Mercurial > hg
view mercurial/commandserver.py @ 25561:50a6c3c55db1 stable
parsers: do not cache RevlogError type (issue4451)
Index lookups raise RevlogError when the lookup fails. The previous
implementation was caching a reference to the RevlogError type in a
static variable. This assumed that the "mercurial.error" module was
only loaded once and there was only a single copy of it floating
around in memory. Unfortunately, in some situations - including
certain mod_wsgi configurations - this was not the case: the
"mercurial.error" module could be reloaded. It was possible for a
"RevlogError" reference from the first interpreter to be used by
a second interpreter. While the underlying thing was a
"mercurial.error.RevlogError," the object IDs were different, so
the Python code in revlog.py was failing to catch the exception! This
error has existed since the C index lookup code was implemented in
changeset e8d37b78acfb, which was first released in Mercurial 2.2 in
2012.
http://emptysqua.re/blog/python-c-extensions-and-mod-wsgi/#static-variables-are-shared
contains more details.
This patch removes the caching of the RevlogError type from the
function.
Since pretty much the entire function was refactored and the return
value of the function wasn't used, I changed the function signature
to not return anything.
For reasons unknown to me, we were calling PyErr_SetObject()
with the type of RevlogError and an instance of RevlogError. This
was equivalent to the Python code "raise RevlogError(RevlogError)".
This seemed wonky and completely unnecessary. The Python code only
cares about the type of the exception, not its contents. So I got
rid of this complexity.
This is my first Python C extension patch. Please give extra scrutiny
to it during review.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 12 Jun 2015 14:43:59 -0700 |
parents | 69f86b937035 |
children | 328739ea70c3 |
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() 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, inst: ui.warn(_('abort: %s\n') % inst) except IOError, 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)