search_worker3.exs

defmodule SearchWorker do
  use GenServer

  @idle_timeout_ms 10 * 60 * 1000

  # client api
  def touch(pid) do
    GenServer.cast(pid, :touch)
  end

  @impl GenServer
  def init(_opts) do
    state = touch_idle_timer(%{})
    {:ok, state}
  end

  @impl GenServer
  def handle_cast(:touch, state) do
    state = touch_idle_timer(state)
    {:noreply, state}
  end

  # we got our idle timeout let's clean it up
  def handle_info({:idle_timeout, idle_timeout_ref}, %{idle_timeout_ref: idle_timeout_ref} = state) do
    # do whatever you want to do to cleanup your process tree
    shutdown_proc_tree(state)
    {:noreply, state}
  end

  # we have an old timeout coming through, we should just ignore it
  def handle_info({:idle_timeout, _ref}, state), do: {:noreply, state}

  defp touch_idle_timer(state) do
    idle_timeout_ref = make_ref()
    # send ourselves a message after 10 seconds and cleanup the proc tree when we get this
    idle_timer = Process.send_after(self(), {:idle_timeout, idle_timeout_ref}, @idle_timeout_ms)
    %{state | idle_timer_ref: idle_timer_ref}
  end
end