wp_schedule_event

The timeline below displays how wordpress function wp_schedule_event has changed across different WordPress versions. If a version is not listed, refer to the next available version below.

WordPress Version: 6.5

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'twicedaily', 'daily', and 'weekly'.
 * These can be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 * @since 5.7.0 The `$wp_error` parameter was added.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur.
 *                           See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing arguments to pass to the
 *                           hook's callback function. Each value in the array
 *                           is passed to the callback as an individual parameter.
 *                           The array keys are ignored. Default empty array.
 * @param bool   $wp_error   Optional. Whether to return a WP_Error on failure. Default false.
 * @return bool|WP_Error True if event successfully scheduled. False or WP_Error on failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array(), $wp_error = false)
{
    // Make sure timestamp is a positive integer.
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        if ($wp_error) {
            return new WP_Error('invalid_timestamp', __('Event timestamp must be a valid Unix timestamp.'));
        }
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        if ($wp_error) {
            return new WP_Error('invalid_schedule', __('Event schedule does not exist.'));
        }
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event, $wp_error);
    if (null !== $pre) {
        if ($wp_error && false === $pre) {
            return new WP_Error('pre_schedule_event_false', __('A plugin prevented the event from being scheduled.'));
        }
        if (!$wp_error && is_wp_error($pre)) {
            return false;
        }
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event.
    if (!$event) {
        if ($wp_error) {
            return new WP_Error('schedule_event_false', __('A plugin disallowed this event.'));
        }
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons, $wp_error);
}

WordPress Version: 6.1

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 * @since 5.7.0 The `$wp_error` parameter was added.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur.
 *                           See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing arguments to pass to the
 *                           hook's callback function. Each value in the array
 *                           is passed to the callback as an individual parameter.
 *                           The array keys are ignored. Default empty array.
 * @param bool   $wp_error   Optional. Whether to return a WP_Error on failure. Default false.
 * @return bool|WP_Error True if event successfully scheduled. False or WP_Error on failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array(), $wp_error = false)
{
    // Make sure timestamp is a positive integer.
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        if ($wp_error) {
            return new WP_Error('invalid_timestamp', __('Event timestamp must be a valid Unix timestamp.'));
        }
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        if ($wp_error) {
            return new WP_Error('invalid_schedule', __('Event schedule does not exist.'));
        }
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event, $wp_error);
    if (null !== $pre) {
        if ($wp_error && false === $pre) {
            return new WP_Error('pre_schedule_event_false', __('A plugin prevented the event from being scheduled.'));
        }
        if (!$wp_error && is_wp_error($pre)) {
            return false;
        }
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event.
    if (!$event) {
        if ($wp_error) {
            return new WP_Error('schedule_event_false', __('A plugin disallowed this event.'));
        }
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons, $wp_error);
}

WordPress Version: 5.9

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Note that scheduling an event to occur within 10 minutes of an existing event
 * with the same action hook will be ignored unless you pass unique `$args` values
 * for each scheduled event.
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 * @since 5.7.0 The `$wp_error` parameter was added.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur.
 *                           See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing arguments to pass to the
 *                           hook's callback function. Each value in the array
 *                           is passed to the callback as an individual parameter.
 *                           The array keys are ignored. Default empty array.
 * @param bool   $wp_error   Optional. Whether to return a WP_Error on failure. Default false.
 * @return bool|WP_Error True if event successfully scheduled. False or WP_Error on failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array(), $wp_error = false)
{
    // Make sure timestamp is a positive integer.
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        if ($wp_error) {
            return new WP_Error('invalid_timestamp', __('Event timestamp must be a valid Unix timestamp.'));
        }
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        if ($wp_error) {
            return new WP_Error('invalid_schedule', __('Event schedule does not exist.'));
        }
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event, $wp_error);
    if (null !== $pre) {
        if ($wp_error && false === $pre) {
            return new WP_Error('pre_schedule_event_false', __('A plugin prevented the event from being scheduled.'));
        }
        if (!$wp_error && is_wp_error($pre)) {
            return false;
        }
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event.
    if (!$event) {
        if ($wp_error) {
            return new WP_Error('schedule_event_false', __('A plugin disallowed this event.'));
        }
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    if (!is_array($crons)) {
        $crons = array();
    }
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons, $wp_error);
}

WordPress Version: 5.7

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Note that scheduling an event to occur within 10 minutes of an existing event
 * with the same action hook will be ignored unless you pass unique `$args` values
 * for each scheduled event.
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 * @since 5.7.0 The `$wp_error` parameter was added.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur.
 *                           See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing arguments to pass to the
 *                           hook's callback function. Each value in the array
 *                           is passed to the callback as an individual parameter.
 *                           The array keys are ignored. Default empty array.
 * @param bool   $wp_error   Optional. Whether to return a WP_Error on failure. Default false.
 * @return bool|WP_Error True if event successfully scheduled. False or WP_Error on failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array(), $wp_error = false)
{
    // Make sure timestamp is a positive integer.
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        if ($wp_error) {
            return new WP_Error('invalid_timestamp', __('Event timestamp must be a valid Unix timestamp.'));
        }
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        if ($wp_error) {
            return new WP_Error('invalid_schedule', __('Event schedule does not exist.'));
        }
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event, $wp_error);
    if (null !== $pre) {
        if ($wp_error && false === $pre) {
            return new WP_Error('pre_schedule_event_false', __('A plugin prevented the event from being scheduled.'));
        }
        if (!$wp_error && is_wp_error($pre)) {
            return false;
        }
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event.
    if (!$event) {
        if ($wp_error) {
            return new WP_Error('schedule_event_false', __('A plugin disallowed this event.'));
        }
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons, $wp_error);
}

WordPress Version: 5.6

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Note that scheduling an event to occur within 10 minutes of an existing event
 * with the same action hook will be ignored unless you pass unique `$args` values
 * for each scheduled event.
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur.
 *                           See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing arguments to pass to the
 *                           hook's callback function. Each value in the array is passed
 *                           to the callback as an individual parameter. The array keys
 *                           are ignored. Default: empty array.
 * @return bool True if event successfully scheduled. False for failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer.
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event);
    if (null !== $pre) {
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event.
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons);
}

WordPress Version: 5.4

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Note that scheduling an event to occur within 10 minutes of an existing event
 * with the same action hook will be ignored unless you pass unique `$args` values
 * for each scheduled event.
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur. See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing each separate argument to pass to the hook's callback function.
 * @return bool True if event successfully scheduled. False for failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer.
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event);
    if (null !== $pre) {
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event.
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons);
}

WordPress Version: 5.3

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Note that scheduling an event to occur within 10 minutes of an existing event
 * with the same action hook will be ignored unless you pass unique `$args` values
 * for each scheduled event.
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 *
 * @link https://developer.wordpress.org/reference/functions/wp_schedule_event/
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur. See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing each separate argument to pass to the hook's callback function.
 * @return bool True if event successfully scheduled. False for failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event);
    if (null !== $pre) {
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons);
}

WordPress Version: 5.1

/**
 * Schedules a recurring event.
 *
 * Schedules a hook which will be triggered by WordPress at the specified interval.
 * The action will trigger when someone visits your WordPress site if the scheduled
 * time has passed.
 *
 * Valid values for the recurrence are 'hourly', 'daily', and 'twicedaily'. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Note that scheduling an event to occur within 10 minutes of an existing event
 * with the same action hook will be ignored unless you pass unique `$args` values
 * for each scheduled event.
 *
 * Use wp_next_scheduled() to prevent duplicate events.
 *
 * Use wp_schedule_single_event() to schedule a non-recurring event.
 *
 * @since 2.1.0
 * @since 5.1.0 Return value modified to boolean indicating success or failure,
 *              {@see 'pre_schedule_event'} filter added to short-circuit the function.
 *
 * @link https://codex.wordpress.org/Function_Reference/wp_schedule_event
 *
 * @param int    $timestamp  Unix timestamp (UTC) for when to next run the event.
 * @param string $recurrence How often the event should subsequently recur. See wp_get_schedules() for accepted values.
 * @param string $hook       Action hook to execute when the event is run.
 * @param array  $args       Optional. Array containing each separate argument to pass to the hook's callback function.
 * @return bool True if event successfully scheduled. False for failure.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $pre = apply_filters('pre_schedule_event', null, $event);
    if (null !== $pre) {
        return $pre;
    }
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons = _get_cron_array();
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, 'strnatcasecmp');
    return _set_cron_array($crons);
}

WordPress Version: 4.7

/**
 * Schedule a recurring event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily, and twicedaily. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Unix timestamp (UTC) for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when event is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return false|void False if the event does not get scheduled.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}

WordPress Version: 4.6

/**
 * Schedule a periodic event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily and twicedaily. These can
 * be extended using the {@see 'cron_schedules'} filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Timestamp for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when cron is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return false|void False when an event is not scheduled.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}

WordPress Version: 4.4

/**
 * Schedule a periodic event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily and twicedaily. These can
 * be extended using the cron_schedules filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Timestamp for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when cron is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return false|void False when an event is not scheduled.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    // Make sure timestamp is a positive integer
    if (!is_numeric($timestamp) || $timestamp <= 0) {
        return false;
    }
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}

WordPress Version: 4.3

/**
 * Schedule a periodic event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily and twicedaily. These can
 * be extended using the cron_schedules filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Timestamp for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when cron is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return false|void False when does not schedule event.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}

WordPress Version: 4.1

/**
 * Schedule a periodic event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily and twicedaily. These can
 * be extended using the cron_schedules filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Timestamp for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when cron is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return false|null False on failure, null when complete with scheduling event.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}

WordPress Version: 3.8

/**
 * Schedule a periodic event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily and twicedaily. These can
 * be extended using the cron_schedules filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Timestamp for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when cron is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return bool|null False on failure, null when complete with scheduling event.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    /** This filter is documented in wp-includes/cron.php */
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}

WordPress Version: 3.7

/**
 * Schedule a periodic event.
 *
 * Schedules a hook which will be executed by the WordPress actions core on a
 * specific interval, specified by you. The action will trigger when someone
 * visits your WordPress site, if the scheduled time has passed.
 *
 * Valid values for the recurrence are hourly, daily and twicedaily. These can
 * be extended using the cron_schedules filter in wp_get_schedules().
 *
 * Use wp_next_scheduled() to prevent duplicates
 *
 * @since 2.1.0
 *
 * @param int $timestamp Timestamp for when to run the event.
 * @param string $recurrence How often the event should recur.
 * @param string $hook Action hook to execute when cron is run.
 * @param array $args Optional. Arguments to pass to the hook's callback function.
 * @return bool|null False on failure, null when complete with scheduling event.
 */
function wp_schedule_event($timestamp, $recurrence, $hook, $args = array())
{
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    if (!isset($schedules[$recurrence])) {
        return false;
    }
    $event = (object) array('hook' => $hook, 'timestamp' => $timestamp, 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval']);
    $event = apply_filters('schedule_event', $event);
    // A plugin disallowed this event
    if (!$event) {
        return false;
    }
    $key = md5(serialize($event->args));
    $crons[$event->timestamp][$event->hook][$key] = array('schedule' => $event->schedule, 'args' => $event->args, 'interval' => $event->interval);
    uksort($crons, "strnatcasecmp");
    _set_cron_array($crons);
}