Mercurial > hg
view tests/test-atomictempfile.py @ 46846:2819df466cae
tests: add test-remotefilelog-strip.t to demonstrate an issue with linknodes
### Background
Every time a commit is modified, remotefilelog updates the metadata for the file
object to point to the new commit (I believe that this is different from
non-remotefilelog hg, which leaves the linkrevs pointing to the obsolete
commits; doing otherwise would involve changing data in the middle of revlogs).
With `hg strip` (or other things that use repair.strip()), when you strip a
commit that's not the tip of the revlog, there may be commits after it in revnum
order that aren't descended from it and don't need to be (and shouldn't be)
stripped. These are "saved" by strip in a bundle, and that bundle is reapplied
after truncating the relevant revlogs.
### The problem
Remotefilelog generally avoids being involved at all in strip. Currently, that
includes even providing file contents to this backup bundle. This can cause the
linknode to point to a changeset that is no longer in the repository.
Example:
```
@ 3 df91f74b871e
|
| x 2 70494d7ec5ef
|/
| x 1 1e423846dde0
|/
o 0 b292c1e3311f
```
Commits 1, 2, and 3 are related via obsolescence, and are description-only
changes. The linknode for the file in these commits changed each time we updated
the description, so it's currently df91f7. If I strip commits 1 and 3, however,
the linknode *remains* df91f7, which no longer exists in the repository. Commit
70494d was "saved", stripped, and then reapplied, so it is in the repository (as
revision 1 instead of 2 now), and was unobsoleted since the obsmarker was
stripped as well. The linknode for the file should point to 70494d, the most
recent commit that is in the repository that modified the file.
Remotefilelog has some logic to handle broken linknodes, but it can be slow. We
have actually disabled it internally because it's too slow for our purposes.
Differential Revision: https://phab.mercurial-scm.org/D10319
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Tue, 06 Apr 2021 15:38:33 -0700 |
parents | 2372284d9457 |
children | 6000f5b25c9b |
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from __future__ import absolute_import import glob import os import shutil import stat import tempfile import unittest from mercurial import ( pycompat, util, ) atomictempfile = util.atomictempfile if pycompat.ispy3: xrange = range class testatomictempfile(unittest.TestCase): def setUp(self): self._testdir = tempfile.mkdtemp(b'atomictempfiletest') self._filename = os.path.join(self._testdir, b'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, b'.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, b'.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(b'.')) # if a programmer screws up and passes bad args to atomictempfile, they # get a plain ordinary TypeError, not infinite recursion def testoops(self): with self.assertRaises(TypeError): atomictempfile() # checkambig=True avoids ambiguity of timestamp def testcheckambig(self): def atomicwrite(checkambig): f = atomictempfile(self._filename, checkambig=checkambig) f.write(b'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[stat.ST_CTIME] != oldstat[stat.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[stat.ST_CTIME] != newstat[stat.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) oldtime = (oldstat[stat.ST_MTIME] + repetition) & 0x7FFFFFFF self.assertTrue(newstat[stat.ST_MTIME] == oldtime) # 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=b'rb') self.assertTrue(file.read(), b'foobar\n') file.discard() def testcontextmanagersuccess(self): """When the context closes, the file is closed""" with atomictempfile(b'foo') as f: self.assertFalse(os.path.isfile(b'foo')) f.write(b'argh\n') self.assertTrue(os.path.isfile(b'foo')) def testcontextmanagerfailure(self): """On exception, the file is discarded""" try: with atomictempfile(b'foo') as f: self.assertFalse(os.path.isfile(b'foo')) f.write(b'argh\n') raise ValueError except ValueError: pass self.assertFalse(os.path.isfile(b'foo')) if __name__ == '__main__': import silenttestrunner silenttestrunner.main(__name__)