Synnefo » snf-ganeti

def SimpleRetry(expected, fn, delay, timeout, args=None, wait_fn=time.sleep,

                _time_fn=time.time):

  """A wrapper over L{Retry} implementing a simpler interface.

  All the parameters are the same as for L{Retry}, except it has one

  extra argument: expected, which can be either a value (will be

  compared with the result of the function, or a callable (which will

  get the result passed and has to return a boolean). If the test is

  false, we will retry until either the timeout has passed or the

  tests succeeds. In both cases, the last result from calling the

  function will be returned.

  Note that this function is not expected to raise any retry-related

  exceptions, always simply returning values. As such, the function is

  designed to allow easy wrapping of code that doesn't use retry at

  all (e.g. "if fn(args)" replaced with "if SimpleRetry(True, fn,

  ...)".

  @see: L{Retry}

  """

  rdict = {}

  def helper(*innerargs):

    # pylint: disable-msg=W0142

    result = rdict["result"] = fn(*innerargs)

    if not ((callable(expected) and expected(result)) or result == expected):

      raise RetryAgain()

    return result

  try:

    result = Retry(helper, delay, timeout, args=args,

                   wait_fn=wait_fn, _time_fn=_time_fn)

  except RetryTimeout:

    assert "result" in rdict

    result = rdict["result"]

  return result