diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc index 6abe08a..c7ab3af 100644 --- a/core/includes/bootstrap.inc +++ b/core/includes/bootstrap.inc @@ -3266,3 +3266,98 @@ function _drupal_shutdown_function() { } } } + + +/** + * @defgroup queue Queue operations + * @{ + * Queue items to allow later processing. + * + * The queue system allows placing items in a queue and processing them later. + * The system tries to ensure that only one consumer can process an item. + * + * Before a queue can be used it needs to be created by + * Drupal\Core\Queue\QueueInterface::createQueue(). + * + * Items can be added to the queue by passing an arbitrary data object to + * Drupal\Core\Queue\QueueInterface::createItem(). + * + * To process an item, call Drupal\Core\Queue\QueueInterface::claimItem() and + * specify how long you want to have a lease for working on that item. + * When finished processing, the item needs to be deleted by calling + * Drupal\Core\Queue\QueueInterface::deleteItem(). If the consumer dies, the + * item will be made available again by the Drupal\Core\Queue\QueueInterface + * implementation once the lease expires. Another consumer will then be able to + * receive it when calling Drupal\Core\Queue\QueueInterface::claimItem(). + * Due to this, the processing code should be aware that an item might be handed + * over for processing more than once. + * + * The $item object used by the Drupal\Core\Queue\QueueInterface can contain + * arbitrary metadata depending on the implementation. Systems using the + * interface should only rely on the data property which will contain the + * information passed to Drupal\Core\Queue\QueueInterface::createItem(). + * The full queue item returned by Drupal\Core\Queue\QueueInterface::claimItem() + * needs to be passed to Drupal\Core\Queue\QueueInterface::deleteItem() once + * processing is completed. + * + * There are two kinds of queue backends available: reliable, which preserves + * the order of messages and guarantees that every item will be executed at + * least once. The non-reliable kind only does a best effort to preserve order + * in messages and to execute them at least once but there is a small chance + * that some items get lost. For example, some distributed back-ends like + * Amazon SQS will be managing jobs for a large set of producers and consumers + * where a strict FIFO ordering will likely not be preserved. Another example + * would be an in-memory queue backend which might lose items if it crashes. + * However, such a backend would be able to deal with significantly more writes + * than a reliable queue and for many tasks this is more important. See + * aggregator_cron() for an example of how to effectively utilize a + * non-reliable queue. Another example is doing Twitter statistics -- the small + * possibility of losing a few items is insignificant next to power of the + * queue being able to keep up with writes. As described in the processing + * section, regardless of the queue being reliable or not, the processing code + * should be aware that an item might be handed over for processing more than + * once (because the processing code might time out before it finishes). + */ + +/** + * Instantiates and statically caches the correct class for a queue. + * + * The following variables can be set by variable_set or $conf overrides: + * - queue_class_$name: the class to be used for the queue $name. + * - queue_default_class: the class to use when queue_class_$name is not + * defined. Defaults to Drupal\Core\Queue\System, a reliable backend using + * SQL. + * - queue_default_reliable_class: the class to use when queue_class_$name is + * not defined and the queue_default_class is not reliable. Defaults to + * Drupal\Core\Queue\System. + * + * @param string $name + * The name of the queue to work with. + * @param bool $reliable + * TRUE if the ordering of items and guaranteeing every item executes at + * least once is important, FALSE if scalability is the main concern. Defaults + * to FALSE. + * + * @return Drupal\Core\Queue\QueueInterface + * The queue object for a given name. + * + * @see Drupal\Core\Queue\QueueInterface + */ +function queue($name, $reliable = FALSE) { + static $queues; + if (!isset($queues[$name])) { + $class = variable_get('queue_class_' . $name, NULL); + if ($class && $reliable && in_array('Drupal\Core\Queue\ReliableQueueInterface', class_implements($class))) { + $class = variable_get('queue_default_reliable_class', 'Drupal\Core\Queue\System'); + } + elseif (!$class) { + $class = variable_get('queue_default_class', 'Drupal\Core\Queue\System'); + } + $queues[$name] = new $class($name); + } + return $queues[$name]; +} + +/** + * @} End of "defgroup queue". + */ diff --git a/core/includes/common.inc b/core/includes/common.inc index 353a9b5..cce0fe4 100644 --- a/core/includes/common.inc +++ b/core/includes/common.inc @@ -7610,97 +7610,3 @@ function drupal_get_filetransfer_info() { } return $info; } - -/** - * @defgroup queue Queue operations - * @{ - * Queue items to allow later processing. - * - * The queue system allows placing items in a queue and processing them later. - * The system tries to ensure that only one consumer can process an item. - * - * Before a queue can be used it needs to be created by - * Drupal\Core\Queue\QueueInterface::createQueue(). - * - * Items can be added to the queue by passing an arbitrary data object to - * Drupal\Core\Queue\QueueInterface::createItem(). - * - * To process an item, call Drupal\Core\Queue\QueueInterface::claimItem() and - * specify how long you want to have a lease for working on that item. - * When finished processing, the item needs to be deleted by calling - * Drupal\Core\Queue\QueueInterface::deleteItem(). If the consumer dies, the - * item will be made available again by the Drupal\Core\Queue\QueueInterface - * implementation once the lease expires. Another consumer will then be able to - * receive it when calling Drupal\Core\Queue\QueueInterface::claimItem(). - * Due to this, the processing code should be aware that an item might be handed - * over for processing more than once. - * - * The $item object used by the Drupal\Core\Queue\QueueInterface can contain - * arbitrary metadata depending on the implementation. Systems using the - * interface should only rely on the data property which will contain the - * information passed to Drupal\Core\Queue\QueueInterface::createItem(). - * The full queue item returned by Drupal\Core\Queue\QueueInterface::claimItem() - * needs to be passed to Drupal\Core\Queue\QueueInterface::deleteItem() once - * processing is completed. - * - * There are two kinds of queue backends available: reliable, which preserves - * the order of messages and guarantees that every item will be executed at - * least once. The non-reliable kind only does a best effort to preserve order - * in messages and to execute them at least once but there is a small chance - * that some items get lost. For example, some distributed back-ends like - * Amazon SQS will be managing jobs for a large set of producers and consumers - * where a strict FIFO ordering will likely not be preserved. Another example - * would be an in-memory queue backend which might lose items if it crashes. - * However, such a backend would be able to deal with significantly more writes - * than a reliable queue and for many tasks this is more important. See - * aggregator_cron() for an example of how to effectively utilize a - * non-reliable queue. Another example is doing Twitter statistics -- the small - * possibility of losing a few items is insignificant next to power of the - * queue being able to keep up with writes. As described in the processing - * section, regardless of the queue being reliable or not, the processing code - * should be aware that an item might be handed over for processing more than - * once (because the processing code might time out before it finishes). - */ - -/** - * Instantiates and statically caches the correct class for a queue. - * - * The following variables can be set by variable_set or $conf overrides: - * - queue_class_$name: the class to be used for the queue $name. - * - queue_default_class: the class to use when queue_class_$name is not - * defined. Defaults to Drupal\Core\Queue\System, a reliable backend using - * SQL. - * - queue_default_reliable_class: the class to use when queue_class_$name is - * not defined and the queue_default_class is not reliable. Defaults to - * Drupal\Core\Queue\System. - * - * @param string $name - * The name of the queue to work with. - * @param bool $reliable - * TRUE if the ordering of items and guaranteeing every item executes at - * least once is important, FALSE if scalability is the main concern. Defaults - * to FALSE. - * - * @return Drupal\Core\Queue\QueueInterface - * The queue object for a given name. - * - * @see Drupal\Core\Queue\QueueInterface - */ -function queue($name, $reliable = FALSE) { - static $queues; - if (!isset($queues[$name])) { - $class = variable_get('queue_class_' . $name, NULL); - if ($class && $reliable && in_array('Drupal\Core\Queue\ReliableQueueInterface', class_implements($class))) { - $class = variable_get('queue_default_reliable_class', 'Drupal\Core\Queue\System'); - } - elseif (!$class) { - $class = variable_get('queue_default_class', 'Drupal\Core\Queue\System'); - } - $queues[$name] = new $class($name); - } - return $queues[$name]; -} - -/** - * @} End of "defgroup queue". - */