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
#!/usr/bin/env python3
#
# checkseclevel - checking section title levels in each online help document
import optparse
import os
import sys
# import from the live mercurial repo
os.environ['HGMODULEPOLICY'] = 'py'
sys.path.insert(0, os.path.abspath(".."))
from mercurial import demandimport
demandimport.enable()
from mercurial import (
commands,
extensions,
help,
minirst,
ui as uimod,
)
table = commands.table
helptable = help.helptable
level2mark = [b'"', b'=', b'-', b'.', b'#']
reservedmarks = [b'"']
mark2level = {}
for m, l in zip(level2mark, range(len(level2mark))):
if m not in reservedmarks:
mark2level[m] = l
initlevel_topic = 0
initlevel_cmd = 1
initlevel_ext = 1
initlevel_ext_cmd = 3
def showavailables(ui, initlevel):
avail = ' available marks and order of them in this help: %s\n' % (
', '.join(['%r' % (m * 4) for m in level2mark[initlevel + 1 :]])
)
ui.warn(avail.encode('utf-8'))
def checkseclevel(ui, doc, name, initlevel):
ui.notenoi18n('checking "%s"\n' % name)
if not isinstance(doc, bytes):
doc = doc.encode('utf-8')
blocks, pruned = minirst.parse(doc, 0, ['verbose'])
errorcnt = 0
curlevel = initlevel
for block in blocks:
if block[b'type'] != b'section':
continue
mark = block[b'underline']
title = block[b'lines'][0]
if (mark not in mark2level) or (mark2level[mark] <= initlevel):
ui.warn(
(
'invalid section mark %r for "%s" of %s\n'
% (mark * 4, title, name)
).encode('utf-8')
)
showavailables(ui, initlevel)
errorcnt += 1
continue
nextlevel = mark2level[mark]
if curlevel < nextlevel and curlevel + 1 != nextlevel:
ui.warnnoi18n(
'gap of section level at "%s" of %s\n' % (title, name)
)
showavailables(ui, initlevel)
errorcnt += 1
continue
ui.notenoi18n(
'appropriate section level for "%s %s"\n'
% (mark * (nextlevel * 2), title)
)
curlevel = nextlevel
return errorcnt
def checkcmdtable(ui, cmdtable, namefmt, initlevel):
errorcnt = 0
for k, entry in cmdtable.items():
name = k.split(b"|")[0].lstrip(b"^")
if not entry[0].__doc__:
ui.notenoi18n(
'skip checking %s: no help document\n' % (namefmt % name)
)
continue
errorcnt += checkseclevel(
ui, entry[0].__doc__, namefmt % name, initlevel
)
return errorcnt
def checkhghelps(ui):
errorcnt = 0
for h in helptable:
names, sec, doc = h[0:3]
if callable(doc):
doc = doc(ui)
errorcnt += checkseclevel(
ui, doc, '%s help topic' % names[0], initlevel_topic
)
errorcnt += checkcmdtable(ui, table, '%s command', initlevel_cmd)
for name in sorted(
list(extensions.enabled()) + list(extensions.disabled())
):
mod = extensions.load(ui, name, None)
if not mod.__doc__:
ui.notenoi18n(
'skip checking %s extension: no help document\n' % name
)
continue
errorcnt += checkseclevel(
ui, mod.__doc__, '%s extension' % name, initlevel_ext
)
cmdtable = getattr(mod, 'cmdtable', None)
if cmdtable:
errorcnt += checkcmdtable(
ui,
cmdtable,
'%%s command of %s extension' % name,
initlevel_ext_cmd,
)
return errorcnt
def checkfile(ui, filename, initlevel):
if filename == '-':
filename = 'stdin'
doc = sys.stdin.read()
else:
with open(filename) as fp:
doc = fp.read()
ui.notenoi18n(
'checking input from %s with initlevel %d\n' % (filename, initlevel)
)
return checkseclevel(ui, doc, 'input from %s' % filename, initlevel)
def main():
optparser = optparse.OptionParser(
"""%prog [options]
This checks all help documents of Mercurial (topics, commands,
extensions and commands of them), if no file is specified by --file
option.
"""
)
optparser.add_option(
"-v", "--verbose", help="enable additional output", action="store_true"
)
optparser.add_option(
"-d", "--debug", help="debug mode", action="store_true"
)
optparser.add_option(
"-f",
"--file",
help="filename to read in (or '-' for stdin)",
action="store",
default="",
)
optparser.add_option(
"-t",
"--topic",
help="parse file as help topic",
action="store_const",
dest="initlevel",
const=0,
)
optparser.add_option(
"-c",
"--command",
help="parse file as help of core command",
action="store_const",
dest="initlevel",
const=1,
)
optparser.add_option(
"-e",
"--extension",
help="parse file as help of extension",
action="store_const",
dest="initlevel",
const=1,
)
optparser.add_option(
"-C",
"--extension-command",
help="parse file as help of extension command",
action="store_const",
dest="initlevel",
const=3,
)
optparser.add_option(
"-l",
"--initlevel",
help="set initial section level manually",
action="store",
type="int",
default=0,
)
(options, args) = optparser.parse_args()
ui = uimod.ui.load()
ui.setconfig(b'ui', b'verbose', options.verbose, b'--verbose')
ui.setconfig(b'ui', b'debug', options.debug, b'--debug')
if options.file:
if checkfile(ui, options.file, options.initlevel):
sys.exit(1)
else:
if checkhghelps(ui):
sys.exit(1)
if __name__ == "__main__":
main()