Non-blocking gen_server for erlang

non_blocking_gen_server_erlang.erl

% non-blocking gen_server erlang

% By default handle_call is blocks the gen_server. 
% Using a dispatcher-worker style, we can make 
% handle_call non blocking

% The call below blocks
handle_call({get, Param}, From, State = #state{sock = Sock}) ->
    Reply = do_time_consuming_remote_operation(Param, Sock),
    {reply, Reply, State};

% The call below doesnt block
handle_call({get, Param}, From, State = #state{sock = Sock}) ->
    proc_lib:spawn_link(fun () -> do_time_consuming_remote_operation(Param, Sock) end),
    {noreply, State};

do_time_consuming_remote_operation(Param, Sock) ->
    Results =  do_some_work(Param, Sock),
    gen_server:reply(From, Results).

% Special note on why we use annonymous function for proc_lib:spawn_link.
% If we dont use annonymous function, we need to call the function with
% a format like proc_lib:spawn_link(Module, Function, Arguments).
% The problem is, we dont want to export do_time_consuming_remote_operation/2 function,
% Thus, using an annonymous function to call do_time_consuming_remote_operation 
% is better.