rust-discovery: using from Python code
As previously done in other topics, the Rust version is used if it's been
built.
The version fully in Rust of the partialdiscovery class has the performance
advantage over the Python version (actually using the Rust MissingAncestor) if
the undecided set is big enough. Otherwise no sampling occurs, and the
discovery is reasonably fast anyway.
Note: it's hard to predict the size of the initial undecided set, it can
depend on the kind of topological changes between the local and remote graphs.
The point of the Rust version is to make the bad cases acceptable.
More specifically, the performance advantages are:
- faster sampling, especially takefullsample()
- much faster addmissings() in almost all cases (see commit message in
grandparent of the present changeset)
- no conversion cost of the undecided set at the interface between Rust and
Python
== Measurements with big undecided sets
For an extreme example, discovery between mozilla-try and mozilla-unified
(over one million undecided revisions, same case as in dbd0fcca6dfc), we
get roughly a x2.5/x3 better performance:
Growing sample size (5% starting with 200): time goes down from
210 to 72 seconds.
Constant sample size of 200: time down from 1853 to 659 seconds.
With a sample size computed from number of roots and heads of the
undecided set (`respectsize` is `False`), here are perfdiscovery results:
Before ! wall 9.358729 comb 9.360000 user 9.310000 sys 0.050000 (median of 50)
After ! wall 3.793819 comb 3.790000 user 3.750000 sys 0.040000 (median of 50)
In that later case, the sample sizes are routinely in the hundreds of
thousands of revisions. While still faster, the Rust iteration in
addmissings has less of an advantage than with smaller sample sizes, but
one sees addcommons becoming faster, probably a consequence of not having
to copy big sets back and forth.
This example is not a goal in itself, but it showcases several different
areas in which the process can become slow, due to different factors, and
how this full Rust version can help.
== Measurements with small undecided sets
In cases the undecided set is small enough than no sampling occurs,
the Rust version has a disadvantage at init if `targetheads` is really big
(some time is lost in the translation to Rust data structures),
and that is compensated by the faster `addmissings()`.
On a private repository with over one million commits, we still get a minor
improvement, of 6.8%:
Before ! wall 0.593585 comb 0.590000 user 0.550000 sys 0.040000 (median of 50)
After ! wall 0.553035 comb 0.550000 user 0.520000 sys 0.030000 (median of 50)
What's interesting in that case is the first addinfo() at 180ms for Rust and
233ms for Python+C, mostly due to add_missings and the children cache
computation being done in less than 0.2ms on the Rust side vs over 40ms on the
Python side.
The worst case we have on hand is with mozilla-try, prepared with
discovery-helper.sh for 10 heads and depth 10, time goes up 2.2% on the median.
In this case `targetheads` is really huge with 165842 server heads.
Before ! wall 0.823884 comb 0.810000 user 0.790000 sys 0.020000 (median of 50)
After ! wall 0.842607 comb 0.840000 user 0.800000 sys 0.040000 (median of 50)
If that would be considered a problem, more adjustments can be made, which are
prematurate at this stage: cooking special variants of methods of the inner
MissingAncestors object, retrieving local heads directly from Rust to avoid
the cost of conversion. Effort would probably be better spent at this point
improving the surroundings if needed.
Here's another data point with a smaller repository, pypy, where performance
is almost identical
Before ! wall 0.015121 comb 0.030000 user 0.020000 sys 0.010000 (median of 186)
After ! wall 0.015009 comb 0.010000 user 0.010000 sys 0.000000 (median of 184)
Differential Revision: https://phab.mercurial-scm.org/D6430
# 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)s12ab%(cr)scd%(bs)s%(nl)s" % d
>>> s
'ab\\ncd\\\\\\\\n\\x0012ab\\rcd\\\\\\n'
>>> res = _string_escape(s)
>>> s == _string_unescape(res)
True
"""
# subset of the string_escape codec
text = text.replace('\\', '\\\\').replace('\n', '\\n').replace('\r', '\\r')
return text.replace('\0', '\\0')
def _string_unescape(text):
if '\\0' in text:
# fix up \0 without getting into trouble with \\0
text = text.replace('\\\\', '\\\\\n')
text = text.replace('\\0', '\0')
text = text.replace('\n', '')
return stringutil.unescapestr(text)
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:
k, v = _string_unescape(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 encodecopies(files, copies):
items = []
for i, dst in enumerate(files):
if dst in copies:
items.append('%d\0%s' % (i, copies[dst]))
if len(items) != len(copies):
raise error.ProgrammingError('some copy targets missing from file list')
return "\n".join(items)
def decodecopies(files, data):
try:
copies = {}
if not data:
return copies
for l in data.split('\n'):
strindex, src = l.split('\0')
i = int(strindex)
dst = files[i]
copies[dst] = src
return copies
except (ValueError, IndexError):
# Perhaps someone had chosen the same key name (e.g. "p1copies") and
# used different syntax for the value.
return None
def encodefileindices(files, subset):
subset = set(subset)
indices = []
for i, f in enumerate(files):
if f in subset:
indices.append('%d' % i)
return '\n'.join(indices)
def decodefileindices(files, data):
try:
subset = []
if not data:
return subset
for strindex in data.split('\n'):
i = int(strindex)
if i < 0 or i >= len(files):
return None
subset.append(files[i])
return subset
except (ValueError, IndexError):
# Perhaps someone had chosen the same key name (e.g. "added") and
# used different syntax for the value.
return None
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))
filesadded = attr.ib(default=None)
filesremoved = attr.ib(default=None)
p1copies = attr.ib(default=None)
p2copies = attr.ib(default=None)
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 filesadded(self):
rawindices = self.extra.get('filesadded')
return rawindices and decodefileindices(self.files, rawindices)
@property
def filesremoved(self):
rawindices = self.extra.get('filesremoved')
return rawindices and decodefileindices(self.files, rawindices)
@property
def p1copies(self):
rawcopies = self.extra.get('p1copies')
return rawcopies and decodecopies(self.files, rawcopies)
@property
def p2copies(self):
rawcopies = self.extra.get('p2copies')
return rawcopies and decodecopies(self.files, rawcopies)
@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 _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, p1copies=None, p2copies=None,
filesadded=None, filesremoved=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)
extrasentries = p1copies, p2copies, filesadded, filesremoved
if extra is None and any(x is not None for x in extrasentries):
extra = {}
sortedfiles = sorted(files)
if p1copies is not None:
extra['p1copies'] = encodecopies(sortedfiles, p1copies)
if p2copies is not None:
extra['p2copies'] = encodecopies(sortedfiles, p2copies)
if filesadded is not None:
extra['filesadded'] = encodefileindices(sortedfiles, filesadded)
if filesremoved is not None:
extra['filesremoved'] = encodefileindices(sortedfiles, filesremoved)
if extra:
extra = encodeextra(extra)
parseddate = "%s %s" % (parseddate, extra)
l = [hex(manifest), user, parseddate] + sortedfiles + ["", 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))