commit 4dbc76688cff6cd1dd5065c55c42b11506fdf08a
Author: Bart Feenstra <bart@mynameisbart.com>
Date:   Sun Oct 13 19:19:17 2013 +0200

    1972304

diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 9b0ef4c..4c321f1 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -411,7 +411,8 @@ function install_begin_request(&$install_state) {
 
     // Register a module handler for managing enabled modules.
     $container
-      ->register('module_handler', 'Drupal\Core\Extension\ModuleHandler');
+      ->register('module_handler', 'Drupal\Core\Extension\ModuleHandler')
+      ->addArgument(new Reference('event_dispatcher'));
 
     // Register the Guzzle HTTP client for fetching translation files from a
     // remote translation server such as localization.drupal.org.
diff --git a/core/lib/Drupal/Core/CoreServiceProvider.php b/core/lib/Drupal/Core/CoreServiceProvider.php
index 9cd8f5a..17f7101 100644
--- a/core/lib/Drupal/Core/CoreServiceProvider.php
+++ b/core/lib/Drupal/Core/CoreServiceProvider.php
@@ -89,10 +89,12 @@ protected function registerModuleHandler(ContainerBuilder $container) {
     if ($container->getParameter('kernel.environment') == 'install') {
       // During installation we use the non-cached version.
       $container->register('module_handler', 'Drupal\Core\Extension\ModuleHandler')
+        ->addArgument(new Reference('event_dispatcher'))
         ->addArgument('%container.modules%');
     }
     else {
       $container->register('module_handler', 'Drupal\Core\Extension\CachedModuleHandler')
+        ->addArgument(new Reference('event_dispatcher'))
         ->addArgument('%container.modules%')
         ->addArgument(new Reference('state'))
         ->addArgument(new Reference('cache.bootstrap'));
diff --git a/core/lib/Drupal/Core/DependencyInjection/UpdateServiceProvider.php b/core/lib/Drupal/Core/DependencyInjection/UpdateServiceProvider.php
index d458665..3d0c723 100644
--- a/core/lib/Drupal/Core/DependencyInjection/UpdateServiceProvider.php
+++ b/core/lib/Drupal/Core/DependencyInjection/UpdateServiceProvider.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\DependencyInjection\ServiceProviderInterface;
+use Symfony\Component\DependencyInjection\Reference;
 
 /**
  * ServiceProvider class for update.php service overrides.
@@ -33,6 +34,7 @@ public function register(ContainerBuilder $container) {
       ->register('config.storage', 'Drupal\Core\Config\FileStorage')
       ->addArgument(config_get_config_directory(CONFIG_ACTIVE_DIRECTORY));
     $container->register('module_handler', 'Drupal\Core\Extension\UpdateModuleHandler')
+      ->addArgument(new Reference('event_dispatcher'))
       ->addArgument('%container.modules%');
     $container
       ->register("cache_factory", 'Drupal\Core\Cache\MemoryBackendFactory');
diff --git a/core/lib/Drupal/Core/Extension/CachedModuleHandler.php b/core/lib/Drupal/Core/Extension/CachedModuleHandler.php
index 6e09432..88ad8a6 100644
--- a/core/lib/Drupal/Core/Extension/CachedModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/CachedModuleHandler.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Extension;
 
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\KeyValueStore\KeyValueStoreInterface;
 
@@ -39,8 +41,8 @@ class CachedModuleHandler extends ModuleHandler implements CachedModuleHandlerIn
   /**
    * Constructs a new CachedModuleHandler object.
    */
-  public function __construct(array $module_list = array(), KeyValueStoreInterface $state, CacheBackendInterface $bootstrap_cache) {
-    parent::__construct($module_list);
+  public function __construct(EventDispatcherInterface $dispatcher, KeyValueStoreInterface $state, CacheBackendInterface $bootstrap_cache, array $module_list = array()) {
+    parent::__construct($dispatcher, $module_list);
     $this->state = $state;
     $this->bootstrapCache = $bootstrap_cache;
   }
diff --git a/core/lib/Drupal/Core/Extension/HookEvent.php b/core/lib/Drupal/Core/Extension/HookEvent.php
new file mode 100644
index 0000000..2d2b9a4
--- /dev/null
+++ b/core/lib/Drupal/Core/Extension/HookEvent.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Drupal\Core\Extension;
+
+use Symfony\Component\EventDispatcher\GenericEvent;
+
+/**
+ * Generic event for hooks.
+ *
+ * Every hook that fires will also fire an event named hook.$hookname, using
+ * this class. Modules may listen to this event rather than the hook in order
+ * to have their code be injectable and automatically lazy-load as a class.
+ */
+class HookEvent extends GenericEvent {
+
+  /**
+   * An array of collected values from listeners.
+   *
+   * @param array $value
+   */
+  protected $return = array();
+
+  /**
+   * Adds a value to the collected return values from all listeners.
+   *
+   * Adding a value via this method is equivalent to returning a value
+   * from a procedural hook implementation. All values added here will be merged
+   * into a single array when returned to the calling code.
+   *
+   * @param mixed $value
+   *   The value to "return" from a listener.
+   *
+   * @see \Drupal\Core\Extension\ModuleHandler::invokeAll().
+   */
+  public function addToReturn($value) {
+    $this->return[] = $value;
+  }
+
+  /**
+   * Returns the collected return values from all listeners to this hook event.
+   * @return array
+   */
+  public function getReturn() {
+    return $this->return;
+  }
+
+}
+
diff --git a/core/lib/Drupal/Core/Extension/ModuleHandler.php b/core/lib/Drupal/Core/Extension/ModuleHandler.php
index 92cf2a4..d91150b 100644
--- a/core/lib/Drupal/Core/Extension/ModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/ModuleHandler.php
@@ -8,6 +8,7 @@
 namespace Drupal\Core\Extension;
 
 use Drupal\Component\Graph\Graph;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Yaml\Parser;
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Cache\CacheBackendInterface;
@@ -65,8 +66,17 @@ class ModuleHandler implements ModuleHandlerInterface {
   protected $alterFunctions;
 
   /**
+   * Event dispatcher to use for hook events.
+   *
+   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
+   */
+  protected $dispatcher;
+
+  /**
    * Constructs a ModuleHandler object.
    *
+   * @param \Symfony\Component\EventDispatcher\EventDispatcherInterface $dispatcher
+   *   The event dispatcher that should be used for firing hook events.
    * @param array $module_list
    *   An associative array whose keys are the names of installed modules and
    *   whose values are the module filenames. This is normally the
@@ -75,7 +85,8 @@ class ModuleHandler implements ModuleHandlerInterface {
    * @see \Drupal\Core\DrupalKernel
    * @see \Drupal\Core\CoreServiceProvider
    */
-  public function __construct(array $module_list = array()) {
+  public function __construct(EventDispatcherInterface $dispatcher, array $module_list = array()) {
+    $this->dispatcher = $dispatcher;
     $this->moduleList = $module_list;
   }
 
@@ -289,6 +300,16 @@ public function invokeAll($hook, $args = array()) {
           $return[] = $result;
         }
       }
+      $event = new HookEvent($hook, $args);
+      $this->dispatcher->dispatch("hook.{$hook}", $event);
+      foreach ($event->getReturn() as $result) {
+        if (is_array($result)) {
+          $return = NestedArray::mergeDeep($return, $result);
+        }
+        else {
+          $return[] = $result;
+        }
+      }
     }
 
     return $return;
diff --git a/core/modules/history/history.module b/core/modules/history/history.module
index a3842fc..89d474d 100644
--- a/core/modules/history/history.module
+++ b/core/modules/history/history.module
@@ -120,15 +120,6 @@ function history_write($nid, $account = NULL) {
 }
 
 /**
- * Implements hook_cron().
- */
-function history_cron() {
-  db_delete('history')
-    ->condition('timestamp', HISTORY_READ_LIMIT, '<')
-    ->execute();
-}
-
-/**
  * Implements hook_node_delete().
  */
 function history_node_delete(EntityInterface $node) {
diff --git a/core/modules/history/history.services.yml b/core/modules/history/history.services.yml
new file mode 100644
index 0000000..d042b5c
--- /dev/null
+++ b/core/modules/history/history.services.yml
@@ -0,0 +1,4 @@
+services:
+  history.cron:
+    class: Drupal\history\EventSubscriber\CoreSubscriber
+    arguments: ['@database']
diff --git a/core/modules/history/lib/Drupal/history/EventSubscriber/CronSubscriber.php b/core/modules/history/lib/Drupal/history/EventSubscriber/CronSubscriber.php
new file mode 100644
index 0000000..90a6192
--- /dev/null
+++ b/core/modules/history/lib/Drupal/history/EventSubscriber/CronSubscriber.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace Drupal\history\EventSubscriber;
+
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+use Drupal\Core\Database\Connection;
+use Drupal\Core\Extension\HookEvent;
+
+/**
+ * Respond to cron events.
+ */
+class CronSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The database connection for this subscriber.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * Constructs a new CronSubscriber.
+   *
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The database connection for this subscriber.
+   */
+  public function __construct(Connection $connection) {
+    $this->connection = $connection;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  static function getSubscribedEvents() {
+    $events['hook.cron'][] = array('cleanHistory', 30);
+
+    return $events;
+  }
+
+  /**
+   * Clear out old history events.
+   *
+   * @param \Drupal\Core\Extension\HookEvent $event
+   *   The event to process.
+   */
+  public function cleanHistory(HookEvent $event) {
+   $this->connection->delete('history')
+    ->condition('timestamp', HISTORY_READ_LIMIT, '<')
+    ->execute();
+  }
+}
+