Use destructor to close session (partially reverted #348) (#412)

* Use destructor to shutdown session (partially reverted #348)

* Register shutdown function only if session locking is enabled

Session/Storage/Handler/RedisSessionHandler.php

@@ -99,7 +99,9 @@ public function __construct($redis, array $options = array(), $prefix = 'session
             $this->lockMaxWait = self::DEFAULT_MAX_EXECUTION_TIME;
         }
 
-        register_shutdown_function(array($this, 'shutdown'));
+        if (true === $locking) {
+            register_shutdown_function(array($this, 'shutdown'));
+        }
     }
 
     /**
@@ -270,7 +272,16 @@ protected function getRedisKey($key)
     /**
      * Shutdown handler, replacement for class destructor as it might not be called.
      */
-    public function shutdown() {
+    public function shutdown()
+    {
         $this->close();
     }
+
+    /**
+     * Destructor.
+     */
+    public function __destruct()
+    {
+        $this->shutdown();
+    }
 }