Mercurial > hg
view tests/test-bisect3.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 | 7c324f65e4ef |
children | f51ff655d338 |
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# Here we create a simple DAG which has just enough of the required # topology to test all the bisection status labels: # # 13--14 # / # 0--1--2--3---------9--10--11--12 # \ / # 4--5--6--7--8 $ hg init $ echo '0' >a $ hg add a $ hg ci -u test -d '0 0' -m '0' $ echo '1' >a $ hg ci -u test -d '1 0' -m '1' branch 2-3 $ echo '2' >b $ hg add b $ hg ci -u test -d '2 0' -m '2' $ echo '3' >b $ hg ci -u test -d '3 0' -m '3' branch 4-8 $ hg up -r 1 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo '4' >c $ hg add c $ hg ci -u test -d '4 0' -m '4' created new head $ echo '5' >c $ hg ci -u test -d '5 0' -m '5' $ echo '6' >c $ hg ci -u test -d '6 0' -m '6' $ echo '7' >c $ hg ci -u test -d '7 0' -m '7' $ echo '8' >c $ hg ci -u test -d '8 0' -m '8' merge $ hg merge -r 3 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -u test -d '9 0' -m '9=8+3' $ echo '10' >a $ hg ci -u test -d '10 0' -m '10' $ echo '11' >a $ hg ci -u test -d '11 0' -m '11' $ echo '12' >a $ hg ci -u test -d '12 0' -m '12' unrelated branch $ hg up -r 3 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo '13' >d $ hg add d $ hg ci -u test -d '13 0' -m '13' created new head $ echo '14' >d $ hg ci -u test -d '14 0' -m '14' mark changesets $ hg bisect --reset $ hg bisect --good 4 $ hg bisect --good 6 $ hg bisect --bad 12 Testing changeset 9:2197c557e14c (6 changesets remaining, ~2 tests) 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg bisect --bad 10 Testing changeset 8:e74a86251f58 (4 changesets remaining, ~2 tests) 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg bisect --skip 7 Testing changeset 8:e74a86251f58 (4 changesets remaining, ~2 tests) 0 files updated, 0 files merged, 0 files removed, 0 files unresolved test template $ hg log --template '{rev}:{node|short} {bisect}\n' 14:cbf2f3105bbf 13:e07efca37c43 12:98c6b56349c0 bad 11:03f491376e63 bad (implicit) 10:c012b15e2409 bad 9:2197c557e14c untested 8:e74a86251f58 untested 7:a5f87041c899 skipped 6:7d997bedcd8d good 5:2dd1875f1028 good (implicit) 4:2a1daef14cd4 good 3:8417d459b90c ignored 2:e1355ee1f23e ignored 1:ce7c85e06a9f good (implicit) 0:b4e73ffab476 good (implicit) $ hg log --template '{bisect|shortbisect} {rev}:{node|short}\n' 14:cbf2f3105bbf 13:e07efca37c43 B 12:98c6b56349c0 B 11:03f491376e63 B 10:c012b15e2409 U 9:2197c557e14c U 8:e74a86251f58 S 7:a5f87041c899 G 6:7d997bedcd8d G 5:2dd1875f1028 G 4:2a1daef14cd4 I 3:8417d459b90c I 2:e1355ee1f23e G 1:ce7c85e06a9f G 0:b4e73ffab476 test style $ hg log --style bisect changeset: 14:cbf2f3105bbf bisect: tag: tip user: test date: Thu Jan 01 00:00:14 1970 +0000 summary: 14 changeset: 13:e07efca37c43 bisect: parent: 3:8417d459b90c user: test date: Thu Jan 01 00:00:13 1970 +0000 summary: 13 changeset: 12:98c6b56349c0 bisect: bad user: test date: Thu Jan 01 00:00:12 1970 +0000 summary: 12 changeset: 11:03f491376e63 bisect: bad (implicit) user: test date: Thu Jan 01 00:00:11 1970 +0000 summary: 11 changeset: 10:c012b15e2409 bisect: bad user: test date: Thu Jan 01 00:00:10 1970 +0000 summary: 10 changeset: 9:2197c557e14c bisect: untested parent: 8:e74a86251f58 parent: 3:8417d459b90c user: test date: Thu Jan 01 00:00:09 1970 +0000 summary: 9=8+3 changeset: 8:e74a86251f58 bisect: untested user: test date: Thu Jan 01 00:00:08 1970 +0000 summary: 8 changeset: 7:a5f87041c899 bisect: skipped user: test date: Thu Jan 01 00:00:07 1970 +0000 summary: 7 changeset: 6:7d997bedcd8d bisect: good user: test date: Thu Jan 01 00:00:06 1970 +0000 summary: 6 changeset: 5:2dd1875f1028 bisect: good (implicit) user: test date: Thu Jan 01 00:00:05 1970 +0000 summary: 5 changeset: 4:2a1daef14cd4 bisect: good parent: 1:ce7c85e06a9f user: test date: Thu Jan 01 00:00:04 1970 +0000 summary: 4 changeset: 3:8417d459b90c bisect: ignored user: test date: Thu Jan 01 00:00:03 1970 +0000 summary: 3 changeset: 2:e1355ee1f23e bisect: ignored user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 changeset: 1:ce7c85e06a9f bisect: good (implicit) user: test date: Thu Jan 01 00:00:01 1970 +0000 summary: 1 changeset: 0:b4e73ffab476 bisect: good (implicit) user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: 0 $ hg log --quiet --style bisect 14:cbf2f3105bbf 13:e07efca37c43 B 12:98c6b56349c0 B 11:03f491376e63 B 10:c012b15e2409 U 9:2197c557e14c U 8:e74a86251f58 S 7:a5f87041c899 G 6:7d997bedcd8d G 5:2dd1875f1028 G 4:2a1daef14cd4 I 3:8417d459b90c I 2:e1355ee1f23e G 1:ce7c85e06a9f G 0:b4e73ffab476 $ hg --config extensions.color= --color=debug log --quiet --style bisect [log.bisect| ] 14:cbf2f3105bbf [log.bisect| ] 13:e07efca37c43 [log.bisect bisect.bad|B] 12:98c6b56349c0 [log.bisect bisect.bad|B] 11:03f491376e63 [log.bisect bisect.bad|B] 10:c012b15e2409 [log.bisect bisect.untested|U] 9:2197c557e14c [log.bisect bisect.untested|U] 8:e74a86251f58 [log.bisect bisect.skipped|S] 7:a5f87041c899 [log.bisect bisect.good|G] 6:7d997bedcd8d [log.bisect bisect.good|G] 5:2dd1875f1028 [log.bisect bisect.good|G] 4:2a1daef14cd4 [log.bisect bisect.ignored|I] 3:8417d459b90c [log.bisect bisect.ignored|I] 2:e1355ee1f23e [log.bisect bisect.good|G] 1:ce7c85e06a9f [log.bisect bisect.good|G] 0:b4e73ffab476