[Python-checkins] bpo-43869: Time Epoch is the same on all platforms (GH-30664)
vstinner
webhook-mailer at python.org
Wed Jan 19 05:27:37 EST 2022
https://github.com/python/cpython/commit/a847785b40ed8819bde2dac5849dc31d15e99a74
commit: a847785b40ed8819bde2dac5849dc31d15e99a74
branch: main
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2022-01-19T11:27:11+01:00
summary:
bpo-43869: Time Epoch is the same on all platforms (GH-30664)
files:
A Misc/NEWS.d/next/Library/2022-01-18-17-24-21.bpo-43869.NayN12.rst
M Doc/library/time.rst
M Lib/test/test_time.py
diff --git a/Doc/library/time.rst b/Doc/library/time.rst
index 3a771208519b4..d524f4ffebc75 100644
--- a/Doc/library/time.rst
+++ b/Doc/library/time.rst
@@ -21,10 +21,8 @@ An explanation of some terminology and conventions is in order.
.. index:: single: epoch
-* The :dfn:`epoch` is the point where the time starts, and is platform
- dependent. For Unix and Windows, the epoch is January 1, 1970, 00:00:00 (UTC).
- To find out what the epoch is on a given platform, look at
- ``time.gmtime(0)``.
+* The :dfn:`epoch` is the point where the time starts, the return value of
+ ``time.gmtime(0)``. It is January 1, 1970, 00:00:00 (UTC) on all platforms.
.. _leap seconds: https://en.wikipedia.org/wiki/Leap_second
@@ -37,7 +35,7 @@ An explanation of some terminology and conventions is in order.
.. index:: single: Year 2038
-* The functions in this module may not handle dates and times before the epoch or
+* The functions in this module may not handle dates and times before the epoch_ or
far in the future. The cut-off point in the future is determined by the C
library; for 32-bit systems, it is typically in 2038.
@@ -207,7 +205,7 @@ Functions
.. function:: ctime([secs])
- Convert a time expressed in seconds since the epoch to a string of a form:
+ Convert a time expressed in seconds since the epoch_ to a string of a form:
``'Sun Jun 20 23:21:05 1993'`` representing local time. The day field
is two characters long and is space padded if the day is a single digit,
e.g.: ``'Wed Jun 9 04:26:40 1993'``.
@@ -245,7 +243,7 @@ Functions
.. function:: gmtime([secs])
- Convert a time expressed in seconds since the epoch to a :class:`struct_time` in
+ Convert a time expressed in seconds since the epoch_ to a :class:`struct_time` in
UTC in which the dst flag is always zero. If *secs* is not provided or
:const:`None`, the current time as returned by :func:`.time` is used. Fractions
of a second are ignored. See above for a description of the
@@ -601,14 +599,10 @@ Functions
.. function:: time() -> float
Return the time in seconds since the epoch_ as a floating point
- number. The specific date of the epoch and the handling of
- `leap seconds`_ is platform dependent.
- On Windows and most Unix systems, the epoch is January 1, 1970,
- 00:00:00 (UTC) and leap seconds are not counted towards the time
- in seconds since the epoch. This is commonly referred to as
- `Unix time <https://en.wikipedia.org/wiki/Unix_time>`_.
- To find out what the epoch is on a given platform, look at
- ``gmtime(0)``.
+ number. The handling of `leap seconds`_ is platform dependent.
+ On Windows and most Unix systems, the leap seconds are not counted towards
+ the time in seconds since the epoch_. This is commonly referred to as `Unix
+ time <https://en.wikipedia.org/wiki/Unix_time>`_.
Note that even though the time is always returned as a floating point
number, not all systems provide time with a better precision than 1 second.
@@ -629,8 +623,8 @@ Functions
.. function:: time_ns() -> int
- Similar to :func:`~time.time` but returns time as an integer number of nanoseconds
- since the epoch_.
+ Similar to :func:`~time.time` but returns time as an integer number of
+ nanoseconds since the epoch_.
.. versionadded:: 3.7
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
index 1aa5874dfe272..1c444e381a552 100644
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -159,6 +159,13 @@ def test_sleep(self):
self.assertRaises(ValueError, time.sleep, -1)
time.sleep(1.2)
+ def test_epoch(self):
+ # bpo-43869: Make sure that Python use the same Epoch on all platforms:
+ # January 1, 1970, 00:00:00 (UTC).
+ epoch = time.gmtime(0)
+ # Only test the date and time, ignore other gmtime() members
+ self.assertEqual(tuple(epoch)[:6], (1970, 1, 1, 0, 0, 0), epoch)
+
def test_strftime(self):
tt = time.gmtime(self.t)
for directive in ('a', 'A', 'b', 'B', 'c', 'd', 'H', 'I',
diff --git a/Misc/NEWS.d/next/Library/2022-01-18-17-24-21.bpo-43869.NayN12.rst b/Misc/NEWS.d/next/Library/2022-01-18-17-24-21.bpo-43869.NayN12.rst
new file mode 100644
index 0000000000000..5486c95b0689b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-01-18-17-24-21.bpo-43869.NayN12.rst
@@ -0,0 +1,2 @@
+Python uses the same time Epoch on all platforms. Add an explicit unit test
+to ensure that it's the case. Patch by Victor Stinner.
More information about the Python-checkins
mailing list