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Differential D12008

revlog: demonstrate a bug where transaction can be aborted partially
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Authored by aalekseyev on Jan 20 2022, 9:09 AM.

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Alphare
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rHGf38ae2d7390e: revlog: demonstrate a bug where transaction can be aborted partially

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rHG Mercurial
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stable
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aalekseyev created this revision.Jan 20 2022, 9:09 AM
aalekseyev added a comment.Jan 20 2022, 9:14 AM

This demonstrates a bug that results in a repo corruption any time a transaction is aborted that adds multiple revs of the same revlog while growing it beyond 128KiB.
I would have thought this affects most hg users, since none of the pre-conditions for this bug is very unique.
Probably this went unnoticed for such a long time simply because transactions are rarely aborted.

Alphare accepted this revision.Jan 20 2022, 9:18 AM
This revision is now accepted and ready to land.Jan 20 2022, 9:18 AM

Revision Contents
Changeset List

Diff 31706

tests/test-transaction-rollback-on-revlog-split.t

> def close(orig, *args, **kwargs): > def close(orig, *args, **kwargs):
> path = util.normpath(args[0]._atomictempfile__name) > path = util.normpath(args[0]._atomictempfile__name)
> if path.endswith(b'/.hg/store/data/file.i'): > if path.endswith(b'/.hg/store/data/file.i'):
> os._exit(80) > os._exit(80)
> return orig(*args, **kwargs) > return orig(*args, **kwargs)
> extensions.wrapfunction(util.atomictempfile, 'close', close) > extensions.wrapfunction(util.atomictempfile, 'close', close)
> EOF > EOF
Test offset computation to correctly factor in the index entries themselve. Test offset computation to correctly factor in the index entries themselves.
Also test that the new data size has the correct size if the transaction is aborted Also test that the new data size has the correct size if the transaction is aborted
after the index has been replaced. after the index has been replaced.
Test repo has one small, one moderate and one big change. The clone has Test repo has commits a, b, c, D, where D is large (grows the revlog enough that it
the small and moderate change and will transition to non-inline storage when transitions to non-inline storage). The clone initially has changes a, b
adding the big change. and will transition to non-inline storage when adding c, D.
If the transaction adding c, D is rolled back, then we don't undo the revlog split,
but truncate the index and the data to remove both c and D.
$ hg init troffset-computation --config format.revlog-compression=none $ hg init troffset-computation --config format.revlog-compression=none
$ cd troffset-computation $ cd troffset-computation
$ printf '%20d' '1' > file $ printf '%20d' '1' > file
$ hg commit -Aqm_ $ hg commit -Aqma
$ printf '%1024d' '1' > file $ printf '%1024d' '1' > file
$ hg commit -Aqm_ $ hg commit -Aqmb
$ printf '%20d' '1' > file
$ hg commit -Aqmc
$ dd if=/dev/zero of=file bs=1k count=128 > /dev/null 2>&1 $ dd if=/dev/zero of=file bs=1k count=128 > /dev/null 2>&1
$ hg commit -Aqm_ $ hg commit -AqmD
$ cd .. $ cd ..
$ hg clone -r 1 troffset-computation troffset-computation-copy --config format.revlog-compression=none -q $ hg clone -r 1 troffset-computation troffset-computation-copy --config format.revlog-compression=none -q
$ cd troffset-computation-copy $ cd troffset-computation-copy
Reference size: Reference size:
$ f -s .hg/store/data/file* $ f -s .hg/store/data/file*
.hg/store/data/file.i: size=1174 .hg/store/data/file.i: size=1174
$ cat > .hg/hgrc <<EOF $ cat > .hg/hgrc <<EOF
> [hooks] > [hooks]
> pretxnchangegroup = python:$TESTDIR/helper-killhook.py:killme > pretxnchangegroup = python:$TESTDIR/helper-killhook.py:killme
> EOF > EOF
#if chg #if chg
$ hg pull ../troffset-computation $ hg pull ../troffset-computation
pulling from ../troffset-computation pulling from ../troffset-computation
[255] [255]
#else #else
$ hg pull ../troffset-computation $ hg pull ../troffset-computation
pulling from ../troffset-computation pulling from ../troffset-computation
[80] [80]
#endif #endif
$ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file | tail -1 $ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file | tail -1
data/file.i 128 data/file.i 192
The first file.i entry should match the size above. The first file.i entry should match the "Reference size" above.
The first file.d entry is the temporary record during the split, The first file.d entry is the temporary record during the split,
the second entry after the split happened. The sum of the second file.d the second entry after the split happened. The sum of the second file.d
and the second file.i entry should match the first file.i entry. and the second file.i entry should match the first file.i entry.
$ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file $ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file
data/file.i 1174 data/file.i 1174
data/file.d 0 data/file.d 0
data/file.d 1046 data/file.d 1067
data/file.i 128 data/file.i 192
$ hg recover $ hg recover
rolling back interrupted transaction rolling back interrupted transaction
(verify step skipped, run `hg verify` to check your repository content) (verify step skipped, run `hg verify` to check your repository content)
$ f -s .hg/store/data/file* $ f -s .hg/store/data/file*
.hg/store/data/file.d: size=1046 .hg/store/data/file.d: size=1067
.hg/store/data/file.i: size=128 .hg/store/data/file.i: size=192
$ hg tip $ hg tip
changeset: 1:3ce491143aec changeset: 1:cfa8d6e60429
tag: tip tag: tip
user: test user: test
date: Thu Jan 01 00:00:00 1970 +0000 date: Thu Jan 01 00:00:00 1970 +0000
summary: _ summary: b
$ hg verify -q $ hg verify -q
warning: revlog 'data/file.d' not in fncache! warning: revlog 'data/file.d' not in fncache!
1 warnings encountered! file@?: rev 2 points to nonexistent changeset 2
(expected )
file@?: fa1120531cc1 not in manifests
2 warnings encountered!
hint: run "hg debugrebuildfncache" to recover from corrupt fncache hint: run "hg debugrebuildfncache" to recover from corrupt fncache
2 integrity errors encountered!
[1]
$ hg debugrebuildfncache --only-data $ hg debugrebuildfncache --only-data
adding data/file.d adding data/file.d
1 items added, 0 removed from fncache 1 items added, 0 removed from fncache
$ hg verify -q $ hg verify -q
file@?: rev 2 points to nonexistent changeset 2
(expected )
file@?: fa1120531cc1 not in manifests
1 warnings encountered!
2 integrity errors encountered!
[1]
$ cd .. $ cd ..
Now retry the procedure but intercept the rename of the index and check that Now retry the procedure but intercept the rename of the index and check that
the journal does not contain the new index size. This demonstrates the edge case the journal does not contain the new index size. This demonstrates the edge case
where the data file is left as garbage. where the data file is left as garbage.
$ hg clone -r 1 troffset-computation troffset-computation-copy2 --config format.revlog-compression=none -q $ hg clone -r 1 troffset-computation troffset-computation-copy2 --config format.revlog-compression=none -q
#else #else
$ hg pull ../troffset-computation $ hg pull ../troffset-computation
pulling from ../troffset-computation pulling from ../troffset-computation
[80] [80]
#endif #endif
$ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file $ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file
data/file.i 1174 data/file.i 1174
data/file.d 0 data/file.d 0
data/file.d 1046 data/file.d 1067
$ hg recover $ hg recover
rolling back interrupted transaction rolling back interrupted transaction
(verify step skipped, run `hg verify` to check your repository content) (verify step skipped, run `hg verify` to check your repository content)
$ f -s .hg/store/data/file* $ f -s .hg/store/data/file*
.hg/store/data/file.d: size=1046 .hg/store/data/file.d: size=1067
.hg/store/data/file.i: size=1174 .hg/store/data/file.i: size=1174
$ hg tip $ hg tip
changeset: 1:3ce491143aec changeset: 1:cfa8d6e60429
tag: tip tag: tip
user: test user: test
date: Thu Jan 01 00:00:00 1970 +0000 date: Thu Jan 01 00:00:00 1970 +0000
summary: _ summary: b
$ hg verify -q $ hg verify -q
$ cd .. $ cd ..
Repeat the original test but let hg rollback the transaction. Repeat the original test but let hg rollback the transaction.
$ hg clone -r 1 troffset-computation troffset-computation-copy-rb --config format.revlog-compression=none -q $ hg clone -r 1 troffset-computation troffset-computation-copy-rb --config format.revlog-compression=none -q
$ cd troffset-computation-copy-rb $ cd troffset-computation-copy-rb
$ cat > .hg/hgrc <<EOF $ cat > .hg/hgrc <<EOF
> [hooks] > [hooks]
> pretxnchangegroup = false > pretxnchangegroup = false
> EOF > EOF
$ hg pull ../troffset-computation $ hg pull ../troffset-computation
pulling from ../troffset-computation pulling from ../troffset-computation
searching for changes searching for changes
adding changesets adding changesets
adding manifests adding manifests
adding file changes adding file changes
transaction abort! transaction abort!
rollback completed rollback completed
abort: pretxnchangegroup hook exited with status 1 abort: pretxnchangegroup hook exited with status 1
[40] [40]
$ f -s .hg/store/data/file* $ f -s .hg/store/data/file*
.hg/store/data/file.d: size=1046 .hg/store/data/file.d: size=1067
.hg/store/data/file.i: size=128 .hg/store/data/file.i: size=192
$ hg tip $ hg tip
changeset: 1:3ce491143aec changeset: 1:cfa8d6e60429
tag: tip tag: tip
user: test user: test
date: Thu Jan 01 00:00:00 1970 +0000 date: Thu Jan 01 00:00:00 1970 +0000
summary: _ summary: b
$ hg verify -q $ hg verify -q
warning: revlog 'data/file.d' not in fncache! warning: revlog 'data/file.d' not in fncache!
1 warnings encountered! file@?: rev 2 points to nonexistent changeset 2
(expected )
file@?: fa1120531cc1 not in manifests
2 warnings encountered!
hint: run "hg debugrebuildfncache" to recover from corrupt fncache hint: run "hg debugrebuildfncache" to recover from corrupt fncache
2 integrity errors encountered!
[1]
$ cd .. $ cd ..