annotate mercurial/wireprotov1peer.py @ 37630:e1b32dc4646c

wireproto: implement command executor interface for version 1 peers

Now that we've defined our new interface for issuing commands,
let's implement it.

We add the interface to the base peer interface. This means all
peer types must implement it.

The only peer types that we have are the local peer in localrepo
and a shared wire peer for version 1 of the wire protocol.

The local peer implementation is pretty straightforward. We
don't do anything fancy and just return a resolved future with
the result of a method call. This is similar to what
localiterbatcher does.

The wire protocol version 1 implementation is a bit more complicated
and is a more robust implementation.

The wire executor queues commands by default. And because the new
executor interface always allows multiple commands but not all version
1 commands are @batchable, it has to check that the requested commands
are batchable if multiple commands are being requested.

The wire executor currently only supports executing a single command.
This is for simplicity reasons. Support for multiple commands will
be added in a separate commit.

To prove the new interface works, a call to the "known" command
during discovery has been updated to use the new API.

It's worth noting that both implementations require a method having
the command name to exist on the peer. There is at least one caller
in core that don't have a method calls peer._call() directly. We
may need to shore up the requirements later...

Differential Revision: https://phab.mercurial-scm.org/D3268

# wireprotov1peer.py - Client-side functionality for wire protocol version 1.
#
# Copyright 2005-2010 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 __future__ import absolute_import

import hashlib
import sys

from .i18n import _
from .node import (
    bin,
)
from .thirdparty.zope import (
    interface as zi,
)
from . import (
    bundle2,
    changegroup as changegroupmod,
    encoding,
    error,
    pushkey as pushkeymod,
    pycompat,
    repository,
    util,
    wireprototypes,
)

urlreq = util.urlreq

def batchable(f):
    '''annotation for batchable methods

    Such methods must implement a coroutine as follows:

    @batchable
    def sample(self, one, two=None):
        # Build list of encoded arguments suitable for your wire protocol:
        encargs = [('one', encode(one),), ('two', encode(two),)]
        # Create future for injection of encoded result:
        encresref = future()
        # Return encoded arguments and future:
        yield encargs, encresref
        # Assuming the future to be filled with the result from the batched
        # request now. Decode it:
        yield decode(encresref.value)

    The decorator returns a function which wraps this coroutine as a plain
    method, but adds the original method as an attribute called "batchable",
    which is used by remotebatch to split the call into separate encoding and
    decoding phases.
    '''
    def plain(*args, **opts):
        batchable = f(*args, **opts)
        encargsorres, encresref = next(batchable)
        if not encresref:
            return encargsorres # a local result in this case
        self = args[0]
        cmd = pycompat.bytesurl(f.__name__)  # ensure cmd is ascii bytestr
        encresref.set(self._submitone(cmd, encargsorres))
        return next(batchable)
    setattr(plain, 'batchable', f)
    return plain

class future(object):
    '''placeholder for a value to be set later'''
    def set(self, value):
        if util.safehasattr(self, 'value'):
            raise error.RepoError("future is already set")
        self.value = value

class batcher(object):
    '''base class for batches of commands submittable in a single request

    All methods invoked on instances of this class are simply queued and
    return a a future for the result. Once you call submit(), all the queued
    calls are performed and the results set in their respective futures.
    '''
    def __init__(self):
        self.calls = []
    def __getattr__(self, name):
        def call(*args, **opts):
            resref = future()
            # Please don't invent non-ascii method names, or you will
            # give core hg a very sad time.
            self.calls.append((name.encode('ascii'), args, opts, resref,))
            return resref
        return call
    def submit(self):
        raise NotImplementedError()

class iterbatcher(batcher):

    def submit(self):
        raise NotImplementedError()

    def results(self):
        raise NotImplementedError()

class remoteiterbatcher(iterbatcher):
    def __init__(self, remote):
        super(remoteiterbatcher, self).__init__()
        self._remote = remote

    def __getattr__(self, name):
        # Validate this method is batchable, since submit() only supports
        # batchable methods.
        fn = getattr(self._remote, name)
        if not getattr(fn, 'batchable', None):
            raise error.ProgrammingError('Attempted to batch a non-batchable '
                                         'call to %r' % name)

        return super(remoteiterbatcher, self).__getattr__(name)

    def submit(self):
        """Break the batch request into many patch calls and pipeline them.

        This is mostly valuable over http where request sizes can be
        limited, but can be used in other places as well.
        """
        # 2-tuple of (command, arguments) that represents what will be
        # sent over the wire.
        requests = []

        # 4-tuple of (command, final future, @batchable generator, remote
        # future).
        results = []

        for command, args, opts, finalfuture in self.calls:
            mtd = getattr(self._remote, command)
            batchable = mtd.batchable(mtd.__self__, *args, **opts)

            commandargs, fremote = next(batchable)
            assert fremote
            requests.append((command, commandargs))
            results.append((command, finalfuture, batchable, fremote))

        if requests:
            self._resultiter = self._remote._submitbatch(requests)

        self._results = results

    def results(self):
        for command, finalfuture, batchable, remotefuture in self._results:
            # Get the raw result, set it in the remote future, feed it
            # back into the @batchable generator so it can be decoded, and
            # set the result on the final future to this value.
            remoteresult = next(self._resultiter)
            remotefuture.set(remoteresult)
            finalfuture.set(next(batchable))

            # Verify our @batchable generators only emit 2 values.
            try:
                next(batchable)
            except StopIteration:
                pass
            else:
                raise error.ProgrammingError('%s @batchable generator emitted '
                                             'unexpected value count' % command)

            yield finalfuture.value

def encodebatchcmds(req):
    """Return a ``cmds`` argument value for the ``batch`` command."""
    escapearg = wireprototypes.escapebatcharg

    cmds = []
    for op, argsdict in req:
        # Old servers didn't properly unescape argument names. So prevent
        # the sending of argument names that may not be decoded properly by
        # servers.
        assert all(escapearg(k) == k for k in argsdict)

        args = ','.join('%s=%s' % (escapearg(k), escapearg(v))
                        for k, v in argsdict.iteritems())
        cmds.append('%s %s' % (op, args))

    return ';'.join(cmds)

@zi.implementer(repository.ipeercommandexecutor)
class peerexecutor(object):
    def __init__(self, peer):
        self._peer = peer
        self._sent = False
        self._closed = False
        self._calls = []

    def __enter__(self):
        return self

    def __exit__(self, exctype, excvalee, exctb):
        self.close()

    def callcommand(self, command, args):
        if self._sent:
            raise error.ProgrammingError('callcommand() cannot be used '
                                         'after commands are sent')

        if self._closed:
            raise error.ProgrammingError('callcommand() cannot be used '
                                         'after close()')

        # Commands are dispatched through methods on the peer.
        fn = getattr(self._peer, pycompat.sysstr(command), None)

        if not fn:
            raise error.ProgrammingError(
                'cannot call command %s: method of same name not available '
                'on peer' % command)

        # Commands are either batchable or they aren't. If a command
        # isn't batchable, we send it immediately because the executor
        # can no longer accept new commands after a non-batchable command.
        # If a command is batchable, we queue it for later.

        if getattr(fn, 'batchable', False):
            pass
        else:
            if self._calls:
                raise error.ProgrammingError(
                    '%s is not batchable and cannot be called on a command '
                    'executor along with other commands' % command)

        # We don't support batching yet. So resolve it immediately.
        f = pycompat.futures.Future()
        self._calls.append((command, args, fn, f))
        self.sendcommands()
        return f

    def sendcommands(self):
        if self._sent:
            return

        if not self._calls:
            return

        self._sent = True

        calls = self._calls
        # Mainly to destroy references to futures.
        self._calls = None

        if len(calls) == 1:
            command, args, fn, f = calls[0]

            # Future was cancelled. Ignore it.
            if not f.set_running_or_notify_cancel():
                return

            try:
                result = fn(**pycompat.strkwargs(args))
            except Exception:
                f.set_exception_info(*sys.exc_info()[1:])
            else:
                f.set_result(result)

            return

        raise error.ProgrammingError('support for multiple commands not '
                                     'yet implemented')

    def close(self):
        self.sendcommands()

        self._closed = True

class wirepeer(repository.legacypeer):
    """Client-side interface for communicating with a peer repository.

    Methods commonly call wire protocol commands of the same name.

    See also httppeer.py and sshpeer.py for protocol-specific
    implementations of this interface.
    """
    def commandexecutor(self):
        return peerexecutor(self)

    # Begin of ipeercommands interface.

    def iterbatch(self):
        return remoteiterbatcher(self)

    @batchable
    def lookup(self, key):
        self.requirecap('lookup', _('look up remote revision'))
        f = future()
        yield {'key': encoding.fromlocal(key)}, f
        d = f.value
        success, data = d[:-1].split(" ", 1)
        if int(success):
            yield bin(data)
        else:
            self._abort(error.RepoError(data))

    @batchable
    def heads(self):
        f = future()
        yield {}, f
        d = f.value
        try:
            yield wireprototypes.decodelist(d[:-1])
        except ValueError:
            self._abort(error.ResponseError(_("unexpected response:"), d))

    @batchable
    def known(self, nodes):
        f = future()
        yield {'nodes': wireprototypes.encodelist(nodes)}, f
        d = f.value
        try:
            yield [bool(int(b)) for b in d]
        except ValueError:
            self._abort(error.ResponseError(_("unexpected response:"), d))

    @batchable
    def branchmap(self):
        f = future()
        yield {}, f
        d = f.value
        try:
            branchmap = {}
            for branchpart in d.splitlines():
                branchname, branchheads = branchpart.split(' ', 1)
                branchname = encoding.tolocal(urlreq.unquote(branchname))
                branchheads = wireprototypes.decodelist(branchheads)
                branchmap[branchname] = branchheads
            yield branchmap
        except TypeError:
            self._abort(error.ResponseError(_("unexpected response:"), d))

    @batchable
    def listkeys(self, namespace):
        if not self.capable('pushkey'):
            yield {}, None
        f = future()
        self.ui.debug('preparing listkeys for "%s"\n' % namespace)
        yield {'namespace': encoding.fromlocal(namespace)}, f
        d = f.value
        self.ui.debug('received listkey for "%s": %i bytes\n'
                      % (namespace, len(d)))
        yield pushkeymod.decodekeys(d)

    @batchable
    def pushkey(self, namespace, key, old, new):
        if not self.capable('pushkey'):
            yield False, None
        f = future()
        self.ui.debug('preparing pushkey for "%s:%s"\n' % (namespace, key))
        yield {'namespace': encoding.fromlocal(namespace),
               'key': encoding.fromlocal(key),
               'old': encoding.fromlocal(old),
               'new': encoding.fromlocal(new)}, f
        d = f.value
        d, output = d.split('\n', 1)
        try:
            d = bool(int(d))
        except ValueError:
            raise error.ResponseError(
                _('push failed (unexpected response):'), d)
        for l in output.splitlines(True):
            self.ui.status(_('remote: '), l)
        yield d

    def stream_out(self):
        return self._callstream('stream_out')

    def getbundle(self, source, **kwargs):
        kwargs = pycompat.byteskwargs(kwargs)
        self.requirecap('getbundle', _('look up remote changes'))
        opts = {}
        bundlecaps = kwargs.get('bundlecaps') or set()
        for key, value in kwargs.iteritems():
            if value is None:
                continue
            keytype = wireprototypes.GETBUNDLE_ARGUMENTS.get(key)
            if keytype is None:
                raise error.ProgrammingError(
                    'Unexpectedly None keytype for key %s' % key)
            elif keytype == 'nodes':
                value = wireprototypes.encodelist(value)
            elif keytype == 'csv':
                value = ','.join(value)
            elif keytype == 'scsv':
                value = ','.join(sorted(value))
            elif keytype == 'boolean':
                value = '%i' % bool(value)
            elif keytype != 'plain':
                raise KeyError('unknown getbundle option type %s'
                               % keytype)
            opts[key] = value
        f = self._callcompressable("getbundle", **pycompat.strkwargs(opts))
        if any((cap.startswith('HG2') for cap in bundlecaps)):
            return bundle2.getunbundler(self.ui, f)
        else:
            return changegroupmod.cg1unpacker(f, 'UN')

    def unbundle(self, cg, heads, url):
        '''Send cg (a readable file-like object representing the
        changegroup to push, typically a chunkbuffer object) to the
        remote server as a bundle.

        When pushing a bundle10 stream, return an integer indicating the
        result of the push (see changegroup.apply()).

        When pushing a bundle20 stream, return a bundle20 stream.

        `url` is the url the client thinks it's pushing to, which is
        visible to hooks.
        '''

        if heads != ['force'] and self.capable('unbundlehash'):
            heads = wireprototypes.encodelist(
                ['hashed', hashlib.sha1(''.join(sorted(heads))).digest()])
        else:
            heads = wireprototypes.encodelist(heads)

        if util.safehasattr(cg, 'deltaheader'):
            # this a bundle10, do the old style call sequence
            ret, output = self._callpush("unbundle", cg, heads=heads)
            if ret == "":
                raise error.ResponseError(
                    _('push failed:'), output)
            try:
                ret = int(ret)
            except ValueError:
                raise error.ResponseError(
                    _('push failed (unexpected response):'), ret)

            for l in output.splitlines(True):
                self.ui.status(_('remote: '), l)
        else:
            # bundle2 push. Send a stream, fetch a stream.
            stream = self._calltwowaystream('unbundle', cg, heads=heads)
            ret = bundle2.getunbundler(self.ui, stream)
        return ret

    # End of ipeercommands interface.

    # Begin of ipeerlegacycommands interface.

    def branches(self, nodes):
        n = wireprototypes.encodelist(nodes)
        d = self._call("branches", nodes=n)
        try:
            br = [tuple(wireprototypes.decodelist(b)) for b in d.splitlines()]
            return br
        except ValueError:
            self._abort(error.ResponseError(_("unexpected response:"), d))

    def between(self, pairs):
        batch = 8 # avoid giant requests
        r = []
        for i in xrange(0, len(pairs), batch):
            n = " ".join([wireprototypes.encodelist(p, '-')
                          for p in pairs[i:i + batch]])
            d = self._call("between", pairs=n)
            try:
                r.extend(l and wireprototypes.decodelist(l) or []
                         for l in d.splitlines())
            except ValueError:
                self._abort(error.ResponseError(_("unexpected response:"), d))
        return r

    def changegroup(self, nodes, kind):
        n = wireprototypes.encodelist(nodes)
        f = self._callcompressable("changegroup", roots=n)
        return changegroupmod.cg1unpacker(f, 'UN')

    def changegroupsubset(self, bases, heads, kind):
        self.requirecap('changegroupsubset', _('look up remote changes'))
        bases = wireprototypes.encodelist(bases)
        heads = wireprototypes.encodelist(heads)
        f = self._callcompressable("changegroupsubset",
                                   bases=bases, heads=heads)
        return changegroupmod.cg1unpacker(f, 'UN')

    # End of ipeerlegacycommands interface.

    def _submitbatch(self, req):
        """run batch request <req> on the server

        Returns an iterator of the raw responses from the server.
        """
        ui = self.ui
        if ui.debugflag and ui.configbool('devel', 'debug.peer-request'):
            ui.debug('devel-peer-request: batched-content\n')
            for op, args in req:
                msg = 'devel-peer-request:    - %s (%d arguments)\n'
                ui.debug(msg % (op, len(args)))

        unescapearg = wireprototypes.unescapebatcharg

        rsp = self._callstream("batch", cmds=encodebatchcmds(req))
        chunk = rsp.read(1024)
        work = [chunk]
        while chunk:
            while ';' not in chunk and chunk:
                chunk = rsp.read(1024)
                work.append(chunk)
            merged = ''.join(work)
            while ';' in merged:
                one, merged = merged.split(';', 1)
                yield unescapearg(one)
            chunk = rsp.read(1024)
            work = [merged, chunk]
        yield unescapearg(''.join(work))

    def _submitone(self, op, args):
        return self._call(op, **pycompat.strkwargs(args))

    def debugwireargs(self, one, two, three=None, four=None, five=None):
        # don't pass optional arguments left at their default value
        opts = {}
        if three is not None:
            opts[r'three'] = three
        if four is not None:
            opts[r'four'] = four
        return self._call('debugwireargs', one=one, two=two, **opts)

    def _call(self, cmd, **args):
        """execute <cmd> on the server

        The command is expected to return a simple string.

        returns the server reply as a string."""
        raise NotImplementedError()

    def _callstream(self, cmd, **args):
        """execute <cmd> on the server

        The command is expected to return a stream. Note that if the
        command doesn't return a stream, _callstream behaves
        differently for ssh and http peers.

        returns the server reply as a file like object.
        """
        raise NotImplementedError()

    def _callcompressable(self, cmd, **args):
        """execute <cmd> on the server

        The command is expected to return a stream.

        The stream may have been compressed in some implementations. This
        function takes care of the decompression. This is the only difference
        with _callstream.

        returns the server reply as a file like object.
        """
        raise NotImplementedError()

    def _callpush(self, cmd, fp, **args):
        """execute a <cmd> on server

        The command is expected to be related to a push. Push has a special
        return method.

        returns the server reply as a (ret, output) tuple. ret is either
        empty (error) or a stringified int.
        """
        raise NotImplementedError()

    def _calltwowaystream(self, cmd, fp, **args):
        """execute <cmd> on server

        The command will send a stream to the server and get a stream in reply.
        """
        raise NotImplementedError()

    def _abort(self, exception):
        """clearly abort the wire protocol connection and raise the exception
        """
        raise NotImplementedError()