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   1  <?php
   2  /**
   3   * Degenerate job that does nothing.
   4   *
   5   * This program is free software; you can redistribute it and/or modify
   6   * it under the terms of the GNU General Public License as published by
   7   * the Free Software Foundation; either version 2 of the License, or
   8   * (at your option) any later version.
   9   *
  10   * This program is distributed in the hope that it will be useful,
  11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13   * GNU General Public License for more details.
  14   *
  15   * You should have received a copy of the GNU General Public License along
  16   * with this program; if not, write to the Free Software Foundation, Inc.,
  17   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18   * http://www.gnu.org/copyleft/gpl.html
  19   *
  20   * @file
  21   * @ingroup Cache
  22   */
  23  
  24  /**
  25   * Degenerate job that does nothing, but can optionally replace itself
  26   * in the queue and/or sleep for a brief time period. These can be used
  27   * to represent "no-op" jobs or test lock contention and performance.
  28   *
  29   * @par Example:
  30   * Inserting a null job in the configured job queue:
  31   * @code
  32   * $ php maintenance/eval.php
  33   * > $queue = JobQueueGroup::singleton();
  34   * > $job = new NullJob( Title::newMainPage(), array( 'lives' => 10 ) );
  35   * > $queue->push( $job );
  36   * @endcode
  37   * You can then confirm the job has been enqueued by using the showJobs.php
  38   * maintenance utility:
  39   * @code
  40   * $ php maintenance/showJobs.php --group
  41   * null: 1 queue; 0 claimed (0 active, 0 abandoned)
  42   * $
  43   * @endcode
  44   *
  45   * @ingroup JobQueue
  46   */
  47  class NullJob extends Job {
  48      /**
  49       * @param Title $title
  50       * @param array $params Job parameters (lives, usleep)
  51       */
  52  	function __construct( $title, $params ) {
  53          parent::__construct( 'null', $title, $params );
  54          if ( !isset( $this->params['lives'] ) ) {
  55              $this->params['lives'] = 1;
  56          }
  57          if ( !isset( $this->params['usleep'] ) ) {
  58              $this->params['usleep'] = 0;
  59          }
  60          $this->removeDuplicates = !empty( $this->params['removeDuplicates'] );
  61      }
  62  
  63  	public function run() {
  64          if ( $this->params['usleep'] > 0 ) {
  65              usleep( $this->params['usleep'] );
  66          }
  67          if ( $this->params['lives'] > 1 ) {
  68              $params = $this->params;
  69              $params['lives']--;
  70              $job = new self( $this->title, $params );
  71              JobQueueGroup::singleton()->push( $job );
  72          }
  73  
  74          return true;
  75      }
  76  }