copies: calculate mergecopies() based on pathcopies()
When copies are stored in changesets, we need a changeset-centric
version of mergecopies() just like we have a changeset-centric version
of pathcopies(). I think the natural way of thinking about
mergecopies() is in terms of pathcopies() from the base to each of the
commits. So if we can rewrite mergecopies() based on two such
pathcopies() calls, we'll get the changeset-centric version for
free. That's what this patch does.
A nice bonus is that it ends up being a lot simpler. mergecopies() has
accumulated a lot of technical debt over time. One good example is the
code for dealing with grafts (the "partial/incomplete/dirty"
stuff). Since pathcopies() already deals with backwards renames and
ping-pong renames, we get that for free.
I've run tests with hard-coded debug logging for "fullcopy" and while
I haven't looked at every difference it produces, all the ones I have
looked at seemed reasonable to me. I'm a little surprised that no more
tests fail when run with '--extra-config-opt
experimental.copies.read-from=compatibility' compared to before this
patch. This patch also fixes the broken cases in test-annotate.t and
test-fastannotate.t. It also enables the part of test-copies.t that
was previously disabled exactly because mergecopies() needed to get a
changeset-centric version.
One drawback of the rewritten code is that we may now make
remotefilelog prefetch more files. We used to prefetch files that were
unique to either side of the merge compared to the other. We now
prefetch files that are unique to either side of the merge compared to
the base. This means that if you added the same file to each side, we
would not prefetch it before, but we would now. Such cases are
probably quite rare, but one likely scenario where they happen is when
moving from a commit to its successor (or the other way around). The
user will probably already have the files in the cache in such cases,
so it's probably not a big deal.
Some timings for calculating mergecopies between two revisions
(revisions shown on each line, all using the common ancestor as base):
In the hg repo:
4.8 4.9: 0.21s -> 0.21s
4.0 4.8: 0.35s -> 0.63s
In and old copy of the mozilla-unified repo:
FIREFOX_BETA_60_BASE^ FIREFOX_BETA_60_BASE: 0.82s -> 0.82s
FIREFOX_NIGHTLY_59_END FIREFOX_BETA_60_BASE: 2.5s -> 2.6s
FIREFOX_BETA_59_END FIREFOX_BETA_60_BASE: 3.9s -> 4.1s
FIREFOX_AURORA_50_BASE FIREFOX_BETA_60_BASE: 31s -> 33s
So it's measurably slower in most cases. The most significant
difference is in the hg repo between revisions 4.0 and 4.8. In that
case it seems to come from the fact that pathcopies() uses
fctx.isintroducedafter() (in _tracefile), while the old mergecopies()
used fctx.linkrev() (in _checkcopies()). That results in a single call
to filectx._adjustlinkrev(), which is responsible for the entire
difference in time (in my repo). So we pay a performance penalty but
we get more correct code (see change in
test-mv-cp-st-diff.t). Deleting the "== f.filenode()" in _tracefile()
recovers the lost performance in the hg repo.
There were are few other optimizations in _checkcopies() that I could
not measure any impact from. One was from the "seen" set. Another was
from a "continue" when the file was not in the destination manifest
(corresponding to "am" in _tracefile).
Also note that merge copies are not calculated when updating with a
clean working copy, which is probably the most common case. I
therefore think the much simpler code is worth the slowdown.
Differential Revision: https://phab.mercurial-scm.org/D6255
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
> drawdag=$TESTDIR/drawdag.py
> [alias]
> tglog = log -G --template "{rev}: {node|short} '{desc}' {branches}\n"
> EOF
$ hg init repo
$ cd repo
$ echo A > a
$ echo >> a
$ hg ci -Am A
adding a
$ echo B > a
$ echo >> a
$ hg ci -m B
$ echo C > a
$ echo >> a
$ hg ci -m C
$ hg up -q -C 0
$ echo D >> a
$ hg ci -Am AD
created new head
$ hg tglog
@ 3: 3878212183bd 'AD'
|
| o 2: 30ae917c0e4f 'C'
| |
| o 1: 0f4f7cb4f549 'B'
|/
o 0: 1e635d440a73 'A'
$ hg rebase -s 1 -d 3
rebasing 1:0f4f7cb4f549 "B"
merging a
rebasing 2:30ae917c0e4f "C"
merging a
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/0f4f7cb4f549-82b3b163-rebase.hg
$ hg tglog
o 3: 25773bc4b4b0 'C'
|
o 2: c09015405f75 'B'
|
@ 1: 3878212183bd 'AD'
|
o 0: 1e635d440a73 'A'
$ cd ..
Test rebasing of merges with ancestors of the rebase destination - a situation
that often happens when trying to recover from repeated merging with a mainline
branch.
The test case creates a dev branch that contains a couple of merges from the
default branch. When rebasing to the default branch, these merges would be
merges with ancestors on the same branch. The merges _could_ contain some
interesting conflict resolutions or additional changes in the merge commit, but
that is mixed up with the actual merge stuff and there is in general no way to
separate them.
Note: The dev branch contains _no_ changes to f-default. It might be unclear
how rebasing of ancestor merges should be handled, but the current behavior
with spurious prompts for conflicts in files that didn't change seems very
wrong.
$ hg init ancestor-merge
$ cd ancestor-merge
$ touch f-default
$ hg ci -Aqm 'default: create f-default'
$ hg branch -q dev
$ hg ci -qm 'dev: create branch'
$ echo stuff > f-dev
$ hg ci -Aqm 'dev: f-dev stuff'
$ hg up -q default
$ echo stuff > f-default
$ hg ci -m 'default: f-default stuff'
$ hg up -q dev
$ hg merge -q default
$ hg ci -m 'dev: merge default'
$ hg up -q default
$ hg rm f-default
$ hg ci -m 'default: remove f-default'
$ hg up -q dev
$ hg merge -q default
$ hg ci -m 'dev: merge default'
$ hg up -q default
$ echo stuff > f-other
$ hg ci -Aqm 'default: f-other stuff'
$ hg tglog
@ 7: e08089805d82 'default: f-other stuff'
|
| o 6: 9455ee510502 'dev: merge default' dev
|/|
o | 5: 462860db70a1 'default: remove f-default'
| |
| o 4: 4b019212aaf6 'dev: merge default' dev
|/|
o | 3: f157ecfd2b6b 'default: f-default stuff'
| |
| o 2: ec2c14fb2984 'dev: f-dev stuff' dev
| |
| o 1: 1d1a643d390e 'dev: create branch' dev
|/
o 0: e90e8eb90b6f 'default: create f-default'
$ hg clone -qU . ../ancestor-merge-2
Full rebase all the way back from branching point:
$ hg rebase -r 'only(dev,default)' -d default --config ui.interactive=True << EOF
> c
> EOF
rebasing 1:1d1a643d390e "dev: create branch"
note: not rebasing 1:1d1a643d390e "dev: create branch", its destination already has all its changes
rebasing 2:ec2c14fb2984 "dev: f-dev stuff"
rebasing 4:4b019212aaf6 "dev: merge default"
file 'f-default' was deleted in local [dest] but was modified in other [source].
What do you want to do?
use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c
rebasing 6:9455ee510502 "dev: merge default"
saved backup bundle to $TESTTMP/ancestor-merge/.hg/strip-backup/1d1a643d390e-43e9e04b-rebase.hg
$ hg tglog
o 6: fbc098e72227 'dev: merge default'
|
o 5: eda7b7f46f5d 'dev: merge default'
|
o 4: 3e075b1c0a40 'dev: f-dev stuff'
|
@ 3: e08089805d82 'default: f-other stuff'
|
o 2: 462860db70a1 'default: remove f-default'
|
o 1: f157ecfd2b6b 'default: f-default stuff'
|
o 0: e90e8eb90b6f 'default: create f-default'
Grafty cherry picking rebasing:
$ cd ../ancestor-merge-2
$ hg phase -fdr0:
$ hg rebase -r 'children(only(dev,default))' -d default --config ui.interactive=True << EOF
> c
> EOF
rebasing 2:ec2c14fb2984 "dev: f-dev stuff"
rebasing 4:4b019212aaf6 "dev: merge default"
file 'f-default' was deleted in local [dest] but was modified in other [source].
What do you want to do?
use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c
rebasing 6:9455ee510502 "dev: merge default"
saved backup bundle to $TESTTMP/ancestor-merge-2/.hg/strip-backup/ec2c14fb2984-62d0b222-rebase.hg
$ hg tglog
o 7: fbc098e72227 'dev: merge default'
|
o 6: eda7b7f46f5d 'dev: merge default'
|
o 5: 3e075b1c0a40 'dev: f-dev stuff'
|
o 4: e08089805d82 'default: f-other stuff'
|
o 3: 462860db70a1 'default: remove f-default'
|
o 2: f157ecfd2b6b 'default: f-default stuff'
|
| o 1: 1d1a643d390e 'dev: create branch' dev
|/
o 0: e90e8eb90b6f 'default: create f-default'
$ cd ..
Test order of parents of rebased merged with un-rebased changes as p1.
$ hg init parentorder
$ cd parentorder
$ touch f
$ hg ci -Aqm common
$ touch change
$ hg ci -Aqm change
$ touch target
$ hg ci -Aqm target
$ hg up -qr 0
$ touch outside
$ hg ci -Aqm outside
$ hg merge -qr 1
$ hg ci -m 'merge p1 3=outside p2 1=ancestor'
$ hg par
changeset: 4:6990226659be
tag: tip
parent: 3:f59da8fc0fcf
parent: 1:dd40c13f7a6f
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: merge p1 3=outside p2 1=ancestor
$ hg up -qr 1
$ hg merge -qr 3
$ hg ci -qm 'merge p1 1=ancestor p2 3=outside'
$ hg par
changeset: 5:a57575f79074
tag: tip
parent: 1:dd40c13f7a6f
parent: 3:f59da8fc0fcf
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: merge p1 1=ancestor p2 3=outside
$ hg tglog
@ 5: a57575f79074 'merge p1 1=ancestor p2 3=outside'
|\
+---o 4: 6990226659be 'merge p1 3=outside p2 1=ancestor'
| |/
| o 3: f59da8fc0fcf 'outside'
| |
+---o 2: a60552eb93fb 'target'
| |
o | 1: dd40c13f7a6f 'change'
|/
o 0: 02f0f58d5300 'common'
$ hg rebase -r 4 -d 2
rebasing 4:6990226659be "merge p1 3=outside p2 1=ancestor"
saved backup bundle to $TESTTMP/parentorder/.hg/strip-backup/6990226659be-4d67a0d3-rebase.hg
$ hg tip
changeset: 5:cca50676b1c5
tag: tip
parent: 2:a60552eb93fb
parent: 3:f59da8fc0fcf
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: merge p1 3=outside p2 1=ancestor
$ hg rebase -r 4 -d 2
rebasing 4:a57575f79074 "merge p1 1=ancestor p2 3=outside"
saved backup bundle to $TESTTMP/parentorder/.hg/strip-backup/a57575f79074-385426e5-rebase.hg
$ hg tip
changeset: 5:f9daf77ffe76
tag: tip
parent: 2:a60552eb93fb
parent: 3:f59da8fc0fcf
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: merge p1 1=ancestor p2 3=outside
$ hg tglog
@ 5: f9daf77ffe76 'merge p1 1=ancestor p2 3=outside'
|\
+---o 4: cca50676b1c5 'merge p1 3=outside p2 1=ancestor'
| |/
| o 3: f59da8fc0fcf 'outside'
| |
o | 2: a60552eb93fb 'target'
| |
o | 1: dd40c13f7a6f 'change'
|/
o 0: 02f0f58d5300 'common'
rebase of merge of ancestors
$ hg up -qr 2
$ hg merge -qr 3
$ echo 'other change while merging future "rebase ancestors"' > other
$ hg ci -Aqm 'merge rebase ancestors'
$ hg rebase -d 5 -v
rebasing 6:4c5f12f25ebe "merge rebase ancestors" (tip)
resolving manifests
removing other
note: merging f9daf77ffe76+ and 4c5f12f25ebe using bids from ancestors a60552eb93fb and f59da8fc0fcf
calculating bids for ancestor a60552eb93fb
resolving manifests
calculating bids for ancestor f59da8fc0fcf
resolving manifests
auction for merging merge bids
other: consensus for g
end of auction
getting other
committing files:
other
committing manifest
committing changelog
rebase merging completed
1 changesets found
uncompressed size of bundle content:
199 (changelog)
216 (manifests)
182 other
saved backup bundle to $TESTTMP/parentorder/.hg/strip-backup/4c5f12f25ebe-f46990e5-rebase.hg
1 changesets found
uncompressed size of bundle content:
254 (changelog)
167 (manifests)
182 other
adding branch
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
rebase completed
$ hg tglog
@ 6: 113755df812b 'merge rebase ancestors'
|
o 5: f9daf77ffe76 'merge p1 1=ancestor p2 3=outside'
|\
+---o 4: cca50676b1c5 'merge p1 3=outside p2 1=ancestor'
| |/
| o 3: f59da8fc0fcf 'outside'
| |
o | 2: a60552eb93fb 'target'
| |
o | 1: dd40c13f7a6f 'change'
|/
o 0: 02f0f58d5300 'common'
Due to the limitation of 3-way merge algorithm (1 merge base), rebasing a merge
may include unwanted content:
$ hg init $TESTTMP/dual-merge-base1
$ cd $TESTTMP/dual-merge-base1
$ hg debugdrawdag <<'EOS'
> F
> /|
> D E
> | |
> B C
> |/
> A Z
> |/
> R
> EOS
$ hg rebase -r D+E+F -d Z
rebasing 5:5f2c926dfecf "D" (D)
rebasing 6:b296604d9846 "E" (E)
rebasing 7:caa9781e507d "F" (F tip)
abort: rebasing 7:caa9781e507d will include unwanted changes from 4:d6003a550c2c or 3:c1e6b162678d
[255]
The warning does not get printed if there is no unwanted change detected:
$ hg init $TESTTMP/dual-merge-base2
$ cd $TESTTMP/dual-merge-base2
$ hg debugdrawdag <<'EOS'
> D
> /|
> B C
> |/
> A Z
> |/
> R
> EOS
$ hg rebase -r B+C+D -d Z
rebasing 3:c1e6b162678d "B" (B)
rebasing 4:d6003a550c2c "C" (C)
rebasing 5:c8f78076273e "D" (D tip)
saved backup bundle to $TESTTMP/dual-merge-base2/.hg/strip-backup/d6003a550c2c-6f1424b6-rebase.hg
$ hg manifest -r 'desc(D)'
B
C
R
Z
The merge base could be different from old p1 (changed parent becomes new p1):
$ hg init $TESTTMP/chosen-merge-base1
$ cd $TESTTMP/chosen-merge-base1
$ hg debugdrawdag <<'EOS'
> F
> /|
> D E
> | |
> B C Z
> EOS
$ hg rebase -r D+F -d Z
rebasing 3:004dc1679908 "D" (D)
rebasing 5:4be4cbf6f206 "F" (F tip)
saved backup bundle to $TESTTMP/chosen-merge-base1/.hg/strip-backup/004dc1679908-06a66a3c-rebase.hg
$ hg manifest -r 'desc(F)'
C
D
E
Z
$ hg log -r `hg log -r 'desc(F)' -T '{p1node}'` -T '{desc}\n'
D
$ hg init $TESTTMP/chosen-merge-base2
$ cd $TESTTMP/chosen-merge-base2
$ hg debugdrawdag <<'EOS'
> F
> /|
> D E
> | |
> B C Z
> EOS
$ hg rebase -r E+F -d Z
rebasing 4:974e4943c210 "E" (E)
rebasing 5:4be4cbf6f206 "F" (F tip)
saved backup bundle to $TESTTMP/chosen-merge-base2/.hg/strip-backup/974e4943c210-b2874da5-rebase.hg
$ hg manifest -r 'desc(F)'
B
D
E
Z
$ hg log -r `hg log -r 'desc(F)' -T '{p1node}'` -T '{desc}\n'
E