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。

<?php
 
class daemon {
 
  const dlog_to_console = 1;
  const dlog_notice = 2;
  const dlog_warning = 4;
  const dlog_error = 8;
  const dlog_critical = 16;
 
  const dapc_path = '/tmp/daemon_apc_keys';
 
  /**
   * user id
   *
   * @var int
   */
  public $userid = 65534; // nobody
 
  /**
   * group id
   *
   * @var integer
   */
  public $groupid = 65533; // nobody
 
  /**
   * terminate daemon when set identity failure ?
   *
   * @var bool
   * @since 1.0.3
   */
  public $requiresetidentity = false;
 
  /**
   * path to pid file
   *
   * @var string
   * @since 1.0.1
   */
  public $pidfilelocation = '/tmp/daemon.pid';
 
  /**
   * processlocation
   * 进程信息记录目录
   *
   * @var string
   */
  public $processlocation = '';
 
  /**
   * processheartlocation
   * 进程心跳包文件
   *
   * @var string
   */
  public $processheartlocation = '';
 
  /**
   * home path
   *
   * @var string
   * @since 1.0
   */
  public $homepath = '/';
 
  /**
   * current process id
   *
   * @var int
   * @since 1.0
   */
  protected $_pid = 0;
 
  /**
   * is this process a children
   *
   * @var boolean
   * @since 1.0
   */
  protected $_ischildren = false;
 
  /**
   * is daemon running
   *
   * @var boolean
   * @since 1.0
   */
  protected $_isrunning = false;
 
  /**
   * constructor
   *
   * @return void
   */
  public function __construct() {
 
    error_reporting(0);
    set_time_limit(0);
    ob_implicit_flush();
 
    register_shutdown_function(array(&$this, 'releasedaemon'));
  }
 
  /**
   * 启动进程
   *
   * @return bool
   */
  public function main() {
 
    $this->_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;
  }
 
  /**
   * 停止进程
   *
   * @return void
   */
  public function stop() {
 
    $this->_logmessage('stoping daemon');
 
    $this->_isrunning = false;
  }
 
  /**
   * do task
   *
   * @return void
   */
  protected function _dotask() {
    // override this method
  }
 
  /**
   * _logmessage
   * 记录日志
   *
   * @param string 消息
   * @param integer 级别
   * @return void
   */
  protected function _logmessage($msg, $level = self::dlog_notice) {
    // override this method
  }
 
  /**
   * daemonize
   *
   * several rules or characteristics that most daemons possess:
   * 1) check is daemon already running
   * 2) fork child process
   * 3) sets identity
   * 4) make current process a session laeder
   * 5) write process id to file
   * 6) change home path
   * 7) umask(0)
   *
   * @access private
   * @since 1.0
   * @return void
   */
  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;
  }
 
  /**
   * cheks is daemon already running
   *
   * @return bool
   */
  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;
    }
  }
 
  /**
   * forks process
   *
   * @return bool
   */
  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;
    }
  }
 
  /**
   * sets identity of a daemon and returns result
   *
   * @return bool
   */
  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;
    }
  }
 
  /**
   * signals handler
   *
   * @access public
   * @since 1.0
   * @return void
   */
  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;
    }
  }
 
  /**
   * signals handler: usr1
   * 主要用于定时清理每个进程里被缓存的域名dns解析记录
   *
   * @return void
   */
  protected function _sighandleruser1() {
    apc_clear_cache('user');
  }
 
  /**
   * signals handler: usr2
   * 用于写入心跳包文件
   *
   * @return void
   */
  protected function _sighandleruser2() {
 
    $this->_initprocesslocation();
 
    file_put_contents($this->processheartlocation, time());
 
    return true;
  }
 
  /**
   * releases daemon pid file
   * this method is called on exit (destructor like)
   *
   * @return void
   */
  public function releasedaemon() {
 
    if ($this->_ischildren && is_file($this->pidfilelocation)) {
      $this->_logmessage('releasing daemon');
 
      unlink($this->pidfilelocation);
    }
  }
 
  /**
   * writeprocess
   * 将当前进程信息写入监控日志，另外的脚本会扫描监控日志的数据发送信号，如果没有响应则重启进程
   *
   * @return void
   */
  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;
  }
 
  /**
   * _initprocesslocation
   * 初始化
   *
   * @return void
   */
  protected function _initprocesslocation() {
 
    $this->processlocation = root_path . '/app/data/proc';
    $this->processheartlocation = $this->processlocation . '/' . $this->_pid . '/heart';
  }
}