Include commanded#431 in CHANGELOG

CHANGELOG.md

@@ -7,7 +7,8 @@
 - Telemetry `[:commanded, :aggregate, :execute]` events ([#407](https://github.com/commanded/commanded/pull/407)).
 - Telemetry `[:commanded, :event, :handle]` events ([#408](https://github.com/commanded/commanded/pull/408)).
 - Telemetry `[:commanded, :process_manager, :handle]` events ([#418](https://github.com/commanded/commanded/pull/418)).
-- Telemetry `[:commanded, :application, :dispatch]` ([#423 ](https://github.com/commanded/commanded/pull/423)).
+- Telemetry `[:commanded, :application, :dispatch]` ([#423](https://github.com/commanded/commanded/pull/423)).
+- Graceful shutdown of event handlers ([#431](https://github.com/commanded/commanded/pull/431)).
 
 ## v1.2.0
 

README.md

@@ -138,6 +138,7 @@ Commanded exists thanks to the following people who have contributed.
 - [Chris Brodt](https://github.com/uberbrodt)
 - [Chris Martin](https://github.com/trbngr)
 - [Christophe Juniet](https://github.com/cjuniet)
+- [Danilo Silva](https://github.com/silvadanilo)
 - [Dave Lucia](https://github.com/davydog187)
 - [David Carlin](https://github.com/davich)
 - [Danni Friedland](https://github.com/BlueHotDog)

lib/commanded/event/handler.ex

@@ -652,6 +652,7 @@ defmodule Commanded.Event.Handler do
   @impl GenServer
   def init(%Handler{} = state) do
     Process.flag(:trap_exit, true)
+
     {:ok, state, {:continue, :subscribe_to_events}}
   end
 

test/commands/dispatch_consistency_test.exs

@@ -127,8 +127,8 @@ defmodule Commanded.Commands.DispatchConsistencyTest do
   end
 
   def start_event_handlers(_context) do
-    start_supervised!(StronglyConsistentEventHandler)
-    start_supervised!(EventuallyConsistentEventHandler)
+    start_supervised!(StronglyConsistentEventHandler, shutdown: :brutal_kill)
+    start_supervised!(EventuallyConsistentEventHandler, shutdown: :brutal_kill)
 
     :ok
   end

test/event/event_handler_graceful_shutdown_test.exs

@@ -1,13 +1,13 @@
 defmodule Commanded.Event.EventHandlerGracefulShutdownTest do
   use ExUnit.Case
 
-  alias Commanded.Event.GracefulShutdownHandler
   alias Commanded.DefaultApp
+  alias Commanded.Event.GracefulShutdownHandler
   alias Commanded.Helpers.EventFactory
 
   defmodule AnEvent do
     @derive Jason.Encoder
-    defstruct [:reply_to, :sleep_for]
+    defstruct [:reply_to]
   end
 
   defmodule EventHandlersSupervisor do
@@ -39,14 +39,24 @@ defmodule Commanded.Event.EventHandlerGracefulShutdownTest do
 
     test "stop the event handler while it is handling an event" do
       supervisor = start_supervised!(EventHandlersSupervisor, restart: :transient)
-      {_, handler, _, _} = supervisor |> Supervisor.which_children() |> List.first()
+      [{_, handler, _, _}] = Supervisor.which_children(supervisor)
 
-      event = %AnEvent{reply_to: self(), sleep_for: 200}
+      event = %AnEvent{reply_to: self()}
       send_events_to_handler(handler, [event])
-      Supervisor.stop(supervisor, {:shutdown, :graceful})
 
-      assert Process.whereis(EventHandlersSupervisor) == nil
-      assert_received {:event, ^event, _metadata}
+      Task.async(fn ->
+        Supervisor.stop(supervisor, :shutdown)
+      end)
+
+      assert_receive {:event, ^event, _metadata}
+      refute_receive {:continue, ^event, _metadata}
+
+      ref = Process.monitor(handler)
+
+      send(handler, :continue)
+
+      assert_receive {:continue, ^event, _metadata}
+      assert_receive {:DOWN, ^ref, :process, ^handler, :shutdown}
     end
   end
 

test/event/support/graceful_shutdown/graceful_shutdown_handler.ex

@@ -3,13 +3,18 @@ defmodule Commanded.Event.GracefulShutdownHandler do
     application: Commanded.DefaultApp,
     name: __MODULE__
 
-  def handle(%{sleep_for: milliseconds} = event, metadata) do
+  def handle(event, metadata) do
     %{reply_to: reply_to} = event
 
-    Process.sleep(milliseconds)
-
     send(reply_to, {:event, event, metadata})
 
+    receive do
+      :continue ->
+        send(reply_to, {:continue, event, metadata})
+
+        :ok
+    end
+
     :ok
   end
 end