[OpenSIPS-Users] [NEW]memcached implementation for memory caching

[andrei dragus]

Hello,

A new module that provides a new caching method using memcached servers was added.
It provides a way to access memcached servers using the existing memcache API.

Advantages over the existing "localcache" module:
	- memory costs are no longer on the server
	- many servers may be used so the memory is virtually unlimited
	- the cache is persistent so a restart of the server will not affect the cache
	- memcached is an open-source project so it can be used to exchange data with various other applications
	- servers may be grouped together (e.g. for security purposes : some can be inside a private network, some can be in a public one).
	  
Limitations:
	- keys (in key:value pairs) may not contain spaces or control characters
	
Requirements:
	- libmemcahed is a dependency of the module ( see docs)
	- memcached servers must exist somewhere accessible via the network.
	
Usage:
	- memcached module must be loaded
	- server parameters must be set
	E.g:
	
	...
	modparam("memcached", "server","group1 = localhost:9999,127.0.0.1" );
	modparam("memcached", "server","y = random_url:8888" );
	...
	This creates two groups of servers( one called "group1" and one called "y").
	
	
	- Calls to the two groups will be done via the memcache API by passing the first parameter as "memcached_($GROUP_NAME)".
	E.g:
	
	...
	cache_store("memcached_group1","key","$ru value");
	... 
	This stores "key"="$ru value" on the group denoted by "group1".
	The key is only stored on one of the servers in a consistent fashion	(subsequent calls with "key" will be stored, deleted from the same server).
	
	
	...
	cache_fetch("memcached_y","key",$avp(i:10));
	cache_remove("memcached_y","key");
	...
	This attempts to fetch/remove key from the group named "y".
	
Thanks, Andrei.