search_worker2.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
    # cancel current timer
    Process.cancel_timer(state.idle_timer)
    # create a new timer
    state = touch_idle_timer(state)
    {:noreply, state}
  end

  def handle_info(:idle_timeout, state) do
    # do whatever you want to do to cleanup your process tree
    shutdown_proc_tree(state)
    {:noreply, state}
  end

  defp touch_idle_timer(state) do
    # 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_ms)
    %{state | idle_timer: idle_timer}
  end
end