Mercurial > hg
view tests/test-atomictempfile.py @ 31063:18fb3cf572b4 stable
worker: ignore meaningless exit status indication returned by os.waitpid()
Before this patch, worker implementation assumes that os.waitpid()
with os.WNOHANG returns '(0, 0)' for still running child process. This
is explicitly specified as below in Python API document.
os.WNOHANG
The option for waitpid() to return immediately if no child
process status is available immediately. The function returns
(0, 0) in this case.
On the other hand, POSIX specification doesn't define the "stat_loc"
value returned by waitpid() with WNOHANG for such child process.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/waitpid.html
CPython implementation for os.waitpid() on POSIX doesn't take any care
of this gap, and this may cause unexpected "exit status indication"
even on POSIX conformance platform.
For example, os.waitpid() with os.WNOHANG returns non-zero "exit
status indication" on FreeBSD. This implies os.kill() with own pid or
sys.exit() with non-zero exit code, even if no child process fails.
To ignore meaningless exit status indication returned by os.waitpid(),
this patch skips subsequent steps forcibly, if os.waitpid() returns 0
as pid.
This patch also arranges examination of 'p' value for readability.
FYI, there are some issues below about this behavior reported for
CPython.
https://bugs.python.org/issue21791
https://bugs.python.org/issue27808
author | FUJIWARA Katsunori <foozy@lares.dti.ne.jp> |
---|---|
date | Sat, 25 Feb 2017 01:07:52 +0900 |
parents | 318a24b52eeb |
children | 68c43a416585 |
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from __future__ import absolute_import import glob import os import shutil import tempfile import unittest from mercurial import ( util, ) atomictempfile = util.atomictempfile class testatomictempfile(unittest.TestCase): def setUp(self): self._testdir = tempfile.mkdtemp('atomictempfiletest') self._filename = os.path.join(self._testdir, 'testfilename') def tearDown(self): shutil.rmtree(self._testdir, True) def testsimple(self): file = atomictempfile(self._filename) self.assertFalse(os.path.isfile(self._filename)) tempfilename = file._tempname self.assertTrue(tempfilename in glob.glob( os.path.join(self._testdir, '.testfilename-*'))) file.write(b'argh\n') file.close() self.assertTrue(os.path.isfile(self._filename)) self.assertTrue(tempfilename not in glob.glob( os.path.join(self._testdir, '.testfilename-*'))) # discard() removes the temp file without making the write permanent def testdiscard(self): file = atomictempfile(self._filename) (dir, basename) = os.path.split(file._tempname) file.write(b'yo\n') file.discard() self.assertFalse(os.path.isfile(self._filename)) self.assertTrue(basename not in os.listdir('.')) # if a programmer screws up and passes bad args to atomictempfile, they # get a plain ordinary TypeError, not infinite recursion def testoops(self): self.assertRaises(TypeError, atomictempfile) # checkambig=True avoids ambiguity of timestamp def testcheckambig(self): def atomicwrite(checkambig): f = atomictempfile(self._filename, checkambig=checkambig) f.write('FOO') f.close() # try some times, because reproduction of ambiguity depends on # "filesystem time" for i in xrange(5): atomicwrite(False) oldstat = os.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 = os.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 testread(self): with open(self._filename, 'wb') as f: f.write(b'foobar\n') file = atomictempfile(self._filename, mode='rb') self.assertTrue(file.read(), b'foobar\n') file.discard() def testcontextmanagersuccess(self): """When the context closes, the file is closed""" with atomictempfile('foo') as f: self.assertFalse(os.path.isfile('foo')) f.write(b'argh\n') self.assertTrue(os.path.isfile('foo')) def testcontextmanagerfailure(self): """On exception, the file is discarded""" try: with atomictempfile('foo') as f: self.assertFalse(os.path.isfile('foo')) f.write(b'argh\n') raise ValueError except ValueError: pass self.assertFalse(os.path.isfile('foo')) if __name__ == '__main__': import silenttestrunner silenttestrunner.main(__name__)