class DatabaseQueue in Zircon Profile 8
Same name and namespace in other branches
- 8.0 core/lib/Drupal/Core/Queue/DatabaseQueue.php \Drupal\Core\Queue\DatabaseQueue
Default queue implementation.
Hierarchy
- class \Drupal\Core\Queue\DatabaseQueue implements ReliableQueueInterface uses DependencySerializationTrait
Expanded class hierarchy of DatabaseQueue
Related topics
1 file declares its use of DatabaseQueue
- QueueTest.php in core/
modules/ system/ src/ Tests/ Queue/ QueueTest.php - Contains \Drupal\system\Tests\Queue\QueueTest.
File
- core/
lib/ Drupal/ Core/ Queue/ DatabaseQueue.php, line 18 - Contains \Drupal\Core\Queue\DatabaseQueue.
Namespace
Drupal\Core\QueueView source
class DatabaseQueue implements ReliableQueueInterface {
use DependencySerializationTrait;
/**
* The name of the queue this instance is working with.
*
* @var string
*/
protected $name;
/**
* The database connection.
*
* @var \Drupal\Core\Database\Connection $connection
*/
protected $connection;
/**
* Constructs a \Drupal\Core\Queue\DatabaseQueue object.
*
* @param string $name
* The name of the queue.
* @param \Drupal\Core\Database\Connection $connection
* The Connection object containing the key-value tables.
*/
function __construct($name, Connection $connection) {
$this->name = $name;
$this->connection = $connection;
}
/**
* {@inheritdoc}
*/
public function createItem($data) {
$query = $this->connection
->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 the new serial ID, or FALSE on failure.
return $query
->execute();
}
/**
* {@inheritdoc}
*/
public function numberOfItems() {
return $this->connection
->query('SELECT COUNT(item_id) FROM {queue} WHERE name = :name', array(
':name' => $this->name,
))
->fetchField();
}
/**
* {@inheritdoc}
*/
public function claimItem($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 = $this->connection
->queryRange('SELECT data, created, item_id FROM {queue} q WHERE expire = 0 AND name = :name ORDER BY created, item_id 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 = $this->connection
->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 $item;
}
}
else {
// No items currently available to claim.
return FALSE;
}
}
}
/**
* {@inheritdoc}
*/
public function releaseItem($item) {
$update = $this->connection
->update('queue')
->fields(array(
'expire' => 0,
))
->condition('item_id', $item->item_id);
return $update
->execute();
}
/**
* {@inheritdoc}
*/
public function deleteItem($item) {
$this->connection
->delete('queue')
->condition('item_id', $item->item_id)
->execute();
}
/**
* {@inheritdoc}
*/
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.
}
/**
* {@inheritdoc}
*/
public function deleteQueue() {
$this->connection
->delete('queue')
->condition('name', $this->name)
->execute();
}
}
Members
Name | Modifiers | Type | Description | Overrides |
---|---|---|---|---|
DatabaseQueue:: |
protected | property | The database connection. | |
DatabaseQueue:: |
protected | property | The name of the queue this instance is working with. | |
DatabaseQueue:: |
public | function |
Claims an item in the queue for processing. Overrides QueueInterface:: |
1 |
DatabaseQueue:: |
public | function |
Adds a queue item and store it directly to the queue. Overrides QueueInterface:: |
|
DatabaseQueue:: |
public | function |
Creates a queue. Overrides QueueInterface:: |
|
DatabaseQueue:: |
public | function |
Deletes a finished item from the queue. Overrides QueueInterface:: |
|
DatabaseQueue:: |
public | function |
Deletes a queue and every item in the queue. Overrides QueueInterface:: |
|
DatabaseQueue:: |
public | function |
Retrieves the number of items in the queue. Overrides QueueInterface:: |
|
DatabaseQueue:: |
public | function |
Releases an item that the worker could not process. Overrides QueueInterface:: |
|
DatabaseQueue:: |
function | Constructs a \Drupal\Core\Queue\DatabaseQueue object. | ||
DependencySerializationTrait:: |
protected | property | An array of service IDs keyed by property name used for serialization. | |
DependencySerializationTrait:: |
public | function | 1 | |
DependencySerializationTrait:: |
public | function | 2 |