PHP中实现crontab代码分享

// 从./crontab读取cron项，也可以从其他持久存储（mysql、redis）读取
$crontab = file('./crontab');
$now = $_SERVER['REQUEST_TIME'];

foreach ( $crontab as $cron ) {
 $slices = preg_split("/[\s]+/", $cron, 6);
 if( count($slices) !== 6 ) continue;

$cmd       = array_pop($slices);
 $cron_time = implode(' ', $slices);
 $next_time = Crontab::parse($cron_time, $now);
 if ( $next_time !== $now ) continue; 

$pid = pcntl_fork();
 if ($pid == -1) {
  die('could not fork');
 } else if ($pid) {
  // we are the parent
  pcntl_wait($status, WNOHANG); //Protect against Zombie children
 } else {
      // we are the child
  `$cmd`;
  exit;
 }
}

/* https://github.com/jkonieczny/PHP-Crontab */
class Crontab {
   /**
 * Finds next execution time(stamp) parsin crontab syntax,
 * after given starting timestamp (or current time if ommited)
 *
 * @param string $_cron_string:
 *
 * 0 1 2 3 4
 * * * * * *
 * - - - - -
 * | | | | |
 * | | | | +----- day of week (0 - 6) (Sunday=0)
 * | | | +------- month (1 - 12)
 * | | +--------- day of month (1 - 31)
 * | +----------- hour (0 - 23)
 * +------------- min (0 - 59)
 * @param int $_after_timestamp timestamp [default=current timestamp]
 * @return int unix timestamp - next execution time will be greater
 * than given timestamp (defaults to the current timestamp)
 * @throws InvalidArgumentException
 */
    public static function parse($_cron_string,$_after_timestamp=null)
    {
        if(!preg_match('/^((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)$/i',trim($_cron_string))){
            throw new InvalidArgumentException("Invalid cron string: ".$_cron_string);
        }
        if($_after_timestamp && !is_numeric($_after_timestamp)){
            throw new InvalidArgumentException("\$_after_timestamp must be a valid unix timestamp ($_after_timestamp given)");
        }
        $cron = preg_split("/[\s]+/i",trim($_cron_string));
        $start = empty($_after_timestamp)?time():$_after_timestamp;

$date = array( 'minutes' =>self::_parseCronNumbers($cron[0],0,59),
                            'hours' =>self::_parseCronNumbers($cron[1],0,23),
                            'dom' =>self::_parseCronNumbers($cron[2],1,31),
                            'month' =>self::_parseCronNumbers($cron[3],1,12),
                            'dow' =>self::_parseCronNumbers($cron[4],0,6),
                        );
        // limited to time()+366 - no need to check more than 1year ahead
        for($i=0;$i<=60*60*24*366;$i+=60){
            if( in_array(intval(date('j',$start+$i)),$date['dom']) &&
                in_array(intval(date('n',$start+$i)),$date['month']) &&
                in_array(intval(date('w',$start+$i)),$date['dow']) &&
                in_array(intval(date('G',$start+$i)),$date['hours']) &&
                in_array(intval(date('i',$start+$i)),$date['minutes'])