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
Preparing the subrepository 'sub'
$ hg init sub
$ echo sub > sub/sub
$ hg add -R sub
adding sub/sub
$ hg commit -R sub -m "sub import"
Preparing the 'main' repo which depends on the subrepo 'sub'
$ hg init main
$ echo main > main/main
$ echo "sub = ../sub" > main/.hgsub
$ hg clone sub main/sub
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg add -R main
adding main/.hgsub
adding main/main
$ hg commit -R main -m "main import"
Cleaning both repositories, just as a clone -U
$ hg up -C -R sub null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg up -C -R main null
0 files updated, 0 files merged, 3 files removed, 0 files unresolved
$ rm -rf main/sub
hide outer repo
$ hg init
Serving them both using hgweb
$ printf '[paths]\n/main = main\nsub = sub\n' > webdir.conf
$ hg serve --webdir-conf webdir.conf -a localhost -p $HGPORT \
> -A /dev/null -E /dev/null --pid-file hg.pid -d
$ cat hg.pid >> $DAEMON_PIDS
Clone main from hgweb
$ hg clone "http://user:pass@localhost:$HGPORT/main" cloned
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets fdfeeb3e979e
updating to branch default
cloning subrepo sub from http://user@localhost:$HGPORT/sub
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 863c1745b441
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
Ensure that subrepos pay attention to default:pushurl
$ cat > cloned/.hg/hgrc << EOF
> [paths]
> default:pushurl = http://user:pass@localhost:$HGPORT/main
> EOF
$ hg -R cloned out -S --config paths.default=bogus://invalid
comparing with http://user:***@localhost:$HGPORT/main
searching for changes
no changes found
comparing with http://user:***@localhost:$HGPORT/sub
searching for changes
no changes found
[1]
TODO: Figure out why, if the password is left out of the default:pushurl URL,
this says "no changes made to subrepo sub since last push". It looks like from
the original clone command above, the password is getting stripped off, not
just masked out, and that would make the hashed URL different.
$ hg -R cloned push --config paths.default=bogus://invalid
pushing to http://user:***@localhost:$HGPORT/main
pushing subrepo sub to http://user:***@localhost:$HGPORT/sub
searching for changes
no changes found
searching for changes
no changes found
abort: HTTP Error 403: ssl required
[100]
Checking cloned repo ids
$ hg id -R cloned
fdfeeb3e979e tip
$ hg id -R cloned/sub
863c1745b441 tip
subrepo debug for 'main' clone
$ hg debugsub -R cloned
path sub
source ../sub
revision 863c1745b441bd97a8c4a096e87793073f4fb215
Test sharing with a remote URL reference
$ hg init absolute_subrepo
$ cd absolute_subrepo
$ echo foo > foo.txt
$ hg ci -Am 'initial commit'
adding foo.txt
$ echo "sub = http://localhost:$HGPORT/sub" > .hgsub
$ hg ci -Am 'add absolute subrepo'
adding .hgsub
$ cd ..
Clone pooling works for local clones with a remote subrepo reference. The
subrepo is cloned to the pool and shared from there, so that all clones will
share the same subrepo.
$ hg --config extensions.share= --config share.pool=$TESTTMP/pool \
> clone absolute_subrepo cloned_from_abs
(sharing from new pooled repository 8d6a2f1e993b34b6557de0042cfe825ae12a8dae)
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 3 changes to 3 files
new changesets 8d6a2f1e993b:* (glob)
searching for changes
no changes found
updating working directory
cloning subrepo sub from http://localhost:$HGPORT/sub
(sharing from new pooled repository 863c1745b441bd97a8c4a096e87793073f4fb215)
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 863c1745b441
searching for changes
no changes found
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
Vanilla sharing with a subrepo remote path reference will clone the subrepo.
Each share of these top level repos will end up with independent subrepo copies
(potentially leaving the shared parent with dangling cset references).
$ hg --config extensions.share= share absolute_subrepo shared_from_abs
updating working directory
cloning subrepo sub from http://localhost:$HGPORT/sub
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 863c1745b441
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --config extensions.share= share -U absolute_subrepo shared_from_abs2
$ hg -R shared_from_abs2 update -r tip
cloning subrepo sub from http://localhost:$HGPORT/sub
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 863c1745b441
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
A parent repo without its subrepo available locally can be shared if the
subrepo is referenced by absolute path.
$ hg clone -U absolute_subrepo cloned_null_from_abs
$ hg --config extensions.share= share cloned_null_from_abs shared_from_null_abs
updating working directory
cloning subrepo sub from http://localhost:$HGPORT/sub
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 863c1745b441
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ killdaemons.py
subrepo paths with ssh urls
$ hg clone ssh://user@dummy/cloned sshclone
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets fdfeeb3e979e
updating to branch default
cloning subrepo sub from ssh://user@dummy/sub
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 863c1745b441
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R sshclone push ssh://user@dummy/`pwd`/cloned
pushing to ssh://user@dummy/$TESTTMP/cloned
pushing subrepo sub to ssh://user@dummy/$TESTTMP/sub
searching for changes
no changes found
searching for changes
no changes found
[1]
$ cat dummylog
Got arguments 1:user@dummy 2:hg -R cloned serve --stdio
Got arguments 1:user@dummy 2:hg -R sub serve --stdio
Got arguments 1:user@dummy 2:hg -R $TESTTMP/cloned serve --stdio
Got arguments 1:user@dummy 2:hg -R $TESTTMP/sub serve --stdio