MEMCACHED

Andrei Dragus

   OpenSIPS

Edited by

Andrei Dragus

Edited by

Vladut-Stefan Paiu

   Copyright © 2009 Voice System

   Copyright © 2009 Andrei Dragus
   Revision History
   Revision $Revision: 5901 $ $Date$
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Advantages
        1.3. Limitations
        1.4. Dependencies

              1.4.1. OpenSIPS Modules
              1.4.2. External Libraries or Applications

        1.5. Exported Parameters

              1.5.1. cachedb_url (string)
              1.5.2. exec_threshold (int)
              1.5.3. Exported Functions

   List of Examples

   1.1. Set cachedb_url parameter
   1.2. Use memcached servers
   1.3. Set exec_threshold parameter

Chapter 1. Admin Guide

1.1. Overview

   This module is an implementation of a cache system designed to
   work with a memcached server. It uses libmemcached client
   library to connect to several memcached servers that store
   data. It uses the Key-Value interface exported from the core.

1.2. Advantages

     * 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)

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:
     * libmemcached:
       libmemcached can be downloaded from:
       http://tangent.org/552/libmemcached.html. Download the
       archive, extract sources, run ./configure, make,sudo make
       install.
       ...
       wget http://download.tangent.org/libmemcached-0.31.tar.gz
       tar -xzvf libmemcached-0.31.tar.gz
       cd libmemcached-0.31
       ./configure
       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_memcached", "cachedb_url","memcached:group1://localhos
t:9999,127.0.0.1/");
modparam("cachedb_memcached", "cachedb_url","memcached:y://random_url:88
88/");
...

   Example 1.2. Use memcached servers
...
cache_store("memcached:group1","key","$ru value");
cache_fetch("memcached:y","key",$avp(10));
cache_remove("memcached:group1","key");
...

1.5.2. exec_threshold (int)

   The maximum number of microseconds that a local cache query can
   last. Anything above the threshold will trigger a warning
   message to the log

   Default value is “0 ( unlimited - no warnings )”.

   Example 1.3. Set exec_threshold parameter
...
modparam("cachedb_memcached", "exec_threshold", 100000)
...

1.5.3. Exported Functions

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