- Patch #578676 by chx | neclimdul, Crell, Dave Reid: introduce a queue for cron.

includes/common.inc

@@ -3837,6 +3837,11 @@ function drupal_cron_run() {
 
   // Fetch the cron semaphore
   $semaphore = variable_get('cron_semaphore', FALSE);
+  
+  $return = FALSE;
+  // Grab the defined cron queues.
+  $queues = module_invoke_all('cron_queue_info');
+  drupal_alter('cron_queue_info', $queues);
 
   if ($semaphore) {
     if (REQUEST_TIME - $semaphore > 3600) {
@@ -3853,6 +3858,11 @@ function drupal_cron_run() {
     }
   }
   else {
+    // Make sure every queue exists. There is no harm in trying to recreate an
+    // existing queue.
+    foreach ($queues as $queue_name => $info) {
+      DrupalQueue::get($queue_name)->createQueue();
+    }
     // Register shutdown callback
     register_shutdown_function('drupal_cron_cleanup');
 
@@ -3870,8 +3880,19 @@ function drupal_cron_run() {
     variable_del('cron_semaphore');
 
     // Return TRUE so other functions can check if it did run successfully
-    return TRUE;
+    $return = TRUE;
   }
+  
+  foreach ($queues as $queue_name => $info) {
+    $function = $info['worker callback'];
+    $end = time() + (isset($info['time']) ? $info['time'] : 15);
+    $queue = DrupalQueue::get($queue_name);
+    while (time() < $end && ($item = $queue->claimItem())) {
+      $function($item->data);
+      $queue->deleteItem($item);
+    }
+  }
+  return $return;
 }
 
 /**

modules/aggregator/aggregator.module

@@ -306,18 +306,30 @@ function aggregator_permission() {
 /**
  * Implement hook_cron().
  *
- * Checks news feeds for updates once their refresh interval has elapsed.
+ * Queues news feeds for updates once their refresh interval has elapsed.
  */
 function aggregator_cron() {
   $result = db_query('SELECT * FROM {aggregator_feed} WHERE checked + refresh < :time AND refresh != :never', array(
     ':time' => REQUEST_TIME,
     ':never' => AGGREGATOR_CLEAR_NEVER
   ));
+  $queue = DrupalQueue::get('aggregator_feeds');
   foreach ($result as $feed) {
-    aggregator_refresh($feed);
+    $queue->createItem($feed);
   }
 }
 
+/**
+ * Implement hook_cron_queue_info().
+ */
+function aggregator_cron_queue_info() {
+  $queues['aggregator_feeds'] = array(
+    'worker callback' => 'aggregator_refresh',
+    'time' => 60,
+  );
+  return $queues;
+}
+
 /**
  * Implement hook_block_info().
  */

modules/aggregator/aggregator.test

@@ -128,7 +128,8 @@ class AggregatorTestCase extends DrupalWebTestCase {
    */
   function updateAndRemove($feed, $expected_count) {
     $this->updateFeedItems($feed, $expected_count);
-    $this->assertText('There is new syndicated content from');
+    $count = db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->fid))->fetchField();
+    $this->assertTrue($count);
     $this->removeFeedItems($feed);
     $count = db_query('SELECT COUNT(*) FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->fid))->fetchField();
     $this->assertTrue($count == 0);

modules/system/system.api.php

@@ -124,19 +124,51 @@ function hook_entity_info_alter(&$entity_info) {
  * intervals can implement hook_cron(). The engine will then call the hook
  * at the appropriate intervals defined by the administrator. This interface
  * is particularly handy to implement timers or to automate certain tasks.
- * Database maintenance, recalculation of settings or parameters, and
- * automatic mailings are good candidates for cron tasks.
+ * Database maintenance, recalculation of settings or parameters are good
+ * candidates for cron tasks.
+ * Long running tasks should use the queue API, define one or more queues with
+ * hook_cron_queue_info() and put items in the queue instead of running them in
+ * hook_cron(). Examples of jobs that are good candidates for hook_cron_queue_info
+ * include automated mailing, retrieving remote data, and intensive file tasks.
  *
  * This hook will only be called if cron.php is run (e.g. by crontab).
  */
 function hook_cron() {
   $result = db_query('SELECT * FROM {site} WHERE checked = 0 OR checked + refresh < :time', array(':time' => REQUEST_TIME));
+  $queue = DrupalQueue::get('aggregator_feeds');
 
   foreach ($result as $site) {
-    cloud_update($site);
+    $queue->createItem($site);
   }
 }
 
+/**
+ * Declare queues holding items that need to be run periodically.
+ *
+ * While there can be only one hook_cron() process running at the same time,
+ * there can be any number of processes defined here running. Because of
+ * this, long running tasks are much better suited for this API. Items queued
+ * in hook_cron might be processed in the same cron run if there are not many
+ * items in the queue, otherwise it might take several requests.which can be run
+ * in parallel.
+ *
+ * @return
+ *   An associative array where the key is the queue name and the value is
+ *   again an associative array. Possible keys are:
+ *     'worker callback'  The name of the function to call. It will be called
+ *                        with one argument, the $item from createItem called
+ *                        in hook_cron.
+ *     'time'             How much time Drupal should spend on calling this
+ *                        worker in seconds. Optional, defaults to 15.
+ */
+function hook_cron_queue_info() {
+  $queues['aggregator_feeds'] = array(
+    'worker callback' => 'aggregator_refresh',
+    'time' => 15,
+  );
+  return $queues;
+}
+
 /**
  * Allows modules to declare their own Forms API element types and specify their
  * default values.