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   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  /* Don't make the request block till we finish, if possible. */
  22  if ( function_exists( 'fastcgi_finish_request' ) && version_compare( phpversion(), '7.0.16', '>=' ) ) {
  23      if ( ! headers_sent() ) {
  24          header( 'Expires: Wed, 11 Jan 1984 05:00:00 GMT' );
  25          header( 'Cache-Control: no-cache, must-revalidate, max-age=0' );
  26      }
  27  
  28      fastcgi_finish_request();
  29  }
  30  
  31  if ( ! empty( $_POST ) || defined( 'DOING_AJAX' ) || defined( 'DOING_CRON' ) ) {
  32      die();
  33  }
  34  
  35  /**
  36   * Tell WordPress we are doing the CRON task.
  37   *
  38   * @var bool
  39   */
  40  define( 'DOING_CRON', true );
  41  
  42  if ( ! defined( 'ABSPATH' ) ) {
  43      /** Set up WordPress environment */
  44      require_once( dirname( __FILE__ ) . '/wp-load.php' );
  45  }
  46  
  47  /**
  48   * Retrieves the cron lock.
  49   *
  50   * Returns the uncached `doing_cron` transient.
  51   *
  52   * @ignore
  53   * @since 3.3.0
  54   *
  55   * @global wpdb $wpdb WordPress database abstraction object.
  56   *
  57   * @return string|false Value of the `doing_cron` transient, 0|false otherwise.
  58   */
  59  function _get_cron_lock() {
  60      global $wpdb;
  61  
  62      $value = 0;
  63      if ( wp_using_ext_object_cache() ) {
  64          /*
  65           * Skip local cache and force re-fetch of doing_cron transient
  66           * in case another process updated the cache.
  67           */
  68          $value = wp_cache_get( 'doing_cron', 'transient', true );
  69      } else {
  70          $row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", '_transient_doing_cron' ) );
  71          if ( is_object( $row ) ) {
  72              $value = $row->option_value;
  73          }
  74      }
  75  
  76      return $value;
  77  }
  78  
  79  $crons = wp_get_ready_cron_jobs();
  80  if ( empty( $crons ) ) {
  81      die();
  82  }
  83  
  84  $gmt_time = microtime( true );
  85  
  86  // The cron lock: a unix timestamp from when the cron was spawned.
  87  $doing_cron_transient = get_transient( 'doing_cron' );
  88  
  89  // Use global $doing_wp_cron lock, otherwise use the GET lock. If no lock, try to grab a new lock.
  90  if ( empty( $doing_wp_cron ) ) {
  91      if ( empty( $_GET['doing_wp_cron'] ) ) {
  92          // Called from external script/job. Try setting a lock.
  93          if ( $doing_cron_transient && ( $doing_cron_transient + WP_CRON_LOCK_TIMEOUT > $gmt_time ) ) {
  94              return;
  95          }
  96          $doing_wp_cron        = sprintf( '%.22F', microtime( true ) );
  97          $doing_cron_transient = $doing_wp_cron;
  98          set_transient( 'doing_cron', $doing_wp_cron );
  99      } else {
 100          $doing_wp_cron = $_GET['doing_wp_cron'];
 101      }
 102  }
 103  
 104  /*
 105   * The cron lock (a unix timestamp set when the cron was spawned),
 106   * must match $doing_wp_cron (the "key").
 107   */
 108  if ( $doing_cron_transient != $doing_wp_cron ) {
 109      return;
 110  }
 111  
 112  foreach ( $crons as $timestamp => $cronhooks ) {
 113      if ( $timestamp > $gmt_time ) {
 114          break;
 115      }
 116  
 117      foreach ( $cronhooks as $hook => $keys ) {
 118  
 119          foreach ( $keys as $k => $v ) {
 120  
 121              $schedule = $v['schedule'];
 122  
 123              if ( $schedule ) {
 124                  wp_reschedule_event( $timestamp, $schedule, $hook, $v['args'] );
 125              }
 126  
 127              wp_unschedule_event( $timestamp, $hook, $v['args'] );
 128  
 129              /**
 130               * Fires scheduled events.
 131               *
 132               * @ignore
 133               * @since 2.1.0
 134               *
 135               * @param string $hook Name of the hook that was scheduled to be fired.
 136               * @param array  $args The arguments to be passed to the hook.
 137               */
 138              do_action_ref_array( $hook, $v['args'] );
 139  
 140              // If the hook ran too long and another cron process stole the lock, quit.
 141              if ( _get_cron_lock() != $doing_wp_cron ) {
 142                  return;
 143              }
 144          }
 145      }
 146  }
 147  
 148  if ( _get_cron_lock() == $doing_wp_cron ) {
 149      delete_transient( 'doing_cron' );
 150  }
 151  
 152  die();


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