+def FormatTime(val):
+ """Formats a time value.
+
+ @type val: float or None
+ @param val: the timestamp as returned by time.time()
+ @return: a string value or N/A if we don't have a valid timestamp
+
+ """
+ if val is None or not isinstance(val, (int, float)):
+ return "N/A"
+ # these two codes works on Linux, but they are not guaranteed on all
+ # platforms
+ return time.strftime("%F %T", time.localtime(val))
+
+
+def ReadWatcherPauseFile(filename, now=None, remove_after=3600):
+ """Reads the watcher pause file.
+
+ @type filename: string
+ @param filename: Path to watcher pause file
+ @type now: None, float or int
+ @param now: Current time as Unix timestamp
+ @type remove_after: int
+ @param remove_after: Remove watcher pause file after specified amount of
+ seconds past the pause end time
+
+ """
+ if now is None:
+ now = time.time()
+
+ try:
+ value = ReadFile(filename)
+ except IOError, err:
+ if err.errno != errno.ENOENT:
+ raise
+ value = None
+
+ if value is not None:
+ try:
+ value = int(value)
+ except ValueError:
+ logging.warning(("Watcher pause file (%s) contains invalid value,"
+ " removing it"), filename)
+ RemoveFile(filename)
+ value = None
+
+ if value is not None:
+ # Remove file if it's outdated
+ if now > (value + remove_after):
+ RemoveFile(filename)
+ value = None
+
+ elif now > value:
+ value = None
+
+ return value
+
+
+class RetryTimeout(Exception):
+ """Retry loop timed out.
+
+ """
+
+
+class RetryAgain(Exception):
+ """Retry again.
+
+ """
+
+
+class _RetryDelayCalculator(object):
+ """Calculator for increasing delays.
+
+ """
+ __slots__ = [
+ "_factor",
+ "_limit",
+ "_next",
+ "_start",
+ ]
+
+ def __init__(self, start, factor, limit):
+ """Initializes this class.
+
+ @type start: float
+ @param start: Initial delay
+ @type factor: float
+ @param factor: Factor for delay increase
+ @type limit: float or None
+ @param limit: Upper limit for delay or None for no limit
+
+ """
+ assert start > 0.0
+ assert factor >= 1.0
+ assert limit is None or limit >= 0.0
+
+ self._start = start
+ self._factor = factor
+ self._limit = limit
+
+ self._next = start
+
+ def __call__(self):
+ """Returns current delay and calculates the next one.
+
+ """
+ current = self._next
+
+ # Update for next run
+ if self._limit is None or self._next < self._limit:
+ self._next = min(self._limit, self._next * self._factor)
+
+ return current
+
+
+#: Special delay to specify whole remaining timeout
+RETRY_REMAINING_TIME = object()
+
+
+def Retry(fn, delay, timeout, args=None, wait_fn=time.sleep,
+ _time_fn=time.time):
+ """Call a function repeatedly until it succeeds.
+
+ The function C{fn} is called repeatedly until it doesn't throw L{RetryAgain}
+ anymore. Between calls a delay, specified by C{delay}, is inserted. After a
+ total of C{timeout} seconds, this function throws L{RetryTimeout}.
+
+ C{delay} can be one of the following:
+ - callable returning the delay length as a float
+ - Tuple of (start, factor, limit)
+ - L{RETRY_REMAINING_TIME} to sleep until the timeout expires (this is
+ useful when overriding L{wait_fn} to wait for an external event)
+ - A static delay as a number (int or float)
+
+ @type fn: callable
+ @param fn: Function to be called
+ @param delay: Either a callable (returning the delay), a tuple of (start,
+ factor, limit) (see L{_RetryDelayCalculator}),
+ L{RETRY_REMAINING_TIME} or a number (int or float)
+ @type timeout: float
+ @param timeout: Total timeout
+ @type wait_fn: callable
+ @param wait_fn: Waiting function
+ @return: Return value of function
+
+ """
+ assert callable(fn)
+ assert callable(wait_fn)
+ assert callable(_time_fn)
+
+ if args is None:
+ args = []
+
+ end_time = _time_fn() + timeout
+
+ if callable(delay):
+ # External function to calculate delay
+ calc_delay = delay
+
+ elif isinstance(delay, (tuple, list)):
+ # Increasing delay with optional upper boundary
+ (start, factor, limit) = delay
+ calc_delay = _RetryDelayCalculator(start, factor, limit)
+
+ elif delay is RETRY_REMAINING_TIME:
+ # Always use the remaining time
+ calc_delay = None
+
+ else:
+ # Static delay
+ calc_delay = lambda: delay
+
+ assert calc_delay is None or callable(calc_delay)
+
+ while True:
+ try:
+ # pylint: disable-msg=W0142
+ return fn(*args)
+ except RetryAgain:
+ pass
+
+ remaining_time = end_time - _time_fn()
+
+ if remaining_time < 0.0:
+ raise RetryTimeout()
+
+ assert remaining_time >= 0.0
+
+ if calc_delay is None:
+ wait_fn(remaining_time)
+ else:
+ current_delay = calc_delay()
+ if current_delay > 0.0:
+ wait_fn(current_delay)
+
+
projects / ganeti-local / blobdiff