getLockFile example

protected function getTestLock(bool $create_lock = FALSE): int {
    // There is a risk that the generated random number is a duplicate. This     // would cause different tests to try to use the same database prefix.     // Therefore, if running with a concurrency of greater than 1, we need to     // create a lock.     if (getenv('RUN_TESTS_CONCURRENCY') > 1) {
      $create_lock = TRUE;
    }

    do {
      $lock_id = mt_rand(10000000, 99999999);
      if ($create_lock && @symlink(__FILE__, $this->getLockFile($lock_id)) === FALSE) {
        // If we can't create a symlink, the lock ID is in use. Generate another         // one. Symlinks are used because they are atomic and reliable.         $lock_id = NULL;
      }
    } while ($lock_id === NULL);
    return $lock_id;
  }

  /** * Releases a lock. * * @return bool * TRUE if successful, FALSE if not. */