Bind session handling to request lifecycle

With this change, session objects are no longer instantiated
globally, but instead created within a middleware during the
request lifecycle.

In addition, session garbage collection is integrated with
the already existing middleware for this purpose.

src/Foundation/Application.php

@@ -718,8 +718,6 @@ class Application extends Container implements ApplicationContract
             'filesystem.cloud'     => [\Illuminate\Contracts\Filesystem\Cloud::class],
             'hash'                 => [\Illuminate\Contracts\Hashing\Hasher::class],
             'mailer'               => [\Illuminate\Mail\Mailer::class, \Illuminate\Contracts\Mail\Mailer::class, \Illuminate\Contracts\Mail\MailQueue::class],
-            'session'              => [\Illuminate\Session\SessionManager::class],
-            'session.driver'       => [\Illuminate\Contracts\Session\Session::class],
             'validator'            => [\Illuminate\Validation\Factory::class, \Illuminate\Contracts\Validation\Factory::class],
             'view'                 => [\Illuminate\View\Factory::class, \Illuminate\Contracts\View\Factory::class],
         ];

src/Foundation/Site.php

@@ -240,12 +240,8 @@ class Site
                 ]
             ],
             'session' => [
-                'driver' => 'file',
                 'lifetime' => 120,
-                'expire_on_close' => false,
-                'encrypt' => false,
                 'files' => $app->storagePath().'/sessions',
-                'lottery' => [2, 100],
                 'cookie' => 'session'
             ]
         ]);

src/Http/Middleware/CollectGarbage.php

@@ -15,12 +15,30 @@ use Flarum\Http\AccessToken;
 use Flarum\User\AuthToken;
 use Flarum\User\EmailToken;
 use Flarum\User\PasswordToken;
+use Illuminate\Contracts\Config\Repository as ConfigRepository;
 use Interop\Http\ServerMiddleware\DelegateInterface;
 use Interop\Http\ServerMiddleware\MiddlewareInterface;
 use Psr\Http\Message\ServerRequestInterface as Request;
+use SessionHandlerInterface;
 
 class CollectGarbage implements MiddlewareInterface
 {
+    /**
+     * @var SessionHandlerInterface
+     */
+    protected $sessionHandler;
+
+    /**
+     * @var array
+     */
+    protected $sessionConfig;
+
+    public function __construct(SessionHandlerInterface $handler, ConfigRepository $config)
+    {
+        $this->sessionHandler = $handler;
+        $this->sessionConfig = $config->get('session');
+    }
+
     public function process(Request $request, DelegateInterface $delegate)
     {
         $this->collectGarbageSometimes();
@@ -43,10 +61,17 @@ class CollectGarbage implements MiddlewareInterface
         EmailToken::where('created_at', '<=', $earliestToKeep)->delete();
         PasswordToken::where('created_at', '<=', $earliestToKeep)->delete();
         AuthToken::where('created_at', '<=', $earliestToKeep)->delete();
+
+        $this->sessionHandler->gc($this->getSessionLifetimeInSeconds());
     }
 
     private function hit()
     {
         return mt_rand(1, 100) <= 2;
     }
+
+    private function getSessionLifetimeInSeconds()
+    {
+        return $this->sessionConfig['lifetime'] * 60;
+    }
 }

src/Http/Middleware/StartSession.php

@@ -13,19 +13,21 @@ namespace Flarum\Http\Middleware;
 
 use Dflydev\FigCookies\FigResponseCookies;
 use Flarum\Http\CookieFactory;
+use Illuminate\Contracts\Config\Repository as ConfigRepository;
 use Illuminate\Contracts\Session\Session;
-use Illuminate\Session\SessionManager;
+use Illuminate\Session\Store;
 use Interop\Http\ServerMiddleware\DelegateInterface;
 use Interop\Http\ServerMiddleware\MiddlewareInterface;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
+use SessionHandlerInterface;
 
 class StartSession implements MiddlewareInterface
 {
     /**
-     * @var SessionManager
+     * @var SessionHandlerInterface
      */
-    protected $manager;
+    protected $handler;
 
     /**
      * @var CookieFactory
@@ -33,25 +35,29 @@ class StartSession implements MiddlewareInterface
     protected $cookie;
 
     /**
-     * @param SessionManager $manager
+     * @var array
+     */
+    protected $config;
+
+    /**
      * @param CookieFactory $cookie
      */
-    public function __construct(SessionManager $manager, CookieFactory $cookie)
+    public function __construct(SessionHandlerInterface $handler, CookieFactory $cookie, ConfigRepository $config)
     {
-        $this->manager = $manager;
+        $this->handler = $handler;
         $this->cookie = $cookie;
+        $this->config = $config->get('session');
     }
 
     public function process(Request $request, DelegateInterface $delegate)
     {
-        $request = $request->withAttribute('session',
-            $session = $this->startSession($request)
+        $request = $request->withAttribute(
+            'session',
+            $session = $this->makeSession($request)
         );
 
-        $this->collectGarbage($session);
-
+        $session->start();
         $response = $delegate->process($request);
-
         $session->save();
 
         $response = $this->withCsrfTokenHeader($response, $session);
@@ -59,37 +65,20 @@ class StartSession implements MiddlewareInterface
         return $this->withSessionCookie($response, $session);
     }
 
-    private function startSession(Request $request)
+    private function makeSession(Request $request)
     {
-        $session = $this->manager->driver();
+        $cookieName = $this->cookie->getName($this->config['cookie']);
 
-        $id = array_get($request->getCookieParams(), $this->cookie->getName($session->getName()));
-
-        $session->setId($id);
-        $session->start();
-
-        return $session;
-    }
-
-    private function collectGarbage(Session $session)
-    {
-        $config = $this->manager->getSessionConfig();
-
-        if ($this->configHitsLottery($config)) {
-            $session->getHandler()->gc($this->getSessionLifetimeInSeconds());
-        }
-    }
-
-    private function configHitsLottery(array $config)
-    {
-        return random_int(1, $config['lottery'][1]) <= $config['lottery'][0];
+        return new Store(
+            $cookieName,
+            $this->handler,
+            array_get($request->getCookieParams(), $cookieName)
+        );
     }
 
     private function withCsrfTokenHeader(Response $response, Session $session)
     {
-        $response = $response->withHeader('X-CSRF-Token', $session->token());
-
-        return $response;
+        return $response->withHeader('X-CSRF-Token', $session->token());
     }
 
     private function withSessionCookie(Response $response, Session $session)
@@ -102,6 +91,6 @@ class StartSession implements MiddlewareInterface
 
     private function getSessionLifetimeInSeconds()
     {
-        return ($this->manager->getSessionConfig()['lifetime'] ?? null) * 60;
+        return $this->config['lifetime'] * 60;
     }
 }

src/User/UserServiceProvider.php

@@ -15,7 +15,9 @@ use Flarum\Event\ConfigureUserPreferences;
 use Flarum\Event\GetPermission;
 use Flarum\Foundation\AbstractServiceProvider;
 use Illuminate\Contracts\Container\Container;
+use Illuminate\Session\FileSessionHandler;
 use RuntimeException;
+use SessionHandlerInterface;
 
 class UserServiceProvider extends AbstractServiceProvider
 {
@@ -23,6 +25,26 @@ class UserServiceProvider extends AbstractServiceProvider
      * {@inheritdoc}
      */
     public function register()
+    {
+        $this->registerSession();
+        $this->registerGate();
+        $this->registerAvatarsFilesystem();
+    }
+
+    protected function registerSession()
+    {
+        $this->app->singleton('session.handler', function ($app) {
+            return new FileSessionHandler(
+                $app['files'],
+                $app['config']['session.files'],
+                $app['config']['session.lifetime']
+            );
+        });
+
+        $this->app->alias('session.handler', SessionHandlerInterface::class);
+    }
+
+    protected function registerGate()
     {
         $this->app->singleton('flarum.gate', function ($app) {
             return new Gate($app, function () {
@@ -32,8 +54,6 @@ class UserServiceProvider extends AbstractServiceProvider
 
         $this->app->alias('flarum.gate', 'Illuminate\Contracts\Auth\Access\Gate');
         $this->app->alias('flarum.gate', Gate::class);
-
-        $this->registerAvatarsFilesystem();
     }
 
     protected function registerAvatarsFilesystem()