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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.
This commit is contained in:
Victor Stinner 2015-09-04 23:57:25 +02:00
parent 19bbb9af67
commit adfefa527a
4 changed files with 43 additions and 40 deletions
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50
Lib/datetime.py
View File

@ -1373,6 +1373,26 @@ class datetime(date):
"""timezone info object"""
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 @@ class datetime(date):
"""
_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 @@ class datetime(date):
@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):

12
Lib/test/datetimetester.py
View File

@ -668,6 +668,8 @@ class TestTimeDelta(HarmlessMixedComparison, unittest.TestCase):
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 @@ class TestDateTime(TestDate):
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 @@ class TestDateTime(TestDate):
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,

13
Lib/test/test_time.py
View File

@ -655,7 +655,7 @@ class TestPytime(unittest.TestCase):
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 @@ class TestPytime(unittest.TestCase):
(-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 @@ class TestPytime(unittest.TestCase):
(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 @@ class TestOldPyTime(unittest.TestCase):
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 @@ class TestOldPyTime(unittest.TestCase):
# 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 @@ class TestOldPyTime(unittest.TestCase):
(-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),

8
Python/pytime.c
View File

@ -82,10 +82,6 @@ _PyTime_DoubleToDenominator(double d, time_t *sec, long *numerator,
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 @@ _PyTime_DoubleToDenominator(double d, time_t *sec, long *numerator,
floatpart -= denominator;
intpart += 1.0;
}
else if (floatpart < 0) {
floatpart += denominator;
intpart -= 1.0;
}
assert(0.0 <= floatpart && floatpart < denominator);
*sec = (time_t)intpart;