GS noreply

‽Erlang/OTP 19 [erts-8.3] [64-bit] [smp:8:8] [async-threads:10]

Interactive Elixir (1.4.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> c("tst_gen.ex")
[TstGen]
iex(2)> 
nil
iex(3)> {:ok, pid} = TstGen.start_link
{:ok, #PID<0.88.0>}
iex(4)> 
nil
iex(5)> TstGen.test(pid)

18:48:27.508 [info]  1 fast_get -> GS

18:48:27.509 [info]  1 fast_result=1 <- GS

18:48:28.020 [info]  1 long_get -> GS

18:48:28.535 [info]  2 fast_get -> GS

18:48:28.535 [info]  2 fast_result=3 <- GS

18:48:29.035 [info]  2 long_get -> GS

18:48:29.035 [info]  1 long_result=2 <- GS

18:48:29.549 [info]  3 fast_get -> GS

18:48:29.550 [info]  3 fast_result=5 <- GS

18:48:30.049 [info]  3 long_get -> GS

18:48:30.049 [info]  2 long_result=4 <- GS

18:48:30.563 [info]  4 fast_get -> GS

18:48:30.563 [info]  4 fast_result=7 <- GS

18:48:31.063 [info]  4 long_get -> GS
:ok

18:48:31.063 [info]  3 long_result=6 <- GS
iex(6)> 
18:48:32.077 [info]  4 long_result=8 <- GS

tst_gen.ex

defmodule TstGen do
  use GenServer
  require Logger

  def start_link do
    GenServer.start_link(__MODULE__, 1)
  end
  def test(pid) do
    for i <- [1, 2, 3, 4] do
      :timer.sleep(500)
      spawn(fn() ->
        Logger.info "#{inspect i} fast_get -> GS"
        result = GenServer.call(pid, :fast)
        Logger.info "#{inspect i} fast_result=#{result} <- GS"
      end)
      :timer.sleep(500)
      spawn(fn() ->
        Logger.info "#{inspect i} long_get -> GS"
        result = GenServer.call(pid, :long)
        Logger.info "#{inspect i} long_result=#{result} <- GS"
      end)
    end
    :ok
  end
  
  # SERVER
  def init(state) do
    {:ok, state}
  end
  def handle_call(:long, from, state) do
    # start long process
    spawn(fn() ->
      :timer.sleep(1000)
      :gen_server.reply(from, state)
    end)
    {:noreply, state+1}
  end
  def handle_call(:fast, _from, state) do
    {:reply, state, state+1}
  end
end

gen_server call with delayed reply