match: convert O(n) to O(log n) in exactmatcher.visitchildrenset
When using narrow, during rebase this is called (at least) once per directory in
the set of files in the commit being rebased. Every time it's called, we did the
set arithmetic (now extracted and cached), which was probably pretty cheap but
not necessary to repeat each time, looped over every item in the matcher and
kept things that started with the directory we were querying.
With very large narrowspecs, and a commit that touched a file in a large number
of directories, this was slow. In a pathological repo, the rebase of a single
commit (that touched over 17k files, I believe in approximately as many
directories) with a narrowspec that had >32k entries took 8,246s of profiled
time, with 5,007s of that spent in visitchildrenset (transitively). With this
change, the time spent in visitchildrenset is less than 34s (which is where my
profile cut off). Most of the remaining time was network access due to our
custom remotefilelog-based setup not properly prefetching.
Differential Revision: https://phab.mercurial-scm.org/D10294
# Mercurial extension to provide 'hg relink' command
#
# Copyright (C) 2007 Brendan Cully <brendan@kublai.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""recreates hardlinks between repository clones"""
from __future__ import absolute_import
import os
import stat
from mercurial.i18n import _
from mercurial.pycompat import open
from mercurial import (
error,
hg,
registrar,
util,
)
from mercurial.utils import stringutil
cmdtable = {}
command = registrar.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'
@command(
b'relink', [], _(b'[ORIGIN]'), helpcategory=command.CATEGORY_MAINTENANCE
)
def relink(ui, repo, origin=None, **opts):
"""recreate hardlinks between two repositories
When repositories are cloned locally, their data files will be
hardlinked so that they only use the space of a single repository.
Unfortunately, subsequent pulls into either repository will break
hardlinks for any files touched by the new changesets, even if
both repositories end up pulling the same changes.
Similarly, passing --rev to "hg clone" will fail to use any
hardlinks, falling back to a complete copy of the source
repository.
This command lets you recreate those hardlinks and reclaim that
wasted space.
This repository will be relinked to share space with ORIGIN, which
must be on the same local disk. If ORIGIN is omitted, looks for
"default-relink", then "default", in [paths].
Do not attempt any read operations on this repository while the
command is running. (Both repositories will be locked against
writes.)
"""
if not util.safehasattr(util, b'samefile') or not util.safehasattr(
util, b'samedevice'
):
raise error.Abort(_(b'hardlinks are not supported on this system'))
src = hg.repository(
repo.baseui,
ui.expandpath(origin or b'default-relink', origin or b'default'),
)
ui.status(_(b'relinking %s to %s\n') % (src.store.path, repo.store.path))
if repo.root == src.root:
ui.status(_(b'there is nothing to relink\n'))
return
if not util.samedevice(src.store.path, repo.store.path):
# No point in continuing
raise error.Abort(_(b'source and destination are on different devices'))
with repo.lock(), src.lock():
candidates = sorted(collect(src, ui))
targets = prune(candidates, src.store.path, repo.store.path, ui)
do_relink(src.store.path, repo.store.path, targets, ui)
def collect(src, ui):
seplen = len(os.path.sep)
candidates = []
live = len(src[b'tip'].manifest())
# Your average repository has some files which were deleted before
# the tip revision. We account for that by assuming that there are
# 3 tracked files for every 2 live files as of the tip version of
# the repository.
#
# mozilla-central as of 2010-06-10 had a ratio of just over 7:5.
total = live * 3 // 2
src = src.store.path
progress = ui.makeprogress(_(b'collecting'), unit=_(b'files'), total=total)
pos = 0
ui.status(
_(b"tip has %d files, estimated total number of files: %d\n")
% (live, total)
)
for dirpath, dirnames, filenames in os.walk(src):
dirnames.sort()
relpath = dirpath[len(src) + seplen :]
for filename in sorted(filenames):
if filename[-2:] not in (b'.d', b'.i'):
continue
st = os.stat(os.path.join(dirpath, filename))
if not stat.S_ISREG(st.st_mode):
continue
pos += 1
candidates.append((os.path.join(relpath, filename), st))
progress.update(pos, item=filename)
progress.complete()
ui.status(_(b'collected %d candidate storage files\n') % len(candidates))
return candidates
def prune(candidates, src, dst, ui):
def linkfilter(src, dst, st):
try:
ts = os.stat(dst)
except OSError:
# Destination doesn't have this file?
return False
if util.samefile(src, dst):
return False
if not util.samedevice(src, dst):
# No point in continuing
raise error.Abort(
_(b'source and destination are on different devices')
)
if st.st_size != ts.st_size:
return False
return st
targets = []
progress = ui.makeprogress(
_(b'pruning'), unit=_(b'files'), total=len(candidates)
)
pos = 0
for fn, st in candidates:
pos += 1
srcpath = os.path.join(src, fn)
tgt = os.path.join(dst, fn)
ts = linkfilter(srcpath, tgt, st)
if not ts:
ui.debug(b'not linkable: %s\n' % fn)
continue
targets.append((fn, ts.st_size))
progress.update(pos, item=fn)
progress.complete()
ui.status(
_(b'pruned down to %d probably relinkable files\n') % len(targets)
)
return targets
def do_relink(src, dst, files, ui):
def relinkfile(src, dst):
bak = dst + b'.bak'
os.rename(dst, bak)
try:
util.oslink(src, dst)
except OSError:
os.rename(bak, dst)
raise
os.remove(bak)
CHUNKLEN = 65536
relinked = 0
savedbytes = 0
progress = ui.makeprogress(
_(b'relinking'), unit=_(b'files'), total=len(files)
)
pos = 0
for f, sz in files:
pos += 1
source = os.path.join(src, f)
tgt = os.path.join(dst, f)
# Binary mode, so that read() works correctly, especially on Windows
sfp = open(source, b'rb')
dfp = open(tgt, b'rb')
sin = sfp.read(CHUNKLEN)
while sin:
din = dfp.read(CHUNKLEN)
if sin != din:
break
sin = sfp.read(CHUNKLEN)
sfp.close()
dfp.close()
if sin:
ui.debug(b'not linkable: %s\n' % f)
continue
try:
relinkfile(source, tgt)
progress.update(pos, item=f)
relinked += 1
savedbytes += sz
except OSError as inst:
ui.warn(b'%s: %s\n' % (tgt, stringutil.forcebytestr(inst)))
progress.complete()
ui.status(
_(b'relinked %d files (%s reclaimed)\n')
% (relinked, util.bytecount(savedbytes))
)