Mercurial > hg
view mercurial/commandserver.py @ 26379:39d643252b9f
revlog: use existing file handle when reading during _addrevision
_addrevision() may need to read from revlogs as part of computing
deltas. Previously, we would flush existing file handles and open
a new, short-lived file handle to perform the reading.
If we have an existing file handle, it seems logical to reuse it
for reading instead of opening a new file handle. This patch
makes that the new behavior.
After this patch, revlog files are only reopened when adding
revisions if the revlog is switched from inline to non-inline.
On Linux when unbundling a bundle of the mozilla-central repo, this
patch has the following impact on system call counts:
Call Before After Delta
write 827,639 673,390 -154,249
open 700,103 684,089 -16,014
read 74,489 74,489 0
fstat 493,924 461,896 -32,028
close 249,131 233,117 -16,014
stat 242,001 242,001 0
lstat 18,676 18,676 0
lseek 20,268 20,268 0
ioctl 14,652 13,173 -1,479
TOTAL 3,180,758 2,930,679 -250,079
It's worth noting that many of the open() calls fail due to missing
files. That's why there are many more open() calls than close().
Despite the significant system call reduction, this change does not
seem to have a significant performance impact on Linux.
On Windows 10 (not a VM, on a SSD), this patch appears to reduce
unbundle time for mozilla-central from ~960s to ~920s. This isn't
as significant as I was hoping. But a decrease it is nonetheless.
Still, Windows unbundle performance is still >2x slower than Linux.
Despite the lack of significant gains, fewer system calls is fewer
system calls. If nothing else, this will narrow the focus of potential
areas to optimize in the future.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 27 Sep 2015 16:08:18 -0700 |
parents | 5857be01962e |
children | 56b2bcea2529 |
line wrap: on
line source
# commandserver.py - communicate with Mercurial's API over a pipe # # Copyright 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 i18n import _ import struct import sys, os, errno, traceback, SocketServer import dispatch, encoding, util logfile = None def log(*args): if not logfile: return for a in args: logfile.write(str(a)) logfile.flush() class channeledoutput(object): """ Write data to out in the following format: data length (unsigned int), data """ def __init__(self, out, channel): self.out = out self.channel = channel def write(self, data): if not data: return self.out.write(struct.pack('>cI', self.channel, len(data))) self.out.write(data) self.out.flush() def __getattr__(self, attr): if attr in ('isatty', 'fileno'): raise AttributeError(attr) return getattr(self.out, attr) class channeledinput(object): """ Read data from in_. Requests for input are written to out in the following format: channel identifier - 'I' for plain input, 'L' line based (1 byte) how many bytes to send at most (unsigned int), The client replies with: data length (unsigned int), 0 meaning EOF data """ maxchunksize = 4 * 1024 def __init__(self, in_, out, channel): self.in_ = in_ self.out = out self.channel = channel def read(self, size=-1): if size < 0: # if we need to consume all the clients input, ask for 4k chunks # so the pipe doesn't fill up risking a deadlock size = self.maxchunksize s = self._read(size, self.channel) buf = s while s: s = self._read(size, self.channel) buf += s return buf else: return self._read(size, self.channel) def _read(self, size, channel): if not size: return '' assert size > 0 # tell the client we need at most size bytes self.out.write(struct.pack('>cI', channel, size)) self.out.flush() length = self.in_.read(4) length = struct.unpack('>I', length)[0] if not length: return '' else: return self.in_.read(length) def readline(self, size=-1): if size < 0: size = self.maxchunksize s = self._read(size, 'L') buf = s # keep asking for more until there's either no more or # we got a full line while s and s[-1] != '\n': s = self._read(size, 'L') buf += s return buf else: return self._read(size, 'L') def __iter__(self): return self def next(self): l = self.readline() if not l: raise StopIteration return l def __getattr__(self, attr): if attr in ('isatty', 'fileno'): raise AttributeError(attr) return getattr(self.in_, attr) class server(object): """ Listens for commands on fin, runs them and writes the output on a channel based stream to fout. """ def __init__(self, ui, repo, fin, fout): self.cwd = os.getcwd() # developer config: cmdserver.log logpath = ui.config("cmdserver", "log", None) if logpath: global logfile if logpath == '-': # write log on a special 'd' (debug) channel logfile = channeledoutput(fout, 'd') else: logfile = open(logpath, 'a') if repo: # the ui here is really the repo ui so take its baseui so we don't # end up with its local configuration self.ui = repo.baseui self.repo = repo self.repoui = repo.ui else: self.ui = ui self.repo = self.repoui = None self.cerr = channeledoutput(fout, 'e') self.cout = channeledoutput(fout, 'o') self.cin = channeledinput(fin, fout, 'I') self.cresult = channeledoutput(fout, 'r') self.client = fin def _read(self, size): if not size: return '' data = self.client.read(size) # is the other end closed? if not data: raise EOFError return data def runcommand(self): """ reads a list of \0 terminated arguments, executes and writes the return code to the result channel """ length = struct.unpack('>I', self._read(4))[0] if not length: args = [] else: args = self._read(length).split('\0') # copy the uis so changes (e.g. --config or --verbose) don't # persist between requests copiedui = self.ui.copy() uis = [copiedui] if self.repo: self.repo.baseui = copiedui # clone ui without using ui.copy because this is protected repoui = self.repoui.__class__(self.repoui) repoui.copy = copiedui.copy # redo copy protection uis.append(repoui) self.repo.ui = self.repo.dirstate._ui = repoui self.repo.invalidateall() for ui in uis: # any kind of interaction must use server channels ui.setconfig('ui', 'nontty', 'true', 'commandserver') req = dispatch.request(args[:], copiedui, self.repo, self.cin, self.cout, self.cerr) ret = (dispatch.dispatch(req) or 0) & 255 # might return None # restore old cwd if '--cwd' in args: os.chdir(self.cwd) self.cresult.write(struct.pack('>i', int(ret))) def getencoding(self): """ writes the current encoding to the result channel """ self.cresult.write(encoding.encoding) def serveone(self): cmd = self.client.readline()[:-1] if cmd: handler = self.capabilities.get(cmd) if handler: handler(self) else: # clients are expected to check what commands are supported by # looking at the servers capabilities raise util.Abort(_('unknown command %s') % cmd) return cmd != '' capabilities = {'runcommand' : runcommand, 'getencoding' : getencoding} def serve(self): hellomsg = 'capabilities: ' + ' '.join(sorted(self.capabilities)) hellomsg += '\n' hellomsg += 'encoding: ' + encoding.encoding hellomsg += '\n' hellomsg += 'pid: %d' % os.getpid() # write the hello msg in -one- chunk self.cout.write(hellomsg) try: while self.serveone(): pass except EOFError: # we'll get here if the client disconnected while we were reading # its request return 1 return 0 def _protectio(ui): """ duplicates streams and redirect original to null if ui uses stdio """ ui.flush() newfiles = [] nullfd = os.open(os.devnull, os.O_RDWR) for f, sysf, mode in [(ui.fin, sys.stdin, 'rb'), (ui.fout, sys.stdout, 'wb')]: if f is sysf: newfd = os.dup(f.fileno()) os.dup2(nullfd, f.fileno()) f = os.fdopen(newfd, mode) newfiles.append(f) os.close(nullfd) return tuple(newfiles) def _restoreio(ui, fin, fout): """ restores streams from duplicated ones """ ui.flush() for f, uif in [(fin, ui.fin), (fout, ui.fout)]: if f is not uif: os.dup2(f.fileno(), uif.fileno()) f.close() class pipeservice(object): def __init__(self, ui, repo, opts): self.ui = ui self.repo = repo def init(self): pass def run(self): ui = self.ui # redirect stdio to null device so that broken extensions or in-process # hooks will never cause corruption of channel protocol. fin, fout = _protectio(ui) try: sv = server(ui, self.repo, fin, fout) return sv.serve() finally: _restoreio(ui, fin, fout) class _requesthandler(SocketServer.StreamRequestHandler): def handle(self): ui = self.server.ui repo = self.server.repo sv = server(ui, repo, self.rfile, self.wfile) try: try: sv.serve() # handle exceptions that may be raised by command server. most of # known exceptions are caught by dispatch. except util.Abort as inst: ui.warn(_('abort: %s\n') % inst) except IOError as inst: if inst.errno != errno.EPIPE: raise except KeyboardInterrupt: pass except: # re-raises # also write traceback to error channel. otherwise client cannot # see it because it is written to server's stderr by default. traceback.print_exc(file=sv.cerr) raise class unixservice(object): """ Listens on unix domain socket and forks server per connection """ def __init__(self, ui, repo, opts): self.ui = ui self.repo = repo self.address = opts['address'] if not util.safehasattr(SocketServer, 'UnixStreamServer'): raise util.Abort(_('unsupported platform')) if not self.address: raise util.Abort(_('no socket path specified with --address')) def init(self): class cls(SocketServer.ForkingMixIn, SocketServer.UnixStreamServer): ui = self.ui repo = self.repo self.server = cls(self.address, _requesthandler) self.ui.status(_('listening at %s\n') % self.address) self.ui.flush() # avoid buffering of status message def run(self): try: self.server.serve_forever() finally: os.unlink(self.address) _servicemap = { 'pipe': pipeservice, 'unix': unixservice, } def createservice(ui, repo, opts): mode = opts['cmdserver'] try: return _servicemap[mode](ui, repo, opts) except KeyError: raise util.Abort(_('unknown mode %s') % mode)