feature symfony#38563 [Messenger][Redis] Adding support for lazy connect (Nyholm)

This PR was squashed before being merged into the 5.x branch.

Discussion
----------

[Messenger][Redis] Adding support for lazy connect

| Q             | A
| ------------- | ---
| Branch?       | 5.x
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | Fix symfony#38558
| License       | MIT
| Doc PR        | Should be added

With inspiration from the CacheComponent. This PR makes it possible to make the connection to Redis only when you first use it.

Commits
-------

1d7c801 [Messenger][Redis] Adding support for lazy connect

Author: fabpot

src/Symfony/Component/Messenger/Bridge/Redis/CHANGELOG.md

@@ -6,6 +6,7 @@ CHANGELOG
 
  * Added a `delete_after_reject` option to the DSN to allow control over message
    deletion, similar to `delete_after_ack`.
+ * Added option `lazy` to delay connecting to Redis server until we first use it.
 
 5.1.0
 -----

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

@@ -387,4 +387,16 @@ public function testLastErrorGetsCleared()
 
         $this->assertSame('xack error', $e->getMessage());
     }
+
+    public function testLazy()
+    {
+        $redis = new \Redis();
+        $connection = Connection::fromDsn('redis://localhost/messenger-lazy?lazy=1', [], $redis);
+
+        $connection->add('1', []);
+        $this->assertNotEmpty($message = $connection->get());
+        $this->assertSame('1', $message['body']);
+        $connection->reject($message['id']);
+        $redis->del('messenger-lazy');
+    }
 }

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

@@ -39,6 +39,7 @@ class Connection
         'tls' => false,
         'redeliver_timeout' => 3600, // Timeout before redeliver messages still in pending state (seconds)
         'claim_interval' => 60000, // Interval by which pending/abandoned messages should be checked
+        'lazy' => false,
     ];
 
     private $connection;
@@ -61,23 +62,42 @@ public function __construct(array $configuration, array $connectionCredentials =
             throw new LogicException('The redis transport requires php-redis 4.3.0 or higher.');
         }
 
-        $this->connection = $redis ?: new \Redis();
-        $this->connection->connect($connectionCredentials['host'] ?? '127.0.0.1', $connectionCredentials['port'] ?? 6379);
-        $this->connection->setOption(\Redis::OPT_SERIALIZER, $redisOptions['serializer'] ?? \Redis::SERIALIZER_PHP);
-
+        $host = $connectionCredentials['host'] ?? '127.0.0.1';
+        $port = $connectionCredentials['port'] ?? 6379;
+        $serializer = $redisOptions['serializer'] ?? \Redis::SERIALIZER_PHP;
+        $dbIndex = $configuration['dbindex'] ?? self::DEFAULT_OPTIONS['dbindex'];
         $auth = $connectionCredentials['auth'] ?? null;
         if ('' === $auth) {
             $auth = null;
         }
 
-        if (null !== $auth && !$this->connection->auth($auth)) {
-            throw new InvalidArgumentException('Redis connection failed: '.$this->connection->getLastError());
+        $initializer = static function ($redis) use ($host, $port, $auth, $serializer, $dbIndex) {
+            $redis->connect($host, $port);
+            $redis->setOption(\Redis::OPT_SERIALIZER, $serializer);
+
+            if (null !== $auth && !$redis->auth($auth)) {
+                throw new InvalidArgumentException('Redis connection failed: '.$redis->getLastError());
+            }
+
+            if ($dbIndex && !$redis->select($dbIndex)) {
+                throw new InvalidArgumentException('Redis connection failed: '.$redis->getLastError());
+            }
+
+            return true;
+        };
+
+        if (null === $redis) {
+            $redis = new \Redis();
         }
 
-        if (($dbIndex = $configuration['dbindex'] ?? self::DEFAULT_OPTIONS['dbindex']) && !$this->connection->select($dbIndex)) {
-            throw new InvalidArgumentException('Redis connection failed: '.$this->connection->getLastError());
+        if ($configuration['lazy'] ?? self::DEFAULT_OPTIONS['lazy']) {
+            $redis = new RedisProxy($redis, $initializer);
+        } else {
+            $initializer($redis);
         }
 
+        $this->connection = $redis;
+
         foreach (['stream', 'group', 'consumer'] as $key) {
             if (isset($configuration[$key]) && '' === $configuration[$key]) {
                 throw new InvalidArgumentException(sprintf('"%s" should be configured, got an empty string.', $key));
@@ -165,6 +185,7 @@ public static function fromDsn(string $dsn, array $redisOptions = [], \Redis $re
             'stream' => $redisOptions['stream'] ?? null,
             'group' => $redisOptions['group'] ?? null,
             'consumer' => $redisOptions['consumer'] ?? null,
+            'lazy' => $redisOptions['lazy'] ?? self::DEFAULT_OPTIONS['lazy'],
             'auto_setup' => $autoSetup,
             'stream_max_entries' => $maxEntries,
             'delete_after_ack' => $deleteAfterAck,

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

@@ -0,0 +1,40 @@
+<?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\Bridge\Redis\Transport;
+
+/**
+ * Allow to delay connection to Redis.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @internal
+ */
+class RedisProxy
+{
+    private $redis;
+    private $initializer;
+    private $ready = false;
+
+    public function __construct(\Redis $redis, \Closure $initializer)
+    {
+        $this->redis = $redis;
+        $this->initializer = $initializer;
+    }
+
+    public function __call(string $method, array $args)
+    {
+        $this->ready ?: $this->ready = $this->initializer->__invoke($this->redis);
+
+        return $this->redis->{$method}(...$args);
+    }
+}