Commit 77c2039a authored by Tim Peters's avatar Tim Peters

Collector #1397: testTimeStamp fails on FreeBSD

Forward-porting from Zope 2.7.
Merged from 3.3 branch, revision 26085.

The checkFullTimeStamp() test was sensitive to unique mktime() behavior
on FreeBSD.  See:

http://lists.freebsd.org/pipermail/freebsd-standards/2003-November/000268.html 

The purpose of this test is to exercise ZODB's TimeStamp object, so got
rid of dependence on platform mktime() and time.timezone quirks --
TimeStamp works in GMT, so how mktime() treats tm_isdst should be
irrelevant in all TimeStamp tests.

Also added a comment about the highly non-obvious numeric characteristics
of TimeStamp's treatment of seconds (round-tripping is surprisingly
inaccurate, but for a real reason).
parent 33d3d6f6
...@@ -5,7 +5,8 @@ Release date: DD-MMM-2004 ...@@ -5,7 +5,8 @@ Release date: DD-MMM-2004
Storages Storages
-------- --------
Collector #1327 FileStorage init confused by time travel. Collector #1327: FileStorage init confused by time travel
If the system clock "went backwards" a long time between the times a If the system clock "went backwards" a long time between the times a
FileStorage was closed and reopened, new transaction ids could be FileStorage was closed and reopened, new transaction ids could be
smaller than transaction ids already in the storage, violating a smaller than transaction ids already in the storage, violating a
...@@ -16,6 +17,15 @@ warning level; if time appears to have run backwards at least 30 ...@@ -16,6 +17,15 @@ warning level; if time appears to have run backwards at least 30
minutes, the message is logged at critical level (and you should minutes, the message is logged at critical level (and you should
investigate to find and repair the true cause). investigate to find and repair the true cause).
Test suite
----------
Collector #1397: testTimeStamp fails on FreeBSD
The *BSD distributions are unique in that their mktime() implementation
usually ignores the input tm_isdst value. Test checkFullTimeStamp()
was sensitive to this platform quirk.
What's new in ZODB3 3.3 beta 1 What's new in ZODB3 3.3 beta 1
============================== ==============================
......
...@@ -41,16 +41,28 @@ class TimeStampTests(unittest.TestCase): ...@@ -41,16 +41,28 @@ class TimeStampTests(unittest.TestCase):
self.assertEquals(dy, t[2]) self.assertEquals(dy, t[2])
def checkFullTimeStamp(self): def checkFullTimeStamp(self):
t = time.gmtime() native_ts = int(time.time()) # fractional seconds get in the way
t = time.gmtime(native_ts) # the corresponding GMT struct tm
ts = TimeStamp(*t[:6]) ts = TimeStamp(*t[:6])
# XXX floating point comparison # Seconds are stored internally via (conceptually) multiplying by
self.assertEquals(ts.timeTime() + time.timezone, time.mktime(t)) # 2**32 then dividing by 60, ending up with a 32-bit integer.
# While this gives a lot of room for cramming many distinct
# TimeStamps into a second, it's not good at roundtrip accuracy.
# For example, 1 second is stored as int(2**32/60) == 71582788.
# Converting back gives 71582788*60.0/2**32 == 0.9999999962747097.
# In general, we can lose up to 0.999... to truncation during
# storing, creating an absolute error up to about 1*60.0/2**32 ==
# 0.000000014 on the seconds value we get back. This is so even
# when we have an exact integral second value going in (as we
# do in this test), so we can't expect equality in any comparison
# involving seconds. Minutes (etc) are stored exactly, so we
# can expect equality for those.
self.assert_(abs(ts.timeTime() - native_ts) < EPSILON)
self.assertEqual(ts.year(), t[0]) self.assertEqual(ts.year(), t[0])
self.assertEqual(ts.month(), t[1]) self.assertEqual(ts.month(), t[1])
self.assertEqual(ts.day(), t[2]) self.assertEqual(ts.day(), t[2])
self.assertEquals(ts.hour(), t[3]) self.assertEquals(ts.hour(), t[3])
self.assertEquals(ts.minute(), t[4]) self.assertEquals(ts.minute(), t[4])
self.assert_(abs(ts.second() - t[5]) < EPSILON) self.assert_(abs(ts.second() - t[5]) < EPSILON)
......
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