%% 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) 2007-2012 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/2]).

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

-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}, _State) -> 8;

prioritise_cast(_Msg,                          _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.