interface LockBackendInterface

interface LockBackendInterface {
  
  /**
   * Acquires a lock.
   *
   * @param string $name
   *   Lock name. Limit of name's length is 255 characters.
   * @param float $timeout
   *   (optional) Lock lifetime in seconds. Defaults to 30.0.
   *
   * @return bool
   *   TRUE if the lock was successfully acquired, FALSE otherwise.
   */
  public function acquire($name, $timeout = 30.0);
  
  /**
   * Checks if a lock is available for acquiring.
   *
   * @param string $name
   *   Lock to acquire.
   *
   * @return bool
   *   TRUE if the lock can be acquired, FALSE otherwise.
   */
  public function lockMayBeAvailable($name);
  
  /**
   * Waits a short amount of time before a second lock acquire attempt.
   *
   * While this method is subject to have a generic implementation in abstract
   * backend implementation, some backends may provide non blocking or less I/O
   * intensive wait mechanism: this is why this method remains on the backend
   * interface.
   *
   * @param string $name
   *   Lock name currently being locked.
   * @param int $delay
   *   Seconds to wait for. Defaults to 30.
   *
   * @return bool
   *   TRUE if the lock holds, FALSE if it may be available. You still need to
   *   acquire the lock manually and it may fail again.
   */
  public function wait($name, $delay = 30);
  
  /**
   * Releases the given lock.
   *
   * @param string $name
   *   The lock name.
   */
  public function release($name);
  
  /**
   * Releases all locks for the given lock token identifier.
   *
   * @param string $lockId
   *   (optional) If none given, remove all locks from the current page.
   *   Defaults to NULL.
   */
  public function releaseAll($lockId = NULL);
  
  /**
   * Gets the unique page token for locks.
   *
   * Locks will be wiped out at the end of each page request on a token basis.
   *
   * @return string
   *   The lock ID.
   */
  public function getLockId();

}