feature symfony#46229 [Messenger] Make Redis messages countable (Jean-Beru)

This PR was squashed before being merged into the 6.2 branch.

Discussion
----------

[Messenger] Make Redis messages countable

| Q             | A
| ------------- | ---
| Branch?       | 6.1
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

Each Messenger Transport can return the number of messages present in the queue. For example, when we use the `messenger:failed:retry` command, Messenger displays the number of messages to retry.

Actually, this count is not displayed when using `RedisTransport`. This PR adds this functionality.

Commits
-------

e1a896f [Messenger] Make Redis messages countable

Author: fabpot

src/Symfony/Component/Messenger/Bridge/Redis/Tests/Transport/RedisExtIntegrationTest.php

@@ -339,6 +339,27 @@ public function testGetAfterReject()
         $redis->del('messenger-rejectthenget');
     }
 
+    public function testItCountMessages()
+    {
+        $this->assertSame(0, $this->connection->getMessageCount());
+
+        $this->connection->add('{"message": "Hi"}', ['type' => DummyMessage::class]);
+        $this->connection->add('{"message": "Hi"}', ['type' => DummyMessage::class]);
+        $this->connection->add('{"message": "Hi"}', ['type' => DummyMessage::class]);
+
+        $this->assertSame(3, $this->connection->getMessageCount());
+
+        $message = $this->connection->get();
+        $this->connection->ack($message['id']);
+
+        $this->assertSame(2, $this->connection->getMessageCount());
+
+        $message = $this->connection->get();
+        $this->connection->reject($message['id']);
+
+        $this->assertSame(1, $this->connection->getMessageCount());
+    }
+
     private function getConnectionGroup(Connection $connection): string
     {
         $property = (new \ReflectionClass(Connection::class))->getProperty('group');

src/Symfony/Component/Messenger/Bridge/Redis/Transport/Connection.php

@@ -521,6 +521,51 @@ public function cleanup(): void
         }
     }
 
+    public function getMessageCount(): int
+    {
+        $groups = $this->connection->xinfo('GROUPS', $this->stream) ?: [];
+
+        $lastDeliveredId = null;
+        foreach ($groups as $group) {
+            if ($group['name'] !== $this->group) {
+                continue;
+            }
+
+            // Use "lag" key provided by Redis 7.x. See https://redis.io/commands/xinfo-groups/#consumer-group-lag.
+            if (isset($group['lag'])) {
+                return $group['lag'];
+            }
+
+            if (!isset($group['last-delivered-id'])) {
+                return 0;
+            }
+
+            $lastDeliveredId = $group['last-delivered-id'];
+            break;
+        }
+
+        if (null === $lastDeliveredId) {
+            return 0;
+        }
+
+        // Iterate through the stream. See https://redis.io/commands/xrange/#iterating-a-stream.
+        $useExclusiveRangeInterval = version_compare(phpversion('redis'), '6.2.0', '>=');
+        $total = 0;
+        do {
+            if (!$range = $this->connection->xRange($this->stream, $lastDeliveredId, '+', 100)) {
+                return $total;
+            }
+
+            $total += \count($range);
+
+            if ($useExclusiveRangeInterval) {
+                $lastDeliveredId = preg_replace_callback('#\d+$#', static fn(array $matches) => (int) $matches[0] + 1, array_key_last($range));
+            } else {
+                $lastDeliveredId = '('.array_key_last($range);
+            }
+        } while (true);
+    }
+
     private function rawCommand(string $command, ...$arguments): mixed
     {
         try {

src/Symfony/Component/Messenger/Bridge/Redis/Transport/RedisReceiver.php

@@ -14,6 +14,7 @@
 use Symfony\Component\Messenger\Envelope;
 use Symfony\Component\Messenger\Exception\LogicException;
 use Symfony\Component\Messenger\Exception\MessageDecodingFailedException;
+use Symfony\Component\Messenger\Transport\Receiver\MessageCountAwareInterface;
 use Symfony\Component\Messenger\Transport\Receiver\ReceiverInterface;
 use Symfony\Component\Messenger\Transport\Serialization\PhpSerializer;
 use Symfony\Component\Messenger\Transport\Serialization\SerializerInterface;
@@ -22,7 +23,7 @@
  * @author Alexander Schranz <[email protected]>
  * @author Antoine Bluchet <[email protected]>
  */
-class RedisReceiver implements ReceiverInterface
+class RedisReceiver implements ReceiverInterface, MessageCountAwareInterface
 {
     private Connection $connection;
     private SerializerInterface $serializer;
@@ -84,6 +85,14 @@ public function reject(Envelope $envelope): void
         $this->connection->reject($this->findRedisReceivedStamp($envelope)->getId());
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function getMessageCount(): int
+    {
+        return $this->connection->getMessageCount();
+    }
+
     private function findRedisReceivedStamp(Envelope $envelope): RedisReceivedStamp
     {
         /** @var RedisReceivedStamp|null $redisReceivedStamp */

src/Symfony/Component/Messenger/Bridge/Redis/Transport/RedisTransport.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Messenger\Bridge\Redis\Transport;
 
 use Symfony\Component\Messenger\Envelope;
+use Symfony\Component\Messenger\Transport\Receiver\MessageCountAwareInterface;
 use Symfony\Component\Messenger\Transport\Serialization\PhpSerializer;
 use Symfony\Component\Messenger\Transport\Serialization\SerializerInterface;
 use Symfony\Component\Messenger\Transport\SetupableTransportInterface;
@@ -21,7 +22,7 @@
  * @author Alexander Schranz <[email protected]>
  * @author Antoine Bluchet <[email protected]>
  */
-class RedisTransport implements TransportInterface, SetupableTransportInterface
+class RedisTransport implements TransportInterface, SetupableTransportInterface, MessageCountAwareInterface
 {
     private SerializerInterface $serializer;
     private Connection $connection;
@@ -74,6 +75,14 @@ public function setup(): void
         $this->connection->setup();
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function getMessageCount(): int
+    {
+        return $this->getReceiver()->getMessageCount();
+    }
+
     private function getReceiver(): RedisReceiver
     {
         return $this->receiver ??= new RedisReceiver($this->connection, $this->serializer);