pooler/doc/overview.edoc

@author Seth Falcon <seth@userprimary.net>
@copyright 2011 Seth Falcon
@title pooler - An OTP Process Pool Application
@doc 
The pooler application allows you to manage pools of OTP behaviors
such as gen_servers, gen_fsms, or supervisors, and provide consumers
with exclusive access to pool members using pooler:take_member.

See the README.org file for a good introduction to what pooler is all
about.

== Pooler Configuration ==

Pool configuration is specified in the pooler application's
environment.  This can be provided in a config file using `-config' or
set at startup using `application:set_env(pooler, pools, Pools)'.
Here's an example config file that creates three pools of
Riak pb clients each talking to a different node in a local cluster:

```
% pooler.config
% Start Erlang as: erl -config pooler
% -*- mode: erlang -*-
% pooler app config
[
 {pooler, [
         {pools, [
                  [{name, "rc8081"},
                   {max_count, 5},
                   {init_count, 2},
                   {start_mfa,
                    {riakc_pb_socket, start_link, ["localhost", 8081]}}],

                  [{name, "rc8082"},
                   {max_count, 5},
                   {init_count, 2},
                   {start_mfa,
                    {riakc_pb_socket, start_link, ["localhost", 8082]}}],

                  [{name, "rc8083"},
                   {max_count, 5},
                   {init_count, 2},
                   {start_mfa,
                    {riakc_pb_socket, start_link, ["localhost", 8083]}}]
                 ]}
        ]}
].
'''

== Using pooler ==

Here's an example session:

```
application:start(pooler).
P = pooler:take_member(),
% use P
pooler:return_member(P, ok).
'''

Once started, the main interaction you will have with pooler is through
two functions, `take_member/0' and `return_member/2'.

Call `pooler:take_member()' to obtain a member from a randomly
selected pool.  When you are done with it, return it to the pool using
`pooler:return_member(Pid, ok)'.  If you encountered an error using
the member, you can pass `fail' as the second argument.  In this case,
pooler will permanently remove that member from the pool and start a
new member to replace it.  If your process is short lived, you can
omit the call to `return_member'.  In this case, pooler will detect
the normal exit of the consumer and reclaim the member.