Mercurial > hg
view tests/test-filebranch.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 | 7e9cbb9c6053 |
children | 2428e8ec0793 |
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This test makes sure that we don't mark a file as merged with its ancestor when we do a merge. $ cat <<EOF > merge > import sys, os > print "merging for", os.path.basename(sys.argv[1]) > EOF $ HGMERGE="python ../merge"; export HGMERGE Creating base: $ hg init a $ cd a $ echo 1 > foo $ echo 1 > bar $ echo 1 > baz $ echo 1 > quux $ hg add foo bar baz quux $ hg commit -m "base" $ cd .. $ hg clone a b updating to branch default 4 files updated, 0 files merged, 0 files removed, 0 files unresolved Creating branch a: $ cd a $ echo 2a > foo $ echo 2a > bar $ hg commit -m "branch a" Creating branch b: $ cd .. $ cd b $ echo 2b > foo $ echo 2b > baz $ hg commit -m "branch b" We shouldn't have anything but n state here: $ hg debugstate --nodates | grep -v "^n" [1] Merging: $ hg pull ../a pulling from ../a searching for changes adding changesets adding manifests adding file changes added 1 changesets with 2 changes to 2 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg merge -v resolving manifests getting bar merging foo merging for foo 1 files updated, 1 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ echo 2m > foo $ echo 2b > baz $ echo new > quux $ hg ci -m "merge" main: we should have a merge here: $ hg debugindex --changelog rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 73 ..... 0 cdca01651b96 000000000000 000000000000 (re) 1 73 68 ..... 1 f6718a9cb7f3 cdca01651b96 000000000000 (re) 2 141 68 ..... 2 bdd988058d16 cdca01651b96 000000000000 (re) 3 209 66 ..... 3 d8a521142a3c f6718a9cb7f3 bdd988058d16 (re) log should show foo and quux changed: $ hg log -v -r tip changeset: 3:d8a521142a3c tag: tip parent: 1:f6718a9cb7f3 parent: 2:bdd988058d16 user: test date: Thu Jan 01 00:00:00 1970 +0000 files: foo quux description: merge foo: we should have a merge here: $ hg debugindex foo rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 3 ..... 0 b8e02f643373 000000000000 000000000000 (re) 1 3 4 ..... 1 2ffeddde1b65 b8e02f643373 000000000000 (re) 2 7 4 ..... 2 33d1fb69067a b8e02f643373 000000000000 (re) 3 11 4 ..... 3 aa27919ee430 2ffeddde1b65 33d1fb69067a (re) bar: we should not have a merge here: $ hg debugindex bar rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 3 ..... 0 b8e02f643373 000000000000 000000000000 (re) 1 3 4 ..... 2 33d1fb69067a b8e02f643373 000000000000 (re) baz: we should not have a merge here: $ hg debugindex baz rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 3 ..... 0 b8e02f643373 000000000000 000000000000 (re) 1 3 4 ..... 1 2ffeddde1b65 b8e02f643373 000000000000 (re) quux: we should not have a merge here: $ hg debugindex quux rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 3 ..... 0 b8e02f643373 000000000000 000000000000 (re) 1 3 5 ..... 3 6128c0f33108 b8e02f643373 000000000000 (re) Manifest entries should match tips of all files: $ hg manifest --debug 33d1fb69067a0139622a3fa3b7ba1cdb1367972e 644 bar 2ffeddde1b65b4827f6746174a145474129fa2ce 644 baz aa27919ee4303cfd575e1fb932dd64d75aa08be4 644 foo 6128c0f33108e8cfbb4e0824d13ae48b466d7280 644 quux Everything should be clean now: $ hg status $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 4 files, 4 changesets, 10 total revisions $ cd ..