cachedb_redis Module

This module is an implementation of a cache system designed to work with a Redis server. It uses hiredis client library to connect to either a single Redis server instance, or to a Redis Server inside a Redis Cluster. It uses the Key-Value interface exported from the core.

1.2. Advantages

memory costs are no longer on the server
many servers can be used inside a cluster, so the memory is virtually unlimited
the cache is 100% persistent. A restart of OpenSIPS server will not affect the DB. The Redis DB is also persistent so it can also be restarted without loss of information.
redis is an open-source project so it can be used to exchange data with various other applications
By creating a Redis Cluster, multiple OpenSIPS instances can easily share key-value information

1.3. Limitations

keys (in key:value pairs) may not contain spaces or control characters

1.4. Dependencies

1.4.1. OpenSIPS Modules

None.

1.4.2. External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

hiredis:
On the latest Debian based distributions, hiredis can be installed by running 'apt-get install libhiredis-dev' Alternatively, if hiredis is not available on your OS repos, hiredis can be downloaded from: https://github.com/antirez/hiredis . Download the archive, extract sources, run make,sudo make install.

1.5. Exported Parameters

1.5.1. `cachedb_url` (string)

The urls of the server groups that OpenSIPS will connect to in order to use the from script cache_store,cache_fetch, etc operations. It can be set more than one time. The prefix part of the URL will be the identifier that will be used from the script.

Example 1.1. Set cachedb_url parameter

...
modparam("cachedb_redis", "cachedb_url","redis:group1://localhost:6379/")
modparam("cachedb_redis", "cachedb_url","redis:cluster1://random_url:8888/")
...

Example 1.2. Use Redis servers

...
cache_store("redis:group1","key","$ru value");
cache_fetch("redis:cluster1","key",$avp(10));
cache_remove("redis:cluster1","key");
...

1.5.2. `connect_timeout` (integer)

This parameter specifies how many milliseconds OpenSIPS should wait for connecting to a Redis node.

Default value is “5000 ms”.

Example 1.3. Set connect_timeout parameter

...
# wait 1 seconds for Redis to connect
modparam("cachedb_redis", "connect_timeout",1000)
...

1.5.3. `query_timeout` (integer)

This parameter specifies how many milliseconds OpenSIPS should wait for a query response from a Redis node.

Default value is “5000 ms”.

Example 1.4. Set connect_timeout parameter

...
# wait 1 seconds for Redis queries
modparam("cachedb_redis", "query_timeout",1000)
...

1.6. Exported Functions

The module does not export functions to be used in configuration script.

1.7. Raw Query Syntax

The cachedb_redis module allows to run RAW queries, thus taking full advantage of the capabilities of the back-end. The query syntax is the typical REDIS one.

Here are a couple examples of running some Redis queries :

Example 1.5. Redis Raw Query Examples

...
	$var(my_hash) = "my_hash_name";
	$var(my_key) = "my_key_name";
	$var(my_value) = "my_key_value";
	cache_raw_query("redis","HSET $var(my_hash) $var(my_key) $var(my_value)");
	cache_raw_query("redis","HGET $var(my_hash) $var(my_key)","$avp(result)");
	xlog("We have fetched $avp(result) \n");
...
	$var(my_hash) = "my_hash_name";
	$var(my_key1) = "my_key1_name";
	$var(my_key2) = "my_key2_name";
	$var(my_value1) = "my_key1_value";
	$var(my_value2) = "my_key2_value";
	cache_raw_query("redis","HSET $var(my_hash) $var(my_key1) $var(my_value1)");
	cache_raw_query("redis","HSET $var(my_hash) $var(my_key2) $var(my_value2)");
	cache_raw_query("redis","HGETALL $var(my_hash)","$avp(result)");

	$var(it) = 0;
	while ($(avp(result_final)[$var(it)]) != NULL) {
		xlog("Multiple key reply: - we have fetched $(avp(result_final)[$var(it)]) \n");
		$var(it) = $var(it) + 1;
	}
...

cachedb_redis Module

Vladut-Stefan Paiu

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