fixed session management

Some explanations on how it works now:

 * The Session is an optional dependency of the Request. If you create the
   Request yourself (which is mandatory now in the front controller) and if
   you don't inject a Session yourself (which is recommended if you want the
   session to be configured via dependency injection), the Symfony2 Kernel
   will associate the Session configured in the Container with the Request
   automatically.

 * When duplicating a request, the session is shared between the parent and
   the child (that's because duplicated requests are sub-requests of the main
   one most of the time.) Notice that when you use ::create(), the behavior is
   the same as for the constructor; no session is attached to the Request.

 * Symfony2 tries hard to not create a session cookie when it is not needed
   but a Session object is always available (the cookie is only created when
   "something" is stored in the session.)

 * Symfony2 only starts a session when:

   * A session already exists in the request ($_COOKIE[session_name()] is
     defined -- this is done by RequestListener);

   * There is something written in the session object (the cookie will be sent
     to the Client).

 * Notice that reading from the session does not start the session anymore (as
   we don't need to start a new session to get the default values, and because
   if a session exists, it has already been started by RequestListener.)

src/Symfony/Bundle/FrameworkBundle/Controller/ControllerResolver.php

@@ -42,7 +42,6 @@ public function __construct(ContainerInterface $container, ControllerNameConvert
     {
         $this->container = $container;
         $this->converter = $converter;
-        $this->esiSupport = $container->has('esi') && $container->getEsiService()->hasSurrogateEsiCapability($container->getRequestService());
 
         parent::__construct($logger);
     }
@@ -137,6 +136,10 @@ public function render($controller, array $options = array())
             $options['alt'] = array($options['alt']);
         }
 
+        if (null === $this->esiSupport) {
+            $this->esiSupport = $this->container->has('esi') && $this->container->getEsiService()->hasSurrogateEsiCapability($this->container->getRequestService());
+        }
+
         if ($this->esiSupport && $options['standalone']) {
             $uri = $this->generateInternalUri($controller, $options['attributes'], $options['query']);
 

src/Symfony/Bundle/FrameworkBundle/RequestListener.php

@@ -3,9 +3,11 @@
 namespace Symfony\Bundle\FrameworkBundle;
 
 use Symfony\Component\HttpKernel\Log\LoggerInterface;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\Routing\RouterInterface;
-use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /*
  * This file is part of the Symfony framework.
@@ -25,9 +27,11 @@ class RequestListener
 {
     protected $router;
     protected $logger;
+    protected $container;
 
-    public function __construct(RouterInterface $router, LoggerInterface $logger = null)
+    public function __construct(ContainerInterface $container, RouterInterface $router, LoggerInterface $logger = null)
     {
+        $this->container = $container;
         $this->router = $router;
         $this->logger = $logger;
     }
@@ -40,14 +44,39 @@ public function __construct(RouterInterface $router, LoggerInterface $logger = n
      */
     public function register(EventDispatcher $dispatcher, $priority = 0)
     {
-        $dispatcher->connect('core.request', array($this, 'resolve'), $priority);
+        $dispatcher->connect('core.request', array($this, 'handle'), $priority);
     }
 
-    public function resolve(Event $event)
+    public function handle(Event $event)
     {
         $request = $event->getParameter('request');
+        $master = HttpKernelInterface::MASTER_REQUEST === $event->getParameter('request_type');
+
+        $this->initializeSession($request, $master);
+
+        $this->initializeRequestAttributes($request, $master);
+    }
 
-        if (HttpKernelInterface::MASTER_REQUEST === $event->getParameter('request_type')) {
+    protected function initializeSession(Request $request, $master)
+    {
+        if (!$master) {
+            return;
+        }
+
+        // inject the session object if none is present
+        if (null === $request->getSession()) {
+            $request->setSession($this->container->get('session'));
+        }
+
+        // starts the session if a session cookie already exists in the request...
+        if ($request->hasSession()) {
+            $request->getSession()->start();
+        }
+    }
+
+    protected function initializeRequestAttributes(Request $request, $master)
+    {
+        if ($master) {
             // set the context even if the parsing does not need to be done
             // to have correct link generation
             $this->router->setContext(array(
@@ -59,9 +88,11 @@ public function resolve(Event $event)
         }
 
         if ($request->attributes->has('_controller')) {
+            // routing is already done
             return;
         }
 
+        // add attributes based on the path info (routing)
         if (false !== $parameters = $this->router->match($request->getPathInfo())) {
             if (null !== $this->logger) {
                 $this->logger->info(sprintf('Matched route "%s" (parameters: %s)', $parameters['_route'], str_replace("\n", '', var_export($parameters, true))));

src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml

@@ -7,7 +7,6 @@
     <parameters>
         <parameter key="event_dispatcher.class">Symfony\Bundle\FrameworkBundle\EventDispatcher</parameter>
         <parameter key="http_kernel.class">Symfony\Component\HttpKernel\HttpKernel</parameter>
-        <parameter key="request.class">Symfony\Component\HttpFoundation\Request</parameter>
         <parameter key="response.class">Symfony\Component\HttpFoundation\Response</parameter>
         <parameter key="error_handler.class">Symfony\Component\HttpKernel\Debug\ErrorHandler</parameter>
         <parameter key="error_handler.level">null</parameter>
@@ -30,12 +29,6 @@
             <argument type="service" id="controller_resolver" />
         </service>
 
-        <service id="request" class="%request.class%">
-            <call method="setSession">
-                <argument type="service" id="session" on-invalid="ignore"></argument>
-            </call>
-        </service>
-
         <service id="response" class="%response.class%" shared="false" />
     </services>
 </container>

src/Symfony/Bundle/FrameworkBundle/Resources/config/web.xml

@@ -29,6 +29,7 @@
 
         <service id="request_listener" class="%request_listener.class%">
             <tag name="kernel.listener" />
+            <argument type="service" id="service_container" />
             <argument type="service" id="router" />
             <argument type="service" id="logger" on-invalid="ignore" />
         </service>

src/Symfony/Component/HttpFoundation/Request.php

@@ -200,6 +200,12 @@ public function duplicate(array $query = null, array $request = null, array $att
         return $dup;
     }
 
+    /**
+     * Clones the current request.
+     *
+     * Note that the session is not cloned as duplicated requests
+     * are most of the time sub-requests of the main one.
+     */
     public function __clone()
     {
         $this->query      = clone $this->query;
@@ -245,11 +251,6 @@ public function get($key, $default = null)
 
     public function getSession()
     {
-        if (null === $this->session) {
-            $this->session = new Session(new NativeSessionStorage());
-        }
-        $this->session->start();
-
         return $this->session;
     }
 

src/Symfony/Component/HttpFoundation/Session.php

@@ -36,7 +36,7 @@ public function __construct(SessionStorageInterface $storage, array $options = a
     {
         $this->storage = $storage;
         $this->options = $options;
-        $this->attributes = array();
+        $this->attributes = array('_flash' => array(), '_locale' => $this->getDefaultLocale());
         $this->started = false;
     }
 
@@ -58,7 +58,7 @@ public function start()
         }
 
         if (!isset($this->attributes['_locale'])) {
-            $this->attributes['_locale'] = isset($this->options['default_locale']) ? $this->options['default_locale'] : 'en';
+            $this->attributes['_locale'] = $this->getDefaultLocale();
         }
 
         // flag current flash messages to be removed at shutdown
@@ -76,10 +76,6 @@ public function start()
      */
     public function has($name)
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return array_key_exists($name, $this->attributes);
     }
 
@@ -93,10 +89,6 @@ public function has($name)
      */
     public function get($name, $default = null)
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
     }
 
@@ -122,10 +114,6 @@ public function set($name, $value)
      */
     public function getAttributes()
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return $this->attributes;
     }
 
@@ -187,10 +175,6 @@ public function invalidate()
      */
     public function getLocale()
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return $this->attributes['_locale'];
     }
 
@@ -201,6 +185,10 @@ public function getLocale()
      */
     public function setLocale($locale)
     {
+        if ($locale === $this->getDefaultLocale()) {
+            return;
+        }
+
         if (false === $this->started) {
             $this->start();
         }
@@ -210,10 +198,6 @@ public function setLocale($locale)
 
     public function getFlashMessages()
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return $this->attributes['_flash'];
     }
 
@@ -228,10 +212,6 @@ public function setFlashMessages($values)
 
     public function getFlash($name, $default = null)
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return array_key_exists($name, $this->attributes['_flash']) ? $this->attributes['_flash'][$name] : $default;
     }
 
@@ -247,10 +227,6 @@ public function setFlash($name, $value)
 
     public function hasFlash($name)
     {
-        if (false === $this->started) {
-            $this->start();
-        }
-
         return array_key_exists($name, $this->attributes['_flash']);
     }
 
@@ -280,4 +256,9 @@ public function unserialize($serialized)
         $this->attributes = array();
         $this->started = false;
     }
+
+    protected function getDefaultLocale()
+    {
+        return isset($this->options['default_locale']) ? $this->options['default_locale'] : 'en';
+    }
 }

src/Symfony/Component/HttpKernel/HttpKernel.php

@@ -45,18 +45,13 @@ public function __construct(ContainerInterface $container, EventDispatcher $disp
      */
     public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
     {
-        $currentRequest = null;
-        if (HttpKernelInterface::MASTER_REQUEST === $type) {
-            $currentRequest = $this->container->get('request');
-        }
+        $masterRequest = HttpKernelInterface::MASTER_REQUEST === $type ? $request : $this->container->get('request');
 
         $this->container->set('request', $request);
 
         $response = parent::handle($request, $type, $catch);
 
-        if (null !== $currentRequest) {
-            $this->container->set('request', $currentRequest);
-        }
+        $this->container->set('request', $masterRequest);
 
         return $response;
     }