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/ -> wp-cron.php (source)

   1  <?php
   2  /**
   3   * A pseudo-CRON daemon for scheduling WordPress tasks
   4   *
   5   * WP Cron is triggered when the site receives a visit. In the scenario
   6   * where a site may not receive enough visits to execute scheduled tasks
   7   * in a timely manner, this file can be called directly or via a server
   8   * CRON daemon for X number of times.
   9   *
  10   * Defining DISABLE_WP_CRON as true and calling this file directly are
  11   * mutually exclusive and the latter does not rely on the former to work.
  12   *
  13   * The HTTP request to this file will not slow down the visitor who happens to
  14   * visit when the cron job is needed to run.
  15   *
  16   * @package WordPress
  17   */
  18  
  19  ignore_user_abort(true);
  20  
  21  if ( !empty($_POST) || defined('DOING_AJAX') || defined('DOING_CRON') )
  22      die();
  23  
  24  /**
  25   * Tell WordPress we are doing the CRON task.
  26   *
  27   * @var bool
  28   */
  29  define('DOING_CRON', true);
  30  
  31  if ( !defined('ABSPATH') ) {
  32      /** Set up WordPress environment */
  33      require_once( dirname( __FILE__ ) . '/wp-load.php' );
  34  }
  35  
  36  /**
  37   * Retrieves the cron lock.
  38   *
  39   * Returns the uncached `doing_cron` transient.
  40   *
  41   * @ignore
  42   * @since 3.3.0
  43   *
  44   * @global wpdb $wpdb WordPress database abstraction object.
  45   *
  46   * @return string|false Value of the `doing_cron` transient, 0|false otherwise.
  47   */
  48  function _get_cron_lock() {
  49      global $wpdb;
  50  
  51      $value = 0;
  52      if ( wp_using_ext_object_cache() ) {
  53          /*
  54           * Skip local cache and force re-fetch of doing_cron transient
  55           * in case another process updated the cache.
  56           */
  57          $value = wp_cache_get( 'doing_cron', 'transient', true );
  58      } else {
  59          $row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", '_transient_doing_cron' ) );
  60          if ( is_object( $row ) )
  61              $value = $row->option_value;
  62      }
  63  
  64      return $value;
  65  }
  66  
  67  if ( false === $crons = _get_cron_array() )
  68      die();
  69  
  70  $keys = array_keys( $crons );
  71  $gmt_time = microtime( true );
  72  
  73  if ( isset($keys[0]) && $keys[0] > $gmt_time )
  74      die();
  75  
  76  
  77  // The cron lock: a unix timestamp from when the cron was spawned.
  78  $doing_cron_transient = get_transient( 'doing_cron' );
  79  
  80  // Use global $doing_wp_cron lock otherwise use the GET lock. If no lock, trying grabbing a new lock.
  81  if ( empty( $doing_wp_cron ) ) {
  82      if ( empty( $_GET[ 'doing_wp_cron' ] ) ) {
  83          // Called from external script/job. Try setting a lock.
  84          if ( $doing_cron_transient && ( $doing_cron_transient + WP_CRON_LOCK_TIMEOUT > $gmt_time ) )
  85              return;
  86          $doing_cron_transient = $doing_wp_cron = sprintf( '%.22F', microtime( true ) );
  87          set_transient( 'doing_cron', $doing_wp_cron );
  88      } else {
  89          $doing_wp_cron = $_GET[ 'doing_wp_cron' ];
  90      }
  91  }
  92  
  93  /*
  94   * The cron lock (a unix timestamp set when the cron was spawned),
  95   * must match $doing_wp_cron (the "key").
  96   */
  97  if ( $doing_cron_transient != $doing_wp_cron )
  98      return;
  99  
 100  foreach ( $crons as $timestamp => $cronhooks ) {
 101      if ( $timestamp > $gmt_time )
 102          break;
 103  
 104      foreach ( $cronhooks as $hook => $keys ) {
 105  
 106          foreach ( $keys as $k => $v ) {
 107  
 108              $schedule = $v['schedule'];
 109  
 110              if ( $schedule != false ) {
 111                  $new_args = array($timestamp, $schedule, $hook, $v['args']);
 112                  call_user_func_array('wp_reschedule_event', $new_args);
 113              }
 114  
 115              wp_unschedule_event( $timestamp, $hook, $v['args'] );
 116  
 117              /**
 118               * Fires scheduled events.
 119               *
 120               * @ignore
 121               * @since 2.1.0
 122               *
 123               * @param string $hook Name of the hook that was scheduled to be fired.
 124               * @param array  $args The arguments to be passed to the hook.
 125               */
 126               do_action_ref_array( $hook, $v['args'] );
 127  
 128              // If the hook ran too long and another cron process stole the lock, quit.
 129              if ( _get_cron_lock() != $doing_wp_cron )
 130                  return;
 131          }
 132      }
 133  }
 134  
 135  if ( _get_cron_lock() == $doing_wp_cron )
 136      delete_transient( 'doing_cron' );
 137  
 138  die();


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