Mercurial > hg
view tests/test-narrow-exchange-merges.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 | a2a6e724d61a |
children | 7e5be4a7cda7 |
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$ . "$TESTDIR/narrow-library.sh" create full repo $ hg init master $ cd master $ cat >> .hg/hgrc <<EOF > [narrow] > serveellipses=True > EOF $ mkdir inside $ echo 1 > inside/f $ hg commit -Aqm 'initial inside' $ mkdir outside $ echo 1 > outside/f $ hg commit -Aqm 'initial outside' $ echo 2a > outside/f $ hg commit -Aqm 'outside 2a' $ echo 3 > inside/f $ hg commit -Aqm 'inside 3' $ echo 4a > outside/f $ hg commit -Aqm 'outside 4a' $ hg update '.~3' 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo 2b > outside/f $ hg commit -Aqm 'outside 2b' $ echo 3 > inside/f $ hg commit -Aqm 'inside 3' $ echo 4b > outside/f $ hg commit -Aqm 'outside 4b' $ hg update '.~3' 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo 2c > outside/f $ hg commit -Aqm 'outside 2c' $ echo 3 > inside/f $ hg commit -Aqm 'inside 3' $ echo 4c > outside/f $ hg commit -Aqm 'outside 4c' $ hg update '.~3' 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo 2d > outside/f $ hg commit -Aqm 'outside 2d' $ echo 3 > inside/f $ hg commit -Aqm 'inside 3' $ echo 4d > outside/f $ hg commit -Aqm 'outside 4d' $ hg update -r 'desc("outside 4a")' 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg merge -r 'desc("outside 4b")' 2>&1 | egrep -v '(warning:|incomplete!)' merging outside/f 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon $ echo 5 > outside/f $ rm outside/f.orig $ hg resolve --mark outside/f (no more unresolved files) $ hg commit -m 'merge a/b 5' $ echo 6 > outside/f $ hg commit -Aqm 'outside 6' $ hg merge -r 'desc("outside 4c")' 2>&1 | egrep -v '(warning:|incomplete!)' merging outside/f 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon $ echo 7 > outside/f $ rm outside/f.orig $ hg resolve --mark outside/f (no more unresolved files) $ hg commit -Aqm 'merge a/b/c 7' $ echo 8 > outside/f $ hg commit -Aqm 'outside 8' $ hg merge -r 'desc("outside 4d")' 2>&1 | egrep -v '(warning:|incomplete!)' merging outside/f 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon $ echo 9 > outside/f $ rm outside/f.orig $ hg resolve --mark outside/f (no more unresolved files) $ hg commit -Aqm 'merge a/b/c/d 9' $ echo 10 > outside/f $ hg commit -Aqm 'outside 10' $ echo 11 > inside/f $ hg commit -Aqm 'inside 11' $ echo 12 > outside/f $ hg commit -Aqm 'outside 12' $ hg log -G -T '{rev} {node|short} {desc}\n' @ 21 8d874d57adea outside 12 | o 20 7ef88b4dd4fa inside 11 | o 19 2a20009de83e outside 10 | o 18 3ac1f5779de3 merge a/b/c/d 9 |\ | o 17 38a9c2f7e546 outside 8 | | | o 16 094aa62fc898 merge a/b/c 7 | |\ | | o 15 f29d083d32e4 outside 6 | | | | | o 14 2dc11382541d merge a/b 5 | | |\ o | | | 13 27d07ef97221 outside 4d | | | | o | | | 12 465567bdfb2d inside 3 | | | | o | | | 11 d1c61993ec83 outside 2d | | | | | o | | 10 56859a8e33b9 outside 4c | | | | | o | | 9 bb96a08b062a inside 3 | | | | | o | | 8 b844052e7b3b outside 2c |/ / / | | o 7 9db2d8fcc2a6 outside 4b | | | | | o 6 6418167787a6 inside 3 | | | +---o 5 77344f344d83 outside 2b | | | o 4 9cadde08dc9f outside 4a | | | o 3 019ef06f125b inside 3 | | | o 2 75e40c075a19 outside 2a |/ o 1 906d6c682641 initial outside | o 0 9f8e82b51004 initial inside Now narrow clone this and get a hopefully correct graph $ cd .. $ hg clone --narrow ssh://user@dummy/master narrow --include inside requesting all changes adding changesets adding manifests adding file changes added 14 changesets with 3 changes to 1 files new changesets *:* (glob) updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd narrow To make updating the tests easier, we print the emitted nodes sorted. This makes it easier to identify when the same node structure has been emitted, just in a different order. $ hg log -T '{if(ellipsis,"...")}{node|short} {p1node|short} {p2node|short} {desc}\n' | sort ...094aa62fc898 6418167787a6 bb96a08b062a merge a/b/c 7 ...2a20009de83e 019ef06f125b 3ac1f5779de3 outside 10 ...3ac1f5779de3 465567bdfb2d 094aa62fc898 merge a/b/c/d 9 ...75e40c075a19 9f8e82b51004 000000000000 outside 2a ...77344f344d83 9f8e82b51004 000000000000 outside 2b ...8d874d57adea 7ef88b4dd4fa 000000000000 outside 12 ...b844052e7b3b 9f8e82b51004 000000000000 outside 2c ...d1c61993ec83 9f8e82b51004 000000000000 outside 2d 019ef06f125b 75e40c075a19 000000000000 inside 3 465567bdfb2d d1c61993ec83 000000000000 inside 3 6418167787a6 77344f344d83 000000000000 inside 3 7ef88b4dd4fa 2a20009de83e 000000000000 inside 11 9f8e82b51004 000000000000 000000000000 initial inside bb96a08b062a b844052e7b3b 000000000000 inside 3 But seeing the graph is also nice: $ hg log -G -T '{if(ellipsis,"...")}{node|short} {desc}\n' @ ...8d874d57adea outside 12 | o 7ef88b4dd4fa inside 11 | o ...2a20009de83e outside 10 |\ | o ...3ac1f5779de3 merge a/b/c/d 9 | |\ | | o ...094aa62fc898 merge a/b/c 7 | | |\ | o | | 465567bdfb2d inside 3 | | | | | o | | ...d1c61993ec83 outside 2d | | | | | | | o bb96a08b062a inside 3 | | | | | +---o ...b844052e7b3b outside 2c | | | | | o 6418167787a6 inside 3 | | | | | o ...77344f344d83 outside 2b | |/ o | 019ef06f125b inside 3 | | o | ...75e40c075a19 outside 2a |/ o 9f8e82b51004 initial inside