~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2006, 2007 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Basic server-side logic for dealing with requests."""

import tempfile

from bzrlib import (

    bzrdir,

    errors,

    registry,

    revision,

    )

from bzrlib.bundle.serializer import write_bundle

class SmartServerRequest(object):

    """Base class for request handlers."""

    def __init__(self, backing_transport):

        """Constructor.

        :param backing_transport: the base transport to be used when performing

            this request.

        """

        self._backing_transport = backing_transport

    def _check_enabled(self):

        """Raises DisabledMethod if this method is disabled."""

        pass

    def do(self, *args):

        """Mandatory extension point for SmartServerRequest subclasses.

        Subclasses must implement this.

        This should return a SmartServerResponse if this command expects to

        receive no body.

        """

        raise NotImplementedError(self.do)

    def execute(self, *args):

        """Public entry point to execute this request.

        It will return a SmartServerResponse if the command does not expect a

        body.

        :param *args: the arguments of the request.

        """

        self._check_enabled()

        return self.do(*args)

    def do_body(self, body_bytes):

        """Called if the client sends a body with the request.

        Must return a SmartServerResponse.

        """

        # TODO: if a client erroneously sends a request that shouldn't have a

        # body, what to do?  Probably SmartServerRequestHandler should catch

        # this NotImplementedError and translate it into a 'bad request' error

        # to send to the client.

        raise NotImplementedError(self.do_body)

class SmartServerResponse(object):

    """Response generated by SmartServerRequestHandler."""

    def __init__(self, args, body=None):

        self.args = args

        self.body = body

    def __eq__(self, other):

        if other is None:

            return False

        return other.args == self.args and other.body == self.body

    def __repr__(self):

        return "<SmartServerResponse args=%r body=%r>" % (self.args, self.body)

class SmartServerRequestHandler(object):

    """Protocol logic for smart server.

    This doesn't handle serialization at all, it just processes requests and

    creates responses.

    """

    # IMPORTANT FOR IMPLEMENTORS: It is important that SmartServerRequestHandler

    # not contain encoding or decoding logic to allow the wire protocol to vary

    # from the object protocol: we will want to tweak the wire protocol separate

    # from the object model, and ideally we will be able to do that without

    # having a SmartServerRequestHandler subclass for each wire protocol, rather

    # just a Protocol subclass.

    # TODO: Better way of representing the body for commands that take it,

    # and allow it to be streamed into the server.

    def __init__(self, backing_transport, commands):

        """Constructor.

        :param backing_transport: a Transport to handle requests for.

        :param commands: a registry mapping command names to SmartServerRequest

            subclasses. e.g. bzrlib.transport.smart.vfs.vfs_commands.

        """

        self._backing_transport = backing_transport

        self._commands = commands

        self._body_bytes = ''

        self.response = None

        self.finished_reading = False

        self._command = None

    def accept_body(self, bytes):

        """Accept body data."""

        # TODO: This should be overriden for each command that desired body data

        # to handle the right format of that data, i.e. plain bytes, a bundle,

        # etc.  The deserialisation into that format should be done in the

        # Protocol object.

        # default fallback is to accumulate bytes.

        self._body_bytes += bytes

    def end_of_body(self):

        """No more body data will be received."""

        self._run_handler_code(self._command.do_body, (self._body_bytes,), {})

        # cannot read after this.

        self.finished_reading = True

    def dispatch_command(self, cmd, args):

        """Deprecated compatibility method.""" # XXX XXX

        try:

            command = self._commands.get(cmd)

        except LookupError:

            raise errors.SmartProtocolError("bad request %r" % (cmd,))

        self._command = command(self._backing_transport)

        self._run_handler_code(self._command.execute, args, {})

    def _run_handler_code(self, callable, args, kwargs):

        """Run some handler specific code 'callable'.

        If a result is returned, it is considered to be the commands response,

        and finished_reading is set true, and its assigned to self.response.

        Any exceptions caught are translated and a response object created

        from them.

        """

        result = self._call_converting_errors(callable, args, kwargs)

        if result is not None:

            self.response = result

            self.finished_reading = True

    def _call_converting_errors(self, callable, args, kwargs):

        """Call callable converting errors to Response objects."""

        # XXX: most of this error conversion is VFS-related, and thus ought to

        # be in SmartServerVFSRequestHandler somewhere.

        try:

            return callable(*args, **kwargs)

        except errors.NoSuchFile, e:

            return SmartServerResponse(('NoSuchFile', e.path))

        except errors.FileExists, e:

            return SmartServerResponse(('FileExists', e.path))

        except errors.DirectoryNotEmpty, e:

            return SmartServerResponse(('DirectoryNotEmpty', e.path))

        except errors.ShortReadvError, e:

            return SmartServerResponse(('ShortReadvError',

                e.path, str(e.offset), str(e.length), str(e.actual)))

        except UnicodeError, e:

            # If it is a DecodeError, than most likely we are starting

            # with a plain string

            str_or_unicode = e.object

            if isinstance(str_or_unicode, unicode):

                # XXX: UTF-8 might have \x01 (our seperator byte) in it.  We

                # should escape it somehow.

                val = 'u:' + str_or_unicode.encode('utf-8')

            else:

                val = 's:' + str_or_unicode.encode('base64')

            # This handles UnicodeEncodeError or UnicodeDecodeError

            return SmartServerResponse((e.__class__.__name__,

                    e.encoding, val, str(e.start), str(e.end), e.reason))

        except errors.TransportNotPossible, e:

            if e.msg == "readonly transport":

                return SmartServerResponse(('ReadOnlyError', ))

            else:

                raise

class HelloRequest(SmartServerRequest):

    """Answer a version request with my version."""

    def do(self):

        return SmartServerResponse(('ok', '1'))

class GetBundleRequest(SmartServerRequest):

    """Get a bundle of from the null revision to the specified revision."""

    def do(self, path, revision_id):

        # open transport relative to our base

        t = self._backing_transport.clone(path)

        control, extra_path = bzrdir.BzrDir.open_containing_from_transport(t)

        repo = control.open_repository()

        tmpf = tempfile.TemporaryFile()

        base_revision = revision.NULL_REVISION

        write_bundle(repo, revision_id, base_revision, tmpf)

        tmpf.seek(0)

        return SmartServerResponse((), tmpf.read())

class SmartServerIsReadonly(SmartServerRequest):

    # XXX: this request method belongs somewhere else.

    def do(self):

        if self._backing_transport.is_readonly():

            answer = 'yes'

        else:

            answer = 'no'

        return SmartServerResponse((answer,))

request_handlers = registry.Registry()

request_handlers.register_lazy(

    'append', 'bzrlib.smart.vfs', 'AppendRequest')

request_handlers.register_lazy(

    'delete', 'bzrlib.smart.vfs', 'DeleteRequest')

request_handlers.register_lazy(

    'get', 'bzrlib.smart.vfs', 'GetRequest')

request_handlers.register_lazy(

    'get_bundle', 'bzrlib.smart.request', 'GetBundleRequest')

request_handlers.register_lazy(

    'has', 'bzrlib.smart.vfs', 'HasRequest')

request_handlers.register_lazy(

    'hello', 'bzrlib.smart.request', 'HelloRequest')

request_handlers.register_lazy(

    'iter_files_recursive', 'bzrlib.smart.vfs', 'IterFilesRecursiveRequest')

request_handlers.register_lazy(

    'list_dir', 'bzrlib.smart.vfs', 'ListDirRequest')

request_handlers.register_lazy(

    'mkdir', 'bzrlib.smart.vfs', 'MkdirRequest')

request_handlers.register_lazy(

    'move', 'bzrlib.smart.vfs', 'MoveRequest')

request_handlers.register_lazy(

    'put', 'bzrlib.smart.vfs', 'PutRequest')

request_handlers.register_lazy(

    'put_non_atomic', 'bzrlib.smart.vfs', 'PutNonAtomicRequest')

request_handlers.register_lazy(

    'readv', 'bzrlib.smart.vfs', 'ReadvRequest')

request_handlers.register_lazy(

    'rename', 'bzrlib.smart.vfs', 'RenameRequest')

request_handlers.register_lazy(

    'rmdir', 'bzrlib.smart.vfs', 'RmdirRequest')

request_handlers.register_lazy(

    'stat', 'bzrlib.smart.vfs', 'StatRequest')