bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
Tests discovery against servers without getbundle support:
$ cat >> $HGRCPATH <<EOF
> [ui]
> logtemplate="{rev} {node|short}: {desc} {branches}\n"
> EOF
$ cp $HGRCPATH $HGRCPATH-withcap
$ CAP="getbundle known changegroupsubset bundle2"
$ . "$TESTDIR/notcapable"
$ cp $HGRCPATH $HGRCPATH-nocap
$ cp $HGRCPATH-withcap $HGRCPATH
Prep for test server without branchmap support
$ CAP="branchmap"
$ . "$TESTDIR/notcapable"
$ cp $HGRCPATH $HGRCPATH-nocap-branchmap
$ cp $HGRCPATH-withcap $HGRCPATH
Setup HTTP server control:
$ remote=http://localhost:$HGPORT/
$ export remote
$ tstart() {
> echo '[web]' > $1/.hg/hgrc
> echo 'push_ssl = false' >> $1/.hg/hgrc
> echo 'allow_push = *' >> $1/.hg/hgrc
> cp $HGRCPATH-nocap $HGRCPATH
> hg serve -R $1 -p $HGPORT -d --pid-file=hg.pid -E errors.log
> cat hg.pid >> $DAEMON_PIDS
> }
$ tstop() {
> killdaemons.py
> cp $HGRCPATH-withcap $HGRCPATH
> }
Both are empty:
$ hg init empty1
$ hg init empty2
$ tstart empty2
$ hg incoming -R empty1 $remote
comparing with http://localhost:$HGPORT/
no changes found
[1]
$ hg outgoing -R empty1 $remote
comparing with http://localhost:$HGPORT/
no changes found
[1]
$ hg pull -R empty1 $remote
pulling from http://localhost:$HGPORT/
no changes found
$ hg push -R empty1 $remote
pushing to http://localhost:$HGPORT/
no changes found
[1]
$ tstop
Base repo:
$ hg init main
$ cd main
$ hg debugbuilddag -mo '+2:tbase @name1 +3:thead1 <tbase @name2 +4:thead2 @both /thead1 +2:tmaintip'
$ hg log -G
o 11 a19bfa7e7328: r11 both
|
o 10 8b6bad1512e1: r10 both
|
o 9 025829e08038: r9 both
|\
| o 8 d8f638ac69e9: r8 name2
| |
| o 7 b6b4d315a2ac: r7 name2
| |
| o 6 6c6f5d5f3c11: r6 name2
| |
| o 5 70314b29987d: r5 name2
| |
o | 4 e71dbbc70e03: r4 name1
| |
o | 3 2c8d5d5ec612: r3 name1
| |
o | 2 a7892891da29: r2 name1
|/
o 1 0019a3b924fd: r1
|
o 0 d57206cc072a: r0
$ cd ..
$ tstart main
Full clone:
$ hg clone main full
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd full
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Local is empty:
$ cd empty1
$ hg incoming $remote --rev name1
comparing with http://localhost:$HGPORT/
abort: cannot look up remote changes; remote repository does not support the 'changegroupsubset' capability
[255]
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
0 d57206cc072a: r0
1 0019a3b924fd: r1
2 a7892891da29: r2 name1
3 2c8d5d5ec612: r3 name1
4 e71dbbc70e03: r4 name1
5 70314b29987d: r5 name2
6 6c6f5d5f3c11: r6 name2
7 b6b4d315a2ac: r7 name2
8 d8f638ac69e9: r8 name2
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
no changes found
[1]
$ hg push $remote
pushing to http://localhost:$HGPORT/
no changes found
[1]
$ hg pull $remote
pulling from http://localhost:$HGPORT/
requesting all changes
adding changesets
adding manifests
adding file changes
added 12 changesets with 24 changes to 2 files
new changesets d57206cc072a:a19bfa7e7328
(run 'hg update' to get a working copy)
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Local is subset:
$ cp $HGRCPATH-withcap $HGRCPATH
$ hg clone main subset --rev name2 ; cd subset
adding changesets
adding manifests
adding file changes
added 6 changesets with 12 changes to 2 files
new changesets d57206cc072a:d8f638ac69e9
updating to branch name2
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cp $HGRCPATH-nocap $HGRCPATH
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
6 a7892891da29: r2 name1
7 2c8d5d5ec612: r3 name1
8 e71dbbc70e03: r4 name1
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
adding changesets
adding manifests
adding file changes
added 6 changesets with 12 changes to 2 files
new changesets a7892891da29:a19bfa7e7328
(run 'hg update' to get a working copy)
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Remote is empty:
$ tstop ; tstart empty2
$ cd main
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
0 d57206cc072a: r0
1 0019a3b924fd: r1
2 a7892891da29: r2 name1
3 2c8d5d5ec612: r3 name1
4 e71dbbc70e03: r4 name1
5 70314b29987d: r5 name2
6 6c6f5d5f3c11: r6 name2
7 b6b4d315a2ac: r7 name2
8 d8f638ac69e9: r8 name2
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 12 changesets with 24 changes to 2 files
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Local is superset:
$ tstop
$ hg clone main subset2 --rev name2
adding changesets
adding manifests
adding file changes
added 6 changesets with 12 changes to 2 files
new changesets d57206cc072a:d8f638ac69e9
updating to branch name2
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ tstart subset2
$ cd main
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
2 a7892891da29: r2 name1
3 2c8d5d5ec612: r3 name1
4 e71dbbc70e03: r4 name1
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
abort: push creates new remote branches: both, name1
(use 'hg push --new-branch' to create new remote branches)
[20]
$ hg push $remote --new-branch
pushing to http://localhost:$HGPORT/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 6 changesets with 12 changes to 2 files
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Partial pull:
$ tstop ; tstart main
$ hg clone $remote partial --rev name2
abort: partial pull cannot be done because other repository doesn't support changegroupsubset.
[255]
$ hg init partial; cd partial
$ hg incoming $remote --rev name2
comparing with http://localhost:$HGPORT/
abort: cannot look up remote changes; remote repository does not support the 'changegroupsubset' capability
[255]
$ hg pull $remote --rev name2
pulling from http://localhost:$HGPORT/
abort: partial pull cannot be done because other repository doesn't support changegroupsubset.
[255]
$ cd ..
$ tstop
Exercise pushing to server without branchmap capability
$ cp $HGRCPATH-nocap-branchmap $HGRCPATH-nocap
$ hg init rlocal
$ cd rlocal
$ echo A > A
$ hg ci -Am A
adding A
$ cd ..
$ hg clone rlocal rremote
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd rlocal
$ echo B > B
$ hg ci -Am B
adding B
$ cd ..
$ tstart rremote
$ cd rlocal
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
1 27547f69f254: B
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
1 local changesets published
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
$ tstop