root/trunk/wp-includes/cron.php

<?php

function wp_schedule_single_event( $timestamp, $hook, $args = array()) {
    $crons = _get_cron_array();
    $key = md5(serialize($args));
    $crons[$timestamp][$hook][$key] = array( 'schedule' => false, 'args' => $args );
    uksort( $crons, "strnatcasecmp" );
    _set_cron_array( $crons );
}

function wp_schedule_event( $timestamp, $recurrence, $hook, $args = array()) {
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    $key = md5(serialize($args));
    if ( !isset( $schedules[$recurrence] ) )
        return false;
    $crons[$timestamp][$hook][$key] = array( 'schedule' => $recurrence, 'args' => $args, 'interval' => $schedules[$recurrence]['interval'] );
    uksort( $crons, "strnatcasecmp" );
    _set_cron_array( $crons );
}

function wp_reschedule_event( $timestamp, $recurrence, $hook, $args = array()) {
    $crons = _get_cron_array();
    $schedules = wp_get_schedules();
    $key = md5(serialize($args));
    $interval = 0;

    // First we try to get it from the schedule
    if ( 0 == $interval )
        $interval = $schedules[$recurrence]['interval'];
    // Now we try to get it from the saved interval in case the schedule disappears
    if ( 0 == $interval )
        $interval = $crons[$timestamp][$hook][$key]['interval'];
    // Now we assume something is wrong and fail to schedule
    if ( 0 == $interval )
        return false;

    while ( $timestamp < time() + 1 )
        $timestamp += $interval;

    wp_schedule_event( $timestamp, $recurrence, $hook, $args );
}

function wp_unschedule_event( $timestamp, $hook, $args = array() ) {
    $crons = _get_cron_array();
    $key = md5(serialize($args));
    unset( $crons[$timestamp][$hook][$key] );
    if ( empty($crons[$timestamp][$hook]) )
        unset( $crons[$timestamp][$hook] );
    if ( empty($crons[$timestamp]) )
        unset( $crons[$timestamp] );
    _set_cron_array( $crons );
}

function wp_clear_scheduled_hook( $hook ) {
    $args = array_slice( func_get_args(), 1 );

    while ( $timestamp = wp_next_scheduled( $hook, $args ) )
        wp_unschedule_event( $timestamp, $hook, $args );
}

function wp_next_scheduled( $hook, $args = array() ) {
    $crons = _get_cron_array();
    $key = md5(serialize($args));
    if ( empty($crons) )
        return false;
    foreach ( $crons as $timestamp => $cron ) {
        if ( isset( $cron[$hook][$key] ) )
            return $timestamp;
    }
    return false;
}

function spawn_cron() {
    $crons = _get_cron_array();

    if ( !is_array($crons) )
        return;

    $keys = array_keys( $crons );
    if ( array_shift( $keys ) > time() )
        return;

    $cron_url = get_option( 'siteurl' ) . '/wp-cron.php';
    $parts = parse_url( $cron_url );

    if ($parts['scheme'] == 'https') {
        // support for SSL was added in 4.3.0
        if (version_compare(phpversion(), '4.3.0', '>=') && function_exists('openssl_open')) {
            $port = isset($parts['port']) ? $parts['port'] : 443;
            $argyle = @fsockopen('ssl://' . $parts['host'], $port, $errno, $errstr, 0.01);
        } else {
            return false;
        }
    } else {
        $port = isset($parts['port']) ? $parts['port'] : 80;
        $argyle = @ fsockopen( $parts['host'], $port, $errno, $errstr, 0.01 );
    }

    if ( $argyle )
        fputs( $argyle,
              "GET {$parts['path']}?check=" . wp_hash('187425') . " HTTP/1.0\r\n"
            . "Host: {$_SERVER['HTTP_HOST']}\r\n\r\n"
        );
}

function wp_cron() {
    // Prevent infinite loops caused by lack of wp-cron.php
    if ( strpos($_SERVER['REQUEST_URI'], '/wp-cron.php') !== false )
        return;

    $crons = _get_cron_array();

    if ( !is_array($crons) )
        return;

    $keys = array_keys( $crons );
    if ( isset($keys[0]) && $keys[0] > time() )
        return;

    $schedules = wp_get_schedules();
    foreach ( $crons as $timestamp => $cronhooks ) {
        if ( $timestamp > time() ) break;
        foreach ( $cronhooks as $hook => $args ) {
            if ( isset($schedules[$hook]['callback']) && !call_user_func( $schedules[$hook]['callback'] ) )
                continue;
            spawn_cron();
            break 2;
        }
    }
}

function wp_get_schedules() {
    $schedules = array(
        'hourly' => array( 'interval' => 3600, 'display' => __('Once Hourly') ),
        'daily' => array( 'interval' => 86400, 'display' => __('Once Daily') ),
    );
    return array_merge( apply_filters( 'cron_schedules', array() ), $schedules );
}

function wp_get_schedule($hook, $args = array()) {
    $crons = _get_cron_array();
    $key = md5(serialize($args));
    if ( empty($crons) )
        return false;
    foreach ( $crons as $timestamp => $cron ) {
        if ( isset( $cron[$hook][$key] ) )
            return $cron[$hook][$key]['schedule'];
    }
    return false;
}

//
// Private functions
//

function _get_cron_array()  {
    $cron = get_option('cron');
    if ( ! is_array($cron) )
        return false;

    if ( !isset($cron['version']) )
        $cron = _upgrade_cron_array($cron);

    unset($cron['version']);

    return $cron;
}

function _set_cron_array($cron) {
    $cron['version'] = 2;
    update_option( 'cron', $cron );
}

function _upgrade_cron_array($cron) {
    if ( isset($cron['version']) && 2 == $cron['version'])
        return $cron;

    $new_cron = array();

    foreach ($cron as $timestamp => $hooks) {
        foreach ( $hooks as $hook => $args ) {
            $key = md5(serialize($args['args']));
            $new_cron[$timestamp][$hook][$key] = $args;
        }
    }

    $new_cron['version'] = 2;
    update_option( 'cron', $new_cron );
    return $new_cron;
}

?>