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Description

mcache is an erlang memcached client application. It utilizes many new features to improve performance such as NIF (only from R13B03 on), dynamic compiling modules.

Start/Stop/Configuration

mcache is an OTP application. You may start or stop it as following:

application:start(mcache)
application:stop(mcache).

It requires the following configuration (in -config <ConfigFile> or sys.config)

{mcache,
	[
		{pools,[
			[{name, generic}, % Pool name is "generic"
			 {servers, 
				[ 
					{ {1,0,0,1}, 11211, 256 },   % Servers definition. IP address should be in {A,B,C,D} format
					{ {1,0,0,2}, 11211, 256 }
                ]}
			]
		]}
	]
}

Usage

  1. Get a single key.
 mcache:get(Class, Key).

For example: mcache:get(my.friends, foobar) gets the key "my.friends:foobar"

Which memcached server is selected? The following steps go:

  1. Get expiry config from Class. Default is {generic, 300} (i.e. {PoolName, ExpireSeconds})
  2. Get the server continuum from the pool name. (in ketama's consistent hashing algorithm)
  3. Calc the server from Key's MD5 hash value according the above continuum.

Return values:

  • undefined, if key not found.
  • Value, any other values.
  1. Get multiple keys.
 mcache:mget(Class, [Key|_]).

Note: it gets all the keys with the same Class.

  1. Set a key and value.
 mcache:set(Class, Key, Value, Format, Expiry)

Class is any atom or iolist.

Key can be any iolist.

Format can be the following atoms:

  • raw, an iolist.
  • native, any Erlang term (uses term_to_binary())
  • json, convert to json string (using an enhanced version of EEP0018)
  • int, data in <<Int:32>> format.

Expiry can be as following:

  • default, uses ExpireConfig
  • infinity, no expiration
  • {X, seconds}, or minutes, hours, days, etc.
  • Integer, any numeric seconds.

This argument can be ignored. default is used in this case.

Return

  • A list of {Key, Value} pairs. The key doesn't contain Class part.
  • Missing keys won't show in the list.
  • If all keys are missing, an empty list ([]) is returned.