class DatabaseLockBackend in Drupal driver for SQL Server and SQL Azure 8.2

Workaround for an issue with floats:

Hierarchy

• class \Drupal\Core\Lock\LockBackendAbstract implements LockBackendInterface
  • class \Drupal\Core\Lock\DatabaseLockBackend
    • class \Drupal\sqlsrv\Lock\DatabaseLockBackend

See also

https://github.com/Azure/msphpsql/issues/71

File

src/Lock/DatabaseLockBackend.php, line 21

Contains \Drupal\sqlsrv\Lock\DatabaseLockBackend.

Namespace

Drupal\sqlsrv\Lock

class DatabaseLockBackend extends CoreDatabaseLockBackend {

  /**
   * {@inheritdoc}
   */
  public function lockMayBeAvailable($name) {
    $lock = $this->database
      ->query('SELECT CONVERT(varchar(50), expire, 128) as expire, value FROM {semaphore} WHERE name = :name', array(
      ':name' => $name,
    ))
      ->fetchAssoc();
    if (!$lock) {
      return true;
    }
    $expire = (double) $lock['expire'];
    $now = microtime(true);
    if ($now > $expire) {

      // We check two conditions to prevent a race condition where another
      // request acquired the lock and set a new expire time. We add a small
      // number to $expire to avoid errors with float to string conversion.
      return (bool) $this->database
        ->delete('semaphore')
        ->condition('name', $name)
        ->condition('value', $lock['value'])
        ->condition('expire', 0.0001 + $expire, '<=')
        ->execute();
    }
    return false;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DatabaseLockBackend::$database	protected	property	The database connection.
DatabaseLockBackend::acquire	public	function	Acquires a lock. Overrides LockBackendInterface::acquire
DatabaseLockBackend::catchException	protected	function	Act on an exception when semaphore might be stale.
DatabaseLockBackend::ensureTableExists	protected	function	Check if the semaphore table exists and create it if not.
DatabaseLockBackend::lockMayBeAvailable	public	function	Checks if a lock is available for acquiring. Overrides DatabaseLockBackend::lockMayBeAvailable
DatabaseLockBackend::normalizeName	protected	function	Normalizes a lock name in order to comply with database limitations.
DatabaseLockBackend::release	public	function	Releases the given lock. Overrides LockBackendInterface::release
DatabaseLockBackend::releaseAll	public	function	Releases all locks for the given lock token identifier. Overrides LockBackendInterface::releaseAll
DatabaseLockBackend::schemaDefinition	public	function	Defines the schema for the semaphore table.
DatabaseLockBackend::TABLE_NAME		constant	The database table name.
DatabaseLockBackend::__construct	public	function	Constructs a new DatabaseLockBackend.	1
LockBackendAbstract::$lockId	protected	property	Current page lock token identifier.
LockBackendAbstract::$locks	protected	property	Existing locks for this page.
LockBackendAbstract::getLockId	public	function	Gets the unique page token for locks. Overrides LockBackendInterface::getLockId
LockBackendAbstract::wait	public	function	Waits a short amount of time before a second lock acquire attempt. Overrides LockBackendInterface::wait