view tests/test-obsolete-checkheads.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

Check that obsolete properly strip heads
  $ cat >> $HGRCPATH << EOF
  > [phases]
  > # public changeset are not obsolete
  > publish=false
  > [command-templates]
  > log='{node|short} ({phase}) {desc|firstline}\n'
  > [experimental]
  > evolution.createmarkers=True
  > EOF
  $ mkcommit() {
  >    echo "$1" > "$1"
  >    hg add "$1"
  >    hg ci -m "add $1"
  > }
  $ getid() {
  >    hg id --debug -ir "desc('$1')"
  > }


  $ hg init remote
  $ cd remote
  $ mkcommit base
  $ hg phase --public .
  $ cd ..
  $ cp -R remote base
  $ hg clone remote local
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd local

New head replaces old head
==========================

setup
(we add the 1 flags to prevent bumped error during the test)

  $ mkcommit old
  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  $ hg up -q '.^'
  $ mkcommit new
  created new head
  $ hg debugobsolete --flags 1 `getid old` `getid new`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  71e3228bffe1 (draft) add new
  |
  | x  c70b08862e08 (draft) add old
  |/
  o  b4952fcf48cf (public) add base
  
  $ cp -R ../remote ../backup1

old exists remotely as draft. It is obsoleted by new that we now push.
Push should not warn about creating new head

  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)

old head is now public (public local version)
=============================================

setup

  $ rm -fr ../remote
  $ cp -R ../backup1 ../remote
  $ hg -R ../remote phase --public c70b08862e08
  $ hg pull -v
  pulling from $TESTTMP/remote
  searching for changes
  no changes found
  1 local changesets published
  $ hg log -G --hidden
  @  71e3228bffe1 (draft) add new
  |
  | o  c70b08862e08 (public) add old
  |/
  o  b4952fcf48cf (public) add base
  

Abort: old will still be an head because it's public.

  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  abort: push creates new remote head 71e3228bffe1
  (merge or see 'hg help push' for details about pushing new heads)
  [20]

old head is now public (public remote version)
==============================================

TODO: Not implemented yet.

# setup
#
#   $ rm -fr ../remote
#   $ cp -R ../backup1 ../remote
#   $ hg -R ../remote phase --public c70b08862e08
#   $ hg phase --draft --force c70b08862e08
#   $ hg log -G --hidden
#   @  71e3228bffe1 (draft) add new
#   |
#   | x  c70b08862e08 (draft) add old
#   |/
#   o  b4952fcf48cf (public) add base
#
#
#
# Abort: old will still be an head because it's public.
#
#   $ hg push
#   pushing to $TESTTMP/remote
#   searching for changes
#   abort: push creates new remote head 71e3228bffe1!
#   (merge or see 'hg help push' for details about pushing new heads)
#   [255]

old head is obsolete but replacement is not pushed
==================================================

setup

  $ rm -fr ../remote
  $ cp -R ../backup1 ../remote
  $ hg phase --draft --force '(0::) - 0'
  $ hg up -q '.^'
  $ mkcommit other
  created new head
  $ hg log -G --hidden
  @  d7d41ccbd4de (draft) add other
  |
  | o  71e3228bffe1 (draft) add new
  |/
  | x  c70b08862e08 (draft) add old
  |/
  o  b4952fcf48cf (public) add base
  

old exists remotely as draft. It is obsoleted by new but we don't push new.
Push should abort on new head

  $ hg push -r 'desc("other")'
  pushing to $TESTTMP/remote
  searching for changes
  abort: push creates new remote head d7d41ccbd4de
  (merge or see 'hg help push' for details about pushing new heads)
  [20]



Both precursors and successors are already know remotely. Descendant adds heads
===============================================================================

setup. (The obsolete marker is known locally only

  $ cd ..
  $ rm -rf local
  $ hg clone remote local
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd local
  $ mkcommit old
  old already tracked!
  nothing changed
  [1]
  $ hg up -q '.^'
  $ mkcommit new
  created new head
  $ hg push -f
  pushing to $TESTTMP/remote
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  $ mkcommit desc1
  $ hg up -q '.^'
  $ mkcommit desc2
  created new head
  $ hg debugobsolete `getid old` `getid new`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  5fe37041cc2b (draft) add desc2
  |
  | o  a3ef1d111c5f (draft) add desc1
  |/
  o  71e3228bffe1 (draft) add new
  |
  | x  c70b08862e08 (draft) add old
  |/
  o  b4952fcf48cf (public) add base
  
  $ hg log -G --hidden -R ../remote
  o  71e3228bffe1 (draft) add new
  |
  | o  c70b08862e08 (draft) add old
  |/
  @  b4952fcf48cf (public) add base
  
  $ cp -R ../remote ../backup2

Push should not warn about adding new heads. We create one, but we'll delete
one anyway.

  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)


Remote head is unknown but obsoleted by a local changeset
=========================================================

setup

  $ rm -fr ../remote
  $ cp -R ../backup1 ../remote
  $ cd ..
  $ rm -rf local
  $ hg clone remote local -r 0
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets b4952fcf48cf
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd local
  $ mkcommit new
  $ hg -R ../remote id --debug -r tip
  c70b08862e0838ea6d7c59c85da2f1ed6c8d67da tip
  $ hg  id --debug -r tip
  71e3228bffe1886550777233d6c97bb5a6b2a650 tip
  $ hg debugobsolete c70b08862e0838ea6d7c59c85da2f1ed6c8d67da 71e3228bffe1886550777233d6c97bb5a6b2a650
  1 new obsolescence markers
  $ hg log -G --hidden
  @  71e3228bffe1 (draft) add new
  |
  o  b4952fcf48cf (public) add base
  
  $ hg log -G --hidden -R ../remote
  o  c70b08862e08 (draft) add old
  |
  @  b4952fcf48cf (public) add base
  

We do not have enought data to take the right decision, we should fail

  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  remote has heads on branch 'default' that are not known locally: c70b08862e08
  abort: push creates new remote head 71e3228bffe1
  (pull and merge or see 'hg help push' for details about pushing new heads)
  [20]

Pulling the missing data makes it work

  $ hg pull
  pulling from $TESTTMP/remote
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (1 other changesets obsolete on arrival)
  (run 'hg heads' to see heads)
  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)

Old head is pruned without parent data and new unrelated head added
===================================================================

setup

  $ cd ..
  $ rm -R remote local
  $ cp -R backup1 remote
  $ hg clone remote local -qr c70b08862e08
  $ cd local
  $ hg up -q '.^'
  $ mkcommit new-unrelated
  created new head
  $ hg debugobsolete `getid old`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  350a93b716be (draft) add new-unrelated
  |
  | x  c70b08862e08 (draft) add old
  |/
  o  b4952fcf48cf (public) add base
  

  $ hg push
  pushing to $TESTTMP/remote
  searching for changes
  abort: push creates new remote head 350a93b716be
  (merge or see 'hg help push' for details about pushing new heads)
  [20]