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
Issue586: removing remote files after merge appears to corrupt the
dirstate
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Ama
adding a
$ hg init ../b
$ cd ../b
$ echo b > b
$ hg ci -Amb
adding b
$ hg pull -f ../a
pulling from ../a
searching for changes
warning: repository is unrelated
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets cb9a9f314b8b
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg rm -f a
$ hg ci -Amc
$ hg st -A
C b
$ cd ..
Issue1433: Traceback after two unrelated pull, two move, a merge and
a commit (related to issue586)
create test repos
$ hg init repoa
$ touch repoa/a
$ hg -R repoa ci -Am adda
adding a
$ hg init repob
$ touch repob/b
$ hg -R repob ci -Am addb
adding b
$ hg init repoc
$ cd repoc
$ hg pull ../repoa
pulling from ../repoa
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 7132ab4568ac
(run 'hg update' to get a working copy)
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ mkdir tst
$ hg mv * tst
$ hg ci -m "import a in tst"
$ hg pull -f ../repob
pulling from ../repob
searching for changes
warning: repository is unrelated
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 5ddceb349652
(run 'hg heads' to see heads, 'hg merge' to merge)
merge both repos
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ mkdir src
move b content
$ hg mv b src
$ hg ci -m "import b in src"
$ hg manifest
src/b
tst/a
$ cd ..