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 Rémi 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.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
>
> [alias]
> tlog = log --template "{rev}: '{desc}' {branches}\n"
> tglog = tlog --graph
> EOF
$ hg init a
$ cd a
$ mkdir d
$ echo a > a
$ hg ci -Am A
adding a
$ echo b > d/b
$ hg ci -Am B
adding d/b
$ hg mv d d-renamed
moving d/b to d-renamed/b (glob)
$ hg ci -m 'rename B'
$ hg up -q -C 1
$ hg mv a a-renamed
$ echo x > d/x
$ hg add d/x
$ hg ci -m 'rename A'
created new head
$ hg tglog
@ 3: 'rename A'
|
| o 2: 'rename B'
|/
o 1: 'B'
|
o 0: 'A'
Rename is tracked:
$ hg tlog -p --git -r tip
3: 'rename A'
diff --git a/a b/a-renamed
rename from a
rename to a-renamed
diff --git a/d/x b/d/x
new file mode 100644
--- /dev/null
+++ b/d/x
@@ -0,0 +1,1 @@
+x
Rebase the revision containing the rename:
$ hg rebase -s 3 -d 2
rebasing 3:73a3ee40125d "rename A" (tip)
saved backup bundle to $TESTTMP/a/.hg/strip-backup/73a3ee40125d-backup.hg (glob)
$ hg tglog
@ 3: 'rename A'
|
o 2: 'rename B'
|
o 1: 'B'
|
o 0: 'A'
Rename is not lost:
$ hg tlog -p --git -r tip
3: 'rename A'
diff --git a/a b/a-renamed
rename from a
rename to a-renamed
diff --git a/d-renamed/x b/d-renamed/x
new file mode 100644
--- /dev/null
+++ b/d-renamed/x
@@ -0,0 +1,1 @@
+x
Rebased revision does not contain information about b (issue3739)
$ hg log -r 3 --debug
changeset: 3:032a9b75e83bff1dcfb6cbfa4ef50a704bf1b569
tag: tip
phase: draft
parent: 2:220d0626d185f372d9d8f69d9c73b0811d7725f7
parent: -1:0000000000000000000000000000000000000000
manifest: 3:035d66b27a1b06b2d12b46d41a39adb7a200c370
user: test
date: Thu Jan 01 00:00:00 1970 +0000
files+: a-renamed d-renamed/x
files-: a
extra: branch=default
extra: rebase_source=73a3ee40125d6f0f347082e5831ceccb3f005f8a
description:
rename A
$ cd ..
$ hg init b
$ cd b
$ echo a > a
$ hg ci -Am A
adding a
$ echo b > b
$ hg ci -Am B
adding b
$ hg cp b b-copied
$ hg ci -Am 'copy B'
$ hg up -q -C 1
$ hg cp a a-copied
$ hg ci -m 'copy A'
created new head
$ hg tglog
@ 3: 'copy A'
|
| o 2: 'copy B'
|/
o 1: 'B'
|
o 0: 'A'
Copy is tracked:
$ hg tlog -p --git -r tip
3: 'copy A'
diff --git a/a b/a-copied
copy from a
copy to a-copied
Rebase the revision containing the copy:
$ hg rebase -s 3 -d 2
rebasing 3:0a8162ff18a8 "copy A" (tip)
saved backup bundle to $TESTTMP/b/.hg/strip-backup/0a8162ff18a8-backup.hg (glob)
$ hg tglog
@ 3: 'copy A'
|
o 2: 'copy B'
|
o 1: 'B'
|
o 0: 'A'
Copy is not lost:
$ hg tlog -p --git -r tip
3: 'copy A'
diff --git a/a b/a-copied
copy from a
copy to a-copied
Rebased revision does not contain information about b (issue3739)
$ hg log -r 3 --debug
changeset: 3:98f6e6dbf45ab54079c2237fbd11066a5c41a11d
tag: tip
phase: draft
parent: 2:39e588434882ff77d01229d169cdc77f29e8855e
parent: -1:0000000000000000000000000000000000000000
manifest: 3:2232f329d66fffe3930d43479ae624f66322b04d
user: test
date: Thu Jan 01 00:00:00 1970 +0000
files+: a-copied
extra: branch=default
extra: rebase_source=0a8162ff18a8900df8df8ef7ac0046955205613e
description:
copy A
$ cd ..
Test rebase across repeating renames:
$ hg init repo
$ cd repo
$ echo testing > file1.txt
$ hg add file1.txt
$ hg ci -m "Adding file1"
$ hg rename file1.txt file2.txt
$ hg ci -m "Rename file1 to file2"
$ echo Unrelated change > unrelated.txt
$ hg add unrelated.txt
$ hg ci -m "Unrelated change"
$ hg rename file2.txt file1.txt
$ hg ci -m "Rename file2 back to file1"
$ hg update -r -2
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo Another unrelated change >> unrelated.txt
$ hg ci -m "Another unrelated change"
created new head
$ hg tglog
@ 4: 'Another unrelated change'
|
| o 3: 'Rename file2 back to file1'
|/
o 2: 'Unrelated change'
|
o 1: 'Rename file1 to file2'
|
o 0: 'Adding file1'
$ hg rebase -s 4 -d 3
rebasing 4:b918d683b091 "Another unrelated change" (tip)
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/b918d683b091-backup.hg (glob)
$ hg diff --stat -c .
unrelated.txt | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
$ cd ..
Verify that copies get preserved (issue4192).
$ hg init copy-gets-preserved
$ cd copy-gets-preserved
$ echo a > a
$ hg add a
$ hg commit --message "File a created"
$ hg copy a b
$ echo b > b
$ hg commit --message "File b created as copy of a and modified"
$ hg copy b c
$ echo c > c
$ hg commit --message "File c created as copy of b and modified"
$ hg copy c d
$ echo d > d
$ hg commit --message "File d created as copy of c and modified"
Note that there are four entries in the log for d
$ hg tglog --follow d
@ 3: 'File d created as copy of c and modified'
|
o 2: 'File c created as copy of b and modified'
|
o 1: 'File b created as copy of a and modified'
|
o 0: 'File a created'
Update back to before we performed copies, and inject an unrelated change.
$ hg update 0
0 files updated, 0 files merged, 3 files removed, 0 files unresolved
$ echo unrelated > unrelated
$ hg add unrelated
$ hg commit --message "Unrelated file created"
created new head
$ hg update 4
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
Rebase the copies on top of the unrelated change.
$ hg rebase --source 1 --dest 4
rebasing 1:79d255d24ad2 "File b created as copy of a and modified"
rebasing 2:327f772bc074 "File c created as copy of b and modified"
rebasing 3:421b7e82bb85 "File d created as copy of c and modified"
saved backup bundle to $TESTTMP/copy-gets-preserved/.hg/strip-backup/79d255d24ad2-backup.hg (glob)
$ hg update 4
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
There should still be four entries in the log for d
$ hg tglog --follow d
@ 4: 'File d created as copy of c and modified'
|
o 3: 'File c created as copy of b and modified'
|
o 2: 'File b created as copy of a and modified'
|
o 0: 'File a created'
Same steps as above, but with --collapse on rebase to make sure the
copy records collapse correctly.
$ hg co 1
0 files updated, 0 files merged, 3 files removed, 0 files unresolved
$ echo more >> unrelated
$ hg ci -m 'unrelated commit is unrelated'
created new head
$ hg rebase -s 2 --dest 5 --collapse
rebasing 2:68bf06433839 "File b created as copy of a and modified"
note: rebase of 2:68bf06433839 created no changes to commit
rebasing 3:af74b229bc02 "File c created as copy of b and modified"
merging b and c to c
note: rebase of 3:af74b229bc02 created no changes to commit
rebasing 4:dbb9ba033561 "File d created as copy of c and modified"
merging c and d to d
note: rebase of 4:dbb9ba033561 created no changes to commit
saved backup bundle to $TESTTMP/copy-gets-preserved/.hg/strip-backup/68bf06433839-backup.hg (glob)
$ hg co tip
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
This should show both revision 3 and 0 since 'd' was transitively a
copy of 'a'.
$ hg tglog --follow d
@ 3: 'Collapsed revision
| * File b created as copy of a and modified
| * File c created as copy of b and modified
| * File d created as copy of c and modified'
o 0: 'File a created'
$ cd ..