[Python-checkins] cpython: Issue #23517: Fix implementation of the ROUND_HALF_UP rounding mode in
victor.stinner
python-checkins at python.org
Sat Sep 5 00:09:26 CEST 2015
https://hg.python.org/cpython/rev/3c29d05c0710
changeset: 97679:3c29d05c0710
user: Victor Stinner <victor.stinner at gmail.com>
date: Fri Sep 04 23:57:25 2015 +0200
summary:
Issue #23517: Fix implementation of the ROUND_HALF_UP rounding mode in
datetime.datetime.fromtimestamp() and datetime.datetime.utcfromtimestamp().
microseconds sign should be kept before rounding.
files:
Lib/datetime.py | 50 +++++++++++--------------
Lib/test/datetimetester.py | 12 +++++-
Lib/test/test_time.py | 13 +++---
Python/pytime.c | 8 ++--
4 files changed, 43 insertions(+), 40 deletions(-)
diff --git a/Lib/datetime.py b/Lib/datetime.py
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1374,6 +1374,26 @@
return self._tzinfo
@classmethod
+ def _fromtimestamp(cls, t, utc, tz):
+ """Construct a datetime from a POSIX timestamp (like time.time()).
+
+ A timezone info object may be passed in as well.
+ """
+ frac, t = _math.modf(t)
+ us = _round_half_up(frac * 1e6)
+ if us >= 1000000:
+ t += 1
+ us -= 1000000
+ elif us < 0:
+ t -= 1
+ us += 1000000
+
+ converter = _time.gmtime if utc else _time.localtime
+ y, m, d, hh, mm, ss, weekday, jday, dst = converter(t)
+ ss = min(ss, 59) # clamp out leap seconds if the platform has them
+ return cls(y, m, d, hh, mm, ss, us, tz)
+
+ @classmethod
def fromtimestamp(cls, t, tz=None):
"""Construct a datetime from a POSIX timestamp (like time.time()).
@@ -1381,21 +1401,7 @@
"""
_check_tzinfo_arg(tz)
- converter = _time.localtime if tz is None else _time.gmtime
-
- t, frac = divmod(t, 1.0)
- us = _round_half_up(frac * 1e6)
-
- # If timestamp is less than one microsecond smaller than a
- # full second, us can be rounded up to 1000000. In this case,
- # roll over to seconds, otherwise, ValueError is raised
- # by the constructor.
- if us == 1000000:
- t += 1
- us = 0
- y, m, d, hh, mm, ss, weekday, jday, dst = converter(t)
- ss = min(ss, 59) # clamp out leap seconds if the platform has them
- result = cls(y, m, d, hh, mm, ss, us, tz)
+ result = cls._fromtimestamp(t, tz is not None, tz)
if tz is not None:
result = tz.fromutc(result)
return result
@@ -1403,19 +1409,7 @@
@classmethod
def utcfromtimestamp(cls, t):
"""Construct a naive UTC datetime from a POSIX timestamp."""
- t, frac = divmod(t, 1.0)
- us = _round_half_up(frac * 1e6)
-
- # If timestamp is less than one microsecond smaller than a
- # full second, us can be rounded up to 1000000. In this case,
- # roll over to seconds, otherwise, ValueError is raised
- # by the constructor.
- if us == 1000000:
- t += 1
- us = 0
- y, m, d, hh, mm, ss, weekday, jday, dst = _time.gmtime(t)
- ss = min(ss, 59) # clamp out leap seconds if the platform has them
- return cls(y, m, d, hh, mm, ss, us)
+ return cls._fromtimestamp(t, True, None)
@classmethod
def now(cls, tz=None):
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -668,6 +668,8 @@
eq(td(milliseconds=-0.6/1000), td(microseconds=-1))
eq(td(seconds=0.5/10**6), td(microseconds=1))
eq(td(seconds=-0.5/10**6), td(microseconds=-1))
+ eq(td(seconds=1/2**7), td(microseconds=7813))
+ eq(td(seconds=-1/2**7), td(microseconds=-7813))
# Rounding due to contributions from more than one field.
us_per_hour = 3600e6
@@ -1842,8 +1844,8 @@
18000 + 3600 + 2*60 + 3 + 4*1e-6)
def test_microsecond_rounding(self):
- for fts in [self.theclass.fromtimestamp,
- self.theclass.utcfromtimestamp]:
+ for fts in (datetime.fromtimestamp,
+ self.theclass.utcfromtimestamp):
zero = fts(0)
self.assertEqual(zero.second, 0)
self.assertEqual(zero.microsecond, 0)
@@ -1874,6 +1876,12 @@
t = fts(0.9999999)
self.assertEqual(t.second, 1)
self.assertEqual(t.microsecond, 0)
+ t = fts(1/2**7)
+ self.assertEqual(t.second, 0)
+ self.assertEqual(t.microsecond, 7813)
+ t = fts(-1/2**7)
+ self.assertEqual(t.second, 59)
+ self.assertEqual(t.microsecond, 992187)
def test_insane_fromtimestamp(self):
# It's possible that some platform maps time_t to double,
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -655,7 +655,7 @@
pytime_object_to_time_t, invalid, rnd)
@support.cpython_only
- def test_timespec(self):
+ def test_object_to_timespec(self):
from _testcapi import pytime_object_to_timespec
# Conversion giving the same result for all rounding methods
@@ -666,7 +666,7 @@
(-1, (-1, 0)),
# float
- (-1.2, (-2, 800000000)),
+ (-1/2**7, (-1, 992187500)),
(-1.0, (-1, 0)),
(-1e-9, (-1, 999999999)),
(1e-9, (0, 1)),
@@ -693,7 +693,7 @@
(1.1234567890, (1, 123456789), FLOOR),
(1.1234567899, (1, 123456789), FLOOR),
- (-1.1234567890, (-2, 876543211), FLOOR),
+ (-1.1234567890, (-2, 876543210), FLOOR),
(-1.1234567891, (-2, 876543210), FLOOR),
# Round towards infinity (+inf)
(1.1234567890, (1, 123456790), CEILING),
@@ -1155,7 +1155,7 @@
self.assertRaises(OverflowError,
pytime_object_to_time_t, invalid, rnd)
- def test_timeval(self):
+ def test_object_to_timeval(self):
from _testcapi import pytime_object_to_timeval
# Conversion giving the same result for all rounding methods
@@ -1167,7 +1167,8 @@
# float
(-1.0, (-1, 0)),
- (-1.2, (-2, 800000)),
+ (1/2**6, (0, 15625)),
+ (-1/2**6, (-1, 984375)),
(-1e-6, (-1, 999999)),
(1e-6, (0, 1)),
):
@@ -1225,7 +1226,7 @@
(-1.0, (-1, 0)),
(-1e-9, (-1, 999999999)),
(1e-9, (0, 1)),
- (-1.2, (-2, 800000000)),
+ (-1/2**9, (-1, 998046875)),
):
with self.subTest(obj=obj, round=rnd, timespec=timespec):
self.assertEqual(pytime_object_to_timespec(obj, rnd),
diff --git a/Python/pytime.c b/Python/pytime.c
--- a/Python/pytime.c
+++ b/Python/pytime.c
@@ -82,10 +82,6 @@
volatile double floatpart;
floatpart = modf(d, &intpart);
- if (floatpart < 0) {
- floatpart += 1.0;
- intpart -= 1.0;
- }
floatpart *= denominator;
if (round == _PyTime_ROUND_HALF_UP)
@@ -98,6 +94,10 @@
floatpart -= denominator;
intpart += 1.0;
}
+ else if (floatpart < 0) {
+ floatpart += denominator;
+ intpart -= 1.0;
+ }
assert(0.0 <= floatpart && floatpart < denominator);
*sec = (time_t)intpart;
--
Repository URL: https://hg.python.org/cpython
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