bug #19551 [Cache] Use SCAN instead of KEYS with Redis >= 2.8 (nicolas-grekas)

nicolas-grekas · nicolas-grekas · commit 540842a9bedc · 2016-08-07T17:12:11.000+02:00
This PR was merged into the 3.1 branch. Discussion ---------- [Cache] Use SCAN instead of KEYS with Redis >= 2.8 | Q | A | ------------- | --- | Branch? | 3.1 | Bug fix? | yes | New feature? | no | BC breaks? | no | Deprecations? | no | Tests pass? | yes | Fixed tickets | - | License | MIT | Doc PR | - With #19521 coming, clearing cache keys by prefix is going to be used a lot more often. Time to fix Redis cache clearing. Commits ------- aadeb11 [Cache] Use SCAN instead of KEYS with Redis >= 2.8
diff --git a/src/Symfony/Component/Cache/Adapter/RedisAdapter.php b/src/Symfony/Component/Cache/Adapter/RedisAdapter.php
@@ -165,6 +165,7 @@ protected function doClear($namespace)
         // When using a native Redis cluster, clearing the cache cannot work and always returns false.
         // Clearing the cache should then be done by any other means (e.g. by restarting the cluster).
 
+        $cleared = true;
         $hosts = array($this->redis);
         $evalArgs = array(array($namespace), 0);
 
@@ -181,6 +182,7 @@ protected function doClear($namespace)
                 return false;
             }
         } elseif ($this->redis instanceof \RedisArray) {
+            $hosts = array();
             foreach ($this->redis->_hosts() as $host) {
                 $hosts[] = $this->redis->_instance($host);
             }
@@ -189,17 +191,35 @@ protected function doClear($namespace)
         }
         foreach ($hosts as $host) {
             if (!isset($namespace[0])) {
-                $host->flushDb();
-            } else {
+                $cleared = $host->flushDb() && $cleared;
+                continue;
+            }
+
+            $info = $host->info('Server');
+            $info = isset($info['Server']) ? $info['Server'] : $info;
+
+            if (!version_compare($info['redis_version'], '2.8', '>=')) {
                 // As documented in Redis documentation (http://redis.io/commands/keys) using KEYS
                 // can hang your server when it is executed against large databases (millions of items).
-                // Whenever you hit this scale, it is advised to deploy one Redis database per cache pool
-                // instead of using namespaces, so that FLUSHDB is used instead.
-                $host->eval("local keys=redis.call('KEYS',ARGV[1]..'*') for i=1,#keys,5000 do redis.call('DEL',unpack(keys,i,math.min(i+4999,#keys))) end", $evalArgs[0], $evalArgs[1]);
+                // Whenever you hit this scale, you should really consider upgrading to Redis 2.8 or above.
+                $cleared = $host->eval("local keys=redis.call('KEYS',ARGV[1]..'*') for i=1,#keys,5000 do redis.call('DEL',unpack(keys,i,math.min(i+4999,#keys))) end return 1", $evalArgs[0], $evalArgs[1]) && $cleared;
+                continue;
             }
+
+            $cursor = null;
+            do {
+                $keys = $host instanceof \Predis\Client ? $host->scan($cursor, 'MATCH', $namespace.'*', 'COUNT', 1000) : $host->scan($cursor, $namespace.'*', 1000);
+                if (isset($keys[1]) && is_array($keys[1])) {
+                    $cursor = $keys[0];
+                    $keys = $keys[1];
+                }
+                if ($keys) {
+                    $host->del($keys);
+                }
+            } while ($cursor = (int) $cursor);
         }
 
-        return true;
+        return $cleared;
     }
 
     /**
