Fix #182: Better handle cache/flush-all command when cache component is using shared database

Author: rob006

CHANGELOG.md

@@ -4,6 +4,7 @@ Yii Framework 2 redis extension Change Log
 2.0.12 under development
 ------------------------
 
+- Bug #182: Better handle `cache/flush-all` command when cache component is using shared database (rob006)
 - Enh #195: Use `Instance::ensure()` to initialize `Session::$redis` (rob006)
 - Enh #199: Increase frequency of lock tries when `$timeout` is used in `Mutex::acquire()` (rob006)
 

src/Cache.php

@@ -16,12 +16,15 @@
  *
  * Redis Cache requires redis version 2.6.12 or higher to work properly.
  *
- * It needs to be configured with a redis [[Connection]] that is also configured as an application component.
- * By default it will use the `redis` application component.
+ * It needs to be configured with a redis [[Connection]]. By default it will use the `redis` application component.
  *
- * See [[Cache]] manual for common cache operations that redis Cache supports.
+ * > Note: It is recommended to use separate [[Connection::$database|database]] for cache and do not share it with
+ * > other components. If you need to share database, you should set [[$shareDatabase]] to `true` and make sure that
+ * > [[$keyPrefix]] has unique value which will allow to distinguish between cache keys and other data in database.
  *
- * Unlike the [[Cache]], redis Cache allows the expire parameter of [[set]], [[add]], [[mset]] and [[madd]] to
+ * See [[yii\caching\Cache]] manual for common cache operations that redis Cache supports.
+ *
+ * Unlike the [[yii\caching\Cache]], redis Cache allows the expire parameter of [[set]], [[add]], [[mset]] and [[madd]] to
  * be a floating point number, so you may specify the time in milliseconds (e.g. 0.1 will be 100 milliseconds).
  *
  * To use redis Cache as the cache application component, configure the application as follows,
@@ -137,6 +140,15 @@ class Cache extends \yii\caching\Cache
      * @since 2.0.11
      */
     public $forceClusterMode;
+    /**
+     * @var bool whether redis [[Connection::$database|database]] is shared and can contain other data than cache.
+     * Setting this to `true` will change [[flush()]] behavior - instead of using [`FLUSHDB`](https://redis.io/commands/flushdb)
+     * command, component will iterate through all keys in database and remove only these with matching [[$keyPrefix]].
+     * Note that this will no longer be an atomic operation and it is much less efficient than `FLUSHDB` command. It is
+     * recommended to use separate database for cache and leave this value as `false`.
+     * @since 2.0.12
+     */
+    public $shareDatabase = false;
 
     /**
      * @var Connection currently active connection.
@@ -334,6 +346,17 @@ protected function deleteValue($key)
      */
     protected function flushValues()
     {
+        if ($this->shareDatabase) {
+            $cursor = 0;
+            do {
+                list($cursor, $keys) = $this->redis->scan($cursor, 'MATCH', $this->keyPrefix . '*');
+                $cursor = (int) $cursor;
+                $this->redis->executeCommand('DEL', $keys);
+            } while ($cursor !== 0);
+
+            return true;
+        }
+
         return $this->redis->executeCommand('FLUSHDB');
     }
 

tests/RedisCacheTest.php

@@ -41,7 +41,7 @@ protected function getCacheInstance()
 
     protected function resetCacheInstance()
     {
-        $this->getCacheInstance()->flush();
+        $this->getCacheInstance()->redis->flushdb();
         $this->_cacheInstance = null;
     }
 
@@ -183,4 +183,24 @@ public function testReplica()
 
         $this->resetCacheInstance();
     }
+
+    public function testFlushWithSharedDatabase()
+    {
+        $instance = $this->getCacheInstance();
+        $instance->shareDatabase = true;
+        $instance->keyPrefix = 'myprefix_';
+        $instance->redis->set('testkey', 'testvalue');
+
+        for ($i = 0; $i < 1000; $i++) {
+            $instance->set(sha1($i), uniqid('', true));
+        }
+        $keys = $instance->redis->keys('*');
+        $this->assertCount(1001, $keys);
+
+        $instance->flush();
+
+        $keys = $instance->redis->keys('*');
+        $this->assertCount(1, $keys);
+        $this->assertSame(['testkey'], $keys);
+    }
 }