Synnefo » snf-ganeti

  def __shared_acquire(self):

    """Acquire the lock in shared mode

    This is a private function that presumes you are already holding the

    internal lock.

    """

    self.__nwait_shr += 1

    try:

      wait = False

      # If there is an exclusive holder waiting we have to wait.

      # We'll only do this once, though, when we start waiting for

      # the lock. Then we'll just wait while there are no

      # exclusive holders.

      if self.__nwait_exc > 0:

        # TODO: if !blocking...

        wait = True

        self.__wait(self.__turn_shr)

      while self.__exc is not None:

        wait = True

        # TODO: if !blocking...

        self.__wait(self.__turn_shr)

      self.__shr.add(threading.currentThread())

      # If we were waiting note that we passed

      if wait:

        self.__npass_shr -= 1

    finally:

      self.__nwait_shr -= 1

    assert self.__npass_shr >= 0, "Internal fairness condition weirdness"

        self.__shared_acquire()