Mercurial > hg-stable
view mercurial/windows.py @ 30451:41a8106789ca
util: implement zstd compression engine
Now that zstd is vendored and being built (in some configurations), we
can implement a compression engine for zstd!
The zstd engine is a little different from existing engines. Because
it may not always be present, we have to defer load the module in case
importing it fails. We facilitate this via a cached property that holds
a reference to the module or None. The "available" method is
implemented to reflect reality.
The zstd engine declares its ability to handle bundles using the
"zstd" human name and the "ZS" internal name. The latter was chosen
because internal names are 2 characters (by only convention I think)
and "ZS" seems reasonable.
The engine, like others, supports specifying the compression level.
However, there are no consumers of this API that yet pass in that
argument. I have plans to change that, so stay tuned.
Since all we need to do to support bundle generation with a new
compression engine is implement and register the compression engine,
bundle generation with zstd "just works!" Tests demonstrating this
have been added.
How does performance of zstd for bundle generation compare? On the
mozilla-unified repo, `hg bundle --all -t <engine>-v2` yields the
following on my i7-6700K on Linux:
engine CPU time bundle size vs orig size throughput
none 97.0s 4,054,405,584 100.0% 41.8 MB/s
bzip2 (l=9) 393.6s 975,343,098 24.0% 10.3 MB/s
gzip (l=6) 184.0s 1,140,533,074 28.1% 22.0 MB/s
zstd (l=1) 108.2s 1,119,434,718 27.6% 37.5 MB/s
zstd (l=2) 111.3s 1,078,328,002 26.6% 36.4 MB/s
zstd (l=3) 113.7s 1,011,823,727 25.0% 35.7 MB/s
zstd (l=4) 116.0s 1,008,965,888 24.9% 35.0 MB/s
zstd (l=5) 121.0s 977,203,148 24.1% 33.5 MB/s
zstd (l=6) 131.7s 927,360,198 22.9% 30.8 MB/s
zstd (l=7) 139.0s 912,808,505 22.5% 29.2 MB/s
zstd (l=12) 198.1s 854,527,714 21.1% 20.5 MB/s
zstd (l=18) 681.6s 789,750,690 19.5% 5.9 MB/s
On compression, zstd for bundle generation delivers:
* better compression than gzip with significantly less CPU utilization
* better than bzip2 compression ratios while still being significantly
faster than gzip
* ability to aggressively tune compression level to achieve
significantly smaller bundles
That last point is important. With clone bundles, a server can
pre-generate a bundle file, upload it to a static file server, and
redirect clients to transparently download it during clone. The server
could choose to produce a zstd bundle with the highest compression
settings possible. This would take a very long time - a magnitude
longer than a typical zstd bundle generation - but the result would
be hundreds of megabytes smaller! For the clone volume we do at
Mozilla, this could translate to petabytes of bandwidth savings
per year and faster clones (due to smaller transfer size).
I don't have detailed numbers to report on decompression. However,
zstd decompression is fast: >1 GB/s output throughput on this machine,
even through the Python bindings. And it can do that regardless of the
compression level of the input. By the time you have enough data to
worry about overhead of decompression, you have plenty of other things
to worry about performance wise.
zstd is wins all around. I can't wait to implement support for it
on the wire protocol and in revlogs.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 11 Nov 2016 01:10:07 -0800 |
parents | 4b1af1c867fa |
children | 10d15095d7c2 |
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# windows.py - Windows utility function implementations for Mercurial # # Copyright 2005-2009 Matt Mackall <mpm@selenic.com> and others # # 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 msvcrt import os import re import stat import sys from .i18n import _ from . import ( encoding, osutil, win32, ) try: import _winreg as winreg winreg.CloseKey except ImportError: import winreg executablepath = win32.executablepath getuser = win32.getuser hidewindow = win32.hidewindow makedir = win32.makedir nlinks = win32.nlinks oslink = win32.oslink samedevice = win32.samedevice samefile = win32.samefile setsignalhandler = win32.setsignalhandler spawndetached = win32.spawndetached split = os.path.split testpid = win32.testpid unlink = win32.unlink umask = 0o022 class mixedfilemodewrapper(object): """Wraps a file handle when it is opened in read/write mode. fopen() and fdopen() on Windows have a specific-to-Windows requirement that files opened with mode r+, w+, or a+ make a call to a file positioning function when switching between reads and writes. Without this extra call, Python will raise a not very intuitive "IOError: [Errno 0] Error." This class wraps posixfile instances when the file is opened in read/write mode and automatically adds checks or inserts appropriate file positioning calls when necessary. """ OPNONE = 0 OPREAD = 1 OPWRITE = 2 def __init__(self, fp): object.__setattr__(self, '_fp', fp) object.__setattr__(self, '_lastop', 0) def __getattr__(self, name): return getattr(self._fp, name) def __setattr__(self, name, value): return self._fp.__setattr__(name, value) def _noopseek(self): self._fp.seek(0, os.SEEK_CUR) def seek(self, *args, **kwargs): object.__setattr__(self, '_lastop', self.OPNONE) return self._fp.seek(*args, **kwargs) def write(self, d): if self._lastop == self.OPREAD: self._noopseek() object.__setattr__(self, '_lastop', self.OPWRITE) return self._fp.write(d) def writelines(self, *args, **kwargs): if self._lastop == self.OPREAD: self._noopeseek() object.__setattr__(self, '_lastop', self.OPWRITE) return self._fp.writelines(*args, **kwargs) def read(self, *args, **kwargs): if self._lastop == self.OPWRITE: self._noopseek() object.__setattr__(self, '_lastop', self.OPREAD) return self._fp.read(*args, **kwargs) def readline(self, *args, **kwargs): if self._lastop == self.OPWRITE: self._noopseek() object.__setattr__(self, '_lastop', self.OPREAD) return self._fp.readline(*args, **kwargs) def readlines(self, *args, **kwargs): if self._lastop == self.OPWRITE: self._noopseek() object.__setattr__(self, '_lastop', self.OPREAD) return self._fp.readlines(*args, **kwargs) def posixfile(name, mode='r', buffering=-1): '''Open a file with even more POSIX-like semantics''' try: fp = osutil.posixfile(name, mode, buffering) # may raise WindowsError # The position when opening in append mode is implementation defined, so # make it consistent with other platforms, which position at EOF. if 'a' in mode: fp.seek(0, os.SEEK_END) if '+' in mode: return mixedfilemodewrapper(fp) return fp except WindowsError as err: # convert to a friendlier exception raise IOError(err.errno, '%s: %s' % (name, err.strerror)) class winstdout(object): '''stdout on windows misbehaves if sent through a pipe''' def __init__(self, fp): self.fp = fp def __getattr__(self, key): return getattr(self.fp, key) def close(self): try: self.fp.close() except IOError: pass def write(self, s): try: # This is workaround for "Not enough space" error on # writing large size of data to console. limit = 16000 l = len(s) start = 0 self.softspace = 0 while start < l: end = start + limit self.fp.write(s[start:end]) start = end except IOError as inst: if inst.errno != 0: raise self.close() raise IOError(errno.EPIPE, 'Broken pipe') def flush(self): try: return self.fp.flush() except IOError as inst: if inst.errno != errno.EINVAL: raise self.close() raise IOError(errno.EPIPE, 'Broken pipe') sys.__stdout__ = sys.stdout = winstdout(sys.stdout) def _is_win_9x(): '''return true if run on windows 95, 98 or me.''' try: return sys.getwindowsversion()[3] == 1 except AttributeError: return 'command' in os.environ.get('comspec', '') def openhardlinks(): return not _is_win_9x() def parsepatchoutput(output_line): """parses the output produced by patch and returns the filename""" pf = output_line[14:] if pf[0] == '`': pf = pf[1:-1] # Remove the quotes return pf def sshargs(sshcmd, host, user, port): '''Build argument list for ssh or Plink''' pflag = 'plink' in sshcmd.lower() and '-P' or '-p' args = user and ("%s@%s" % (user, host)) or host return port and ("%s %s %s" % (args, pflag, port)) or args def setflags(f, l, x): pass def copymode(src, dst, mode=None): pass def checkexec(path): return False def checklink(path): return False def setbinary(fd): # When run without console, pipes may expose invalid # fileno(), usually set to -1. fno = getattr(fd, 'fileno', None) if fno is not None and fno() >= 0: msvcrt.setmode(fno(), os.O_BINARY) def pconvert(path): return path.replace(os.sep, '/') def localpath(path): return path.replace('/', '\\') def normpath(path): return pconvert(os.path.normpath(path)) def normcase(path): return encoding.upper(path) # NTFS compares via upper() # see posix.py for definitions normcasespec = encoding.normcasespecs.upper normcasefallback = encoding.upperfallback def samestat(s1, s2): return False # A sequence of backslashes is special iff it precedes a double quote: # - if there's an even number of backslashes, the double quote is not # quoted (i.e. it ends the quoted region) # - if there's an odd number of backslashes, the double quote is quoted # - in both cases, every pair of backslashes is unquoted into a single # backslash # (See http://msdn2.microsoft.com/en-us/library/a1y7w461.aspx ) # So, to quote a string, we must surround it in double quotes, double # the number of backslashes that precede double quotes and add another # backslash before every double quote (being careful with the double # quote we've appended to the end) _quotere = None _needsshellquote = None def shellquote(s): r""" >>> shellquote(r'C:\Users\xyz') '"C:\\Users\\xyz"' >>> shellquote(r'C:\Users\xyz/mixed') '"C:\\Users\\xyz/mixed"' >>> # Would be safe not to quote too, since it is all double backslashes >>> shellquote(r'C:\\Users\\xyz') '"C:\\\\Users\\\\xyz"' >>> # But this must be quoted >>> shellquote(r'C:\\Users\\xyz/abc') '"C:\\\\Users\\\\xyz/abc"' """ global _quotere if _quotere is None: _quotere = re.compile(r'(\\*)("|\\$)') global _needsshellquote if _needsshellquote is None: # ":" is also treated as "safe character", because it is used as a part # of path name on Windows. "\" is also part of a path name, but isn't # safe because shlex.split() (kind of) treats it as an escape char and # drops it. It will leave the next character, even if it is another # "\". _needsshellquote = re.compile(r'[^a-zA-Z0-9._:/-]').search if s and not _needsshellquote(s) and not _quotere.search(s): # "s" shouldn't have to be quoted return s return '"%s"' % _quotere.sub(r'\1\1\\\2', s) def quotecommand(cmd): """Build a command string suitable for os.popen* calls.""" if sys.version_info < (2, 7, 1): # Python versions since 2.7.1 do this extra quoting themselves return '"' + cmd + '"' return cmd def popen(command, mode='r'): # Work around "popen spawned process may not write to stdout # under windows" # http://bugs.python.org/issue1366 command += " 2> %s" % os.devnull return os.popen(quotecommand(command), mode) def explainexit(code): return _("exited with status %d") % code, code # if you change this stub into a real check, please try to implement the # username and groupname functions above, too. def isowner(st): return True def findexe(command): '''Find executable for command searching like cmd.exe does. If command is a basename then PATH is searched for command. PATH isn't searched if command is an absolute or relative path. An extension from PATHEXT is found and added if not present. If command isn't found None is returned.''' pathext = os.environ.get('PATHEXT', '.COM;.EXE;.BAT;.CMD') pathexts = [ext for ext in pathext.lower().split(os.pathsep)] if os.path.splitext(command)[1].lower() in pathexts: pathexts = [''] def findexisting(pathcommand): 'Will append extension (if needed) and return existing file' for ext in pathexts: executable = pathcommand + ext if os.path.exists(executable): return executable return None if os.sep in command: return findexisting(command) for path in os.environ.get('PATH', '').split(os.pathsep): executable = findexisting(os.path.join(path, command)) if executable is not None: return executable return findexisting(os.path.expanduser(os.path.expandvars(command))) _wantedkinds = set([stat.S_IFREG, stat.S_IFLNK]) def statfiles(files): '''Stat each file in files. Yield each stat, or None if a file does not exist or has a type we don't care about. Cluster and cache stat per directory to minimize number of OS stat calls.''' dircache = {} # dirname -> filename -> status | None if file does not exist getkind = stat.S_IFMT for nf in files: nf = normcase(nf) dir, base = os.path.split(nf) if not dir: dir = '.' cache = dircache.get(dir, None) if cache is None: try: dmap = dict([(normcase(n), s) for n, k, s in osutil.listdir(dir, True) if getkind(s.st_mode) in _wantedkinds]) except OSError as err: # Python >= 2.5 returns ENOENT and adds winerror field # EINVAL is raised if dir is not a directory. if err.errno not in (errno.ENOENT, errno.EINVAL, errno.ENOTDIR): raise dmap = {} cache = dircache.setdefault(dir, dmap) yield cache.get(base, None) def username(uid=None): """Return the name of the user with the given uid. If uid is None, return the name of the current user.""" return None def groupname(gid=None): """Return the name of the group with the given gid. If gid is None, return the name of the current group.""" return None def removedirs(name): """special version of os.removedirs that does not remove symlinked directories or junction points if they actually contain files""" if osutil.listdir(name): return os.rmdir(name) head, tail = os.path.split(name) if not tail: head, tail = os.path.split(head) while head and tail: try: if osutil.listdir(head): return os.rmdir(head) except (ValueError, OSError): break head, tail = os.path.split(head) def unlinkpath(f, ignoremissing=False): """unlink and remove the directory if it is empty""" try: unlink(f) except OSError as e: if not (ignoremissing and e.errno == errno.ENOENT): raise # try removing directories that might now be empty try: removedirs(os.path.dirname(f)) except OSError: pass def rename(src, dst): '''atomically rename file src to dst, replacing dst if it exists''' try: os.rename(src, dst) except OSError as e: if e.errno != errno.EEXIST: raise unlink(dst) os.rename(src, dst) def gethgcmd(): return [sys.executable] + sys.argv[:1] def groupmembers(name): # Don't support groups on Windows for now raise KeyError def isexec(f): return False class cachestat(object): def __init__(self, path): pass def cacheable(self): return False def lookupreg(key, valname=None, scope=None): ''' Look up a key/value name in the Windows registry. valname: value name. If unspecified, the default value for the key is used. scope: optionally specify scope for registry lookup, this can be a sequence of scopes to look up in order. Default (CURRENT_USER, LOCAL_MACHINE). ''' if scope is None: scope = (winreg.HKEY_CURRENT_USER, winreg.HKEY_LOCAL_MACHINE) elif not isinstance(scope, (list, tuple)): scope = (scope,) for s in scope: try: val = winreg.QueryValueEx(winreg.OpenKey(s, key), valname)[0] # never let a Unicode string escape into the wild return encoding.tolocal(val.encode('UTF-8')) except EnvironmentError: pass expandglobs = True def statislink(st): '''check whether a stat result is a symlink''' return False def statisexec(st): '''check whether a stat result is an executable file''' return False def poll(fds): # see posix.py for description raise NotImplementedError() def readpipe(pipe): """Read all available data from a pipe.""" chunks = [] while True: size = win32.peekpipe(pipe) if not size: break s = pipe.read(size) if not s: break chunks.append(s) return ''.join(chunks) def bindunixsocket(sock, path): raise NotImplementedError('unsupported platform')