gistfile1.txt

-module(pinger).

-behaviour(gen_server).

%% API                                                                                                                                 
-export([start_link/1, pong/0]).

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

-define(SERVER, ?MODULE).

-record(state, {async_pid, worker_pid, worker_ref}).

start_link(AsyncPid) ->
    gen_server:start_link({local, ?SERVER}, ?MODULE, [AsyncPid], []).

init([AsyncPid]) ->
    erlang:send_after(10000, self(), ping_someone),
    {ok, #state{async_pid=AsyncPid}}.

handle_call(_Request, _From, State) ->
    Reply = ok,
    {reply, Reply, State}.

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

handle_info(ping_someone, State) ->
    {WorkerPid, WorkerRef} = async:spawn_call(pinger, pong, [], State#state.async_pid),
    {noreply, State#state{worker_pid=WorkerPid, worker_ref=WorkerRef}};
handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

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


pong() ->
    timer:sleep(10000).