Mercurial > hg
view mercurial/changelog.py @ 42043:1fac9b931d46
compression: introduce a `storage.revlog.zlib.level` configuration
This option control the zlib compression level used when compression revlog
chunk.
This is also a good excuse to pave the way for a similar configuration option
for the zstd compression engine. Having a dedicated option for each compression
algorithm is useful because they don't support the same range of values.
Using a higher zlib compression impact CPU consumption at compression time, but
does not directly affected decompression time. However dealing with small
compressed chunk can directly help decompression and indirectly help other
revlog logic.
I ran some basic test on repositories using different level. I am using the
mercurial, pypy, netbeans and mozilla-central clone from our benchmark suite.
All tested repository use sparse-revlog and got all their delta recomputed.
The different compression level has a small effect on the repository size
(about 10% variation in the total range). My quick analysis is that revlog
mostly store small delta, that are not affected by the compression level much.
So the variation probably mostly comes from better compression of the snapshots
revisions, and snapshot revision only represent a small portion of the
repository content.
I also made some basic timings measurements. The "read" timings are gathered using
simple run of `hg perfrevlogrevisions`, the "write" timings using `hg
perfrevlogwrite` (restricted to the last 5000 revisions for netbeans and
mozilla central). The timings are gathered on a generic machine, (not one of
our performance locked machine), so small variation might not be meaningful.
However large trend remains relevant.
Keep in mind that these numbers are not pure compression/decompression time.
They also involve the full revlog logic. In particular the difference in chunk
size has an impact on the delta chain structure, affecting performance when
writing or reading them.
On read/write performance, the compression level has a bigger impact.
Counter-intuitively, the higher compression levels improve "write" performance
for the large repositories in our tested setting. Maybe because the last 5000
delta chain end up having a very different shape in this specific spot? Or maybe
because of a more general trend of better delta chains thanks to the smaller
chunk and snapshot.
This series does not intend to change the default compression level. However,
these result call for a deeper analysis of this performance difference in the
future.
Full data
=========
repo level .hg/store size 00manifest.d read write
----------------------------------------------------------------
mercurial 1 49,402,813 5,963,475 0.170159 53.250304
mercurial 6 47,197,397 5,875,730 0.182820 56.264320
mercurial 9 47,121,596 5,849,781 0.189219 56.293612
pypy 1 370,830,572 28,462,425 2.679217 460.721984
pypy 6 340,112,317 27,648,747 2.768691 467.537158
pypy 9 338,360,736 27,639,003 2.763495 476.589918
netbeans 1 1,281,847,810 165,495,457 122.477027 520.560316
netbeans 6 1,205,284,353 159,161,207 139.876147 715.930400
netbeans 9 1,197,135,671 155,034,586 141.620281 678.297064
mozilla 1 2,775,497,186 298,527,987 147.867662 751.263721
mozilla 6 2,596,856,420 286,597,671 170.572118 987.056093
mozilla 9 2,587,542,494 287,018,264 163.622338 739.803002
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Wed, 27 Mar 2019 18:35:27 +0100 |
parents | ae189674bdad |
children | caa067ee21dc |
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# changelog.py - changelog class for mercurial # # Copyright 2005-2007 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import from .i18n import _ from .node import ( bin, hex, nullid, ) from .thirdparty import ( attr, ) from . import ( encoding, error, pycompat, revlog, util, ) from .utils import ( dateutil, stringutil, ) _defaultextra = {'branch': 'default'} def _string_escape(text): """ >>> from .pycompat import bytechr as chr >>> d = {b'nl': chr(10), b'bs': chr(92), b'cr': chr(13), b'nul': chr(0)} >>> s = b"ab%(nl)scd%(bs)s%(bs)sn%(nul)sab%(cr)scd%(bs)s%(nl)s" % d >>> s 'ab\\ncd\\\\\\\\n\\x00ab\\rcd\\\\\\n' >>> res = _string_escape(s) >>> s == stringutil.unescapestr(res) True """ # subset of the string_escape codec text = text.replace('\\', '\\\\').replace('\n', '\\n').replace('\r', '\\r') return text.replace('\0', '\\0') def decodeextra(text): """ >>> from .pycompat import bytechr as chr >>> sorted(decodeextra(encodeextra({b'foo': b'bar', b'baz': chr(0) + b'2'}) ... ).items()) [('baz', '\\x002'), ('branch', 'default'), ('foo', 'bar')] >>> sorted(decodeextra(encodeextra({b'foo': b'bar', ... b'baz': chr(92) + chr(0) + b'2'}) ... ).items()) [('baz', '\\\\\\x002'), ('branch', 'default'), ('foo', 'bar')] """ extra = _defaultextra.copy() for l in text.split('\0'): if l: if '\\0' in l: # fix up \0 without getting into trouble with \\0 l = l.replace('\\\\', '\\\\\n') l = l.replace('\\0', '\0') l = l.replace('\n', '') k, v = stringutil.unescapestr(l).split(':', 1) extra[k] = v return extra def encodeextra(d): # keys must be sorted to produce a deterministic changelog entry items = [ _string_escape('%s:%s' % (k, pycompat.bytestr(d[k]))) for k in sorted(d) ] return "\0".join(items) def stripdesc(desc): """strip trailing whitespace and leading and trailing empty lines""" return '\n'.join([l.rstrip() for l in desc.splitlines()]).strip('\n') class appender(object): '''the changelog index must be updated last on disk, so we use this class to delay writes to it''' def __init__(self, vfs, name, mode, buf): self.data = buf fp = vfs(name, mode) self.fp = fp self.offset = fp.tell() self.size = vfs.fstat(fp).st_size self._end = self.size def end(self): return self._end def tell(self): return self.offset def flush(self): pass @property def closed(self): return self.fp.closed def close(self): self.fp.close() def seek(self, offset, whence=0): '''virtual file offset spans real file and data''' if whence == 0: self.offset = offset elif whence == 1: self.offset += offset elif whence == 2: self.offset = self.end() + offset if self.offset < self.size: self.fp.seek(self.offset) def read(self, count=-1): '''only trick here is reads that span real file and data''' ret = "" if self.offset < self.size: s = self.fp.read(count) ret = s self.offset += len(s) if count > 0: count -= len(s) if count != 0: doff = self.offset - self.size self.data.insert(0, "".join(self.data)) del self.data[1:] s = self.data[0][doff:doff + count] self.offset += len(s) ret += s return ret def write(self, s): self.data.append(bytes(s)) self.offset += len(s) self._end += len(s) def __enter__(self): self.fp.__enter__() return self def __exit__(self, *args): return self.fp.__exit__(*args) def _divertopener(opener, target): """build an opener that writes in 'target.a' instead of 'target'""" def _divert(name, mode='r', checkambig=False): if name != target: return opener(name, mode) return opener(name + ".a", mode) return _divert def _delayopener(opener, target, buf): """build an opener that stores chunks in 'buf' instead of 'target'""" def _delay(name, mode='r', checkambig=False): if name != target: return opener(name, mode) return appender(opener, name, mode, buf) return _delay @attr.s class _changelogrevision(object): # Extensions might modify _defaultextra, so let the constructor below pass # it in extra = attr.ib() manifest = attr.ib(default=nullid) user = attr.ib(default='') date = attr.ib(default=(0, 0)) files = attr.ib(default=attr.Factory(list)) description = attr.ib(default='') class changelogrevision(object): """Holds results of a parsed changelog revision. Changelog revisions consist of multiple pieces of data, including the manifest node, user, and date. This object exposes a view into the parsed object. """ __slots__ = ( r'_offsets', r'_text', ) def __new__(cls, text): if not text: return _changelogrevision(extra=_defaultextra) self = super(changelogrevision, cls).__new__(cls) # We could return here and implement the following as an __init__. # But doing it here is equivalent and saves an extra function call. # format used: # nodeid\n : manifest node in ascii # user\n : user, no \n or \r allowed # time tz extra\n : date (time is int or float, timezone is int) # : extra is metadata, encoded and separated by '\0' # : older versions ignore it # files\n\n : files modified by the cset, no \n or \r allowed # (.*) : comment (free text, ideally utf-8) # # changelog v0 doesn't use extra nl1 = text.index('\n') nl2 = text.index('\n', nl1 + 1) nl3 = text.index('\n', nl2 + 1) # The list of files may be empty. Which means nl3 is the first of the # double newline that precedes the description. if text[nl3 + 1:nl3 + 2] == '\n': doublenl = nl3 else: doublenl = text.index('\n\n', nl3 + 1) self._offsets = (nl1, nl2, nl3, doublenl) self._text = text return self @property def manifest(self): return bin(self._text[0:self._offsets[0]]) @property def user(self): off = self._offsets return encoding.tolocal(self._text[off[0] + 1:off[1]]) @property def _rawdate(self): off = self._offsets dateextra = self._text[off[1] + 1:off[2]] return dateextra.split(' ', 2)[0:2] @property def _rawextra(self): off = self._offsets dateextra = self._text[off[1] + 1:off[2]] fields = dateextra.split(' ', 2) if len(fields) != 3: return None return fields[2] @property def date(self): raw = self._rawdate time = float(raw[0]) # Various tools did silly things with the timezone. try: timezone = int(raw[1]) except ValueError: timezone = 0 return time, timezone @property def extra(self): raw = self._rawextra if raw is None: return _defaultextra return decodeextra(raw) @property def files(self): off = self._offsets if off[2] == off[3]: return [] return self._text[off[2] + 1:off[3]].split('\n') @property def description(self): return encoding.tolocal(self._text[self._offsets[3] + 2:]) class changelog(revlog.revlog): def __init__(self, opener, trypending=False): """Load a changelog revlog using an opener. If ``trypending`` is true, we attempt to load the index from a ``00changelog.i.a`` file instead of the default ``00changelog.i``. The ``00changelog.i.a`` file contains index (and possibly inline revision) data for a transaction that hasn't been finalized yet. It exists in a separate file to facilitate readers (such as hooks processes) accessing data before a transaction is finalized. """ if trypending and opener.exists('00changelog.i.a'): indexfile = '00changelog.i.a' else: indexfile = '00changelog.i' datafile = '00changelog.d' revlog.revlog.__init__(self, opener, indexfile, datafile=datafile, checkambig=True, mmaplargeindex=True) if self._initempty and (self.version & 0xFFFF == revlog.REVLOGV1): # changelogs don't benefit from generaldelta. self.version &= ~revlog.FLAG_GENERALDELTA self._generaldelta = False # Delta chains for changelogs tend to be very small because entries # tend to be small and don't delta well with each. So disable delta # chains. self._storedeltachains = False self._realopener = opener self._delayed = False self._delaybuf = None self._divert = False self.filteredrevs = frozenset() def tiprev(self): for i in pycompat.xrange(len(self) -1, -2, -1): if i not in self.filteredrevs: return i def tip(self): """filtered version of revlog.tip""" return self.node(self.tiprev()) def __contains__(self, rev): """filtered version of revlog.__contains__""" return (0 <= rev < len(self) and rev not in self.filteredrevs) def __iter__(self): """filtered version of revlog.__iter__""" if len(self.filteredrevs) == 0: return revlog.revlog.__iter__(self) def filterediter(): for i in pycompat.xrange(len(self)): if i not in self.filteredrevs: yield i return filterediter() def revs(self, start=0, stop=None): """filtered version of revlog.revs""" for i in super(changelog, self).revs(start, stop): if i not in self.filteredrevs: yield i def reachableroots(self, minroot, heads, roots, includepath=False): return self.index.reachableroots2(minroot, heads, roots, includepath) def _checknofilteredinrevs(self, revs): """raise the appropriate error if 'revs' contains a filtered revision This returns a version of 'revs' to be used thereafter by the caller. In particular, if revs is an iterator, it is converted into a set. """ safehasattr = util.safehasattr if safehasattr(revs, '__next__'): # Note that inspect.isgenerator() is not true for iterators, revs = set(revs) filteredrevs = self.filteredrevs if safehasattr(revs, 'first'): # smartset offenders = revs & filteredrevs else: offenders = filteredrevs.intersection(revs) for rev in offenders: raise error.FilteredIndexError(rev) return revs def headrevs(self, revs=None): if revs is None and self.filteredrevs: try: return self.index.headrevsfiltered(self.filteredrevs) # AttributeError covers non-c-extension environments and # old c extensions without filter handling. except AttributeError: return self._headrevs() if self.filteredrevs: revs = self._checknofilteredinrevs(revs) return super(changelog, self).headrevs(revs) def strip(self, *args, **kwargs): # XXX make something better than assert # We can't expect proper strip behavior if we are filtered. assert not self.filteredrevs super(changelog, self).strip(*args, **kwargs) def rev(self, node): """filtered version of revlog.rev""" r = super(changelog, self).rev(node) if r in self.filteredrevs: raise error.FilteredLookupError(hex(node), self.indexfile, _('filtered node')) return r def node(self, rev): """filtered version of revlog.node""" if rev in self.filteredrevs: raise error.FilteredIndexError(rev) return super(changelog, self).node(rev) def linkrev(self, rev): """filtered version of revlog.linkrev""" if rev in self.filteredrevs: raise error.FilteredIndexError(rev) return super(changelog, self).linkrev(rev) def parentrevs(self, rev): """filtered version of revlog.parentrevs""" if rev in self.filteredrevs: raise error.FilteredIndexError(rev) return super(changelog, self).parentrevs(rev) def flags(self, rev): """filtered version of revlog.flags""" if rev in self.filteredrevs: raise error.FilteredIndexError(rev) return super(changelog, self).flags(rev) def delayupdate(self, tr): "delay visibility of index updates to other readers" if not self._delayed: if len(self) == 0: self._divert = True if self._realopener.exists(self.indexfile + '.a'): self._realopener.unlink(self.indexfile + '.a') self.opener = _divertopener(self._realopener, self.indexfile) else: self._delaybuf = [] self.opener = _delayopener(self._realopener, self.indexfile, self._delaybuf) self._delayed = True tr.addpending('cl-%i' % id(self), self._writepending) tr.addfinalize('cl-%i' % id(self), self._finalize) def _finalize(self, tr): "finalize index updates" self._delayed = False self.opener = self._realopener # move redirected index data back into place if self._divert: assert not self._delaybuf tmpname = self.indexfile + ".a" nfile = self.opener.open(tmpname) nfile.close() self.opener.rename(tmpname, self.indexfile, checkambig=True) elif self._delaybuf: fp = self.opener(self.indexfile, 'a', checkambig=True) fp.write("".join(self._delaybuf)) fp.close() self._delaybuf = None self._divert = False # split when we're done self._enforceinlinesize(tr) def _writepending(self, tr): "create a file containing the unfinalized state for pretxnchangegroup" if self._delaybuf: # make a temporary copy of the index fp1 = self._realopener(self.indexfile) pendingfilename = self.indexfile + ".a" # register as a temp file to ensure cleanup on failure tr.registertmp(pendingfilename) # write existing data fp2 = self._realopener(pendingfilename, "w") fp2.write(fp1.read()) # add pending data fp2.write("".join(self._delaybuf)) fp2.close() # switch modes so finalize can simply rename self._delaybuf = None self._divert = True self.opener = _divertopener(self._realopener, self.indexfile) if self._divert: return True return False def _enforceinlinesize(self, tr, fp=None): if not self._delayed: revlog.revlog._enforceinlinesize(self, tr, fp) def read(self, node): """Obtain data from a parsed changelog revision. Returns a 6-tuple of: - manifest node in binary - author/user as a localstr - date as a 2-tuple of (time, timezone) - list of files - commit message as a localstr - dict of extra metadata Unless you need to access all fields, consider calling ``changelogrevision`` instead, as it is faster for partial object access. """ c = changelogrevision(self.revision(node)) return ( c.manifest, c.user, c.date, c.files, c.description, c.extra ) def changelogrevision(self, nodeorrev): """Obtain a ``changelogrevision`` for a node or revision.""" return changelogrevision(self.revision(nodeorrev)) def readfiles(self, node): """ short version of read that only returns the files modified by the cset """ text = self.revision(node) if not text: return [] last = text.index("\n\n") l = text[:last].split('\n') return l[3:] def add(self, manifest, files, desc, transaction, p1, p2, user, date=None, extra=None): # Convert to UTF-8 encoded bytestrings as the very first # thing: calling any method on a localstr object will turn it # into a str object and the cached UTF-8 string is thus lost. user, desc = encoding.fromlocal(user), encoding.fromlocal(desc) user = user.strip() # An empty username or a username with a "\n" will make the # revision text contain two "\n\n" sequences -> corrupt # repository since read cannot unpack the revision. if not user: raise error.StorageError(_("empty username")) if "\n" in user: raise error.StorageError(_("username %r contains a newline") % pycompat.bytestr(user)) desc = stripdesc(desc) if date: parseddate = "%d %d" % dateutil.parsedate(date) else: parseddate = "%d %d" % dateutil.makedate() if extra: branch = extra.get("branch") if branch in ("default", ""): del extra["branch"] elif branch in (".", "null", "tip"): raise error.StorageError(_('the name \'%s\' is reserved') % branch) if extra: extra = encodeextra(extra) parseddate = "%s %s" % (parseddate, extra) l = [hex(manifest), user, parseddate] + sorted(files) + ["", desc] text = "\n".join(l) return self.addrevision(text, transaction, len(self), p1, p2) def branchinfo(self, rev): """return the branch name and open/close state of a revision This function exists because creating a changectx object just to access this is costly.""" extra = self.read(rev)[5] return encoding.tolocal(extra.get("branch")), 'close' in extra def _nodeduplicatecallback(self, transaction, node): # keep track of revisions that got "re-added", eg: unbunde of know rev. # # We track them in a list to preserve their order from the source bundle duplicates = transaction.changes.setdefault('revduplicates', []) duplicates.append(self.rev(node))