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 test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ check_code="$TESTDIR"/../contrib/check-code.py
$ cd "$TESTDIR"/..
New errors are not allowed. Warnings are strongly discouraged.
(The writing "no-che?k-code" is for not skipping this file when checking.)
$ testrepohg locate \
> -X contrib/python-zstandard \
> -X hgext/fsmonitor/pywatchman \
> -X mercurial/thirdparty \
> -X mercurial/pythoncapi_compat.h \
> | sed 's-\\-/-g' | "$check_code" --warnings --per-file=0 - || false
Skipping contrib/automation/hgautomation/__init__.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/aws.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/cli.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/linux.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/pypi.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/ssh.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/try_server.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/windows.py it has no-che?k-code (glob)
Skipping contrib/automation/hgautomation/winrm.py it has no-che?k-code (glob)
Skipping contrib/fuzz/FuzzedDataProvider.h it has no-che?k-code (glob)
Skipping contrib/fuzz/standalone_fuzz_target_runner.cc it has no-che?k-code (glob)
Skipping contrib/packaging/hgpackaging/cli.py it has no-che?k-code (glob)
Skipping contrib/packaging/hgpackaging/downloads.py it has no-che?k-code (glob)
Skipping contrib/packaging/hgpackaging/inno.py it has no-che?k-code (glob)
Skipping contrib/packaging/hgpackaging/pyoxidizer.py it has no-che?k-code (glob)
Skipping contrib/packaging/hgpackaging/util.py it has no-che?k-code (glob)
Skipping contrib/packaging/hgpackaging/wix.py it has no-che?k-code (glob)
Skipping hgext/fsmonitor/__init__.py it has no-che?k-code (glob)
Skipping i18n/polib.py it has no-che?k-code (glob)
Skipping mercurial/statprof.py it has no-che?k-code (glob)
Skipping tests/testlib/badserverext.py it has no-che?k-code (glob)
@commands in debugcommands.py should be in alphabetical order.
>>> import re
>>> commands = []
>>> with open('mercurial/debugcommands.py', 'rb') as fh:
... for line in fh:
... m = re.match(br"^@command\('([a-z]+)", line)
... if m:
... commands.append(m.group(1))
>>> scommands = list(sorted(commands))
>>> for i, command in enumerate(scommands):
... if command != commands[i]:
... print('commands in debugcommands.py not sorted; first differing '
... 'command is %s; expected %s' % (commands[i], command))
... break
Prevent adding new files in the root directory accidentally.
$ testrepohg files 'glob:*'
.arcconfig
.clang-format
.editorconfig
.hgignore
.hgsigs
.hgtags
.jshintrc
CONTRIBUTING
CONTRIBUTORS
COPYING
Makefile
README.rst
hg
hgeditor
hgweb.cgi
pyproject.toml
rustfmt.toml
setup.py
Prevent adding modules which could be shadowed by ancient .so/.dylib.
$ testrepohg files \
> mercurial/base85.py \
> mercurial/bdiff.py \
> mercurial/diffhelpers.py \
> mercurial/mpatch.py \
> mercurial/osutil.py \
> mercurial/parsers.py \
> mercurial/zstd.py
[1]
Keep python3 tests sorted:
$ sort < contrib/python3-whitelist > $TESTTMP/py3sorted
$ cmp contrib/python3-whitelist $TESTTMP/py3sorted || echo 'Please sort passing tests!'
Keep Windows line endings in check
$ testrepohg files 'set:eol(dos)'
contrib/win32/hg.bat
contrib/win32/mercurial.ini