rbuserdb.py 文件源码

def uidNumber_getnext(self):
        """Get the next available uidNumber for adding a new user.
        Locks uidNumber file, reads number. Returns (file descriptor,
        uidNumber). uidNumber_savenext() must be called once the
        uidNumber is used successfully."""

        uid_num_file = os.open(rbconfig.file_uidNumber, os.O_RDWR)
        retries = 0

        while 1:
            try:
                fcntl.lockf(uid_num_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
            except IOError:
                retries += 1
                if retries == 20:
                    raise RBFatalError(
                        ('Could not lock uidNumber.txt file after 20 attempts.'
                         'Please try again!'))
                time.sleep(0.5)
            else:
                break
        num_uid = int(os.read(uid_num_file, 32))
        return uid_num_file, num_uid