Source code for heat.common.timeutils

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"""Utilities for handling ISO 8601 duration format."""

import random
import re
import time

from heat.common.i18n import _

iso_duration_re = re.compile(r'PT(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S)?$')
wallclock = time.time

[docs]class Duration(object): # (NOTE): we don't attempt to handle leap seconds or large clock # jumps here. The latter are assumed to be rare and the former # negligible in the context of the timeout. Time zone adjustments, # Daylight Savings and the like *are* handled. PEP 418 adds a proper # monotonic clock, but only in Python 3.3. def __init__(self, timeout=0): self._endtime = wallclock() + timeout
[docs] def expired(self): return wallclock() > self._endtime
[docs] def endtime(self): return self._endtime
[docs]def parse_isoduration(duration): """Convert duration in ISO 8601 format to second(s). Year, Month, Week, and Day designators are not supported. Example: 'PT12H30M5S' """ result = iso_duration_re.match(duration) if not result: raise ValueError(_('Only ISO 8601 duration format of the form ' 'PT#H#M#S is supported.')) t = 0 t += (3600 * int( if else 0 t += (60 * int( if else 0 t += int( if else 0 return t
[docs]def retry_backoff_delay(attempt, scale_factor=1.0, jitter_max=0.0): """Calculate an exponential backoff delay with jitter. Delay is calculated as 2^attempt + (uniform random from [0,1) * jitter_max) :param attempt: The count of the current retry attempt :param scale_factor: Multiplier to scale the exponential delay by :param jitter_max: Maximum of random seconds to add to the delay :returns: Seconds since epoch to wait until """ exp = float(2 ** attempt) * float(scale_factor) if jitter_max == 0.0: return exp return exp + random.random() * jitter_max
[docs]def isotime(at): """Stringify UTC time in ISO 8601 format. :param at: Timestamp in UTC to format. """ if at is None: return None return at.strftime('%Y-%m-%dT%H:%M:%SZ')