Mercurial > public > mercurial-scm > hg-stable
view mercurial/server.py @ 37060:2ec1fb9de638
wireproto: add request IDs to frames
One of my primary goals with the new wire protocol is to make
operations faster and enable both client and server-side
operations to scale to multiple CPU cores.
One of the ways we make server interactions faster is by reducing
the number of round trips to that server.
With the existing wire protocol, the "batch" command facilitates
executing multiple commands from a single request payload. The way
it works is the requests for multiple commands are serialized. The
server executes those commands sequentially then serializes all
their results. As an optimization for reducing round trips, this
is very effective. The technical implementation, however, is pretty
bad and suffers from a number of deficiencies. For example, it
creates a new place where authorization to run a command must be
checked. (The lack of this checking in older Mercurial releases
was CVE-2018-1000132.)
The principles behind the "batch" command are sound. However, the
execution is not. Therefore, I want to ditch "batch" in the
new wire protocol and have protocol level support for issuing
multiple requests in a single round trip.
This commit introduces support in the frame-based wire protocol to
facilitate this. We do this by adding a "request ID" to each frame.
If a server sees frames associated with different "request IDs," it
handles them as separate requests. All of this happening possibly
as part of the same message from client to server (the same request
body in the case of HTTP).
We /could/ model the exchange the way pipelined HTTP requests do,
where the server processes requests in order they are issued and
received. But this artifically constrains scalability. A better
model is to allow multi-requests to be executed concurrently and
for responses to be sent and handled concurrently. So the
specification explicitly allows this. There is some work to be done
around specifying dependencies between multi-requests. We take
the easy road for now and punt on this problem, declaring that
if order is important, clients must not issue the request until
responses to dependent requests have been received.
This commit focuses on the boilerplate of implementing the request
ID. The server reactor still can't manage multiple, in-flight
request IDs. This will be addressed in a subsequent commit.
Because the wire semantics have changed, we bump the version of the
media type.
Differential Revision: https://phab.mercurial-scm.org/D2869
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 14 Mar 2018 16:51:34 -0700 |
parents | bfcd0d227972 |
children | d4a2e0d5d042 |
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# server.py - utility and factory of server # # 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 import os import tempfile from .i18n import _ from . import ( chgserver, cmdutil, commandserver, error, hgweb, pycompat, util, ) def runservice(opts, parentfn=None, initfn=None, runfn=None, logfile=None, runargs=None, appendpid=False): '''Run a command as a service.''' def writepid(pid): if opts['pid_file']: if appendpid: mode = 'ab' else: mode = 'wb' fp = open(opts['pid_file'], mode) fp.write('%d\n' % pid) fp.close() if opts['daemon'] and not opts['daemon_postexec']: # Signal child process startup with file removal lockfd, lockpath = tempfile.mkstemp(prefix='hg-service-') os.close(lockfd) try: if not runargs: runargs = util.hgcmd() + pycompat.sysargv[1:] runargs.append('--daemon-postexec=unlink:%s' % lockpath) # Don't pass --cwd to the child process, because we've already # changed directory. for i in xrange(1, len(runargs)): if runargs[i].startswith('--cwd='): del runargs[i] break elif runargs[i].startswith('--cwd'): del runargs[i:i + 2] break def condfn(): return not os.path.exists(lockpath) pid = util.rundetached(runargs, condfn) if pid < 0: raise error.Abort(_('child process failed to start')) writepid(pid) finally: util.tryunlink(lockpath) if parentfn: return parentfn(pid) else: return if initfn: initfn() if not opts['daemon']: writepid(util.getpid()) if opts['daemon_postexec']: try: os.setsid() except AttributeError: pass for inst in opts['daemon_postexec']: if inst.startswith('unlink:'): lockpath = inst[7:] os.unlink(lockpath) elif inst.startswith('chdir:'): os.chdir(inst[6:]) elif inst != 'none': raise error.Abort(_('invalid value for --daemon-postexec: %s') % inst) util.hidewindow() util.stdout.flush() util.stderr.flush() nullfd = os.open(os.devnull, os.O_RDWR) logfilefd = nullfd if logfile: logfilefd = os.open(logfile, os.O_RDWR | os.O_CREAT | os.O_APPEND, 0o666) os.dup2(nullfd, 0) os.dup2(logfilefd, 1) os.dup2(logfilefd, 2) if nullfd not in (0, 1, 2): os.close(nullfd) if logfile and logfilefd not in (0, 1, 2): os.close(logfilefd) if runfn: return runfn() _cmdservicemap = { 'chgunix': chgserver.chgunixservice, 'pipe': commandserver.pipeservice, 'unix': commandserver.unixforkingservice, } def _createcmdservice(ui, repo, opts): mode = opts['cmdserver'] try: return _cmdservicemap[mode](ui, repo, opts) except KeyError: raise error.Abort(_('unknown mode %s') % mode) def _createhgwebservice(ui, repo, opts): # this way we can check if something was given in the command-line if opts.get('port'): opts['port'] = util.getport(opts.get('port')) alluis = {ui} if repo: baseui = repo.baseui alluis.update([repo.baseui, repo.ui]) else: baseui = ui webconf = opts.get('web_conf') or opts.get('webdir_conf') if webconf: if opts.get('subrepos'): raise error.Abort(_('--web-conf cannot be used with --subrepos')) # load server settings (e.g. web.port) to "copied" ui, which allows # hgwebdir to reload webconf cleanly servui = ui.copy() servui.readconfig(webconf, sections=['web']) alluis.add(servui) elif opts.get('subrepos'): servui = ui # If repo is None, hgweb.createapp() already raises a proper abort # message as long as webconf is None. if repo: webconf = dict() cmdutil.addwebdirpath(repo, "", webconf) else: servui = ui optlist = ("name templates style address port prefix ipv6" " accesslog errorlog certificate encoding") for o in optlist.split(): val = opts.get(o, '') if val in (None, ''): # should check against default options instead continue for u in alluis: u.setconfig("web", o, val, 'serve') app = hgweb.createapp(baseui, repo, webconf) return hgweb.httpservice(servui, app, opts) def createservice(ui, repo, opts): if opts["cmdserver"]: return _createcmdservice(ui, repo, opts) else: return _createhgwebservice(ui, repo, opts)