daemon.py 文件源码

def start(self):
        """Start the daemon."""

        # Check for a pidfile to see if the daemon already runs
        try:
            with open(self.pidfile, 'r') as pidf:
                pid = int(pidf.read().strip())
        except Exception:
            pid = None

        if pid:
            message = "pidfile {0} already exist. " + \
                    "Daemon already running?\n"
            sys.stderr.write(message.format(self.pidfile))
            sys.exit(1)

        # Start the daemon
        self.daemonize()
        syslog.syslog(syslog.LOG_INFO, '{}: started'.format(os.path.basename(sys.argv[0])))
        self.on_start()
        while True:
            try:
                self.run()
            except Exception as e: # pylint: disable=W0703
                syslog.syslog(syslog.LOG_ERR, '{}: {!s}'.format(os.path.basename(sys.argv[0]), e))
            time.sleep(2)