分享PHP守护进程类

用PHP实现的Daemon类。可以在服务器上实现队列或者脱离 crontab 的计划任务。 
使用的时候，继承于这个类，并重写 _doTask 方法，通过 main 初始化执行。

_logMessage('Starting daemon');
 
    if (!$this->_daemonize()) {
      $this->_logMessage('Could not start daemon', self::DLOG_ERROR);
 
      return false;
    }
 
    $this->_logMessage('Running...');
 
    $this->_isRunning = true;
 
    while ($this->_isRunning) {
      $this->_doTask();
    }
 
    return true;
  }
 
  
  public function stop() {
 
    $this->_logMessage('Stoping daemon');
 
    $this->_isRunning = false;
  }
 
  
  protected function _doTask() {
    // override this method
  }
 
  
  protected function _logMessage($msg, $level = self::DLOG_NOTICE) {
    // override this method
  }
 
  
  private function _daemonize() {
 
    ob_end_flush();
 
    if ($this->_isDaemonRunning()) {
      // Deamon is already running. Exiting
      return false;
    }
 
    if (!$this->_fork()) {
      // Coudn't fork. Exiting.
      return false;
    }
 
    if (!$this->_setIdentity() && $this->requireSetIdentity) {
      // Required identity set failed. Exiting
      return false;
    }
 
    if (!posix_setsid()) {
      $this->_logMessage('Could not make the current process a session leader', self::DLOG_ERROR);
 
      return false;
    }
 
    if (!$fp = fopen($this->pidFileLocation, 'w')) {
      $this->_logMessage('Could not write to PID file', self::DLOG_ERROR);
      return false;
    } else {
      fputs($fp, $this->_pid);
      fclose($fp);
    }
 
    // 写入监控日志
    $this->writeProcess();
 
    chdir($this->homePath);
    umask(0);
 
    declare(ticks = 1);
 
    pcntl_signal(SIGCHLD, array(&$this, 'sigHandler'));
    pcntl_signal(SIGTERM, array(&$this, 'sigHandler'));
    pcntl_signal(SIGUSR1, array(&$this, 'sigHandler'));
    pcntl_signal(SIGUSR2, array(&$this, 'sigHandler'));
 
    return true;
  }
 
  
  private function _isDaemonRunning() {
 
    $oldPid = file_get_contents($this->pidFileLocation);
 
    if ($oldPid !== false && posix_kill(trim($oldPid),0))
    {
      $this->_logMessage('Daemon already running with PID: '.$oldPid, (self::DLOG_TO_ConSOLE | self::DLOG_ERROR));
 
      return true;
    }
    else
    {
      return false;
    }
  }
 
  
  private function _fork() {
 
    $this->_logMessage('Forking...');
 
    $pid = pcntl_fork();
 
    if ($pid == -1) {
      // 出错
      $this->_logMessage('Could not fork', self::DLOG_ERROR);
 
      return false;
    } elseif ($pid) {
      // 父进程
      $this->_logMessage('Killing parent');
 
      exit();
    } else {
      // fork的子进程
      $this->_isChildren = true;
      $this->_pid = posix_getpid();
 
      return true;
    }
  }
 
  
  private function _setIdentity() {
 
    if (!posix_setgid($this->groupID) || !posix_setuid($this->userID))
    {
      $this->_logMessage('Could not set identity', self::DLOG_WARNING);
 
      return false;
    }
    else
    {
      return true;
    }
  }
 
  
  public function sigHandler($sigNo) {
 
    switch ($sigNo)
    {
      case SIGTERM:  // Shutdown
 $this->_logMessage('Shutdown signal');
 exit();
 break;
 
      case SIGCHLD:  // Halt
 $this->_logMessage('Halt signal');
 while (pcntl_waitpid(-1, $status, WNOHANG) > 0);
 break;
      case SIGUSR1:  // User-defined
 $this->_logMessage('User-defined signal 1');
 $this->_sigHandlerUser1();
 break;
      case SIGUSR2:  // User-defined
 $this->_logMessage('User-defined signal 2');
 $this->_sigHandlerUser2();
 break;
    }
  }
 
  
  protected function _sigHandlerUser1() {
    apc_clear_cache('user');
  }
 
  
  protected function _sigHandlerUser2() {
 
    $this->_initProcessLocation();
 
    file_put_contents($this->processHeartLocation, time());
 
    return true;
  }
 
  
  public function releaseDaemon() {
 
    if ($this->_isChildren && is_file($this->pidFileLocation)) {
      $this->_logMessage('Releasing daemon');
 
      unlink($this->pidFileLocation);
    }
  }
 
  
  public function writeProcess() {
 
    // 初始化 proc
    $this->_initProcessLocation();
 
    $command = trim(implode(' ', $_SERVER['argv']));
 
    // 指定进程的目录
    $processDir = $this->processLocation . '/' . $this->_pid;
    $processCmdFile = $processDir . '/cmd';
    $processPwdFile = $processDir . '/pwd';
 
    // 所有进程所在的目录
    if (!is_dir($this->processLocation)) {
      mkdir($this->processLocation, 0777);
      chmod($processDir, 0777);
    }
 
    // 查询重复的进程记录
    $pDirObject = dir($this->processLocation);
    while ($pDirObject && (($pid = $pDirObject->read()) !== false)) {
      if ($pid == '.' || $pid == '..' || intval($pid) != $pid) {
 continue;
      }
 
      $pDir = $this->processLocation . '/' . $pid;
      $pCmdFile = $pDir . '/cmd';
      $pPwdFile = $pDir . '/pwd';
      $pHeartFile = $pDir . '/heart';
 
      // 根据cmd检查启动相同参数的进程
      if (is_file($pCmdFile) && trim(file_get_contents($pCmdFile)) == $command) {
 unlink($pCmdFile);
 unlink($pPwdFile);
 unlink($pHeartFile);
 
 // 删目录有缓存
 usleep(1000);
 
 rmdir($pDir);
      }
    }
 
    // 新进程目录
    if (!is_dir($processDir)) {
      mkdir($processDir, 0777);
      chmod($processDir, 0777);
    }
 
    // 写入命令参数
    file_put_contents($processCmdFile, $command);
    file_put_contents($processPwdFile, $_SERVER['PWD']);
 
    // 写文件有缓存
    usleep(1000);
 
    return true;
  }
 
  
  protected function _initProcessLocation() {
 
    $this->processLocation = ROOT_PATH . '/app/data/proc';
    $this->processHeartLocation = $this->processLocation . '/' . $this->_pid . '/heart';
  }
}