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
# this is hack to make sure no escape characters are inserted into the output
import doctest
import os
import re
import subprocess
import sys
ispy3 = sys.version_info[0] >= 3
if 'TERM' in os.environ:
del os.environ['TERM']
class py3docchecker(doctest.OutputChecker):
def check_output(self, want, got, optionflags):
want2 = re.sub(r'''\bu(['"])(.*?)\1''', r'\1\2\1', want) # py2: u''
got2 = re.sub(r'''\bb(['"])(.*?)\1''', r'\1\2\1', got) # py3: b''
# py3: <exc.name>: b'<msg>' -> <name>: <msg>
# <exc.name>: <others> -> <name>: <others>
got2 = re.sub(
r'''^mercurial\.\w+\.(\w+): (['"])(.*?)\2''',
r'\1: \3',
got2,
re.MULTILINE,
)
got2 = re.sub(r'^mercurial\.\w+\.(\w+): ', r'\1: ', got2, re.MULTILINE)
return any(
doctest.OutputChecker.check_output(self, w, g, optionflags)
for w, g in [(want, got), (want2, got2)]
)
def testmod(name, optionflags=0, testtarget=None):
__import__(name)
mod = sys.modules[name]
if testtarget is not None:
mod = getattr(mod, testtarget)
# minimal copy of doctest.testmod()
finder = doctest.DocTestFinder()
checker = None
if ispy3:
checker = py3docchecker()
runner = doctest.DocTestRunner(checker=checker, optionflags=optionflags)
for test in finder.find(mod, name):
runner.run(test)
runner.summarize()
DONT_RUN = []
# Exceptions to the defaults for a given detected module. The value for each
# module name is a list of dicts that specify the kwargs to pass to testmod.
# testmod is called once per item in the list, so an empty list will cause the
# module to not be tested.
testmod_arg_overrides = {
'i18n.check-translation': DONT_RUN, # may require extra installation
'mercurial.dagparser': [{'optionflags': doctest.NORMALIZE_WHITESPACE}],
'mercurial.keepalive': DONT_RUN, # >>> is an example, not a doctest
'mercurial.posix': DONT_RUN, # run by mercurial.platform
'mercurial.statprof': DONT_RUN, # >>> is an example, not a doctest
'mercurial.util': [{}, {'testtarget': 'platform'}], # run twice!
'mercurial.windows': DONT_RUN, # run by mercurial.platform
'tests.test-url': [{'optionflags': doctest.NORMALIZE_WHITESPACE}],
}
fileset = 'set:(**.py)'
cwd = os.path.dirname(os.environ["TESTDIR"])
if not os.path.isdir(os.path.join(cwd, ".hg")):
sys.exit(0)
files = subprocess.check_output(
"hg files --print0 \"%s\"" % fileset,
shell=True,
cwd=cwd,
).split(b'\0')
if sys.version_info[0] >= 3:
cwd = os.fsencode(cwd)
mods_tested = set()
for f in files:
if not f:
continue
with open(os.path.join(cwd, f), "rb") as fh:
if not re.search(br'\n\s*>>>', fh.read()):
continue
if ispy3:
f = f.decode()
modname = f.replace('.py', '').replace('\\', '.').replace('/', '.')
# Third-party modules aren't our responsibility to test, and the modules in
# contrib generally do not have doctests in a good state, plus they're hard
# to import if this test is running with py2, so we just skip both for now.
if modname.startswith('mercurial.thirdparty.') or modname.startswith(
'contrib.'
):
continue
for kwargs in testmod_arg_overrides.get(modname, [{}]):
mods_tested.add((modname, '%r' % (kwargs,)))
if modname.startswith('tests.'):
# On py2, we can't import from tests.foo, but it works on both py2
# and py3 with the way that PYTHONPATH is setup to import without
# the 'tests.' prefix, so we do that.
modname = modname[len('tests.') :]
testmod(modname, **kwargs)
# Meta-test: let's make sure that we actually ran what we expected to, above.
# Each item in the set is a 2-tuple of module name and stringified kwargs passed
# to testmod.
expected_mods_tested = set(
[
('hgext.convert.convcmd', '{}'),
('hgext.convert.cvsps', '{}'),
('hgext.convert.filemap', '{}'),
('hgext.convert.p4', '{}'),
('hgext.convert.subversion', '{}'),
('hgext.fix', '{}'),
('hgext.mq', '{}'),
('mercurial.changelog', '{}'),
('mercurial.cmdutil', '{}'),
('mercurial.color', '{}'),
('mercurial.dagparser', "{'optionflags': 4}"),
('mercurial.dirstateutils.v2', '{}'),
('mercurial.encoding', '{}'),
('mercurial.fancyopts', '{}'),
('mercurial.formatter', '{}'),
('mercurial.hg', '{}'),
('mercurial.hgweb.hgwebdir_mod', '{}'),
('mercurial.match', '{}'),
('mercurial.mdiff', '{}'),
('mercurial.minirst', '{}'),
('mercurial.parser', '{}'),
('mercurial.patch', '{}'),
('mercurial.pathutil', '{}'),
('mercurial.pycompat', '{}'),
('mercurial.revlogutils.deltas', '{}'),
('mercurial.revset', '{}'),
('mercurial.revsetlang', '{}'),
('mercurial.simplemerge', '{}'),
('mercurial.smartset', '{}'),
('mercurial.store', '{}'),
('mercurial.subrepo', '{}'),
('mercurial.templater', '{}'),
('mercurial.ui', '{}'),
('mercurial.util', "{'testtarget': 'platform'}"),
('mercurial.util', '{}'),
('mercurial.utils.dateutil', '{}'),
('mercurial.utils.stringutil', '{}'),
('mercurial.utils.urlutil', '{}'),
('tests.drawdag', '{}'),
('tests.test-run-tests', '{}'),
('tests.test-url', "{'optionflags': 4}"),
]
)
unexpectedly_run = mods_tested.difference(expected_mods_tested)
not_run = expected_mods_tested.difference(mods_tested)
if unexpectedly_run:
print('Unexpectedly ran (probably need to add to list):')
for r in sorted(unexpectedly_run):
print(' %r' % (r,))
if not_run:
print('Expected to run, but was not run (doctest removed?):')
for r in sorted(not_run):
print(' %r' % (r,))