted to a RedisModuleClientInfo structure, documented in RedisModule_GetClientInfoById(). The following sub events are available:
REDISMODULE_SUBEVENT_CLIENT_CHANGE_CONNECTED
REDISMODULE_SUBEVENT_CLIENT_CHANGE_DISCONNECTED
-
RedisModuleEvent_Shutdown
The server is shutting down. No subevents are available.
-
RedisModuleEvent_ReplicaChange
This event is called when the instance (that can be both a master or a replica) get a new online replica, or lose a replica since it gets disconnected. The following sub events are available:
REDISMODULE_SUBEVENT_REPLICA_CHANGE_ONLINE
REDISMODULE_SUBEVENT_REPLICA_CHANGE_OFFLINE
No additional information is available so far: future versions of Redis will have an API in order to enumerate the replicas connected and their state.
-
RedisModuleEvent_CronLoop
This event is called every time Redis calls the serverCron() function in order to do certain bookkeeping. Modules that are required to do operations from time to time may use this callback. Normally Redis calls this function 10 times per second, but this changes depending on the "hz" configuration. No sub events are available.
The data pointer can be casted to a RedisModuleCronLoop structure with the following fields:
int32_t hz; // Approximate number of events per second.
-
RedisModuleEvent_MasterLinkChange
This is called for replicas in order to notify when the replication link becomes functional (up) with our master, or when it goes down. Note that the link is not considered up when we just connected to the master, but only if the replication is happening correctly. The following sub events are available:
REDISMODULE_SUBEVENT_MASTER_LINK_UP
REDISMODULE_SUBEVENT_MASTER_LINK_DOWN
-
RedisModuleEvent_ModuleChange
This event is called when a new module is loaded or one is unloaded. The following sub events are available:
REDISMODULE_SUBEVENT_MODULE_LOADED
REDISMODULE_SUBEVENT_MODULE_UNLOADED
The data pointer can be casted to a RedisModuleModuleChange structure with the following fields:
const char* module_name; // Name of module loaded or unloaded. int32_t module_version; // Module version.
-
RedisModuleEvent_LoadingProgress
This event is called repeatedly called while an RDB or AOF file is being loaded. The following sub events are available:
REDISMODULE_SUBEVENT_LOADING_PROGRESS_RDB
REDISMODULE_SUBEVENT_LOADING_PROGRESS_AOF
The data pointer can be casted to a RedisModuleLoadingProgress structure with the following fields:
int32_t hz; // Approximate number of events per second. int32_t progress; // Approximate progress between 0 and 1024, // or -1 if unknown.
-
RedisModuleEvent_SwapDB
This event is called when a SWAPDB command has been successfully Executed. For this event call currently there is no subevents available.
The data pointer can be casted to a RedisModuleSwapDbInfo structure with the following fields:
int32_t dbnum_first; // Swap Db first dbnum int32_t dbnum_second; // Swap Db second dbnum
-
RedisModuleEvent_ReplBackup
WARNING: Replication Backup events are deprecated since Redis 7.0 and are never fired. See RedisModuleEvent_ReplAsyncLoad for understanding how Async Replication Loading events are now triggered when repl-diskless-load is set to swapdb.
Called when repl-diskless-load config is set to swapdb, And redis needs to backup the current database for the possibility to be restored later. A module with global data and maybe with aux_load and aux_save callbacks may need to use this notification to backup / restore / discard its globals. The following sub events are available:
REDISMODULE_SUBEVENT_REPL_BACKUP_CREATE
REDISMODULE_SUBEVENT_REPL_BACKUP_RESTORE
REDISMODULE_SUBEVENT_REPL_BACKUP_DISCARD
-
RedisModuleEvent_ReplAsyncLoad
Called when repl-diskless-load config is set to swapdb and a replication with a master of same data set history (matching replication ID) occurs. In which case redis serves current data set while loading new database in memory from socket. Modules must have declared they support this mechanism in order to activate it, through REDISMODULE_OPTIONS_HANDLE_REPL_ASYNC_LOAD flag. The following sub events are available:
REDISMODULE_SUBEVENT_REPL_ASYNC_LOAD_STARTED
REDISMODULE_SUBEVENT_REPL_ASYNC_LOAD_ABORTED
REDISMODULE_SUBEVENT_REPL_ASYNC_LOAD_COMPLETED
-
RedisModuleEvent_ForkChild
Called when a fork child (AOFRW, RDBSAVE, module fork...) is born/dies The following sub events are available:
REDISMODULE_SUBEVENT_FORK_CHILD_BORN
REDISMODULE_SUBEVENT_FORK_CHILD_DIED
-
RedisModuleEvent_EventLoop
Called on each event loop iteration, once just before the event loop goes to sleep or just after it wakes up. The following sub events are available:
REDISMODULE_SUBEVENT_EVENTLOOP_BEFORE_SLEEP
REDISMODULE_SUBEVENT_EVENTLOOP_AFTER_SLEEP
-
RedisModule_Event_Config
Called when a configuration event happens The following sub events are available:
REDISMODULE_SUBEVENT_CONFIG_CHANGE
The data pointer can be casted to a RedisModuleConfigChange structure with the following fields:
const char **config_names; // An array of C string pointers containing the // name of each modified configuration item uint32_t num_changes; // The number of elements in the config_names array
-
RedisModule_Event_Key
Called when a key is removed from the keyspace. We can't modify any key in the event. The following sub events are available:
REDISMODULE_SUBEVENT_KEY_DELETED
REDISMODULE_SUBEVENT_KEY_EXPIRED
REDISMODULE_SUBEVENT_KEY_EVICTED
REDISMODULE_SUBEVENT_KEY_OVERWRITTEN
The data pointer can be casted to a RedisModuleKeyInfo structure with the following fields:
RedisModuleKey *key; // Key name
The function returns REDISMODULE_OK
if the module was successfully subscribed
for the specified event. If the API is called from a wrong context or unsupported event
is given then REDISMODULE_ERR
is returned.
RedisModule_IsSubEventSupported
int RedisModule_IsSubEventSupported(RedisModuleEvent event, int64_t subevent);
Available since: 6.0.9
For a given server event and subevent, return zero if the subevent is not supported and non-zero otherwise.
Module Configurations API
RedisModule_RegisterStringConfig
int RedisModule_RegisterStringConfig(RedisModuleCtx *ctx,
const char *name,
const char *default_val,
unsigned int flags,
RedisModuleConfigGetStringFunc getfn,
RedisModuleConfigSetStringFunc setfn,
RedisModuleConfigApplyFunc applyfn,
void *privdata);
Available since: 7.0.0
Create a string config that Redis users can interact with via the Redis config file,
CONFIG SET
, CONFIG GET
, and CONFIG REWRITE
commands.
The actual config value is owned by the module, and the getfn
, setfn
and optional
applyfn
callbacks that are provided to Redis in order to access or manipulate the
value. The getfn
callback retrieves the value from the module, while the setfn
callback provides a value to be stored into the module config.
The optional applyfn
callback is called after a CONFIG SET
command modified one or
more configs using the setfn
callback and can be used to atomically apply a config
after several configs were changed together.
If there are multiple configs with applyfn
callbacks set by a single CONFIG SET
command, they will be deduplicated if their applyfn
function and privdata
pointers
are identical, and the callback will only be run once.
Both the setfn
and applyfn
can return an error if the provided value is invalid or
cannot be used.
The config also declares a type for the value that is validated by Redis and
provided to the module. The config system provides the following types:
- Redis String: Binary safe string data.
- Enum: One of a finite number of string tokens, provided during registration.
- Numeric: 64 bit signed integer, which also supports min and max values.
- Bool: Yes or no value.
The setfn
callback is expected to return REDISMODULE_OK
when the value is successfully
applied. It can also return REDISMODULE_ERR
if the value can't be applied, and the
*err pointer can be set with a RedisModuleString
error message to provide to the client.
This RedisModuleString
will be freed by redis after returning from the set callback.
All configs are registered with a name, a type, a default value, private data that is made available in the callbacks, as well as several flags that modify the behavior of the config. The name must only contain alphanumeric characters or dashes. The supported flags are:
REDISMODULE_CONFIG_DEFAULT
: The default flags for a config. This creates a config that can be modified after startup.REDISMODULE_CONFIG_IMMUTABLE
: This config can only be provided loading time.REDISMODULE_CONFIG_SENSITIVE
: The value stored in this config is redacted from all logging.REDISMODULE_CONFIG_HIDDEN
: The name is hidden fromCONFIG GET
with pattern matching.REDISMODULE_CONFIG_PROTECTED
: This config will be only be modifiable based off the value of enable-protected-configs.REDISMODULE_CONFIG_DENY_LOADING
: This config is not modifiable while the server is loading data.REDISMODULE_CONFIG_MEMORY
: For numeric configs, this config will convert data unit notations into their byte equivalent.REDISMODULE_CONFIG_BITFLAGS
: For enum configs, this config will allow multiple entries to be combined as bit flags.
Default values are used on startup to set the value if it is not provided via the config file or command line. Default values are also used to compare to on a config rewrite.
Notes:
- On string config sets that the string passed to the set callback will be freed after execution and the module must retain it.
- On string config gets the string will not be consumed and will be valid after execution.
Example implementation:
RedisModuleString *strval;
int adjustable = 1;
RedisModuleString *getStringConfigCommand(const char *name, void *privdata) {
return strval;
}
int setStringConfigCommand(const char *name, RedisModuleString *new, void *privdata, RedisModuleString **err) {
if (adjustable) {
RedisModule_Free(strval);
RedisModule_RetainString(NULL, new);
strval = new;
return REDISMODULE_OK;
}
*err = RedisModule_CreateString(NULL, "Not adjustable.", 15);
return REDISMODULE_ERR;
}
...
RedisModule_RegisterStringConfig(ctx, "string", NULL, REDISMODULE_CONFIG_DEFAULT, getStringConfigCommand, setStringConfigCommand, NULL, NULL);
If the registration fails, REDISMODULE_ERR
is returned and one of the following
errno is set:
- EBUSY: Registering the Config outside of
RedisModule_OnLoad
. - EINVAL: The provided flags are invalid for the registration or the name of the config contains invalid characters.
- EALREADY: The provided configuration name is already used.
RedisModule_RegisterBoolConfig
int RedisModule_RegisterBoolConfig(RedisModuleCtx *ctx,
const char *name,
int default_val,
unsigned int flags,
RedisModuleConfigGetBoolFunc getfn,
RedisModuleConfigSetBoolFunc setfn,
RedisModuleConfigApplyFunc applyfn,
void *privdata);
Available since: 7.0.0
Create a bool config that server clients can interact with via the
CONFIG SET
, CONFIG GET
, and CONFIG REWRITE
commands. See
RedisModule_RegisterStringConfig
for detailed information about configs.
RedisModule_RegisterEnumConfig
int RedisModule_RegisterEnumConfig(RedisModuleCtx *ctx,
const char *name,
int default_val,
unsigned int flags,
const char **enum_values,
const int *int_values,
int num_enum_vals,
RedisModuleConfigGetEnumFunc getfn,
RedisModuleConfigSetEnumFunc setfn,
RedisModuleConfigApplyFunc applyfn,
void *privdata);
Available since: 7.0.0
Create an enum config that server clients can interact with via the
CONFIG SET
, CONFIG GET
, and CONFIG REWRITE
commands.
Enum configs are a set of string tokens to corresponding integer values, where
the string value is exposed to Redis clients but the value passed Redis and the
module is the integer value. These values are defined in enum_values
, an array
of null-terminated c strings, and int_vals
, an array of enum values who has an
index partner in enum_values
.
Example Implementation:
const char *enum_vals[3] = {"first", "second", "third"};
const int int_vals[3] = {0, 2, 4};
int enum_val = 0;
int getEnumConfigCommand(const char *name, void *privdata) {
return enum_val;
}
int setEnumConfigCommand(const char *name, int val, void *privdata, const char **err) {
enum_val = val;
return REDISMODULE_OK;
}
...
RedisModule_RegisterEnumConfig(ctx, "enum", 0, REDISMODULE_CONFIG_DEFAULT, enum_vals, int_vals, 3, getEnumConfigCommand, setEnumConfigCommand, NULL, NULL);
Note that you can use REDISMODULE_CONFIG_BITFLAGS
so that multiple enum string
can be combined into one integer as bit flags, in which case you may want to
sort your enums so that the preferred combinations are present first.
See RedisModule_RegisterStringConfig
for detailed general information about configs.
RedisModule_RegisterNumericConfig
int RedisModule_RegisterNumericConfig(RedisModuleCtx *ctx,
const char *name,
long long default_val,
unsigned int flags,
long long min,
long long max,
RedisModuleConfigGetNumericFunc getfn,
RedisModuleConfigSetNumericFunc setfn,
RedisModuleConfigApplyFunc applyfn,
void *privdata);
Available since: 7.0.0
Create an integer config that server clients can interact with via the
CONFIG SET
, CONFIG GET
, and CONFIG REWRITE
commands. See
RedisModule_RegisterStringConfig
for detailed information about configs.
RedisModule_LoadConfigs
int RedisModule_LoadConfigs(RedisModuleCtx *ctx);
Available since: 7.0.0
Applies all pending configurations on the module load. This should be called
after all of the configurations have been registered for the module inside of RedisModule_OnLoad
.
This will return REDISMODULE_ERR
if it is called outside RedisModule_OnLoad
.
This API needs to be called when configurations are provided in either MODULE LOADEX
or provided as startup arguments.
RDB load/save API
RedisModule_RdbStreamCreateFromFile
RedisModuleRdbStream *RedisModule_RdbStreamCreateFromFile(const char *filename);
Available since: 7.2.0
Create a stream object to save/load RDB to/from a file.
This function returns a pointer to RedisModuleRdbStream
which is owned
by the caller. It requires a call to RedisModule_RdbStreamFree()
to free
the object.
RedisModule_RdbStreamFree
void RedisModule_RdbStreamFree(RedisModuleRdbStream *stream);
Available since: 7.2.0
Release an RDB stream object.
RedisModule_RdbLoad
int RedisModule_RdbLoad(RedisModuleCtx *ctx,
RedisModuleRdbStream *stream,
int flags);
Available since: 7.2.0
Load RDB file from the stream
. Dataset will be cleared first and then RDB
file will be loaded.
flags
must be zero. This parameter is for future use.
On success REDISMODULE_OK
is returned, otherwise REDISMODULE_ERR
is returned
and errno is set accordingly.
Example:
RedisModuleRdbStream *s = RedisModule_RdbStreamCreateFromFile("exp.rdb");
RedisModule_RdbLoad(ctx, s, 0);
RedisModule_RdbStreamFree(s);
RedisModule_RdbSave
int RedisModule_RdbSave(RedisModuleCtx *ctx,
RedisModuleRdbStream *stream,
int flags);
Available since: 7.2.0
Save dataset to the RDB stream.
flags
must be zero. This parameter is for future use.
On success REDISMODULE_OK
is returned, otherwise REDISMODULE_ERR
is returned
and errno is set accordingly.
Example:
RedisModuleRdbStream *s = RedisModule_RdbStreamCreateFromFile("exp.rdb");
RedisModule_RdbSave(ctx, s, 0);
RedisModule_RdbStreamFree(s);
Key eviction API
RedisModule_SetLRU
int RedisModule_SetLRU(RedisModuleKey *key, mstime_t lru_idle);
Available since: 6.0.0
Set the key last access time for LRU based eviction. not relevant if the
servers's maxmemory policy is LFU based. Value is idle time in milliseconds.
returns REDISMODULE_OK
if the LRU was updated, REDISMODULE_ERR
otherwise.
RedisModule_GetLRU
int RedisModule_GetLRU(RedisModuleKey *key, mstime_t *lru_idle);
Available since: 6.0.0
Gets the key last access time.
Value is idletime in milliseconds or -1 if the server's eviction policy is
LFU based.
returns REDISMODULE_OK
if when key is valid.
RedisModule_SetLFU
int RedisModule_SetLFU(RedisModuleKey *key, long long lfu_freq);
Available since: 6.0.0
Set the key access frequency. only relevant if the server's maxmemory policy
is LFU based.
The frequency is a logarithmic counter that provides an indication of
the access frequencyonly (must be <= 255).
returns REDISMODULE_OK
if the LFU was updated, REDISMODULE_ERR
otherwise.
RedisModule_GetLFU
int RedisModule_GetLFU(RedisModuleKey *key, long long *lfu_freq);
Available since: 6.0.0
Gets the key access frequency or -1 if the server's eviction policy is not
LFU based.
returns REDISMODULE_OK
if when key is valid.
Miscellaneous APIs
RedisModule_GetModuleOptionsAll
int RedisModule_GetModuleOptionsAll(void);
Available since: 7.2.0
Returns the full module options flags mask, using the return value the module can check if a certain set of module options are supported by the redis server version in use. Example:
int supportedFlags = RedisModule_GetModuleOptionsAll();
if (supportedFlags & REDISMODULE_OPTIONS_ALLOW_NESTED_KEYSPACE_NOTIFICATIONS) {
// REDISMODULE_OPTIONS_ALLOW_NESTED_KEYSPACE_NOTIFICATIONS is supported
} else{
// REDISMODULE_OPTIONS_ALLOW_NESTED_KEYSPACE_NOTIFICATIONS is not supported
}
RedisModule_GetContextFlagsAll
int RedisModule_GetContextFlagsAll(void);
Available since: 6.0.9
Returns the full ContextFlags mask, using the return value the module can check if a certain set of flags are supported by the redis server version in use. Example:
int supportedFlags = RedisModule_GetContextFlagsAll();
if (supportedFlags & REDISMODULE_CTX_FLAGS_MULTI) {
// REDISMODULE_CTX_FLAGS_MULTI is supported
} else{
// REDISMODULE_CTX_FLAGS_MULTI is not supported
}
RedisModule_GetKeyspaceNotificationFlagsAll
int RedisModule_GetKeyspaceNotificationFlagsAll(void);
Available since: 6.0.9
Returns the full KeyspaceNotification mask, using the return value the module can check if a certain set of flags are supported by the redis server version in use. Example:
int supportedFlags = RedisModule_GetKeyspaceNotificationFlagsAll();
if (supportedFlags & REDISMODULE_NOTIFY_LOADED) {
// REDISMODULE_NOTIFY_LOADED is supported
} else{
// REDISMODULE_NOTIFY_LOADED is not supported
}
RedisModule_GetServerVersion
int RedisModule_GetServerVersion(void);
Available since: 6.0.9
Return the redis version in format of 0x00MMmmpp. Example for 6.0.7 the return value will be 0x00060007.
RedisModule_GetTypeMethodVersion
int RedisModule_GetTypeMethodVersion(void);
Available since: 6.2.0
Return the current redis-server runtime value of REDISMODULE_TYPE_METHOD_VERSION
.
You can use that when calling RedisModule_CreateDataType
to know which fields of
RedisModuleTypeMethods
are gonna be supported and which will be ignored.
RedisModule_ModuleTypeReplaceValue
int RedisModule_ModuleTypeReplaceValue(RedisModuleKey *key,
moduleType *mt,
void *new_value,
void **old_value);
Available since: 6.0.0
Replace the value assigned to a module type.
The key must be open for writing, have an existing value, and have a moduleType that matches the one specified by the caller.
Unlike RedisModule_ModuleTypeSetValue()
which will free the old value, this function
simply swaps the old value with the new value.
The function returns REDISMODULE_OK
on success, REDISMODULE_ERR
on errors
such as:
- Key is not opened for writing.
- Key is not a module data type key.
- Key is a module datatype other than 'mt'.
If old_value
is non-NULL, the old value is returned by reference.
RedisModule_GetCommandKeysWithFlags
int *RedisModule_GetCommandKeysWithFlags(RedisModuleCtx *ctx,
RedisModuleString **argv,
int argc,
int *num_keys,
int **out_flags);
Available since: 7.0.0
For a specified command, parse its arguments and return an array that
contains the indexes of all key name arguments. This function is
essentially a more efficient way to do COMMAND GETKEYS
.
The out_flags
argument is optional, and can be set to NULL.
When provided it is filled with REDISMODULE_CMD_KEY_
flags in matching
indexes with the key indexes of the returned array.
A NULL return value indicates the specified command has no keys, or an error condition. Error conditions are indicated by setting errno as follows:
- ENOENT: Specified command does not exist.
- EINVAL: Invalid command arity specified.
NOTE: The returned array is not a Redis Module object so it does not
get automatically freed even when auto-memory is used. The caller
must explicitly call RedisModule_Free()
to free it, same as the out_flags
pointer if
used.
RedisModule_GetCommandKeys
int *RedisModule_GetCommandKeys(RedisModuleCtx *ctx,
RedisModuleString **argv,
int argc,
int *num_keys);
Available since: 6.0.9
Identical to RedisModule_GetCommandKeysWithFlags
when flags are not needed.
RedisModule_GetCurrentCommandName
const char *RedisModule_GetCurrentCommandName(RedisModuleCtx *ctx);
Available since: 6.2.5
Return the name of the command currently running
Defrag API
RedisModule_RegisterDefragFunc
int RedisModule_RegisterDefragFunc(RedisModuleCtx *ctx,
RedisModuleDefragFunc cb);
Available since: 6.2.0
Register a defrag callback for global data, i.e. anything that the module may allocate that is not tied to a specific data type.
RedisModule_DefragShouldStop
int RedisModule_DefragShouldStop(RedisModuleDefragCtx *ctx);
Available since: 6.2.0
When the data type defrag callback iterates complex structures, this function should be called periodically. A zero (false) return indicates the callback may continue its work. A non-zero value (true) indicates it should stop.
When stopped, the callback may use RedisModule_DefragCursorSet()
to store its
position so it can later use RedisModule_DefragCursorGet()
to resume defragging.
When stopped and more work is left to be done, the callback should return 1. Otherwise, it should return 0.
NOTE: Modules should consider the frequency in which this function is called, so it generally makes sense to do small batches of work in between calls.
RedisModule_DefragCursorSet
int RedisModule_DefragCursorSet(RedisModuleDefragCtx *ctx,
unsigned long cursor);
Available since: 6.2.0
Store an arbitrary cursor value for future re-use.
This should only be called if RedisModule_DefragShouldStop()
has returned a non-zero
value and the defrag callback is about to exit without fully iterating its
data type.
This behavior is reserved to cases where late defrag is performed. Late
defrag is selected for keys that implement the free_effort
callback and
return a free_effort
value that is larger than the defrag
'active-defrag-max-scan-fields' configuration directive.
Smaller keys, keys that do not implement free_effort
or the global
defrag callback are not called in late-defrag mode. In those cases, a
call to this function will return REDISMODULE_ERR
.
The cursor may be used by the module to represent some progress into the module's data type. Modules may also store additional cursor-related information locally and use the cursor as a flag that indicates when traversal of a new key begins. This is possible because the API makes a guarantee that concurrent defragmentation of multiple keys will not be performed.
RedisModule_DefragCursorGet
int RedisModule_DefragCursorGet(RedisModuleDefragCtx *ctx,
unsigned long *cursor);
Available since: 6.2.0
Fetch a cursor value that has been previously stored using RedisModule_DefragCursorSet()
.
If not called for a late defrag operation, REDISMODULE_ERR
will be returned and
the cursor should be ignored. See RedisModule_DefragCursorSet()
for more details on
defrag cursors.
RedisModule_DefragAlloc
void *RedisModule_DefragAlloc(RedisModuleDefragCtx *ctx, void *ptr);
Available since: 6.2.0
Defrag a memory allocation previously allocated by RedisModule_Alloc
, RedisModule_Calloc
, etc.
The defragmentation process involves allocating a new memory block and copying
the contents to it, like realloc()
.
If defragmentation was not necessary, NULL is returned and the operation has no other effect.
If a non-NULL value is returned, the caller should use the new pointer instead of the old one and update any reference to the old pointer, which must not be used again.
RedisModule_DefragRedisModuleString
RedisModuleString *RedisModule_DefragRedisModuleString(RedisModuleDefragCtx *ctx,
RedisModuleString *str);
Available since: 6.2.0
Defrag a RedisModuleString
previously allocated by RedisModule_Alloc
, RedisModule_Calloc
, etc.
See RedisModule_DefragAlloc()
for more information on how the defragmentation process
works.
NOTE: It is only possible to defrag strings that have a single reference.
Typically this means strings retained with RedisModule_RetainString
or RedisModule_HoldString
may not be defragmentable. One exception is command argvs which, if retained
by the module, will end up with a single reference (because the reference
on the Redis side is dropped as soon as the command callback returns).
RedisModule_GetKeyNameFromDefragCtx
const RedisModuleString *RedisModule_GetKeyNameFromDefragCtx(RedisModuleDefragCtx *ctx);
Available since: 7.0.0
Returns the name of the key currently being processed. There is no guarantee that the key name is always available, so this may return NULL.
RedisModule_GetDbIdFromDefragCtx
int RedisModule_GetDbIdFromDefragCtx(RedisModuleDefragCtx *ctx);
Available since: 7.0.0
Returns the database id of the key currently being processed. There is no guarantee that this info is always available, so this may return -1.
Function index
RedisModule_ACLAddLogEntry
RedisModule_ACLAddLogEntryByUserName
RedisModule_ACLCheckChannelPermissions
RedisModule_ACLCheckCommandPermissions
RedisModule_ACLCheckKeyPermissions
RedisModule_AbortBlock
RedisModule_AddPostNotificationJob
RedisModule_Alloc
RedisModule_AuthenticateClientWithACLUser
RedisModule_AuthenticateClientWithUser
RedisModule_AutoMemory
RedisModule_AvoidReplicaTraffic
RedisModule_BlockClient
RedisModule_BlockClientGetPrivateData
RedisModule_BlockClientOnAuth
RedisModule_BlockClientOnKeys
RedisModule_BlockClientOnKeysWithFlags
RedisModule_BlockClientSetPrivateData
RedisModule_BlockedClientDisconnected
RedisModule_BlockedClientMeasureTimeEnd
RedisModule_BlockedClientMeasureTimeStart
RedisModule_CachedMicroseconds
RedisModule_Call
RedisModule_CallReplyArrayElement
RedisModule_CallReplyAttribute
RedisModule_CallReplyAttributeElement
RedisModule_CallReplyBigNumber
RedisModule_CallReplyBool
RedisModule_CallReplyDouble
RedisModule_CallReplyInteger
RedisModule_CallReplyLength
RedisModule_CallReplyMapElement
RedisModule_CallReplyPromiseAbort
RedisModule_CallReplyPromiseSetUnblockHandler
RedisModule_CallReplyProto
RedisModule_CallReplySetElement
RedisModule_CallReplyStringPtr
RedisModule_CallReplyType
RedisModule_CallReplyVerbatim
RedisModule_Calloc
RedisModule_ChannelAtPosWithFlags
RedisModule_CloseKey
RedisModule_CommandFilterArgDelete
RedisModule_CommandFilterArgGet
RedisModule_CommandFilterArgInsert
RedisModule_CommandFilterArgReplace
RedisModule_CommandFilterArgsCount
RedisModule_CommandFilterGetClientId
RedisModule_CreateCommand
RedisModule_CreateDataType
RedisModule_CreateDict
RedisModule_CreateModuleUser
RedisModule_CreateString
RedisModule_CreateStringFromCallReply
RedisModule_CreateStringFromDouble
RedisModule_CreateStringFromLongDouble
RedisModule_CreateStringFromLongLong
RedisModule_CreateStringFromStreamID
RedisModule_CreateStringFromString
RedisModule_CreateStringFromULongLong
RedisModule_CreateStringPrintf
RedisModule_CreateSubcommand
RedisModule_CreateTimer
RedisModule_DbSize
RedisModule_DeauthenticateAndCloseClient
RedisModule_DefragAlloc
RedisModule_DefragCursorGet
RedisModule_DefragCursorSet
RedisModule_DefragRedisModuleString
RedisModule_DefragShouldStop
RedisModule_DeleteKey
RedisModule_DictCompare
RedisModule_DictCompareC
RedisModule_DictDel
RedisModule_DictDelC
RedisModule_DictGet
RedisModule_DictGetC
RedisModule_DictIteratorReseek
RedisModule_DictIteratorReseekC
RedisModule_DictIteratorStart
RedisModule_DictIteratorStartC
RedisModule_DictIteratorStop
RedisModule_DictNext
RedisModule_DictNextC
RedisModule_DictPrev
RedisModule_DictPrevC
RedisModule_DictReplace
RedisModule_DictReplaceC
RedisModule_DictSet
RedisModule_DictSetC
RedisModule_DictSize
RedisModule_DigestAddLongLong
RedisModule_DigestAddStringBuffer
RedisModule_DigestEndSequence
RedisModule_EmitAOF
RedisModule_EventLoopAdd
RedisModule_EventLoopAddOneShot
RedisModule_EventLoopDel
RedisModule_ExitFromChild
RedisModule_ExportSharedAPI
RedisModule_Fork
RedisModule_Free
RedisModule_FreeCallReply
RedisModule_FreeClusterNodesList
RedisModule_FreeDict
RedisModule_FreeModuleUser
RedisModule_FreeServerInfo
RedisModule_FreeString
RedisModule_FreeThreadSafeContext
RedisModule_GetAbsExpire
RedisModule_GetBlockedClientHandle
RedisModule_GetBlockedClientPrivateData
RedisModule_GetBlockedClientReadyKey
RedisModule_GetClientCertificate
RedisModule_GetClientId
RedisModule_GetClientInfoById
RedisModule_GetClientNameById
RedisModule_GetClientUserNameById
RedisModule_GetClusterNodeInfo
RedisModule_GetClusterNodesList
RedisModule_GetClusterSize
RedisModule_GetCommand
RedisModule_GetCommandKeys
RedisModule_GetCommandKeysWithFlags
RedisModule_GetContextFlags
RedisModule_GetContextFlagsAll
RedisModule_GetCurrentCommandName
RedisModule_GetCurrentUserName
RedisModule_GetDbIdFromDefragCtx
RedisModule_GetDbIdFromDigest
RedisModule_GetDbIdFromIO
RedisModule_GetDbIdFromModuleKey
RedisModule_GetDbIdFromOptCtx
RedisModule_GetDetachedThreadSafeContext
RedisModule_GetExpire
RedisModule_GetKeyNameFromDefragCtx
RedisModule_GetKeyNameFromDigest
RedisModule_GetKeyNameFromIO
RedisModule_GetKeyNameFromModuleKey
RedisModule_GetKeyNameFromOptCtx
RedisModule_GetKeyspaceNotificationFlagsAll
RedisModule_GetLFU
RedisModule_GetLRU
RedisModule_GetModuleOptionsAll
RedisModule_GetModuleUserACLString
RedisModule_GetModuleUserFromUserName
RedisModule_GetMyClusterID
RedisModule_GetNotifyKeyspaceEvents
RedisModule_GetOpenKeyModesAll
RedisModule_GetRandomBytes
RedisModule_GetRandomHexChars
RedisModule_GetSelectedDb
RedisModule_GetServerInfo
RedisModule_GetServerVersion
RedisModule_GetSharedAPI
RedisModule_GetThreadSafeContext
RedisModule_GetTimerInfo
RedisModule_GetToDbIdFromOptCtx
RedisModule_GetToKeyNameFromOptCtx
RedisModule_GetTypeMethodVersion
RedisModule_GetUsedMemoryRatio
RedisModule_HashGet
RedisModule_HashSet
RedisModule_HoldString
RedisModule_InfoAddFieldCString
RedisModule_InfoAddFieldDouble
RedisModule_InfoAddFieldLongLong
RedisModule_InfoAddFieldString
RedisModule_InfoAddFieldULongLong
RedisModule_InfoAddSection
RedisModule_InfoBeginDictField
RedisModule_InfoEndDictField
RedisModule_IsBlockedReplyRequest
RedisModule_IsBlockedTimeoutRequest
RedisModule_IsChannelsPositionRequest
RedisModule_IsIOError
RedisModule_IsKeysPositionRequest
RedisModule_IsModuleNameBusy
RedisModule_IsSubEventSupported
RedisModule_KeyAtPos
RedisModule_KeyAtPosWithFlags
RedisModule_KeyExists
RedisModule_KeyType
RedisModule_KillForkChild
RedisModule_LatencyAddSample
RedisModule_ListDelete
RedisModule_ListGet
RedisModule_ListInsert
RedisModule_ListPop
RedisModule_ListPush
RedisModule_ListSet
RedisModule_LoadConfigs
RedisModule_LoadDataTypeFromString
RedisModule_LoadDataTypeFromStringEncver
RedisModule_LoadDouble
RedisModule_LoadFloat
RedisModule_LoadLongDouble
RedisModule_LoadSigned
RedisModule_LoadString
RedisModule_LoadStringBuffer
RedisModule_LoadUnsigned
RedisModule_Log
RedisModule_LogIOError
RedisModule_MallocSize
RedisModule_MallocSizeDict
RedisModule_MallocSizeString
RedisModule_MallocUsableSize
RedisModule_Microseconds
RedisModule_Milliseconds
RedisModule_ModuleTypeGetType
RedisModule_ModuleTypeGetValue
RedisModule_ModuleTypeReplaceValue
RedisModule_ModuleTypeSetValue
RedisModule_MonotonicMicroseconds
RedisModule_NotifyKeyspaceEvent
RedisModule_OpenKey
RedisModule_PoolAlloc
RedisModule_PublishMessage
RedisModule_PublishMessageShard
RedisModule_RandomKey
RedisModule_RdbLoad
RedisModule_RdbSave
RedisModule_RdbStreamCreateFromFile
RedisModule_RdbStreamFree
RedisModule_Realloc
RedisModule_RedactClientCommandArgument
RedisModule_RegisterAuthCallback
RedisModule_RegisterBoolConfig
RedisModule_RegisterClusterMessageReceiver
RedisModule_RegisterCommandFilter
RedisModule_RegisterDefragFunc
RedisModule_RegisterEnumConfig
RedisModule_RegisterInfoFunc
RedisModule_RegisterNumericConfig
RedisModule_RegisterStringConfig
RedisModule_Replicate
RedisModule_ReplicateVerbatim
RedisModule_ReplySetArrayLength
RedisModule_ReplySetAttributeLength
RedisModule_ReplySetMapLength
RedisModule_ReplySetSetLength
RedisModule_ReplyWithArray
RedisModule_ReplyWithAttribute
RedisModule_ReplyWithBigNumber
RedisModule_ReplyWithBool
RedisModule_ReplyWithCString
RedisModule_ReplyWithCallReply
RedisModule_ReplyWithDouble
RedisModule_ReplyWithEmptyArray
RedisModule_ReplyWithEmptyString
RedisModule_ReplyWithError
RedisModule_ReplyWithErrorFormat
RedisModule_ReplyWithLongDouble
RedisModule_ReplyWithLongLong
RedisModule_ReplyWithMap
RedisModule_ReplyWithNull
RedisModule_ReplyWithNullArray
RedisModule_ReplyWithSet
RedisModule_ReplyWithSimpleString
RedisModule_ReplyWithString
RedisModule_ReplyWithStringBuffer
RedisModule_ReplyWithVerbatimString
RedisModule_ReplyWithVerbatimStringType
RedisModule_ResetDataset
RedisModule_RetainString
RedisModule_SaveDataTypeToString
RedisModule_SaveDouble
RedisModule_SaveFloat
RedisModule_SaveLongDouble
RedisModule_SaveSigned
RedisModule_SaveString
RedisModule_SaveStringBuffer
RedisModule_SaveUnsigned
RedisModule_Scan
RedisModule_ScanCursorCreate
RedisModule_ScanCursorDestroy
RedisModule_ScanCursorRestart
RedisModule_ScanKey
RedisModule_SelectDb
RedisModule_SendChildHeartbeat
RedisModule_SendClusterMessage
RedisModule_ServerInfoGetField
RedisModule_ServerInfoGetFieldC
RedisModule_ServerInfoGetFieldDouble
RedisModule_ServerInfoGetFieldSigned
RedisModule_ServerInfoGetFieldUnsigned
RedisModule_SetAbsExpire
RedisModule_SetClientNameById
RedisModule_SetClusterFlags
RedisModule_SetCommandACLCategories
RedisModule_SetCommandInfo
RedisModule_SetContextUser
RedisModule_SetDisconnectCallback
RedisModule_SetExpire
RedisModule_SetLFU
RedisModule_SetLRU
RedisModule_SetModuleOptions
RedisModule_SetModuleUserACL
RedisModule_SetModuleUserACLString
RedisModule_SignalKeyAsReady
RedisModule_SignalModifiedKey
RedisModule_StopTimer
RedisModule_Strdup
RedisModule_StreamAdd
RedisModule_StreamDelete
RedisModule_StreamIteratorDelete
RedisModule_StreamIteratorNextField
RedisModule_StreamIteratorNextID
RedisModule_StreamIteratorStart
RedisModule_StreamIteratorStop
RedisModule_StreamTrimByID
RedisModule_StreamTrimByLength
RedisModule_StringAppendBuffer
RedisModule_StringCompare
RedisModule_StringDMA
RedisModule_StringPtrLen
RedisModule_StringSet
RedisModule_StringToDouble
RedisModule_StringToLongDouble
RedisModule_StringToLongLong
RedisModule_StringToStreamID
RedisModule_StringToULongLong
RedisModule_StringTruncate
RedisModule_SubscribeToKeyspaceEvents
RedisModule_SubscribeToServerEvent
RedisModule_ThreadSafeContextLock
RedisModule_ThreadSafeContextTryLock
RedisModule_ThreadSafeContextUnlock
RedisModule_TrimStringAllocation
RedisModule_TryAlloc
RedisModule_UnblockClient
RedisModule_UnlinkKey
RedisModule_UnregisterCommandFilter
RedisModule_ValueLength
RedisModule_WrongArity
RedisModule_Yield
RedisModule_ZsetAdd
RedisModule_ZsetFirstInLexRange
RedisModule_ZsetFirstInScoreRange
RedisModule_ZsetIncrby
RedisModule_ZsetLastInLexRange
RedisModule_ZsetLastInScoreRange
RedisModule_ZsetRangeCurrentElement
RedisModule_ZsetRangeEndReached
RedisModule_ZsetRangeNext
RedisModule_ZsetRangePrev
RedisModule_ZsetRangeStop
RedisModule_ZsetRem
RedisModule_ZsetScore
RedisModule__Assert