Mercurial > hg
view tests/test-propertycache.py @ 46607:e9901d01d135
revlog: add a mechanism to verify expected file position before appending
If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.
The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)
When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.
For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.
This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.
Differential Revision: https://phab.mercurial-scm.org/D9952
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Wed, 03 Feb 2021 16:33:10 -0800 |
parents | 2372284d9457 |
children | 6000f5b25c9b |
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"""test behavior of propertycache and unfiltered propertycache The repoview overlay is quite complex. We test the behavior of property cache of both localrepo and repoview to prevent regression.""" from __future__ import absolute_import, print_function import os import subprocess from mercurial import ( hg, localrepo, pycompat, ui as uimod, util, ) from mercurial.utils import procutil # create some special property cache that trace they call calllog = [] @util.propertycache def testcachedfoobar(repo): name = repo.filtername if name is None: name = '' val = len(name) calllog.append(val) return val unficalllog = [] @localrepo.unfilteredpropertycache def testcachedunfifoobar(repo): name = repo.filtername if name is None: name = '' val = 100 + len(name) unficalllog.append(val) return val # plug them on repo localrepo.localrepository.testcachedfoobar = testcachedfoobar localrepo.localrepository.testcachedunfifoobar = testcachedunfifoobar # Create an empty repo and instantiate it. It is important to run # these tests on the real object to detect regression. repopath = pycompat.fsencode(os.path.join(os.environ['TESTTMP'], 'repo')) assert ( subprocess.call( pycompat.rapply(procutil.tonativestr, [b'hg', b'init', repopath]) ) == 0 ) ui = uimod.ui.load() repo = hg.repository(ui, path=repopath).unfiltered() print('') print('=== property cache ===') print('') print('calllog:', calllog) print( 'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE') ) print('') print('= first access on unfiltered, should do a call') print('access:', repo.testcachedfoobar) print('calllog:', calllog) print( 'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE') ) print('') print('= second access on unfiltered, should not do call') print('access', repo.testcachedfoobar) print('calllog:', calllog) print( 'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE') ) print('') print('= first access on "visible" view, should do a call') visibleview = repo.filtered('visible') print( 'cached value ("visible" view):', vars(visibleview).get('testcachedfoobar', 'NOCACHE'), ) print('access:', visibleview.testcachedfoobar) print('calllog:', calllog) print( 'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE') ) print( 'cached value ("visible" view):', vars(visibleview).get('testcachedfoobar', 'NOCACHE'), ) print('') print('= second access on "visible view", should not do call') print('access:', visibleview.testcachedfoobar) print('calllog:', calllog) print( 'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE') ) print( 'cached value ("visible" view):', vars(visibleview).get('testcachedfoobar', 'NOCACHE'), ) print('') print('= no effect on other view') immutableview = repo.filtered('immutable') print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedfoobar', 'NOCACHE'), ) print('access:', immutableview.testcachedfoobar) print('calllog:', calllog) print( 'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE') ) print( 'cached value ("visible" view):', vars(visibleview).get('testcachedfoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedfoobar', 'NOCACHE'), ) # unfiltered property cache test print('') print('') print('=== unfiltered property cache ===') print('') print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("visible" view): ', vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'), ) print('') print('= first access on unfiltered, should do a call') print('access (unfiltered):', repo.testcachedunfifoobar) print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print('') print('= second access on unfiltered, should not do call') print('access (unfiltered):', repo.testcachedunfifoobar) print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print('') print('= access on view should use the unfiltered cache') print('access (unfiltered): ', repo.testcachedunfifoobar) print('access ("visible" view): ', visibleview.testcachedunfifoobar) print('access ("immutable" view):', immutableview.testcachedunfifoobar) print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("visible" view): ', vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'), ) print('') print('= even if we clear the unfiltered cache') del repo.__dict__['testcachedunfifoobar'] print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("visible" view): ', vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'), ) print('unficalllog:', unficalllog) print('access ("visible" view): ', visibleview.testcachedunfifoobar) print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("visible" view): ', vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'), ) print('access ("immutable" view):', immutableview.testcachedunfifoobar) print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("visible" view): ', vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'), ) print('access (unfiltered): ', repo.testcachedunfifoobar) print('unficalllog:', unficalllog) print( 'cached value (unfiltered): ', vars(repo).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("visible" view): ', vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'), ) print( 'cached value ("immutable" view):', vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'), )