%%%-----------------------------------------------------------------------------
%%% @Copyright (C) 2012-2015, Feng Lee <feng@emqtt.io>
%%%
%%% Permission is hereby granted, free of charge, to any person obtaining a copy
%%% of this software and associated documentation files (the "Software"), to deal
%%% in the Software without restriction, including without limitation the rights
%%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%%% copies of the Software, and to permit persons to whom the Software is
%%% furnished to do so, subject to the following conditions:
%%%
%%% The above copyright notice and this permission notice shall be included in all
%%% copies or substantial portions of the Software.
%%%
%%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
%%% SOFTWARE.
%%%-----------------------------------------------------------------------------
%%% @doc
%%% emqttd pooler.
%%%
%%% @end
%%%-----------------------------------------------------------------------------
-module(emqttd_pooler).

-author('feng@emqtt.io').

-behaviour(gen_server).

%% API Exports 
-export([start_link/1, submit/1, async_submit/1]).

%% gen_server Function Exports
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
         terminate/2, code_change/3]).

-record(state, {id}).

%%%=============================================================================
%%% API
%%%=============================================================================
-spec start_link(I :: pos_integer()) -> {ok, pid()} | ignore | {error, any()}.
start_link(I) ->
    gen_server:start_link(?MODULE, [I], []).

submit(Fun) ->
   gen_server:call(gproc_pool:pick(pooler), {submit, Fun}, infinity).

async_submit(Fun) ->
    gen_server:cast(gproc_pool:pick(pooler), {async_submit, Fun}).

init([I]) ->
    gproc_pool:connect_worker(pooler, {pooler, I}),
    {ok, #state{id = I}}.

handle_call({submit, Fun}, _From, State) ->
    {reply, run(Fun), State};

handle_call(_Req, _From, State) ->
    {reply, ok, State}.

handle_cast({async_submit, Fun}, State) ->
    run(Fun),
    {noreply, State};

handle_cast(_Msg, State) ->
    {noreply, State}.

handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, #state{id = I}) ->
    gproc_pool:disconnect_worker(pooler, {pooler, I}), ok.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%%%=============================================================================
%%% Internal functions
%%%=============================================================================

run({M, F, A}) ->
    erlang:apply(M, F, A);
run(Fun) when is_function(Fun) ->
    Fun().