%% 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 Developer of the Original Code is VMware, Inc.

 %% Copyright (c) 2007-2013 VMware, Inc.  All rights reserved.

 %%

 -module(worker_pool_worker).

 -behaviour(gen_server2).

 -export([start_link/1, submit/2, submit_async/2, run/1]).

 -export([set_maximum_since_use/2]).

 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,

          terminate/2, code_change/3, prioritise_cast/3]).

 %%----------------------------------------------------------------------------

 -ifdef(use_specs).

 -type(mfargs() :: {atom(), atom(), [any()]}).

 -spec(start_link/1 :: (any()) -> {'ok', pid()} | {'error', any()}).

 -spec(submit/2 :: (pid(), fun (() -> A) | mfargs()) -> A).

 -spec(submit_async/2 :: (pid(), fun (() -> any()) | mfargs()) -> 'ok').

 -spec(run/1 :: (fun (() -> A)) -> A; (mfargs()) -> any()).

 -spec(set_maximum_since_use/2 :: (pid(), non_neg_integer()) -> 'ok').

 -endif.

 %%----------------------------------------------------------------------------

 -define(HIBERNATE_AFTER_MIN, 1000).

 -define(DESIRED_HIBERNATE, 10000).

 %%----------------------------------------------------------------------------

 start_link(WId) ->

     gen_server2:start_link(?MODULE, [WId], [{timeout, infinity}]).

 submit(Pid, Fun) ->

     gen_server2:call(Pid, {submit, Fun}, infinity).

 submit_async(Pid, Fun) ->

     gen_server2:cast(Pid, {submit_async, Fun}).

 set_maximum_since_use(Pid, Age) ->

     gen_server2:cast(Pid, {set_maximum_since_use, Age}).

 run({M, F, A}) ->

     apply(M, F, A);

 run(Fun) ->

     Fun().

 %%----------------------------------------------------------------------------

 init([WId]) ->

     ok = file_handle_cache:register_callback(?MODULE, set_maximum_since_use,

                                              [self()]),

     ok = worker_pool:idle(WId),

     put(worker_pool_worker, true),

     {ok, WId, hibernate,

      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.

 prioritise_cast({set_maximum_since_use, _Age}, _Len, _State) -> 8;

 prioritise_cast(_Msg,                          _Len, _State) -> 0.

 handle_call({submit, Fun}, From, WId) ->

     gen_server2:reply(From, run(Fun)),

     ok = worker_pool:idle(WId),

     {noreply, WId, hibernate};

 handle_call(Msg, _From, State) ->

     {stop, {unexpected_call, Msg}, State}.

 handle_cast({submit_async, Fun}, WId) ->

     run(Fun),

     ok = worker_pool:idle(WId),

     {noreply, WId, hibernate};

 handle_cast({set_maximum_since_use, Age}, WId) ->

     ok = file_handle_cache:set_maximum_since_use(Age),

     {noreply, WId, 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.