Purpose

This application is able to start/stop memcached instances in the host where it runs and also offer configurable connection pools to interact with those instances or others that may be running (locally or remotely).

From a user point of view, the memcache.erl module is the library interface and the only one that should be interacted with.

Internally, this library is a wrapper around poolboy and erlmc_conn. The first one is used to create a pool of connections, while the latter creates a persistent connection to Memcached using its binary protocol.

Features

• Automatically start a local Memcached instance
• Supervision of the local Memcached instance if it was started by this app
• (Named) Pools and their management
• Statistics retrieval from Memcached

Configuration

This application uses the following configuration keys:

• start_memcached: a string template with placeholders for 3 variables: Host (string), Memory and Port (integers).
• stop_memcached: a string template with placeholders for 2 variables: Host (string) and Port (integer).
• pools: a proplist with {Poolname, Poolproperties} tuples, where Poolname is an atom and PoolProperties is a proplist with the following elements:
  • size: an integer with the amount of connections per pool
  • max_overflow: integer
  • port: integer
  • host: string
  • opts: a proplists with options applicable only when starting the memcached server. Currently only memory is supported
  • start: whether this application should be responsible for starting memcached or not (boolean)

An example of configuration follows:

[
    {memcache, [
        {pools, [
            {yaddapool, [
                {size, 10},
                {max_overflow, 20},
                {port, 3333},
                {host, "localhost"},
                {opts, [{memory, 4}]},
                {start_server, true}
            ]}
        ]}
    ]}
]

Notes

• Currently only the memory of a memcached instance (-m) can be set
• Local memcached instances are started and stopped via os commands
• This application has been tested with memcached 1.4.4 un CentOS 5 and 6 and 1.4.13 in Ubuntu 12.04 using Erlang R15B0[1-3]