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%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (the "License"); you may not use this file except in
%% compliance with the License. You may obtain a copy of the License at
%% http://www.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
%% License for the specific language governing rights and limitations
%% under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developers of the Original Code are LShift Ltd,
%% Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
%% Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
%% are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
%% Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created by LShift Ltd are Copyright (C) 2007-2010 LShift
%% Ltd. Portions created by Cohesive Financial Technologies LLC are
%% Copyright (C) 2007-2010 Cohesive Financial Technologies
%% LLC. Portions created by Rabbit Technologies Ltd are Copyright
%% (C) 2007-2010 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(worker_pool).
%% Generic worker pool manager.
%%
%% Supports nested submission of jobs (nested jobs always run
%% immediately in current worker process).
%%
%% Possible future enhancements:
%%
%% 1. Allow priorities (basically, change the pending queue to a
%% priority_queue).
-behaviour(gen_server2).
-export([start_link/0, submit/1, submit_async/1, idle/1]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-spec(start_link/0 :: () -> 'ignore' | rabbit_types:ok_or_error2(pid(), any())).
-spec(submit/1 :: (fun (() -> A) | {atom(), atom(), [any()]}) -> A).
-spec(submit_async/1 ::
(fun (() -> any()) | {atom(), atom(), [any()]}) -> 'ok').
-endif.
%%----------------------------------------------------------------------------
-define(SERVER, ?MODULE).
-define(HIBERNATE_AFTER_MIN, 1000).
-define(DESIRED_HIBERNATE, 10000).
-record(state, { available, pending }).
%%----------------------------------------------------------------------------
start_link() ->
gen_server2:start_link({local, ?SERVER}, ?MODULE, [],
[{timeout, infinity}]).
submit(Fun) ->
case get(worker_pool_worker) of
true -> worker_pool_worker:run(Fun);
_ -> Pid = gen_server2:call(?SERVER, next_free, infinity),
worker_pool_worker:submit(Pid, Fun)
end.
submit_async(Fun) ->
gen_server2:cast(?SERVER, {run_async, Fun}).
idle(WId) ->
gen_server2:cast(?SERVER, {idle, WId}).
%%----------------------------------------------------------------------------
init([]) ->
{ok, #state { pending = queue:new(), available = queue:new() }, hibernate,
{backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
handle_call(next_free, From, State = #state { available = Avail,
pending = Pending }) ->
case queue:out(Avail) of
{empty, _Avail} ->
{noreply,
State #state { pending = queue:in({next_free, From}, Pending) },
hibernate};
{{value, WId}, Avail1} ->
{reply, get_worker_pid(WId), State #state { available = Avail1 },
hibernate}
end;
handle_call(Msg, _From, State) ->
{stop, {unexpected_call, Msg}, State}.
handle_cast({idle, WId}, State = #state { available = Avail,
pending = Pending }) ->
{noreply, case queue:out(Pending) of
{empty, _Pending} ->
State #state { available = queue:in(WId, Avail) };
{{value, {next_free, From}}, Pending1} ->
gen_server2:reply(From, get_worker_pid(WId)),
State #state { pending = Pending1 };
{{value, {run_async, Fun}}, Pending1} ->
worker_pool_worker:submit_async(get_worker_pid(WId), Fun),
State #state { pending = Pending1 }
end, hibernate};
handle_cast({run_async, Fun}, State = #state { available = Avail,
pending = Pending }) ->
{noreply,
case queue:out(Avail) of
{empty, _Avail} ->
State #state { pending = queue:in({run_async, Fun}, Pending)};
{{value, WId}, Avail1} ->
worker_pool_worker:submit_async(get_worker_pid(WId), Fun),
State #state { available = Avail1 }
end, hibernate};
handle_cast(Msg, State) ->
{stop, {unexpected_cast, Msg}, State}.
handle_info(Msg, State) ->
{stop, {unexpected_info, Msg}, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
terminate(_Reason, State) ->
State.
%%----------------------------------------------------------------------------
get_worker_pid(WId) ->
[{WId, Pid, _Type, _Modules} | _] =
lists:dropwhile(fun ({Id, _Pid, _Type, _Modules})
when Id =:= WId -> false;
(_) -> true
end,
supervisor:which_children(worker_pool_sup)),
Pid.
|
