view tests/test-obsmarkers-effectflag.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

Test the 'effect-flags' feature

Global setup
============

  $ . $TESTDIR/testlib/obsmarker-common.sh
  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > interactive = true
  > [phases]
  > publish=False
  > [extensions]
  > rebase =
  > [experimental]
  > evolution = all
  > evolution.effect-flags = 1
  > EOF

  $ hg init $TESTTMP/effect-flags
  $ cd $TESTTMP/effect-flags
  $ mkcommit ROOT

amend touching the description only
-----------------------------------

  $ mkcommit A0
  $ hg commit --amend -m "A1"

check result

  $ hg debugobsolete --rev .
  471f378eab4c5e25f6c77f785b27c936efb22874 fdf9bde5129a28d4548fadd3f62b265cdd3b7a2e 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '1', 'operation': 'amend', 'user': 'test'}

amend touching the user only
----------------------------

  $ mkcommit B0
  $ hg commit --amend -u "bob <[e-mail]>"

check result

  $ hg debugobsolete --rev .
  ef4a313b1e0ade55718395d80e6b88c5ccd875eb 5485c92d34330dac9d7a63dc07e1e3373835b964 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '16', 'operation': 'amend', 'user': 'test'}

amend touching the date only
----------------------------

  $ mkcommit B1
  $ hg commit --amend -d "42 0"

check result

  $ hg debugobsolete --rev .
  2ef0680ff45038ac28c9f1ff3644341f54487280 4dd84345082e9e5291c2e6b3f335bbf8bf389378 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '32', 'operation': 'amend', 'user': 'test'}

amend touching the branch only
----------------------------

  $ mkcommit B2
  $ hg branch my-branch
  marked working directory as branch my-branch
  (branches are permanent and global, did you want a bookmark?)
  $ hg commit --amend

check result

  $ hg debugobsolete --rev .
  bd3db8264ceebf1966319f5df3be7aac6acd1a8e 14a01456e0574f0e0a0b15b2345486a6364a8d79 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '64', 'operation': 'amend', 'user': 'test'}

  $ hg up default
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

rebase (parents change)
-----------------------

  $ mkcommit C0
  $ mkcommit D0
  $ hg rebase -r . -d 'desc(B0)'
  rebasing 10:c85eff83a034 tip "D0"

check result

  $ hg debugobsolete --rev .
  c85eff83a0340efd9da52b806a94c350222f3371 da86aa2f19a30d6686b15cae15c7b6c908ec9699 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '4', 'operation': 'rebase', 'user': 'test'}

amend touching the diff
-----------------------

  $ mkcommit E0
  $ echo 42 >> E0
  $ hg commit --amend

check result

  $ hg debugobsolete --rev .
  ebfe0333e0d96f68a917afd97c0a0af87f1c3b5f 75781fdbdbf58a987516b00c980bccda1e9ae588 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '8', 'operation': 'amend', 'user': 'test'}

amend with multiple effect (desc and meta)
-------------------------------------------

  $ mkcommit F0
  $ hg branch my-other-branch
  marked working directory as branch my-other-branch
  $ hg commit --amend -m F1 -u "bob <[e-mail]>" -d "42 0"

check result

  $ hg debugobsolete --rev .
  fad47e5bd78e6aa4db1b5a0a1751bc12563655ff a94e0fd5f1c81d969381a76eb0d37ce499a44fae 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '113', 'operation': 'amend', 'user': 'test'}

rebase not touching the diff
----------------------------

  $ cat << EOF > H0
  > 0
  > 1
  > 2
  > 3
  > 4
  > 5
  > 6
  > 7
  > 8
  > 9
  > 10
  > EOF
  $ hg add H0
  $ hg commit -m 'H0'
  $ echo "H1" >> H0
  $ hg commit -m "H1"
  $ hg up -r "desc(H0)"
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat << EOF > H0
  > H2
  > 0
  > 1
  > 2
  > 3
  > 4
  > 5
  > 6
  > 7
  > 8
  > 9
  > 10
  > EOF
  $ hg commit -m "H2"
  created new head
  $ hg rebase -s "desc(H1)" -d "desc(H2)" -t :merge3
  rebasing 17:b57fed8d8322 "H1"
  merging H0
  $ hg debugobsolete -r tip
  b57fed8d83228a8ae3748d8c3760a77638dd4f8c e509e2eb3df5d131ff7c02350bf2a9edd0c09478 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '4', 'operation': 'rebase', 'user': 'test'}

amend closing the branch should be detected as meta change
----------------------------------------------------------

  $ hg branch closedbranch
  marked working directory as branch closedbranch
  $ mkcommit G0
  $ mkcommit I0
  $ hg commit --amend --close-branch

check result

  $ hg debugobsolete -r .
  2f599e54c1c6974299065cdf54e1ad640bfb7b5d 12c6238b5e371eea00fd2013b12edce3f070928b 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '2', 'operation': 'amend', 'user': 'test'}