def testcheckambig(self):
def atomicwrite(checkambig):
f = atomictempfile(self._filename, checkambig=checkambig)
f.writeutf8("FOO")
f.close()
# try some times, because reproduction of ambiguity depends on
# "filesystem time"
for i in xrange(5):
atomicwrite(False)
oldstat = util.stat(self._filename)
if oldstat.st_ctime != oldstat.st_mtime:
# subsequent changing never causes ambiguity
continue
repetition = 3
# repeat atomic write with checkambig=True, to examine
# whether st_mtime is advanced multiple times as expected
for j in xrange(repetition):
atomicwrite(True)
newstat = util.stat(self._filename)
if oldstat.st_ctime != newstat.st_ctime:
# timestamp ambiguity was naturally avoided while repetition
continue
# st_mtime should be advanced "repetition" times, because
# all atomicwrite() occurred at same time (in sec)
self.assertTrue(
newstat.st_mtime == ((oldstat.st_mtime + repetition)
& 0x7FFFFFFF))
# no more examination is needed, if assumption above is true
break
else:
# This platform seems too slow to examine anti-ambiguity
# of file timestamp (or test happened to be executed at
# bad timing). Exit silently in this case, because running
# on other faster platforms can detect problems
pass
def antiambiguity():
filename = "ambigcheck"
# try some times, because reproduction of ambiguity depends on
# "filesystem time"
for i in xrange(5):
fp = open(filename, "w")
fp.write("FOO")
fp.close()
oldstat = util.stat(filename)
if oldstat.st_ctime != oldstat.st_mtime:
# subsequent changing never causes ambiguity
continue
repetition = 3
# repeat changing via checkambigatclosing, to examine whether
# st_mtime is advanced multiple times as expected
for i in xrange(repetition):
# explicit closing
fp = vfsmod.checkambigatclosing(open(filename, "a"))
fp.write("FOO")
fp.close()
# implicit closing by "with" statement
with vfsmod.checkambigatclosing(open(filename, "a")) as fp:
fp.write("BAR")
newstat = os.stat(filename)
if oldstat.st_ctime != newstat.st_ctime:
# timestamp ambiguity was naturally avoided while repetition
continue
# st_mtime should be advanced "repetition * 2" times, because
# all changes occurred at same time (in sec)
expected = (oldstat.st_mtime + repetition * 2) & 0x7FFFFFFF
if newstat.st_mtime != expected:
print(
"'newstat.st_mtime %s is not %s (as %s + %s * 2)"
% (newstat.st_mtime, expected, oldstat.st_mtime, repetition)
)
# no more examination is needed regardless of result
break
else:
# This platform seems too slow to examine anti-ambiguity
# of file timestamp (or test happened to be executed at
# bad timing). Exit silently in this case, because running
# on other faster platforms can detect problems
pass