/mcd

Fast memcached protocol client in pure Erlang

Primary LanguageErlangBSD 2-Clause "Simplified" LicenseBSD-2-Clause

Erlang memcached client library.

This library provides two ways of working with memcached servers. One way is to use a single server, as described in #1. Another way is to use a number of memcached servers in a consistent hash ring mode. This is described in #2.

1. RUNNING IN SINGLE-SERVER MODE

1.1 Starting a single memcached

The following will start an anonymous mcd client, addressable by the returned pid().

{ok, Pid} = mcd:start_link(["localhost", 11211]).

The next one will connect to the memcached server on the local host, and will also register the mcd instance under the 'myMcd' name. See #3. The mcd API can use the returned pid() and the registered name interchangeably.

mcd:start_link(myMcd, []).
mcd:set(myMcd, a, b).
mcd:get(myMcd, a).

1.2 A ChildSpec for running the mcd named 'myMcd' under a supervisor

{local_memcache,
    {mcd, start_link, ['myMcd', ["localhost", 11211]]},
    permanent, 10000, worker, [mcd] }

2. RUNNING IN CLUSTERED MODE

mcd_cluster starts a set of mcd processess and a dispatcher attached to them. All mcd processess and the dispatcher are linked to form a proper exit hierarchy.

2.1 Starting memcached cluster from the command line (e.g., for testing)

mcd_cluster:start_link(mainCluster, [
    {host1, ["localhost", 11211], 10},
    {host2, ["localhost", 11211], 20}
]).

2.2 A ChildSpec for running the cluster named 'mainCluster' under a supervisor

{mainCluster,
    {mcd_cluster, start_link, [mainCluster, [
        {host1, ["localhost"], 10},
        {host2, ["localhost"], 20}
    ]]},
    permanent, 60000, worker, [mcd_cluster]}

Note: the default port for "localhost" is 11211.

2.3 Starting memcached cluster as an application

application:set_env(mcd, mcd_hosts, [{localhost, ["localhost"]}]).
application:set_env(mcd, mcd_buckets, [
    {cluster1, {localhost, 11211}},
    {cluster2, {localhost, 11211}}
]).
application:start(mcd).

{error, notfound} = mcd:get(cluster1, foo).
{error, notfound} = mcd:get(cluster2, foo).

3. USING MEMCACHED

{ok, b} = mcd:set(server, a, b).
{error, notfound} = mcd:get(server, foo).
{ok, [42]} = mcd:set(mainCluster, <<"bar">>, [42]).
{ok, [42]} = mcd:get(mainCluster, <<"bar">>).

4. RELEASE NOTES

See CHANGELOG.md