view mercurial/commandserver.py @ 23848:c5456b64eb07

discovery: run discovery on filtered repository

We have been running discovery on unfiltered repository for quite some time.
This was aimed at two things:

- save some bandwith by prevent the repushing of common but hidden changesets
- allow phases changes on secret/hidden changeset on bare push.

The cost of this unfiltered discovery combined with evolution is actually really
high. Evolution likely create thousand of hidden heads, and the discovery is
going to try to discovery if each of them are common or not. For example,
pushing from my development mercurial repository implies 17 discovery
round-trip.

The benefit are rare corner cases while the drawback are massive. So we run the
discovery on a filtered repository again.

We add some hack to detect remote heads that are known locally and adds them to
the common set anyway, so the good behavior of most of the corner case should
remains. But this will not work in all cases.

This bring my discovery phase back from 17 round-trips to 1 or 2.

# commandserver.py - communicate with Mercurial's API over a pipe
#
#  Copyright Matt Mackall <[e-mail]>
#
# 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)