mercurial/commandserver.py

revset: add origin() predicate

This predicate is used to find the original source of csets created by a graft,
transplant or rebase --keep.  If a copied cset is itself copied, only the
source of the original copy is selected.

    hg log -r origin()                # all src csets, anywhere
    hg log -r origin(branch(default)) # all srcs of copies on default

By following through different types of copy commands and only selecting the
original cset, the implementation differences between the copy commands are
hidden.  (A graft of a graft preserves the original source in its 'extra' map,
while transplant and rebase use the immediate source specified for the
command).

Given a repo with a cset S that is grafted to create G(S), which itself is
grafted to become G(G(S))

    o-S
   /
  o-o-G(S)
   \
    o-G(G(S))

    hg log -r origin( G(S) )      # { S }
    hg log -r origin( G(G(S)) )   # { S }, NOT { G(S) }

Even if the last graft were a transplant

    hg log -r origin( T(G(S)) )   # { S }

A rebase without --keep essentially strips the source, so providing the cset
that results to this predicate will yield an empty set.

Note that the convert extension does not currently update the 'extra' map in
its destination csets, and therefore copies made prior to the convert will be
unable to find their source.

# 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
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 from in_ to out in the following format:

    data length (unsigned int),
    data
    """
    def __init__(self, in_, out, channel):
        self.in_ = in_
        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.in_, 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 stdin, runs them and writes the output on a channel
    based stream to stdout.
    """
    def __init__(self, ui, repo, mode):
        self.cwd = os.getcwd()

        logpath = ui.config("cmdserver", "log", None)
        if logpath:
            global logfile
            if logpath == '-':
                # write log on a special 'd'ebug channel
                logfile = channeledoutput(sys.stdout, sys.stdout, 'd')
            else:
                logfile = open(logpath, 'a')

        # 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

        if mode == 'pipe':
            self.cerr = channeledoutput(sys.stderr, sys.stdout, 'e')
            self.cout = channeledoutput(sys.stdout, sys.stdout, 'o')
            self.cin = channeledinput(sys.stdin, sys.stdout, 'I')
            self.cresult = channeledoutput(sys.stdout, sys.stdout, 'r')

            self.client = sys.stdin
        else:
            raise util.Abort(_('unknown mode %s') % mode)

    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()
        self.repo.baseui = copiedui
        self.repo.ui = self.repo.dirstate._ui = self.repoui.copy()
        self.repo.invalidate()
        self.repo.invalidatedirstate()

        req = dispatch.request(args[:], copiedui, self.repo, self.cin,
                               self.cout, self.cerr)

        ret = dispatch.dispatch(req) or 0 # 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(self.capabilities.keys())
        hellomsg += '\n'
        hellomsg += 'encoding: ' + encoding.encoding

        # 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