Mercurial > hg
view tests/test-bookmarks-strip.t @ 23702:c48924787eaa
filectx.parents: enforce changeid of parent to be in own changectx ancestors
Because of the way filenodes are computed, you can have multiple changesets
"introducing" the same file revision. For example, in the changeset graph
below, changeset 2 and 3 both change a file -to- and -from- the same content.
o 3: content = new
|
| o 2: content = new
|/
o 1: content = old
In such cases, the file revision is create once, when 2 is added, and just reused
for 3. So the file change in '3' (from "old" to "new)" has no linkrev pointing
to it). We'll call this situation "linkrev-shadowing". As the linkrev is used for
optimization purposes when walking a file history, the linkrev-shadowing
results in an unexpected jump to another branch during such a walk.. This leads to
multiple bugs with log, annotate and rename detection.
One element to fix such bugs is to ensure that walking the file history sticks on
the same topology as the changeset's history. For this purpose, we extend the
logic in 'basefilectx.parents' so that it always defines the proper changeset
to associate the parent file revision with. This "proper" changeset has to be an
ancestor of the changeset associated with the child file revision.
This logic is performed in the '_adjustlinkrev' function. This function is
given the starting changeset and all the information regarding the parent file
revision. If the linkrev for the file revision is an ancestor of the starting
changeset, the linkrev is valid and will be used. If it is not, we detected a
topological jump caused by linkrev shadowing, we are going to walk the
ancestors of the starting changeset until we find one setting the file to the
revision we are trying to create.
The performance impact appears acceptable:
- We are walking the changelog once for each filelog traversal (as there should
be no overlap between searches),
- changelog traversal itself is fairly cheap, compared to what is likely going
to be perform on the result on the filelog traversal,
- We only touch the manifest for ancestors touching the file, And such
changesets are likely to be the one introducing the file. (except in
pathological cases involving merge),
- We use manifest diff instead of full manifest unpacking to check manifest
content, so it does not involve applying multiple diffs in most case.
- linkrev shadowing is not the common case.
Tests for fixed issues in log, annotate and rename detection have been
added.
But this changeset does not solve all problems. It fixes -ancestry-
computation, but if the linkrev-shadowed changesets is the starting one, we'll
still get things wrong. We'll have to fix the bootstrapping of such operations
in a later changeset. Also, the usage of `hg log FILE` without --follow still
has issues with linkrev pointing to hidden changesets, because it relies on the
`filelog` revset which implement its own traversal logic that is still to be
fixed.
Thanks goes to:
- Matt Mackall: for nudging me in the right direction
- Julien Cristau and RĂ©mi Cardona: for keep telling me linkrev bug were an
evolution show stopper for 3 years.
- Durham Goode: for finding a new linkrev issue every few weeks
- Mads Kiilerich: for that last rename bug who raise this topic over my
anoyance limit.
author | Pierre-Yves David <pierre-yves.david@fb.com> |
---|---|
date | Tue, 23 Dec 2014 15:30:38 -0800 |
parents | ca275f7ec576 |
children | e78a80f8f51e |
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$ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH $ hg init $ echo qqq>qqq.txt rollback dry run without rollback information $ hg rollback no rollback information available [1] add file $ hg add adding qqq.txt commit first revision $ hg ci -m 1 set bookmark $ hg book test $ echo www>>qqq.txt commit second revision $ hg ci -m 2 set bookmark $ hg book test2 update to -2 (deactivates the active bookmark) $ hg update -r -2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (leaving bookmark test2) $ echo eee>>qqq.txt commit new head $ hg ci -m 3 created new head bookmarks updated? $ hg book test 1:25e1ee7a0081 test2 1:25e1ee7a0081 strip to revision 1 $ hg strip 1 saved backup bundle to $TESTTMP/.hg/strip-backup/*-backup.hg (glob) list bookmarks $ hg book test 0:5c9ad3787638 test2 0:5c9ad3787638 immediate rollback and reentrancy issue $ echo "mq=!" >> $HGRCPATH $ hg init repo $ cd repo $ echo a > a $ hg ci -Am adda adding a $ echo b > b $ hg ci -Am addb adding b $ hg bookmarks markb $ hg rollback repository tip rolled back to revision 0 (undo commit) working directory now based on revision 0 are you there? $ hg bookmarks no bookmarks set can we commit? (issue2692) $ echo c > c $ hg ci -Am rockon adding c can you be added again? $ hg bookmarks markb $ hg bookmarks * markb 1:fdb34407462c rollback dry run with rollback information $ hg rollback -n repository tip rolled back to revision 0 (undo commit) $ hg bookmarks * markb 1:fdb34407462c rollback dry run with rollback information and no commit undo $ rm .hg/store/undo $ hg rollback -n no rollback information available [1] $ hg bookmarks * markb 1:fdb34407462c $ cd ..