Mercurial > hg
view tests/test-mq-qdelete.t @ 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 | 95c4cca641f6 |
children | 5ced12cfa41b |
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$ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH $ hg init a $ cd a $ echo 'base' > base $ hg ci -Ambase -d '1 0' adding base $ hg qnew -d '1 0' pa $ hg qnew -d '1 0' pb $ hg qnew -d '1 0' pc $ hg qdel abort: qdelete requires at least one revision or patch name [255] $ hg qdel pc abort: cannot delete applied patch pc [255] $ hg qpop popping pc now at: pb Delete the same patch twice in one command (issue2427) $ hg qdel pc pc $ hg qseries pa pb $ ls .hg/patches pa pb series status $ hg qpop popping pb now at: pa $ hg qdel -k 1 $ ls .hg/patches pa pb series status $ hg qdel -r pa patch pa finalized without changeset message $ hg qapplied $ hg log --template '{rev} {desc}\n' 1 [mq]: pa 0 base $ hg qnew pd $ hg qnew pe $ hg qnew pf $ hg qdel -r pe abort: cannot delete revision 3 above applied patches [255] $ hg qdel -r qbase:pe patch pd finalized without changeset message patch pe finalized without changeset message $ hg qapplied pf $ hg log --template '{rev} {desc}\n' 4 [mq]: pf 3 [mq]: pe 2 [mq]: pd 1 [mq]: pa 0 base $ cd .. $ hg init b $ cd b $ echo 'base' > base $ hg ci -Ambase -d '1 0' adding base $ hg qfinish abort: no revisions specified [255] $ hg qfinish -a no patches applied $ hg qnew -d '1 0' pa $ hg qnew -d '1 0' pb $ hg qnew pc # XXX fails to apply by /usr/bin/patch if we put a date $ hg qfinish 0 abort: revision 0 is not managed [255] $ hg qfinish pb abort: cannot delete revision 2 above applied patches [255] $ hg qpop popping pc now at: pb $ hg qfinish -a pc abort: unknown revision 'pc' [255] $ hg qpush applying pc patch pc is empty now at: pc $ hg qfinish qbase:pb patch pa finalized without changeset message patch pb finalized without changeset message $ hg qapplied pc $ hg log --template '{rev} {desc}\n' 3 imported patch pc 2 [mq]: pb 1 [mq]: pa 0 base $ hg qfinish -a pc patch pc finalized without changeset message $ hg qapplied $ hg log --template '{rev} {desc}\n' 3 imported patch pc 2 [mq]: pb 1 [mq]: pa 0 base $ ls .hg/patches series status qdel -k X && hg qimp -e X used to trigger spurious output with versioned queues $ hg init --mq $ hg qimport -r 3 $ hg qpop popping imported_patch_pc patch queue now empty $ hg qdel -k imported_patch_pc $ hg qimp -e imported_patch_pc adding imported_patch_pc to series file $ hg qfinish -a no patches applied resilience to inconsistency: qfinish -a with applied patches not in series $ hg qser imported_patch_pc $ hg qapplied $ hg qpush applying imported_patch_pc patch imported_patch_pc is empty now at: imported_patch_pc $ echo next >> base $ hg qrefresh -d '1 0' $ echo > .hg/patches/series # remove 3.diff from series to confuse mq $ hg qfinish -a revision 47dfa8501675 refers to unknown patches: imported_patch_pc more complex state 'both known and unknown patches $ echo hip >> base $ hg qnew -f -d '1 0' -m 4 4.diff $ echo hop >> base $ hg qnew -f -d '1 0' -m 5 5.diff $ echo > .hg/patches/series # remove 4.diff and 5.diff from series to confuse mq $ echo hup >> base $ hg qnew -f -d '1 0' -m 6 6.diff $ echo pup > base $ hg qfinish -a warning: uncommitted changes in the working directory revision 2b1c98802260 refers to unknown patches: 5.diff revision 33a6861311c0 refers to unknown patches: 4.diff $ cd ..