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
#require svn svn-bindings
$ cat >> $HGRCPATH <<EOF
> [extensions]
> convert =
> EOF
$ svnadmin create svn-repo
$ svnadmin load -q svn-repo < "$TESTDIR/svn/encoding.svndump"
Convert while testing all possible outputs
$ hg --debug convert svn-repo A-hg --config progress.debug=1
initializing destination A-hg repository
reparent to file:/*/$TESTTMP/svn-repo (glob)
run hg sink pre-conversion action
scanning source...
found trunk at 'trunk'
found tags at 'tags'
found branches at 'branches'
found branch branch\xc3\xa9 at 5 (esc)
found branch branch\xc3\xa9e at 6 (esc)
scanning: 1/4 revisions (25.00%)
reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
fetching revision log for "/trunk" from 4 to 0
parsing revision 4 (2 changes)
parsing revision 3 (4 changes)
parsing revision 2 (3 changes)
parsing revision 1 (3 changes)
no copyfrom path, don't know what to do.
'/branches' is not under '/trunk', ignoring
'/tags' is not under '/trunk', ignoring
scanning: 2/4 revisions (50.00%)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9 (glob)
fetching revision log for "/branches/branch\xc3\xa9" from 5 to 0 (esc)
parsing revision 5 (1 changes)
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9 (glob)
found parent of branch /branches/branch\xc3\xa9 at 4: /trunk (esc)
scanning: 3/4 revisions (75.00%)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
fetching revision log for "/branches/branch\xc3\xa9e" from 6 to 0 (esc)
parsing revision 6 (1 changes)
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
found parent of branch /branches/branch\xc3\xa9e at 5: /branches/branch\xc3\xa9 (esc)
scanning: 4/4 revisions (100.00%)
scanning: 5/4 revisions (125.00%)
scanning: 6/4 revisions (150.00%)
sorting...
converting...
5 init projA
source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@1
converting: 0/6 revisions (0.00%)
reusing manifest from p1 (no file change)
committing changelog
updating the branch cache
4 hello
source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@2
converting: 1/6 revisions (16.67%)
reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
scanning paths: /trunk/\xc3\xa0 0/3 paths (0.00%) (esc)
scanning paths: /trunk/\xc3\xa0/e\xcc\x81 1/3 paths (33.33%) (esc)
scanning paths: /trunk/\xc3\xa9 2/3 paths (66.67%) (esc)
committing files:
\xc3\xa0/e\xcc\x81 (esc)
getting files: \xc3\xa0/e\xcc\x81 1/2 files (50.00%) (esc)
\xc3\xa9 (esc)
getting files: \xc3\xa9 2/2 files (100.00%) (esc)
committing manifest
committing changelog
updating the branch cache
3 copy files
source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@3
converting: 2/6 revisions (33.33%)
scanning paths: /trunk/\xc3\xa0 0/4 paths (0.00%) (esc)
gone from -1
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
scanning paths: /trunk/\xc3\xa8 1/4 paths (25.00%) (esc)
copied to \xc3\xa8 from \xc3\xa9@2 (esc)
scanning paths: /trunk/\xc3\xa9 2/4 paths (50.00%) (esc)
gone from -1
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
scanning paths: /trunk/\xc3\xb9 3/4 paths (75.00%) (esc)
mark /trunk/\xc3\xb9 came from \xc3\xa0:2 (esc)
getting files: \xc3\xa0/e\xcc\x81 1/4 files (25.00%) (esc)
getting files: \xc3\xa9 2/4 files (50.00%) (esc)
committing files:
\xc3\xa8 (esc)
getting files: \xc3\xa8 3/4 files (75.00%) (esc)
\xc3\xa8: copy \xc3\xa9:6b67ccefd5ce6de77e7ead4f5292843a0255329f (esc)
\xc3\xb9/e\xcc\x81 (esc)
getting files: \xc3\xb9/e\xcc\x81 4/4 files (100.00%) (esc)
\xc3\xb9/e\xcc\x81: copy \xc3\xa0/e\xcc\x81:a9092a3d84a37b9993b5c73576f6de29b7ea50f6 (esc)
committing manifest
committing changelog
updating the branch cache
2 remove files
source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@4
converting: 3/6 revisions (50.00%)
scanning paths: /trunk/\xc3\xa8 0/2 paths (0.00%) (esc)
gone from -1
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
scanning paths: /trunk/\xc3\xb9 1/2 paths (50.00%) (esc)
gone from -1
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
getting files: \xc3\xa8 1/2 files (50.00%) (esc)
getting files: \xc3\xb9/e\xcc\x81 2/2 files (100.00%) (esc)
committing files:
committing manifest
committing changelog
updating the branch cache
1 branch to branch?
source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/branches/branch?@5
converting: 4/6 revisions (66.67%)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9 (glob)
scanning paths: /branches/branch\xc3\xa9 0/1 paths (0.00%) (esc)
reusing manifest from p1 (no file change)
committing changelog
updating the branch cache
0 branch to branch?e
source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/branches/branch?e@6
converting: 5/6 revisions (83.33%)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
scanning paths: /branches/branch\xc3\xa9e 0/1 paths (0.00%) (esc)
reusing manifest from p1 (no file change)
committing changelog
updating the branch cache
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
reparent to file:/*/$TESTTMP/svn-repo (glob)
reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
updating tags
committing files:
.hgtags
committing manifest
committing changelog
updating the branch cache
run hg sink post-conversion action
$ cd A-hg
$ hg up
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Check tags are in UTF-8
$ cat .hgtags
e94e4422020e715add80525e8f0f46c9968689f1 branch\xc3\xa9e (esc)
f7e66f98380ed1e53a797c5c7a7a2616a7ab377d branch\xc3\xa9 (esc)
$ cd ..
Subversion sources don't support non-ASCII characters in HTTP(S) URLs.
$ XFF=$("$PYTHON" -c 'from mercurial.utils.procutil import stdout; stdout.write(b"\xff")')
$ hg convert --source-type=svn http://localhost:$HGPORT/$XFF test
initializing destination test repository
Subversion sources don't support non-ASCII characters in HTTP(S) URLs. Please percent-encode them.
http://localhost:$HGPORT/\xff does not look like a Subversion repository (esc)
abort: http://localhost:$HGPORT/\xff: missing or unsupported repository (esc)
[255]
In Subversion, paths are Unicode (encoded as UTF-8). Therefore paths that can't
be converted between UTF-8 and the locale encoding (which is always ASCII in
tests) don't work.
$ cp -R svn-repo $XFF
$ hg convert $XFF test
initializing destination test repository
Subversion requires that paths can be converted to Unicode using the current locale encoding (ascii)
\xff does not look like a CVS checkout (glob) (esc)
$TESTTMP/\xff does not look like a Git repository (esc)
\xff does not look like a Subversion repository (glob) (esc)
\xff is not a local Mercurial repository (glob) (esc)
\xff does not look like a darcs repository (glob) (esc)
\xff does not look like a monotone repository (glob) (esc)
\xff does not look like a GNU Arch repository (glob) (esc)
\xff does not look like a Bazaar repository (glob) (esc)
cannot find required "p4" tool
abort: \xff: missing or unsupported repository (glob) (esc)
[255]
$ hg convert file://$TESTTMP/$XFF test
initializing destination test repository
Subversion requires that file URLs can be converted to Unicode using the current locale encoding (ascii)
file:/*/$TESTTMP/\xff does not look like a CVS checkout (glob) (esc)
$TESTTMP/file:$TESTTMP/\xff does not look like a Git repository (esc)
file:/*/$TESTTMP/\xff does not look like a Subversion repository (glob) (esc)
file:/*/$TESTTMP/\xff is not a local Mercurial repository (glob) (esc)
file:/*/$TESTTMP/\xff does not look like a darcs repository (glob) (esc)
file:/*/$TESTTMP/\xff does not look like a monotone repository (glob) (esc)
file:/*/$TESTTMP/\xff does not look like a GNU Arch repository (glob) (esc)
file:/*/$TESTTMP/\xff does not look like a Bazaar repository (glob) (esc)
file:/*/$TESTTMP/\xff does not look like a P4 repository (glob) (esc)
abort: file:/*/$TESTTMP/\xff: missing or unsupported repository (glob) (esc)
[255]
Subversion decodes percent-encoded bytes on the converted, UTF-8-encoded
string. Therefore, if the percent-encoded bytes aren't valid UTF-8, Subversion
would choke on them when converting them to the locale encoding.
$ hg convert file://$TESTTMP/%FF test
initializing destination test repository
Subversion does not support non-UTF-8 percent-encoded bytes in file URLs
file:/*/$TESTTMP/%FF does not look like a CVS checkout (glob)
$TESTTMP/file:$TESTTMP/%FF does not look like a Git repository
file:/*/$TESTTMP/%FF does not look like a Subversion repository (glob)
file:/*/$TESTTMP/%FF is not a local Mercurial repository (glob)
file:/*/$TESTTMP/%FF does not look like a darcs repository (glob)
file:/*/$TESTTMP/%FF does not look like a monotone repository (glob)
file:/*/$TESTTMP/%FF does not look like a GNU Arch repository (glob)
file:/*/$TESTTMP/%FF does not look like a Bazaar repository (glob)
file:/*/$TESTTMP/%FF does not look like a P4 repository (glob)
abort: file:/*/$TESTTMP/%FF: missing or unsupported repository (glob)
[255]