php fork daemon

<?

  function stop(){
    if(!file_exists(self::PID_FILE))
      return;
    $pid = file_get_contents(self::PID_FILE);
    posix_kill($pid, SIGTERM);
    unlink(self::PID_FILE);
    rbx::ok("Stopped $pid");
  }

  function start() {
    $this->stop();

    $newpid = pcntl_fork();

    if ($newpid === -1)
      die("Couldn't fork()!");
    if($newpid) //this is the parent, now self-destruct
        exit(0);

    //here is the child
    posix_setsid(); // Become the session leader
    sleep(1);
    // Fork again, but now as session leader.
    $newpid = pcntl_fork();
    if ($newpid === -1)
      die("Couldn't fork()!");
    if ($newpid)
      exit(0); // I'm the parent, and I'm going to self-destruct

    $pid = posix_getpid();
    file_put_contents(self::PID_FILE, $pid);
    rbx::ok("Master started with pid $pid");

    $this->workall();
  }