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class SystemQueue
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Error message
User warning: The following module is missing from the file system: theme/theme. For information about how to fix this, see the documentation page. in _drupal_trigger_error_with_delayed_logging() (line 1156 of /var/www/html/elmsln_community/api.elmsln.org/includes/bootstrap.inc).- cis7 modules/system/system.queue.inc SystemQueue
- cle7 modules/system/system.queue.inc SystemQueue
- elmsmedia7 modules/system/system.queue.inc SystemQueue
- icor7 modules/system/system.queue.inc SystemQueue
- meedjum_blog7 modules/system/system.queue.inc SystemQueue
- mooc7 modules/system/system.queue.inc SystemQueue
Default queue implementation.
Hierarchy
- class SystemQueue implements \DrupalReliableQueueInterface
Expanded class hierarchy of SystemQueue
Members
Name![]() |
Modifiers | Type | Description |
---|---|---|---|
SystemQueue::$name | protected | property | The name of the queue this instance is working with. |
SystemQueue::claimItem | public | function | Claim an item in the queue for processing. Overrides DrupalQueueInterface::claimItem |
SystemQueue::createItem | public | function | Add a queue item and store it directly to the queue. Overrides DrupalQueueInterface::createItem |
SystemQueue::createQueue | public | function | Create a queue. Overrides DrupalQueueInterface::createQueue |
SystemQueue::deleteItem | public | function | Delete a finished item from the queue. Overrides DrupalQueueInterface::deleteItem |
SystemQueue::deleteQueue | public | function | Delete a queue and every item in the queue. Overrides DrupalQueueInterface::deleteQueue |
SystemQueue::numberOfItems | public | function | Retrieve the number of items in the queue. Overrides DrupalQueueInterface::numberOfItems |
SystemQueue::releaseItem | public | function | Release an item that the worker could not process, so another worker can come in and process it before the timeout expires. Overrides DrupalQueueInterface::releaseItem |
SystemQueue::__construct | public | function |
File
- modules/
system/ system.queue.inc, line 198 - Queue functionality.
View source
class SystemQueue implements DrupalReliableQueueInterface {
/**
* The name of the queue this instance is working with.
*
* @var string
*/
protected $name;
public function __construct($name) {
$this->name = $name;
}
public function createItem($data) {
// During a Drupal 6.x to 7.x update, drupal_get_schema() does not contain
// the queue table yet, so we cannot rely on drupal_write_record().
$query = db_insert('queue')->fields(array(
'name' => $this->name,
'data' => serialize($data),
// We cannot rely on REQUEST_TIME because many items might be created
// by a single request which takes longer than 1 second.
'created' => time(),
));
return (bool) $query->execute();
}
public function numberOfItems() {
return db_query('SELECT COUNT(item_id) FROM {queue} WHERE name = :name', array(':name' => $this->name))->fetchField();
}
public function claimItem($lease_time = 30) {
// Claim an item by updating its expire fields. If claim is not successful
// another thread may have claimed the item in the meantime. Therefore loop
// until an item is successfully claimed or we are reasonably sure there
// are no unclaimed items left.
while (TRUE) {
$item = db_query_range('SELECT data, item_id FROM {queue} q WHERE expire = 0 AND name = :name ORDER BY created ASC', 0, 1, array(':name' => $this->name))->fetchObject();
if ($item) {
// Try to update the item. Only one thread can succeed in UPDATEing the
// same row. We cannot rely on REQUEST_TIME because items might be
// claimed by a single consumer which runs longer than 1 second. If we
// continue to use REQUEST_TIME instead of the current time(), we steal
// time from the lease, and will tend to reset items before the lease
// should really expire.
$update = db_update('queue')->fields(array(
'expire' => time() + $lease_time,
))->condition('item_id', $item->item_id)->condition('expire', 0);
// If there are affected rows, this update succeeded.
if ($update->execute()) {
$item->data = unserialize($item->data);
return $item;
}
}
else {
// No items currently available to claim.
return FALSE;
}
}
}
public function releaseItem($item) {
$update = db_update('queue')->fields(array(
'expire' => 0,
))->condition('item_id', $item->item_id);
return $update->execute();
}
public function deleteItem($item) {
db_delete('queue')->condition('item_id', $item->item_id)->execute();
}
public function createQueue() {
// All tasks are stored in a single database table (which is created when
// Drupal is first installed) so there is nothing we need to do to create
// a new queue.
}
public function deleteQueue() {
db_delete('queue')->condition('name', $this->name)->execute();
}
}
Related topics
2 string references to 'SystemQueue'
- DrupalQueue::get in modules/
system/ system.queue.inc - Returns the queue object for a given name.
- og-7.x-1.x.database.php in sites/
all/ modules/ ulmus/ og/ tests/ og-7.x-1.x.database.php - Filled installation of Drupal 7.0, for test purposes.