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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Time related utilities and helper functions.
"""
import calendar
import datetime
import iso8601
# ISO 8601 extended time format with microseconds
_ISO8601_TIME_FORMAT_SUBSECOND = '%Y-%m-%dT%H:%M:%S.%f'
_ISO8601_TIME_FORMAT = '%Y-%m-%dT%H:%M:%S'
PERFECT_TIME_FORMAT = _ISO8601_TIME_FORMAT_SUBSECOND
def isotime(at=None, subsecond=False):
"""Stringify time in ISO 8601 format."""
if not at:
at = utcnow()
st = at.strftime(_ISO8601_TIME_FORMAT
if not subsecond
else _ISO8601_TIME_FORMAT_SUBSECOND)
tz = at.tzinfo.tzname(None) if at.tzinfo else 'UTC'
st += ('Z' if tz == 'UTC' else tz)
return st
def parse_isotime(timestr):
"""Parse time from ISO 8601 format."""
try:
return iso8601.parse_date(timestr)
except iso8601.ParseError as e:
raise ValueError(e.message)
except TypeError as e:
raise ValueError(e.message)
def strtime(at=None, fmt=PERFECT_TIME_FORMAT):
"""Returns formatted utcnow."""
if not at:
at = utcnow()
return at.strftime(fmt)
def parse_strtime(timestr, fmt=PERFECT_TIME_FORMAT):
"""Turn a formatted time back into a datetime."""
return datetime.datetime.strptime(timestr, fmt)
def normalize_time(timestamp):
"""Normalize time in arbitrary timezone to UTC naive object."""
offset = timestamp.utcoffset()
if offset is None:
return timestamp
return timestamp.replace(tzinfo=None) - offset
def is_older_than(before, seconds):
"""Return True if before is older than seconds."""
if isinstance(before, basestring):
before = parse_strtime(before).replace(tzinfo=None)
return utcnow() - before > datetime.timedelta(seconds=seconds)
def is_newer_than(after, seconds):
"""Return True if after is newer than seconds."""
if isinstance(after, basestring):
after = parse_strtime(after).replace(tzinfo=None)
return after - utcnow() > datetime.timedelta(seconds=seconds)
def utcnow_ts():
"""Timestamp version of our utcnow function."""
return calendar.timegm(utcnow().timetuple())
def utcnow():
"""Overridable version of utils.utcnow."""
if utcnow.override_time:
try:
return utcnow.override_time.pop(0)
except AttributeError:
return utcnow.override_time
return datetime.datetime.utcnow()
def iso8601_from_timestamp(timestamp):
"""Returns a iso8601 formated date from timestamp."""
return isotime(datetime.datetime.utcfromtimestamp(timestamp))
utcnow.override_time = None
def set_time_override(override_time=datetime.datetime.utcnow()):
"""Overrides utils.utcnow.
Make it return a constant time or a list thereof, one at a time.
"""
utcnow.override_time = override_time
def advance_time_delta(timedelta):
"""Advance overridden time using a datetime.timedelta."""
assert(not utcnow.override_time is None)
try:
for dt in utcnow.override_time:
dt += timedelta
except TypeError:
utcnow.override_time += timedelta
def advance_time_seconds(seconds):
"""Advance overridden time by seconds."""
advance_time_delta(datetime.timedelta(0, seconds))
def clear_time_override():
"""Remove the overridden time."""
utcnow.override_time = None
def marshall_now(now=None):
"""Make an rpc-safe datetime with microseconds.
Note: tzinfo is stripped, but not required for relative times.
"""
if not now:
now = utcnow()
return dict(day=now.day, month=now.month, year=now.year, hour=now.hour,
minute=now.minute, second=now.second,
microsecond=now.microsecond)
def unmarshall_time(tyme):
"""Unmarshall a datetime dict."""
return datetime.datetime(day=tyme['day'],
month=tyme['month'],
year=tyme['year'],
hour=tyme['hour'],
minute=tyme['minute'],
second=tyme['second'],
microsecond=tyme['microsecond'])
def delta_seconds(before, after):
"""Return the difference between two timing objects.
Compute the difference in seconds between two date, time, or
datetime objects (as a float, to microsecond resolution).
"""
delta = after - before
try:
return delta.total_seconds()
except AttributeError:
return ((delta.days * 24 * 3600) + delta.seconds +
float(delta.microseconds) / (10 ** 6))
def is_soon(dt, window):
"""Determines if time is going to happen in the next window seconds.
:params dt: the time
:params window: minimum seconds to remain to consider the time not soon
:return: True if expiration is within the given duration
"""
soon = (utcnow() + datetime.timedelta(seconds=window))
return normalize_time(dt) <= soon
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