548b640208
The existing timeutils provides a way to measure durations that is also used to get actual times and dates; for most cases this dual ability is not needed and the user only cares about the duration between two time points. In cases where ntpd may affect the machine clock this usage is also incorrect and may go backwards in time... To support this kind of specific and frequently occurring usage a stopwatch class can be used that can enable more accurate gathering of *just* durations (and using monotonic time when it's available in python 3.3+ or optionally when the library at http://pypi.python.org/pypi/monotonic is installed). This code comes from taskflow, but oslo.messaging has similar code that they could replace with this (and I imagine tooz could also use this); among others... Change-Id: I950e26c1eb8283a134fb4f16544f87bc5d29fd82
431 lines
13 KiB
Python
431 lines
13 KiB
Python
# Copyright 2011 OpenStack Foundation.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Time related utilities and helper functions.
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"""
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import calendar
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import datetime
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import time
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import iso8601
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import six
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from oslo_utils import reflection
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# ISO 8601 extended time format with microseconds
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_ISO8601_TIME_FORMAT_SUBSECOND = '%Y-%m-%dT%H:%M:%S.%f'
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_ISO8601_TIME_FORMAT = '%Y-%m-%dT%H:%M:%S'
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PERFECT_TIME_FORMAT = _ISO8601_TIME_FORMAT_SUBSECOND
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# Use monotonic time in stopwatches if we can get at it...
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#
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# PEP @ https://www.python.org/dev/peps/pep-0418/
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try:
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now = time.monotonic
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except AttributeError:
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try:
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# Try to use the pypi module if it's available (optionally...)
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from monotonic import monotonic as now
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except (AttributeError, ImportError):
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# Ok fallback to the non-monotonic one...
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now = time.time
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def isotime(at=None, subsecond=False):
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"""Stringify time in ISO 8601 format."""
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if not at:
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at = utcnow()
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st = at.strftime(_ISO8601_TIME_FORMAT
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if not subsecond
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else _ISO8601_TIME_FORMAT_SUBSECOND)
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tz = at.tzinfo.tzname(None) if at.tzinfo else 'UTC'
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st += ('Z' if tz == 'UTC' else tz)
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return st
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def parse_isotime(timestr):
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"""Parse time from ISO 8601 format."""
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try:
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return iso8601.parse_date(timestr)
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except iso8601.ParseError as e:
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raise ValueError(six.text_type(e))
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except TypeError as e:
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raise ValueError(six.text_type(e))
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def strtime(at=None, fmt=PERFECT_TIME_FORMAT):
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"""Returns formatted utcnow."""
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if not at:
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at = utcnow()
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return at.strftime(fmt)
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def parse_strtime(timestr, fmt=PERFECT_TIME_FORMAT):
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"""Turn a formatted time back into a datetime."""
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return datetime.datetime.strptime(timestr, fmt)
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def normalize_time(timestamp):
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"""Normalize time in arbitrary timezone to UTC naive object."""
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offset = timestamp.utcoffset()
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if offset is None:
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return timestamp
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return timestamp.replace(tzinfo=None) - offset
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def is_older_than(before, seconds):
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"""Return True if before is older than seconds."""
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if isinstance(before, six.string_types):
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before = parse_strtime(before).replace(tzinfo=None)
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else:
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before = before.replace(tzinfo=None)
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return utcnow() - before > datetime.timedelta(seconds=seconds)
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def is_newer_than(after, seconds):
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"""Return True if after is newer than seconds."""
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if isinstance(after, six.string_types):
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after = parse_strtime(after).replace(tzinfo=None)
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else:
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after = after.replace(tzinfo=None)
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return after - utcnow() > datetime.timedelta(seconds=seconds)
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def utcnow_ts(microsecond=False):
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"""Timestamp version of our utcnow function.
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See :py:class:`oslo_utils.fixture.TimeFixture`.
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"""
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if utcnow.override_time is None:
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# NOTE(kgriffs): This is several times faster
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# than going through calendar.timegm(...)
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timestamp = time.time()
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if not microsecond:
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timestamp = int(timestamp)
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return timestamp
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now = utcnow()
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timestamp = calendar.timegm(now.timetuple())
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if microsecond:
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timestamp += float(now.microsecond) / 1000000
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return timestamp
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def utcnow():
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"""Overridable version of utils.utcnow.
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See :py:class:`oslo_utils.fixture.TimeFixture`.
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"""
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if utcnow.override_time:
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try:
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return utcnow.override_time.pop(0)
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except AttributeError:
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return utcnow.override_time
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return datetime.datetime.utcnow()
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def iso8601_from_timestamp(timestamp, microsecond=False):
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"""Returns an iso8601 formatted date from timestamp."""
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return isotime(datetime.datetime.utcfromtimestamp(timestamp), microsecond)
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utcnow.override_time = None
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def set_time_override(override_time=None):
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"""Overrides utils.utcnow.
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Make it return a constant time or a list thereof, one at a time.
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See :py:class:`oslo_utils.fixture.TimeFixture`.
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:param override_time: datetime instance or list thereof. If not
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given, defaults to the current UTC time.
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"""
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utcnow.override_time = override_time or datetime.datetime.utcnow()
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def advance_time_delta(timedelta):
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"""Advance overridden time using a datetime.timedelta.
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See :py:class:`oslo_utils.fixture.TimeFixture`.
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"""
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assert utcnow.override_time is not None
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try:
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for dt in utcnow.override_time:
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dt += timedelta
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except TypeError:
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utcnow.override_time += timedelta
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def advance_time_seconds(seconds):
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"""Advance overridden time by seconds.
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See :py:class:`oslo_utils.fixture.TimeFixture`.
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"""
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advance_time_delta(datetime.timedelta(0, seconds))
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def clear_time_override():
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"""Remove the overridden time.
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See :py:class:`oslo_utils.fixture.TimeFixture`.
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"""
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utcnow.override_time = None
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def marshall_now(now=None):
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"""Make an rpc-safe datetime with microseconds.
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Note: tzinfo is stripped, but not required for relative times.
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"""
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if not now:
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now = utcnow()
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return dict(day=now.day, month=now.month, year=now.year, hour=now.hour,
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minute=now.minute, second=now.second,
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microsecond=now.microsecond)
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def unmarshall_time(tyme):
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"""Unmarshall a datetime dict."""
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return datetime.datetime(day=tyme['day'],
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month=tyme['month'],
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year=tyme['year'],
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hour=tyme['hour'],
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minute=tyme['minute'],
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second=tyme['second'],
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microsecond=tyme['microsecond'])
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def delta_seconds(before, after):
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"""Return the difference between two timing objects.
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Compute the difference in seconds between two date, time, or
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datetime objects (as a float, to microsecond resolution).
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"""
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delta = after - before
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return total_seconds(delta)
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def total_seconds(delta):
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"""Return the total seconds of datetime.timedelta object.
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Compute total seconds of datetime.timedelta, datetime.timedelta
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doesn't have method total_seconds in Python2.6, calculate it manually.
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"""
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try:
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return delta.total_seconds()
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except AttributeError:
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return ((delta.days * 24 * 3600) + delta.seconds +
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float(delta.microseconds) / (10 ** 6))
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def is_soon(dt, window):
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"""Determines if time is going to happen in the next window seconds.
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:param dt: the time
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:param window: minimum seconds to remain to consider the time not soon
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:return: True if expiration is within the given duration
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"""
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soon = (utcnow() + datetime.timedelta(seconds=window))
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return normalize_time(dt) <= soon
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class Split(object):
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"""A *immutable* stopwatch split.
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See: http://en.wikipedia.org/wiki/Stopwatch for what this is/represents.
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"""
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__slots__ = ['_elapsed', '_length']
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def __init__(self, elapsed, length):
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self._elapsed = elapsed
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self._length = length
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@property
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def elapsed(self):
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"""Duration from stopwatch start."""
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return self._elapsed
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@property
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def length(self):
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"""Seconds from last split (or the elapsed time if no prior split)."""
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return self._length
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def __repr__(self):
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r = reflection.get_class_name(self, fully_qualified=False)
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r += "(elapsed=%s, length=%s)" % (self._elapsed, self._length)
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return r
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class StopWatch(object):
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"""A simple timer/stopwatch helper class.
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Inspired by: apache-commons-lang java stopwatch.
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Not thread-safe (when a single watch is mutated by multiple threads at
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the same time). Thread-safe when used by a single thread (not shared) or
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when operations are performed in a thread-safe manner on these objects by
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wrapping those operations with locks.
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"""
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_STARTED = 'STARTED'
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_STOPPED = 'STOPPED'
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def __init__(self, duration=None):
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if duration is not None and duration < 0:
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raise ValueError("Duration must be greater or equal to"
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" zero and not %s" % duration)
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self._duration = duration
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self._started_at = None
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self._stopped_at = None
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self._state = None
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self._splits = []
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def start(self):
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"""Starts the watch (if not already started).
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NOTE(harlowja): resets any splits previously captured (if any).
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"""
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if self._state == self._STARTED:
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return self
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self._started_at = now()
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self._stopped_at = None
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self._state = self._STARTED
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self._splits = []
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return self
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@property
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def splits(self):
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"""Accessor to all/any splits that have been captured."""
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return tuple(self._splits)
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def split(self):
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"""Captures a split/elapsed since start time (and doesn't stop)."""
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if self._state == self._STARTED:
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elapsed = self.elapsed()
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if self._splits:
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length = self._delta_seconds(self._splits[-1].elapsed, elapsed)
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else:
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length = elapsed
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self._splits.append(Split(elapsed, length))
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return self._splits[-1]
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else:
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raise RuntimeError("Can not create a split time of a stopwatch"
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" if it has not been started or if it has been"
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" stopped")
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def restart(self):
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"""Restarts the watch from a started/stopped state."""
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if self._state == self._STARTED:
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self.stop()
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self.start()
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return self
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@staticmethod
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def _delta_seconds(earlier, later):
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# Uses max to avoid the delta/time going backwards (and thus negative).
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return max(0.0, later - earlier)
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def elapsed(self, maximum=None):
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"""Returns how many seconds have elapsed."""
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if self._state not in (self._STARTED, self._STOPPED):
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raise RuntimeError("Can not get the elapsed time of a stopwatch"
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" if it has not been started/stopped")
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if self._state == self._STOPPED:
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elapsed = self._delta_seconds(self._started_at, self._stopped_at)
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else:
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elapsed = self._delta_seconds(self._started_at, now())
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if maximum is not None and elapsed > maximum:
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elapsed = max(0.0, maximum)
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return elapsed
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def __enter__(self):
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"""Starts the watch."""
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self.start()
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return self
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def __exit__(self, type, value, traceback):
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"""Stops the watch (ignoring errors if stop fails)."""
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try:
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self.stop()
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except RuntimeError:
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pass
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def leftover(self, return_none=False):
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"""Returns how many seconds are left until the watch expires.
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:param return_none: when ``True`` instead of raising a ``RuntimeError``
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when no duration has been set this call will
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return ``None`` instead.
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:type return_none: boolean
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"""
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if self._state != self._STARTED:
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raise RuntimeError("Can not get the leftover time of a stopwatch"
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" that has not been started")
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if self._duration is None:
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if not return_none:
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raise RuntimeError("Can not get the leftover time of a watch"
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" that has no duration")
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return None
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return max(0.0, self._duration - self.elapsed())
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def expired(self):
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"""Returns if the watch has expired (ie, duration provided elapsed)."""
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if self._state not in (self._STARTED, self._STOPPED):
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raise RuntimeError("Can not check if a stopwatch has expired"
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" if it has not been started/stopped")
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if self._duration is None:
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return False
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return self.elapsed() > self._duration
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def has_started(self):
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return self._state == self._STARTED
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def has_stopped(self):
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return self._state == self._STOPPED
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def resume(self):
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"""Resumes the watch from a stopped state."""
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if self._state == self._STOPPED:
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self._state = self._STARTED
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return self
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else:
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raise RuntimeError("Can not resume a stopwatch that has not been"
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" stopped")
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def stop(self):
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"""Stops the watch."""
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if self._state == self._STOPPED:
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return self
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if self._state != self._STARTED:
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raise RuntimeError("Can not stop a stopwatch that has not been"
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" started")
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self._stopped_at = now()
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self._state = self._STOPPED
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return self
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