feature #31282 [Messenger] Add WorkerStoppedEvent (chalasr)

This PR was merged into the 4.3-dev branch.

Discussion
----------

[Messenger] Add WorkerStoppedEvent

| Q             | A
| ------------- | ---
| Branch?       | 4.3
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

In 4.2, one was able to decorate a transport and hook into `TransportInterface::stop()` to perform some business tasks when the `messenger:consume` process gets killed.
In 4.3 the `stop()` logic has been moved to `Worker` which cannot be decorated when used via `messenger:consume`.
This PR adds a marker event dispatched when the worker is stopped to provide the same capability.

Briefly discussed with @weaverryan.
My use case:
I have a temporary CSV file locally which grows while consuming jobs.
This file is uploaded to AWS S3 and squashed once a while (every 5minutes). It is also uploaded when the `messenger:consume` process gets stopped (to store the remaining lines).
For the former (time-based upload), I can listen on `WorkflowMessageHandledEvent` to make the upload happens in case the 5 minutes delay is elapsed. This solves the latter.

Commits
-------

0e7898b622 [Messenger] Add WorkerStoppedEvent

src/Symfony/Component/Messenger/CHANGELOG.md

@@ -4,6 +4,7 @@ CHANGELOG
 4.3.0
 -----
 
+ * Added `WorkerStoppedEvent` dispatched when a worker is stopped.
  * Added optional `MessageCountAwareInterface` that receivers can implement
    to give information about how many messages are waiting to be processed.
  * [BC BREAK] The `Envelope::__construct()` signature changed:

src/Symfony/Component/Messenger/Event/WorkerStoppedEvent.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Messenger\Event;
+
+/**
+ * Dispatched when a worker has been stopped.
+ *
+ * @author Robin Chalas <robin.chalas@gmail.com>
+ *
+ * @experimental in 4.3
+ */
+class WorkerStoppedEvent
+{
+}

src/Symfony/Component/Messenger/Tests/WorkerTest.php

@@ -16,6 +16,7 @@ use Symfony\Component\Messenger\Envelope;
 use Symfony\Component\Messenger\Event\WorkerMessageFailedEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageHandledEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageReceivedEvent;
+use Symfony\Component\Messenger\Event\WorkerStoppedEvent;
 use Symfony\Component\Messenger\Exception\UnrecoverableMessageHandlingException;
 use Symfony\Component\Messenger\MessageBusInterface;
 use Symfony\Component\Messenger\Retry\RetryStrategyInterface;
@@ -187,11 +188,12 @@ class WorkerTest extends TestCase
 
         $eventDispatcher = $this->getMockBuilder(EventDispatcherInterface::class)->getMock();
 
-        $eventDispatcher->expects($this->exactly(2))
+        $eventDispatcher->expects($this->exactly(3))
             ->method('dispatch')
             ->withConsecutive(
                 [$this->isInstanceOf(WorkerMessageReceivedEvent::class)],
-                [$this->isInstanceOf(WorkerMessageHandledEvent::class)]
+                [$this->isInstanceOf(WorkerMessageHandledEvent::class)],
+                [$this->isInstanceOf(WorkerStoppedEvent::class)]
             );
 
         $worker = new Worker([$receiver], $bus, [], $eventDispatcher);
@@ -214,11 +216,12 @@ class WorkerTest extends TestCase
 
         $eventDispatcher = $this->getMockBuilder(EventDispatcherInterface::class)->getMock();
 
-        $eventDispatcher->expects($this->exactly(2))
+        $eventDispatcher->expects($this->exactly(3))
             ->method('dispatch')
             ->withConsecutive(
                 [$this->isInstanceOf(WorkerMessageReceivedEvent::class)],
-                [$this->isInstanceOf(WorkerMessageFailedEvent::class)]
+                [$this->isInstanceOf(WorkerMessageFailedEvent::class)],
+                [$this->isInstanceOf(WorkerStoppedEvent::class)]
             );
 
         $worker = new Worker([$receiver], $bus, [], $eventDispatcher);

src/Symfony/Component/Messenger/Worker.php

@@ -15,6 +15,7 @@ use Psr\Log\LoggerInterface;
 use Symfony\Component\Messenger\Event\WorkerMessageFailedEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageHandledEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageReceivedEvent;
+use Symfony\Component\Messenger\Event\WorkerStoppedEvent;
 use Symfony\Component\Messenger\Exception\HandlerFailedException;
 use Symfony\Component\Messenger\Exception\LogicException;
 use Symfony\Component\Messenger\Exception\UnrecoverableMessageHandlingException;
@@ -109,6 +110,8 @@ class Worker implements WorkerInterface
                 usleep($options['sleep']);
             }
         }
+
+        $this->dispatchEvent(new WorkerStoppedEvent());
     }
 
     private function handleMessage(Envelope $envelope, ReceiverInterface $receiver, string $receiverName, ?RetryStrategyInterface $retryStrategy)