Implement clearable containers

stof · stof · commit 3f9eee220d91 · 2015-07-03T00:05:34.000+02:00
This allows to release remove references to all services during
shutdown, giving much more chances to destruct services and the
container through refcounting rather than waiting GC, as it will break
cycles between the container and container-aware services.
diff --git a/src/Symfony/Component/DependencyInjection/CHANGELOG.md b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
@@ -7,6 +7,7 @@ CHANGELOG
  * allowed specifying a directory to recursively load all configuration files it contains
  * deprecated the concept of scopes
  * added `Definition::setShared()` and `Definition::isShared()`
+ * added ClearableContainerInterface to be able to clear the container to release memory on shutdown
 
 2.7.0
 -----
diff --git a/src/Symfony/Component/DependencyInjection/ClearableContainerInterface.php b/src/Symfony/Component/DependencyInjection/ClearableContainerInterface.php
@@ -0,0 +1,27 @@
+<?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\DependencyInjection;
+
+/**
+ * ClearableContainerInterface defines additional clearing functionality
+ * for containers, allowing to release shared services when the container is
+ * not needed anymore.
+ *
+ * @author Christophe Coevoet <stof@notk.org>
+ */
+interface ClearableContainerInterface extends ContainerInterface
+{
+    /**
+     * Clears shared services from the container.
+     */
+    public function clear();
+}
diff --git a/src/Symfony/Component/DependencyInjection/Container.php b/src/Symfony/Component/DependencyInjection/Container.php
@@ -60,7 +60,7 @@
  *
  * @api
  */
-class Container implements IntrospectableContainerInterface
+class Container implements IntrospectableContainerInterface, ClearableContainerInterface
 {
     /**
      * @var ParameterBagInterface
@@ -375,6 +375,18 @@ public function initialized($id)
         return isset($this->services[$id]) || array_key_exists($id, $this->services);
     }
 
+    /**
+     * Clears shared services from the container.
+     */
+    public function clear()
+    {
+        if (!empty($this->scopedServices)) {
+            throw new RuntimeException('Clearing the container is not allowed when a scope is active.');
+        }
+
+        $this->services = array();
+    }
+
     /**
      * Gets all service ids.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php b/src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php
@@ -320,6 +320,49 @@ public function testInitialized()
         $this->assertTrue($sc->initialized('alias'), '->initialized() returns true for alias if aliased service is initialized');
     }
 
+    public function testClear()
+    {
+        $c = new Container();
+        $c->set('bar', new \stdClass());
+
+        $c->clear();
+
+        $this->assertNull($c->get('bar', ContainerInterface::NULL_ON_INVALID_REFERENCE));
+    }
+
+    /**
+     * @expectedException \Symfony\Component\DependencyInjection\Exception\RuntimeException
+     * @expectedExceptionMessage Clearing the container is not allowed when a scope is active.
+     * @group legacy
+     */
+    public function testCannotClearInActiveScope()
+    {
+        $c = new Container();
+        $c->addScope(new Scope('foo'));
+        $c->set('bar', new \stdClass());
+
+        $c->enterScope('foo');
+
+        $c->clear();
+    }
+
+    /**
+     * @group legacy
+     */
+    public function testClearAfterLeavingScope()
+    {
+        $c = new Container();
+        $c->addScope(new Scope('foo'));
+        $c->set('bar', new \stdClass());
+
+        $c->enterScope('foo');
+        $c->leaveScope('foo');
+
+        $c->clear();
+
+        $this->assertNull($c->get('bar', ContainerInterface::NULL_ON_INVALID_REFERENCE));
+    }
+
     /**
      * @group legacy
      */
diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -13,6 +13,7 @@
 
 use Symfony\Bridge\ProxyManager\LazyProxy\Instantiator\RuntimeInstantiator;
 use Symfony\Bridge\ProxyManager\LazyProxy\PhpDumper\ProxyDumper;
+use Symfony\Component\DependencyInjection\ClearableContainerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Dumper\PhpDumper;
@@ -180,6 +181,10 @@ public function shutdown()
             $bundle->setContainer(null);
         }
 
+        if ($this->container instanceof ClearableContainerInterface) {
+            $this->container->clear();
+        }
+
         $this->container = null;
     }
 
