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- #!/usr/bin/env python
- # Copyright 2018 The Chromium Authors. All rights reserved.
- # Use of this source code is governed by a BSD-style license that can be
- # found in the LICENSE file.
- """Returns a timestamp that approximates the build date.
- build_type impacts the timestamp generated, both relative to the date of the
- last recent commit:
- - default: the build date is set to the most recent first Sunday of a month at
- 5:00am. The reason is that it is a time where invalidating the build cache
- shouldn't have major repercussions (due to lower load).
- - official: the build date is set to the time of the most recent commit.
- Either way, it is guaranteed to be in the past and always in UTC.
- """
- # The requirements for the timestamp:
- # (1) for the purposes of continuous integration, longer duration
- # between cache invalidation is better, but >=1mo is preferable.
- # (2) for security purposes, timebombs would ideally be as close to
- # the actual time of the build as possible. It must be in the past.
- # (3) HSTS certificate pinning is valid for 70 days. To make CI builds enforce
- # HTST pinning, <=1mo is preferable.
- #
- # On Windows, the timestamp is also written in the PE/COFF file header of
- # executables of dlls. That timestamp and the executable's file size are
- # the only two pieces of information that identify a given executable on
- # the symbol server, so rarely changing timestamps can cause conflicts there
- # as well. We only upload symbols for official builds to the symbol server.
- from __future__ import print_function
- import argparse
- import calendar
- import datetime
- import doctest
- import os
- import sys
- THIS_DIR = os.path.abspath(os.path.dirname(__file__))
- def GetFirstSundayOfMonth(year, month):
- """Returns the first sunday of the given month of the given year.
- >>> GetFirstSundayOfMonth(2016, 2)
- 7
- >>> GetFirstSundayOfMonth(2016, 3)
- 6
- >>> GetFirstSundayOfMonth(2000, 1)
- 2
- """
- weeks = calendar.Calendar().monthdays2calendar(year, month)
- # Return the first day in the first week that is a Sunday.
- return [date_day[0] for date_day in weeks[0] if date_day[1] == 6][0]
- def GetUnofficialBuildDate(build_date):
- """Gets the approximate build date given the specific build type.
- >>> GetUnofficialBuildDate(datetime.datetime(2016, 2, 6, 1, 2, 3))
- datetime.datetime(2016, 1, 3, 5, 0)
- >>> GetUnofficialBuildDate(datetime.datetime(2016, 2, 7, 5))
- datetime.datetime(2016, 2, 7, 5, 0)
- >>> GetUnofficialBuildDate(datetime.datetime(2016, 2, 8, 5))
- datetime.datetime(2016, 2, 7, 5, 0)
- """
- if build_date.hour < 5:
- # The time is locked at 5:00 am in UTC to cause the build cache
- # invalidation to not happen exactly at midnight. Use the same calculation
- # as the day before.
- # See //base/build_time.cc.
- build_date = build_date - datetime.timedelta(days=1)
- build_date = datetime.datetime(build_date.year, build_date.month,
- build_date.day, 5, 0, 0)
- day = build_date.day
- month = build_date.month
- year = build_date.year
- first_sunday = GetFirstSundayOfMonth(year, month)
- # If our build is after the first Sunday, we've already refreshed our build
- # cache on a quiet day, so just use that day.
- # Otherwise, take the first Sunday of the previous month.
- if day >= first_sunday:
- day = first_sunday
- else:
- month -= 1
- if month == 0:
- month = 12
- year -= 1
- day = GetFirstSundayOfMonth(year, month)
- return datetime.datetime(
- year, month, day, build_date.hour, build_date.minute, build_date.second)
- def main():
- if doctest.testmod()[0]:
- return 1
- argument_parser = argparse.ArgumentParser()
- argument_parser.add_argument(
- 'build_type', help='The type of build', choices=('official', 'default'))
- args = argument_parser.parse_args()
- # The mtime of the revision in build/util/LASTCHANGE is stored in a file
- # next to it. Read it, to get a deterministic time close to "now".
- # That date is then modified as described at the top of the file so that
- # it changes less frequently than with every commit.
- # This intentionally always uses build/util/LASTCHANGE's commit time even if
- # use_dummy_lastchange is set.
- lastchange_file = os.path.join(THIS_DIR, 'util', 'LASTCHANGE.committime')
- last_commit_timestamp = int(open(lastchange_file).read())
- build_date = datetime.datetime.utcfromtimestamp(last_commit_timestamp)
- # For official builds we want full fidelity time stamps because official
- # builds are typically added to symbol servers and Windows symbol servers
- # use the link timestamp as the prime differentiator, but for unofficial
- # builds we do lots of quantization to avoid churn.
- if args.build_type != 'official':
- build_date = GetUnofficialBuildDate(build_date)
- print(int(calendar.timegm(build_date.utctimetuple())))
- return 0
- if __name__ == '__main__':
- sys.exit(main())
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