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
# store.py - repository store handling for Mercurial
#
# Copyright 2008 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
import errno
import functools
import hashlib
import os
import stat
from .i18n import _
from . import (
error,
node,
policy,
pycompat,
util,
vfs as vfsmod,
)
parsers = policy.importmod(r'parsers')
# how much bytes should be read from fncache in one read
# It is done to prevent loading large fncache files into memory
fncache_chunksize = 10 ** 6
def _matchtrackedpath(path, matcher):
"""parses a fncache entry and returns whether the entry is tracking a path
matched by matcher or not.
If matcher is None, returns True"""
if matcher is None:
return True
path = decodedir(path)
if path.startswith('data/'):
return matcher(path[len('data/'):-len('.i')])
elif path.startswith('meta/'):
return matcher.visitdir(path[len('meta/'):-len('/00manifest.i')])
raise error.ProgrammingError("cannot decode path %s" % path)
# This avoids a collision between a file named foo and a dir named
# foo.i or foo.d
def _encodedir(path):
'''
>>> _encodedir(b'data/foo.i')
'data/foo.i'
>>> _encodedir(b'data/foo.i/bla.i')
'data/foo.i.hg/bla.i'
>>> _encodedir(b'data/foo.i.hg/bla.i')
'data/foo.i.hg.hg/bla.i'
>>> _encodedir(b'data/foo.i\\ndata/foo.i/bla.i\\ndata/foo.i.hg/bla.i\\n')
'data/foo.i\\ndata/foo.i.hg/bla.i\\ndata/foo.i.hg.hg/bla.i\\n'
'''
return (path
.replace(".hg/", ".hg.hg/")
.replace(".i/", ".i.hg/")
.replace(".d/", ".d.hg/"))
encodedir = getattr(parsers, 'encodedir', _encodedir)
def decodedir(path):
'''
>>> decodedir(b'data/foo.i')
'data/foo.i'
>>> decodedir(b'data/foo.i.hg/bla.i')
'data/foo.i/bla.i'
>>> decodedir(b'data/foo.i.hg.hg/bla.i')
'data/foo.i.hg/bla.i'
'''
if ".hg/" not in path:
return path
return (path
.replace(".d.hg/", ".d/")
.replace(".i.hg/", ".i/")
.replace(".hg.hg/", ".hg/"))
def _reserved():
''' characters that are problematic for filesystems
* ascii escapes (0..31)
* ascii hi (126..255)
* windows specials
these characters will be escaped by encodefunctions
'''
winreserved = [ord(x) for x in u'\\:*?"<>|']
for x in range(32):
yield x
for x in range(126, 256):
yield x
for x in winreserved:
yield x
def _buildencodefun():
'''
>>> enc, dec = _buildencodefun()
>>> enc(b'nothing/special.txt')
'nothing/special.txt'
>>> dec(b'nothing/special.txt')
'nothing/special.txt'
>>> enc(b'HELLO')
'_h_e_l_l_o'
>>> dec(b'_h_e_l_l_o')
'HELLO'
>>> enc(b'hello:world?')
'hello~3aworld~3f'
>>> dec(b'hello~3aworld~3f')
'hello:world?'
>>> enc(b'the\\x07quick\\xADshot')
'the~07quick~adshot'
>>> dec(b'the~07quick~adshot')
'the\\x07quick\\xadshot'
'''
e = '_'
xchr = pycompat.bytechr
asciistr = list(map(xchr, range(127)))
capitals = list(range(ord("A"), ord("Z") + 1))
cmap = dict((x, x) for x in asciistr)
for x in _reserved():
cmap[xchr(x)] = "~%02x" % x
for x in capitals + [ord(e)]:
cmap[xchr(x)] = e + xchr(x).lower()
dmap = {}
for k, v in cmap.iteritems():
dmap[v] = k
def decode(s):
i = 0
while i < len(s):
for l in pycompat.xrange(1, 4):
try:
yield dmap[s[i:i + l]]
i += l
break
except KeyError:
pass
else:
raise KeyError
return (lambda s: ''.join([cmap[s[c:c + 1]]
for c in pycompat.xrange(len(s))]),
lambda s: ''.join(list(decode(s))))
_encodefname, _decodefname = _buildencodefun()
def encodefilename(s):
'''
>>> encodefilename(b'foo.i/bar.d/bla.hg/hi:world?/HELLO')
'foo.i.hg/bar.d.hg/bla.hg.hg/hi~3aworld~3f/_h_e_l_l_o'
'''
return _encodefname(encodedir(s))
def decodefilename(s):
'''
>>> decodefilename(b'foo.i.hg/bar.d.hg/bla.hg.hg/hi~3aworld~3f/_h_e_l_l_o')
'foo.i/bar.d/bla.hg/hi:world?/HELLO'
'''
return decodedir(_decodefname(s))
def _buildlowerencodefun():
'''
>>> f = _buildlowerencodefun()
>>> f(b'nothing/special.txt')
'nothing/special.txt'
>>> f(b'HELLO')
'hello'
>>> f(b'hello:world?')
'hello~3aworld~3f'
>>> f(b'the\\x07quick\\xADshot')
'the~07quick~adshot'
'''
xchr = pycompat.bytechr
cmap = dict([(xchr(x), xchr(x)) for x in pycompat.xrange(127)])
for x in _reserved():
cmap[xchr(x)] = "~%02x" % x
for x in range(ord("A"), ord("Z") + 1):
cmap[xchr(x)] = xchr(x).lower()
def lowerencode(s):
return "".join([cmap[c] for c in pycompat.iterbytestr(s)])
return lowerencode
lowerencode = getattr(parsers, 'lowerencode', None) or _buildlowerencodefun()
# Windows reserved names: con, prn, aux, nul, com1..com9, lpt1..lpt9
_winres3 = ('aux', 'con', 'prn', 'nul') # length 3
_winres4 = ('com', 'lpt') # length 4 (with trailing 1..9)
def _auxencode(path, dotencode):
'''
Encodes filenames containing names reserved by Windows or which end in
period or space. Does not touch other single reserved characters c.
Specifically, c in '\\:*?"<>|' or ord(c) <= 31 are *not* encoded here.
Additionally encodes space or period at the beginning, if dotencode is
True. Parameter path is assumed to be all lowercase.
A segment only needs encoding if a reserved name appears as a
basename (e.g. "aux", "aux.foo"). A directory or file named "foo.aux"
doesn't need encoding.
>>> s = b'.foo/aux.txt/txt.aux/con/prn/nul/foo.'
>>> _auxencode(s.split(b'/'), True)
['~2efoo', 'au~78.txt', 'txt.aux', 'co~6e', 'pr~6e', 'nu~6c', 'foo~2e']
>>> s = b'.com1com2/lpt9.lpt4.lpt1/conprn/com0/lpt0/foo.'
>>> _auxencode(s.split(b'/'), False)
['.com1com2', 'lp~749.lpt4.lpt1', 'conprn', 'com0', 'lpt0', 'foo~2e']
>>> _auxencode([b'foo. '], True)
['foo.~20']
>>> _auxencode([b' .foo'], True)
['~20.foo']
'''
for i, n in enumerate(path):
if not n:
continue
if dotencode and n[0] in '. ':
n = "~%02x" % ord(n[0:1]) + n[1:]
path[i] = n
else:
l = n.find('.')
if l == -1:
l = len(n)
if ((l == 3 and n[:3] in _winres3) or
(l == 4 and n[3:4] <= '9' and n[3:4] >= '1'
and n[:3] in _winres4)):
# encode third letter ('aux' -> 'au~78')
ec = "~%02x" % ord(n[2:3])
n = n[0:2] + ec + n[3:]
path[i] = n
if n[-1] in '. ':
# encode last period or space ('foo...' -> 'foo..~2e')
path[i] = n[:-1] + "~%02x" % ord(n[-1:])
return path
_maxstorepathlen = 120
_dirprefixlen = 8
_maxshortdirslen = 8 * (_dirprefixlen + 1) - 4
def _hashencode(path, dotencode):
digest = node.hex(hashlib.sha1(path).digest())
le = lowerencode(path[5:]).split('/') # skips prefix 'data/' or 'meta/'
parts = _auxencode(le, dotencode)
basename = parts[-1]
_root, ext = os.path.splitext(basename)
sdirs = []
sdirslen = 0
for p in parts[:-1]:
d = p[:_dirprefixlen]
if d[-1] in '. ':
# Windows can't access dirs ending in period or space
d = d[:-1] + '_'
if sdirslen == 0:
t = len(d)
else:
t = sdirslen + 1 + len(d)
if t > _maxshortdirslen:
break
sdirs.append(d)
sdirslen = t
dirs = '/'.join(sdirs)
if len(dirs) > 0:
dirs += '/'
res = 'dh/' + dirs + digest + ext
spaceleft = _maxstorepathlen - len(res)
if spaceleft > 0:
filler = basename[:spaceleft]
res = 'dh/' + dirs + filler + digest + ext
return res
def _hybridencode(path, dotencode):
'''encodes path with a length limit
Encodes all paths that begin with 'data/', according to the following.
Default encoding (reversible):
Encodes all uppercase letters 'X' as '_x'. All reserved or illegal
characters are encoded as '~xx', where xx is the two digit hex code
of the character (see encodefilename).
Relevant path components consisting of Windows reserved filenames are
masked by encoding the third character ('aux' -> 'au~78', see _auxencode).
Hashed encoding (not reversible):
If the default-encoded path is longer than _maxstorepathlen, a
non-reversible hybrid hashing of the path is done instead.
This encoding uses up to _dirprefixlen characters of all directory
levels of the lowerencoded path, but not more levels than can fit into
_maxshortdirslen.
Then follows the filler followed by the sha digest of the full path.
The filler is the beginning of the basename of the lowerencoded path
(the basename is everything after the last path separator). The filler
is as long as possible, filling in characters from the basename until
the encoded path has _maxstorepathlen characters (or all chars of the
basename have been taken).
The extension (e.g. '.i' or '.d') is preserved.
The string 'data/' at the beginning is replaced with 'dh/', if the hashed
encoding was used.
'''
path = encodedir(path)
ef = _encodefname(path).split('/')
res = '/'.join(_auxencode(ef, dotencode))
if len(res) > _maxstorepathlen:
res = _hashencode(path, dotencode)
return res
def _pathencode(path):
de = encodedir(path)
if len(path) > _maxstorepathlen:
return _hashencode(de, True)
ef = _encodefname(de).split('/')
res = '/'.join(_auxencode(ef, True))
if len(res) > _maxstorepathlen:
return _hashencode(de, True)
return res
_pathencode = getattr(parsers, 'pathencode', _pathencode)
def _plainhybridencode(f):
return _hybridencode(f, False)
def _calcmode(vfs):
try:
# files in .hg/ will be created using this mode
mode = vfs.stat().st_mode
# avoid some useless chmods
if (0o777 & ~util.umask) == (0o777 & mode):
mode = None
except OSError:
mode = None
return mode
_data = ('bookmarks narrowspec data meta 00manifest.d 00manifest.i'
' 00changelog.d 00changelog.i phaseroots obsstore')
def isrevlog(f, kind, st):
return kind == stat.S_IFREG and f[-2:] in ('.i', '.d')
class basicstore(object):
'''base class for local repository stores'''
def __init__(self, path, vfstype):
vfs = vfstype(path)
self.path = vfs.base
self.createmode = _calcmode(vfs)
vfs.createmode = self.createmode
self.rawvfs = vfs
self.vfs = vfsmod.filtervfs(vfs, encodedir)
self.opener = self.vfs
def join(self, f):
return self.path + '/' + encodedir(f)
def _walk(self, relpath, recurse, filefilter=isrevlog):
'''yields (unencoded, encoded, size)'''
path = self.path
if relpath:
path += '/' + relpath
striplen = len(self.path) + 1
l = []
if self.rawvfs.isdir(path):
visit = [path]
readdir = self.rawvfs.readdir
while visit:
p = visit.pop()
for f, kind, st in readdir(p, stat=True):
fp = p + '/' + f
if filefilter(f, kind, st):
n = util.pconvert(fp[striplen:])
l.append((decodedir(n), n, st.st_size))
elif kind == stat.S_IFDIR and recurse:
visit.append(fp)
l.sort()
return l
def datafiles(self, matcher=None):
return self._walk('data', True) + self._walk('meta', True)
def topfiles(self):
# yield manifest before changelog
return reversed(self._walk('', False))
def walk(self, matcher=None):
'''yields (unencoded, encoded, size)
if a matcher is passed, storage files of only those tracked paths
are passed with matches the matcher
'''
# yield data files first
for x in self.datafiles(matcher):
yield x
for x in self.topfiles():
yield x
def copylist(self):
return ['requires'] + _data.split()
def write(self, tr):
pass
def invalidatecaches(self):
pass
def markremoved(self, fn):
pass
def __contains__(self, path):
'''Checks if the store contains path'''
path = "/".join(("data", path))
# file?
if self.vfs.exists(path + ".i"):
return True
# dir?
if not path.endswith("/"):
path = path + "/"
return self.vfs.exists(path)
class encodedstore(basicstore):
def __init__(self, path, vfstype):
vfs = vfstype(path + '/store')
self.path = vfs.base
self.createmode = _calcmode(vfs)
vfs.createmode = self.createmode
self.rawvfs = vfs
self.vfs = vfsmod.filtervfs(vfs, encodefilename)
self.opener = self.vfs
def datafiles(self, matcher=None):
for a, b, size in super(encodedstore, self).datafiles():
try:
a = decodefilename(a)
except KeyError:
a = None
if a is not None and not _matchtrackedpath(a, matcher):
continue
yield a, b, size
def join(self, f):
return self.path + '/' + encodefilename(f)
def copylist(self):
return (['requires', '00changelog.i'] +
['store/' + f for f in _data.split()])
class fncache(object):
# the filename used to be partially encoded
# hence the encodedir/decodedir dance
def __init__(self, vfs):
self.vfs = vfs
self.entries = None
self._dirty = False
# set of new additions to fncache
self.addls = set()
def ensureloaded(self, warn=None):
'''read the fncache file if not already read.
If the file on disk is corrupted, raise. If warn is provided,
warn and keep going instead.'''
if self.entries is None:
self._load(warn)
def _load(self, warn=None):
'''fill the entries from the fncache file'''
self._dirty = False
try:
fp = self.vfs('fncache', mode='rb')
except IOError:
# skip nonexistent file
self.entries = set()
return
self.entries = set()
chunk = b''
for c in iter(functools.partial(fp.read, fncache_chunksize), b''):
chunk += c
try:
p = chunk.rindex(b'\n')
self.entries.update(decodedir(chunk[:p + 1]).splitlines())
chunk = chunk[p + 1:]
except ValueError:
# substring '\n' not found, maybe the entry is bigger than the
# chunksize, so let's keep iterating
pass
if chunk:
msg = _("fncache does not ends with a newline")
if warn:
warn(msg + '\n')
else:
raise error.Abort(msg,
hint=_("use 'hg debugrebuildfncache' to "
"rebuild the fncache"))
self._checkentries(fp, warn)
fp.close()
def _checkentries(self, fp, warn):
""" make sure there is no empty string in entries """
if '' in self.entries:
fp.seek(0)
for n, line in enumerate(util.iterfile(fp)):
if not line.rstrip('\n'):
t = _('invalid entry in fncache, line %d') % (n + 1)
if warn:
warn(t + '\n')
else:
raise error.Abort(t)
def write(self, tr):
if self._dirty:
assert self.entries is not None
self.entries = self.entries | self.addls
self.addls = set()
tr.addbackup('fncache')
fp = self.vfs('fncache', mode='wb', atomictemp=True)
if self.entries:
fp.write(encodedir('\n'.join(self.entries) + '\n'))
fp.close()
self._dirty = False
if self.addls:
# if we have just new entries, let's append them to the fncache
tr.addbackup('fncache')
fp = self.vfs('fncache', mode='ab', atomictemp=True)
if self.addls:
fp.write(encodedir('\n'.join(self.addls) + '\n'))
fp.close()
self.entries = None
self.addls = set()
def add(self, fn):
if self.entries is None:
self._load()
if fn not in self.entries:
self.addls.add(fn)
def remove(self, fn):
if self.entries is None:
self._load()
if fn in self.addls:
self.addls.remove(fn)
return
try:
self.entries.remove(fn)
self._dirty = True
except KeyError:
pass
def __contains__(self, fn):
if fn in self.addls:
return True
if self.entries is None:
self._load()
return fn in self.entries
def __iter__(self):
if self.entries is None:
self._load()
return iter(self.entries | self.addls)
class _fncachevfs(vfsmod.proxyvfs):
def __init__(self, vfs, fnc, encode):
vfsmod.proxyvfs.__init__(self, vfs)
self.fncache = fnc
self.encode = encode
def __call__(self, path, mode='r', *args, **kw):
encoded = self.encode(path)
if mode not in ('r', 'rb') and (path.startswith('data/') or
path.startswith('meta/')):
# do not trigger a fncache load when adding a file that already is
# known to exist.
notload = self.fncache.entries is None and self.vfs.exists(encoded)
if notload and 'a' in mode and not self.vfs.stat(encoded).st_size:
# when appending to an existing file, if the file has size zero,
# it should be considered as missing. Such zero-size files are
# the result of truncation when a transaction is aborted.
notload = False
if not notload:
self.fncache.add(path)
return self.vfs(encoded, mode, *args, **kw)
def join(self, path):
if path:
return self.vfs.join(self.encode(path))
else:
return self.vfs.join(path)
class fncachestore(basicstore):
def __init__(self, path, vfstype, dotencode):
if dotencode:
encode = _pathencode
else:
encode = _plainhybridencode
self.encode = encode
vfs = vfstype(path + '/store')
self.path = vfs.base
self.pathsep = self.path + '/'
self.createmode = _calcmode(vfs)
vfs.createmode = self.createmode
self.rawvfs = vfs
fnc = fncache(vfs)
self.fncache = fnc
self.vfs = _fncachevfs(vfs, fnc, encode)
self.opener = self.vfs
def join(self, f):
return self.pathsep + self.encode(f)
def getsize(self, path):
return self.rawvfs.stat(path).st_size
def datafiles(self, matcher=None):
for f in sorted(self.fncache):
if not _matchtrackedpath(f, matcher):
continue
ef = self.encode(f)
try:
yield f, ef, self.getsize(ef)
except OSError as err:
if err.errno != errno.ENOENT:
raise
def copylist(self):
d = ('bookmarks narrowspec data meta dh fncache phaseroots obsstore'
' 00manifest.d 00manifest.i 00changelog.d 00changelog.i')
return (['requires', '00changelog.i'] +
['store/' + f for f in d.split()])
def write(self, tr):
self.fncache.write(tr)
def invalidatecaches(self):
self.fncache.entries = None
self.fncache.addls = set()
def markremoved(self, fn):
self.fncache.remove(fn)
def _exists(self, f):
ef = self.encode(f)
try:
self.getsize(ef)
return True
except OSError as err:
if err.errno != errno.ENOENT:
raise
# nonexistent entry
return False
def __contains__(self, path):
'''Checks if the store contains path'''
path = "/".join(("data", path))
# check for files (exact match)
e = path + '.i'
if e in self.fncache and self._exists(e):
return True
# now check for directories (prefix match)
if not path.endswith('/'):
path += '/'
for e in self.fncache:
if e.startswith(path) and self._exists(e):
return True
return False