daemonize.py 文件源码

def trylock_or_exit(self, timeout=10):

        interval = 0.1
        n = int(timeout / interval) + 1
        flag = fcntl.LOCK_EX | fcntl.LOCK_NB

        for ii in range(n):

            fd = os.open(self.lockfile, os.O_RDWR | os.O_CREAT)

            fcntl.fcntl(fd, fcntl.F_SETFD,
                        fcntl.fcntl(fd, fcntl.F_GETFD, 0)
                        | fcntl.FD_CLOEXEC)

            try:
                fcntl.lockf(fd, flag)

                self.lockfp = os.fdopen(fd, 'w+r')
                break

            except IOError as e:
                os.close(fd)
                if e[0] == errno.EAGAIN:
                    time.sleep(interval)
                else:
                    raise

        else:
            logger.info("Failure acquiring lock %s" % (self.lockfile, ))
            sys.exit(1)

        logger.info("OK acquired lock %s" % (self.lockfile))