def __init__(self, service, channel, config = {}, _lazy = False):
        self._closed = True
        self._config = DEFAULT_CONFIG.copy()
        self._config.update(config)
        if self._config["connid"] is None:
            self._config["connid"] = "conn%d" % (next(_connection_id_generator),)

        self._channel = channel
        self._seqcounter = itertools.count()
        self._recvlock = Lock()
        self._sendlock = Lock()
        self._sync_replies = {}
        self._sync_lock = RLock()
        self._sync_event = Event()
        self._async_callbacks = {}
        self._local_objects = RefCountingColl()
        self._last_traceback = None
        self._proxy_cache = WeakValueDict()
        self._netref_classes_cache = {}
        self._remote_root = None
        self._send_queue = []
        self._local_root = service(weakref.proxy(self))
        if not _lazy:
            self._init_service()
        self._closed = False
Example #2
0
    def __init__(self, root, channel, config={}):
        self._closed = True
        self._config = DEFAULT_CONFIG.copy()
        self._config.update(config)
        if self._config["connid"] is None:
            self._config["connid"] = "conn%d" % (
                next(_connection_id_generator), )

        self._HANDLERS = self._request_handlers()
        self._channel = channel
        self._seqcounter = itertools.count()
        self._recvlock = Lock()
        self._sendlock = Lock()
        self._recv_event = Condition()
        self._request_callbacks = {}
        self._local_objects = RefCountingColl()
        self._last_traceback = None
        self._proxy_cache = WeakValueDict()
        self._netref_classes_cache = {}
        self._remote_root = None
        self._send_queue = []
        self._local_root = root
        self._closed = False
Example #3
0
    are cached. Invoking an async proxy will return an AsyncResult instead of
    blocking"""

    __slots__ = ("proxy", "__weakref__")

    def __init__(self, proxy):
        self.proxy = proxy

    def __call__(self, *args, **kwargs):
        return asyncreq(self.proxy, HANDLE_CALL, args, tuple(kwargs.items()))

    def __repr__(self):
        return "async_(%r)" % (self.proxy, )


_async_proxies_cache = WeakValueDict()


def async_(proxy):
    """
    Returns an asynchronous "version" of the given proxy. Invoking the returned
    proxy will not block; instead it will return an
    :class:`rpyc.core.async_.AsyncResult` object that you can test for completion

    :param proxy: any **callable** RPyC proxy

    :returns: the proxy, wrapped by an asynchronous wrapper

    Example::

        async_sleep = rpyc.async_(conn.modules.time.sleep)
Example #4
0
class Connection(object):
    """The RPyC *connection* (AKA *protocol*).

    :param root: the :class:`~rpyc.core.service.Service` object to expose
    :param channel: the :class:`~rpyc.core.channel.Channel` over which messages are passed
    :param config: the connection's configuration dict (overriding parameters
                   from the :data:`default configuration <DEFAULT_CONFIG>`)
    """
    def __init__(self, root, channel, config={}):
        self._closed = True
        self._config = DEFAULT_CONFIG.copy()
        self._config.update(config)
        if self._config["connid"] is None:
            self._config["connid"] = "conn%d" % (
                next(_connection_id_generator), )

        self._HANDLERS = self._request_handlers()
        self._channel = channel
        self._seqcounter = itertools.count()
        self._recvlock = Lock()
        self._sendlock = Lock()
        self._recv_event = Condition()
        self._request_callbacks = {}
        self._local_objects = RefCountingColl()
        self._last_traceback = None
        self._proxy_cache = WeakValueDict()
        self._netref_classes_cache = {}
        self._remote_root = None
        self._send_queue = []
        self._local_root = root
        self._closed = False

    def __del__(self):
        self.close()

    def __enter__(self):
        return self

    def __exit__(self, t, v, tb):
        self.close()

    def __repr__(self):
        a, b = object.__repr__(self).split(" object ")
        return "%s %r object %s" % (a, self._config["connid"], b)

    #
    # IO
    #
    def _cleanup(self, _anyway=True):
        if self._closed and not _anyway:
            return
        self._closed = True
        self._channel.close()
        self._local_root.on_disconnect(self)
        self._request_callbacks.clear()
        self._local_objects.clear()
        self._proxy_cache.clear()
        self._netref_classes_cache.clear()
        self._last_traceback = None
        self._remote_root = None
        self._local_root = None
        #self._seqcounter = None
        #self._config.clear()
        del self._HANDLERS

    def close(self, _catchall=True):
        """closes the connection, releasing all held resources"""
        if self._closed:
            return
        self._closed = True
        try:
            self._async_request(consts.HANDLE_CLOSE)
        except EOFError:
            pass
        except Exception:
            if not _catchall:
                raise
        finally:
            self._cleanup(_anyway=True)

    @property
    def closed(self):
        """Indicates whether the connection has been closed or not"""
        return self._closed

    def fileno(self):
        """Returns the connectin's underlying file descriptor"""
        return self._channel.fileno()

    def ping(self, data=None, timeout=3):
        """
        Asserts that the other party is functioning properly, by making sure
        the *data* is echoed back before the *timeout* expires

        :param data: the data to send (leave ``None`` for the default buffer)
        :param timeout: the maximal time to wait for echo

        :raises: :class:`PingError` if the echoed data does not match
        :raises: :class:`EOFError` if the remote host closes the connection
        """
        if data is None:
            data = "abcdefghijklmnopqrstuvwxyz" * 20
        res = self.async_request(consts.HANDLE_PING, data, timeout=timeout)
        if res.value != data:
            raise PingError("echo mismatches sent data")

    def _get_seq_id(self):
        return next(self._seqcounter)

    def _send(self, msg, seq, args):
        data = brine.dump((msg, seq, args))
        # GC might run while sending data
        # if so, a BaseNetref.__del__ might be called
        # BaseNetref.__del__ must call asyncreq,
        # which will cause a deadlock
        # Solution:
        # Add the current request to a queue and let the thread that currently
        # holds the sendlock send it when it's done with its current job.
        # NOTE: Atomic list operations should be thread safe,
        # please call me out if they are not on all implementations!
        self._send_queue.append(data)
        # It is crucial to check the queue each time AFTER releasing the lock:
        while self._send_queue:
            if not self._sendlock.acquire(False):
                # Another thread holds the lock. It will send the data after
                # it's done with its current job. We can safely return.
                return
            try:
                # Can happen if another consumer was scheduled in between
                # `while` and `acquire`:
                if not self._send_queue:
                    # Must `continue` to ensure that `send_queue` is checked
                    # after releasing the lock! (in case another producer is
                    # scheduled before `release`)
                    continue
                data = self._send_queue.pop(0)
                self._channel.send(data)
            finally:
                self._sendlock.release()

    #
    # boxing
    #
    def _box(self, obj):
        """store a local object in such a way that it could be recreated on
        the remote party either by-value or by-reference"""
        if brine.dumpable(obj):
            return consts.LABEL_VALUE, obj
        if type(obj) is tuple:
            return consts.LABEL_TUPLE, tuple(self._box(item) for item in obj)
        elif isinstance(obj, netref.BaseNetref) and obj.____conn__ is self:
            return consts.LABEL_LOCAL_REF, obj.____oid__
        else:
            self._local_objects.add(obj)
            try:
                cls = obj.__class__
            except Exception:
                # see issue #16
                cls = type(obj)
            if not isinstance(cls, type):
                cls = type(obj)
            return consts.LABEL_REMOTE_REF, (id(obj), cls.__name__,
                                             cls.__module__)

    def _unbox(self, package):
        """recreate a local object representation of the remote object: if the
        object is passed by value, just return it; if the object is passed by
        reference, create a netref to it"""
        label, value = package
        if label == consts.LABEL_VALUE:
            return value
        if label == consts.LABEL_TUPLE:
            return tuple(self._unbox(item) for item in value)
        if label == consts.LABEL_LOCAL_REF:
            return self._local_objects[value]
        if label == consts.LABEL_REMOTE_REF:
            oid, clsname, modname = value
            if oid in self._proxy_cache:
                proxy = self._proxy_cache[oid]
                proxy.____refcount__ += 1  # other side increased refcount on boxing,
                # if I'm returning from cache instead of new object,
                # must increase refcount to match
                return proxy
            proxy = self._netref_factory(oid, clsname, modname)
            self._proxy_cache[oid] = proxy
            return proxy
        raise ValueError("invalid label %r" % (label, ))

    def _netref_factory(self, oid, clsname, modname):
        typeinfo = (clsname, modname)
        if typeinfo in self._netref_classes_cache:
            cls = self._netref_classes_cache[typeinfo]
        elif typeinfo in netref.builtin_classes_cache:
            cls = netref.builtin_classes_cache[typeinfo]
        else:
            info = self.sync_request(consts.HANDLE_INSPECT, oid)
            cls = netref.class_factory(clsname, modname, info)
            self._netref_classes_cache[typeinfo] = cls
        return cls(self, oid)

    #
    # dispatching
    #
    def _dispatch_request(self, seq, raw_args):
        try:
            handler, args = raw_args
            args = self._unbox(args)
            res = self._HANDLERS[handler](self, *args)
        except:
            # need to catch old style exceptions too
            t, v, tb = sys.exc_info()
            self._last_traceback = tb
            logger = self._config["logger"]
            if logger and t is not StopIteration:
                logger.debug("Exception caught", exc_info=True)
            if t is SystemExit and self._config["propagate_SystemExit_locally"]:
                raise
            if t is KeyboardInterrupt and self._config[
                    "propagate_KeyboardInterrupt_locally"]:
                raise
            self._send(consts.MSG_EXCEPTION, seq, self._box_exc(t, v, tb))
        else:
            self._send(consts.MSG_REPLY, seq, self._box(res))

    def _box_exc(self, typ, val, tb):
        return vinegar.dump(
            typ,
            val,
            tb,
            include_local_traceback=self._config["include_local_traceback"])

    def _unbox_exc(self, raw):
        return vinegar.load(
            raw,
            import_custom_exceptions=self._config["import_custom_exceptions"],
            instantiate_custom_exceptions=self.
            _config["instantiate_custom_exceptions"],
            instantiate_oldstyle_exceptions=self.
            _config["instantiate_oldstyle_exceptions"])

    #
    # serving
    #

    def _dispatch(self, data):
        msg, seq, args = brine.load(data)
        if msg == consts.MSG_REQUEST:
            self._dispatch_request(seq, args)
        elif msg == consts.MSG_REPLY:
            obj = self._unbox(args)
            self._request_callbacks.pop(seq)(False, obj)
        elif msg == consts.MSG_EXCEPTION:
            obj = self._unbox_exc(args)
            self._request_callbacks.pop(seq)(True, obj)
        else:
            raise ValueError("invalid message type: %r" % (msg, ))

    def serve(self, timeout=1, wait_for_lock=True):
        """Serves a single request or reply that arrives within the given
        time frame (default is 1 sec). Note that the dispatching of a request
        might trigger multiple (nested) requests, thus this function may be
        reentrant.

        :returns: ``True`` if a request or reply were received, ``False``
                  otherwise.
        """
        timeout = Timeout(timeout)
        with self._recv_event:
            if not self._recvlock.acquire(False):
                return (wait_for_lock
                        and self._recv_event.wait(timeout.timeleft()))
        try:
            data = self._channel.poll(timeout) and self._channel.recv()
            if not data:
                return False
        except EOFError:
            self.close()
            raise
        finally:
            self._recvlock.release()
            with self._recv_event:
                self._recv_event.notify_all()
        self._dispatch(data)
        return True

    def poll(self, timeout=0):
        """Serves a single transaction, should one arrives in the given
        interval. Note that handling a request/reply may trigger nested
        requests, which are all part of a single transaction.

        :returns: ``True`` if a transaction was served, ``False`` otherwise"""
        return self.serve(timeout, False)

    def serve_all(self):
        """Serves all requests and replies for as long as the connection is
        alive."""
        try:
            while True:
                self.serve(None)
        except (socket.error, select_error, IOError):
            if not self.closed:
                raise
        except EOFError:
            pass
        finally:
            self.close()

    def serve_threaded(self, thread_count=10):
        """Serves all requests and replies for as long as the connection is
        alive."""
        def _thread_target():
            try:
                while True:
                    self.serve(None)
            except (socket.error, select_error, IOError):
                if not self.closed:
                    raise
            except EOFError:
                pass

        try:
            threads = [spawn(_thread_target) for _ in range(thread_count)]

            for thread in threads:
                thread.join()
        finally:
            self.close()

    def poll_all(self, timeout=0):
        """Serves all requests and replies that arrive within the given interval.

        :returns: ``True`` if at least a single transaction was served, ``False`` otherwise
        """
        at_least_once = False
        timeout = Timeout(timeout)
        try:
            while True:
                if self.poll(timeout):
                    at_least_once = True
                if timeout.expired():
                    break
        except EOFError:
            pass
        return at_least_once

    #
    # requests
    #
    def sync_request(self, handler, *args):
        """Sends a synchronous request (waits for the reply to arrive)

        :raises: any exception that the requets may be generated
        :returns: the result of the request
        """
        timeout = self._config["sync_request_timeout"]
        return self.async_request(handler, *args, timeout=timeout).value

    def _async_request(self, handler, args=(), callback=(lambda a, b: None)):
        seq = self._get_seq_id()
        self._request_callbacks[seq] = callback
        try:
            self._send(consts.MSG_REQUEST, seq, (handler, self._box(args)))
        except:
            self._request_callbacks.pop(seq, None)
            raise

    def async_request(self, handler, *args, **kwargs):
        """Send an asynchronous request (does not wait for it to finish)

        :returns: an :class:`rpyc.core.async_.AsyncResult` object, which will
                  eventually hold the result (or exception)
        """
        timeout = kwargs.pop("timeout", None)
        if kwargs:
            raise TypeError("got unexpected keyword argument(s) %s" %
                            (list(kwargs.keys()), ))
        res = AsyncResult(self)
        self._async_request(handler, args, res)
        if timeout is not None:
            res.set_expiry(timeout)
        return res

    @property
    def root(self):
        """Fetches the root object (service) of the other party"""
        if self._remote_root is None:
            self._remote_root = self.sync_request(consts.HANDLE_GETROOT)
        return self._remote_root

    #
    # attribute access
    #
    def _check_attr(self, obj, name, perm):
        config = self._config
        if not config[perm]:
            raise AttributeError("cannot access %r" % (name, ))
        prefix = config["allow_exposed_attrs"] and config["exposed_prefix"]
        plain = (config["allow_all_attrs"]
                 or config["allow_exposed_attrs"] and name.startswith(prefix)
                 or config["allow_safe_attrs"] and name in config["safe_attrs"]
                 or config["allow_public_attrs"] and not name.startswith("_"))
        has_exposed = prefix and hasattr(obj, prefix + name)
        if plain and (not has_exposed or hasattr(obj, name)):
            return name
        if has_exposed:
            return prefix + name
        if plain:
            return name  # chance for better traceback
        raise AttributeError("cannot access %r" % (name, ))

    def _access_attr(self, obj, name, args, overrider, param, default):
        if is_py3k:
            if type(name) is bytes:
                name = str(name, "utf8")
            elif type(name) is not str:
                raise TypeError("name must be a string")
        else:
            if type(name) not in (str, unicode):
                raise TypeError("name must be a string")
            name = str(name)  # IronPython issue #10 + py3k issue
        accessor = getattr(type(obj), overrider, None)
        if accessor is None:
            accessor = default
            name = self._check_attr(obj, name, param)
        return accessor(obj, name, *args)

    #
    # request handlers
    #
    @classmethod
    def _request_handlers(cls):
        return {
            consts.HANDLE_PING: cls._handle_ping,
            consts.HANDLE_CLOSE: cls._handle_close,
            consts.HANDLE_GETROOT: cls._handle_getroot,
            consts.HANDLE_GETATTR: cls._handle_getattr,
            consts.HANDLE_DELATTR: cls._handle_delattr,
            consts.HANDLE_SETATTR: cls._handle_setattr,
            consts.HANDLE_CALL: cls._handle_call,
            consts.HANDLE_CALLATTR: cls._handle_callattr,
            consts.HANDLE_REPR: cls._handle_repr,
            consts.HANDLE_STR: cls._handle_str,
            consts.HANDLE_CMP: cls._handle_cmp,
            consts.HANDLE_HASH: cls._handle_hash,
            consts.HANDLE_DIR: cls._handle_dir,
            consts.HANDLE_PICKLE: cls._handle_pickle,
            consts.HANDLE_DEL: cls._handle_del,
            consts.HANDLE_INSPECT: cls._handle_inspect,
            consts.HANDLE_BUFFITER: cls._handle_buffiter,
            consts.HANDLE_OLDSLICING: cls._handle_oldslicing,
            consts.HANDLE_CTXEXIT: cls._handle_ctxexit,
        }

    def _handle_ping(self, data):
        return data

    def _handle_close(self):
        self._cleanup()

    def _handle_getroot(self):
        return self._local_root

    def _handle_del(self, obj, count=1):
        self._local_objects.decref(id(obj), count)

    def _handle_repr(self, obj):
        return repr(obj)

    def _handle_str(self, obj):
        return str(obj)

    def _handle_cmp(self, obj, other):
        # cmp() might enter recursive resonance... yet another workaround
        #return cmp(obj, other)
        try:
            return type(obj).__cmp__(obj, other)
        except (AttributeError, TypeError):
            return NotImplemented

    def _handle_hash(self, obj):
        return hash(obj)

    def _handle_call(self, obj, args, kwargs=()):
        return obj(*args, **dict(kwargs))

    def _handle_dir(self, obj):
        return tuple(dir(obj))

    def _handle_inspect(self, oid):
        return tuple(netref.inspect_methods(self._local_objects[oid]))

    def _handle_getattr(self, obj, name):
        return self._access_attr(obj, name, (), "_rpyc_getattr",
                                 "allow_getattr", getattr)

    def _handle_delattr(self, obj, name):
        return self._access_attr(obj, name, (), "_rpyc_delattr",
                                 "allow_delattr", delattr)

    def _handle_setattr(self, obj, name, value):
        return self._access_attr(obj, name, (value, ), "_rpyc_setattr",
                                 "allow_setattr", setattr)

    def _handle_callattr(self, obj, name, args, kwargs=()):
        obj = self._handle_getattr(obj, name)
        return self._handle_call(obj, args, kwargs)

    def _handle_ctxexit(self, obj, exc):
        if exc:
            try:
                raise exc
            except:
                exc, typ, tb = sys.exc_info()
        else:
            typ = tb = None
        return self._handle_getattr(obj, "__exit__")(exc, typ, tb)

    def _handle_pickle(self, obj, proto):
        if not self._config["allow_pickle"]:
            raise ValueError("pickling is disabled")
        return bytes(pickle.dumps(obj, proto))

    def _handle_buffiter(self, obj, count):
        return tuple(itertools.islice(obj, count))

    def _handle_oldslicing(self, obj, attempt, fallback, start, stop, args):
        try:
            # first try __xxxitem__
            getitem = self._handle_getattr(obj, attempt)
            return getitem(slice(start, stop), *args)
        except Exception:
            # fallback to __xxxslice__. see issue #41
            if stop is None:
                stop = maxint
            getslice = self._handle_getattr(obj, fallback)
            return getslice(start, stop, *args)
Example #5
0
class Connection(object):
    """The RPyC *connection* (AKA *protocol*).

    :param root: the :class:`~rpyc.core.service.Service` object to expose
    :param channel: the :class:`~rpyc.core.channel.Channel` over which messages are passed
    :param config: the connection's configuration dict (overriding parameters
                   from the :data:`default configuration <DEFAULT_CONFIG>`)
    """
    def __init__(self, root, channel, config={}):
        self._closed = True
        self._config = DEFAULT_CONFIG.copy()
        self._config.update(config)
        if self._config["connid"] is None:
            self._config["connid"] = "conn%d" % (
                next(_connection_id_generator), )

        self._HANDLERS = self._request_handlers()
        self._channel = channel
        self._seqcounter = itertools.count()
        self._recvlock = Lock()
        self._sendlock = Lock()
        self._recv_event = Condition()
        self._request_callbacks = {}
        self._local_objects = RefCountingColl()
        self._last_traceback = None
        self._proxy_cache = WeakValueDict()
        self._netref_classes_cache = {}
        self._remote_root = None
        self._send_queue = []
        self._local_root = root
        self._closed = False

    def __del__(self):
        self.close()

    def __enter__(self):
        return self

    def __exit__(self, t, v, tb):
        self.close()

    def __repr__(self):
        a, b = object.__repr__(self).split(" object ")
        return "%s %r object %s" % (a, self._config["connid"], b)

    def _cleanup(self, _anyway=True):  # IO
        if self._closed and not _anyway:
            return
        self._closed = True
        self._channel.close()
        self._local_root.on_disconnect(self)
        self._request_callbacks.clear()
        self._local_objects.clear()
        self._proxy_cache.clear()
        self._netref_classes_cache.clear()
        self._last_traceback = None
        self._remote_root = None
        self._local_root = None
        # self._seqcounter = None
        # self._config.clear()
        del self._HANDLERS

    def close(self, _catchall=True):  # IO
        """closes the connection, releasing all held resources"""
        if self._closed:
            return
        self._closed = True
        try:
            self._async_request(consts.HANDLE_CLOSE)
        except EOFError:
            pass
        except Exception:
            if not _catchall:
                raise
        finally:
            self._cleanup(_anyway=True)

    @property
    def closed(self):  # IO
        """Indicates whether the connection has been closed or not"""
        return self._closed

    def fileno(self):  # IO
        """Returns the connectin's underlying file descriptor"""
        return self._channel.fileno()

    def ping(self, data=None, timeout=3):  # IO
        """Asserts that the other party is functioning properly, by making sure
        the *data* is echoed back before the *timeout* expires

        :param data: the data to send (leave ``None`` for the default buffer)
        :param timeout: the maximal time to wait for echo

        :raises: :class:`PingError` if the echoed data does not match
        :raises: :class:`EOFError` if the remote host closes the connection
        """
        if data is None:
            data = "abcdefghijklmnopqrstuvwxyz" * 20
        res = self.async_request(consts.HANDLE_PING, data, timeout=timeout)
        if res.value != data:
            raise PingError("echo mismatches sent data")

    def _get_seq_id(self):  # IO
        return next(self._seqcounter)

    def _send(self, msg, seq, args):  # IO
        data = brine.dump((msg, seq, args))
        # GC might run while sending data
        # if so, a BaseNetref.__del__ might be called
        # BaseNetref.__del__ must call asyncreq,
        # which will cause a deadlock
        # Solution:
        # Add the current request to a queue and let the thread that currently
        # holds the sendlock send it when it's done with its current job.
        # NOTE: Atomic list operations should be thread safe,
        # please call me out if they are not on all implementations!
        self._send_queue.append(data)
        # It is crucial to check the queue each time AFTER releasing the lock:
        while self._send_queue:
            if not self._sendlock.acquire(False):
                # Another thread holds the lock. It will send the data after
                # it's done with its current job. We can safely return.
                return
            try:
                # Can happen if another consumer was scheduled in between
                # `while` and `acquire`:
                if not self._send_queue:
                    # Must `continue` to ensure that `send_queue` is checked
                    # after releasing the lock! (in case another producer is
                    # scheduled before `release`)
                    continue
                data = self._send_queue.pop(0)
                self._channel.send(data)
            finally:
                self._sendlock.release()

    def _box(self, obj):  # boxing
        """store a local object in such a way that it could be recreated on
        the remote party either by-value or by-reference"""
        if brine.dumpable(obj):
            return consts.LABEL_VALUE, obj
        if type(obj) is tuple:
            return consts.LABEL_TUPLE, tuple(self._box(item) for item in obj)
        elif isinstance(obj, netref.BaseNetref) and obj.____conn__ is self:
            return consts.LABEL_LOCAL_REF, obj.____id_pack__
        else:
            id_pack = get_id_pack(obj)
            self._local_objects.add(id_pack, obj)
            return consts.LABEL_REMOTE_REF, id_pack

    def _unbox(self, package):  # boxing
        """recreate a local object representation of the remote object: if the
        object is passed by value, just return it; if the object is passed by
        reference, create a netref to it"""
        label, value = package
        if label == consts.LABEL_VALUE:
            return value
        if label == consts.LABEL_TUPLE:
            return tuple(self._unbox(item) for item in value)
        if label == consts.LABEL_LOCAL_REF:
            return self._local_objects[value]
        if label == consts.LABEL_REMOTE_REF:
            id_pack = (str(value[0]), value[1], value[2]
                       )  # so value is a id_pack
            if id_pack in self._proxy_cache:
                proxy = self._proxy_cache[id_pack]
                proxy.____refcount__ += 1  # if cached then remote incremented refcount, so sync refcount
            else:
                proxy = self._netref_factory(id_pack)
                self._proxy_cache[id_pack] = proxy
            return proxy
        raise ValueError("invalid label %r" % (label, ))

    def _netref_factory(self, id_pack):  # boxing
        """id_pack is for remote, so when class id fails to directly match """
        cls = None
        if id_pack[2] == 0 and id_pack in self._netref_classes_cache:
            cls = self._netref_classes_cache[id_pack]
        elif id_pack[0] in netref.builtin_classes_cache:
            cls = netref.builtin_classes_cache[id_pack[0]]
        if cls is None:
            # in the future, it could see if a sys.module cache/lookup hits first
            cls_methods = self.sync_request(consts.HANDLE_INSPECT, id_pack)
            cls = netref.class_factory(id_pack, cls_methods)
            if id_pack[2] == 0:
                # only use cached netrefs for classes
                # ... instance caching after gc of a proxy will take some mental gymnastics
                self._netref_classes_cache[id_pack] = cls
        return cls(self, id_pack)

    def _dispatch_request(self, seq, raw_args):  # dispatch
        try:
            handler, args = raw_args
            args = self._unbox(args)
            res = self._HANDLERS[handler](self, *args)
        except:  # TODO: revist how to catch handle locally, this should simplify when py2 is dropped
            # need to catch old style exceptions too
            t, v, tb = sys.exc_info()
            self._last_traceback = tb
            logger = self._config["logger"]
            if logger and t is not StopIteration:
                logger.debug("Exception caught", exc_info=True)
            if t is SystemExit and self._config["propagate_SystemExit_locally"]:
                raise
            if t is KeyboardInterrupt and self._config[
                    "propagate_KeyboardInterrupt_locally"]:
                raise
            self._send(consts.MSG_EXCEPTION, seq, self._box_exc(t, v, tb))
        else:
            self._send(consts.MSG_REPLY, seq, self._box(res))

    def _box_exc(self, typ, val, tb):  # dispatch?
        return vinegar.dump(
            typ,
            val,
            tb,
            include_local_traceback=self._config["include_local_traceback"],
            include_local_version=self._config["include_local_version"])

    def _unbox_exc(self, raw):  # dispatch?
        return vinegar.load(
            raw,
            import_custom_exceptions=self._config["import_custom_exceptions"],
            instantiate_custom_exceptions=self.
            _config["instantiate_custom_exceptions"],
            instantiate_oldstyle_exceptions=self.
            _config["instantiate_oldstyle_exceptions"])

    def _seq_request_callback(self, msg, seq, is_exc, obj):
        _callback = self._request_callbacks.pop(seq, None)
        if _callback is not None:
            _callback(is_exc, obj)
        elif self._config["logger"] is not None:
            debug_msg = 'Recieved {} seq {} and a related request callback did not exist'
            self._config["logger"].debug(debug_msg.format(msg, seq))

    def _dispatch(self, data):  # serving---dispatch?
        msg, seq, args = brine.load(data)
        if msg == consts.MSG_REQUEST:
            self._dispatch_request(seq, args)
        elif msg == consts.MSG_REPLY:
            obj = self._unbox(args)
            self._seq_request_callback(msg, seq, False, obj)
        elif msg == consts.MSG_EXCEPTION:
            obj = self._unbox_exc(args)
            self._seq_request_callback(msg, seq, True, obj)
        else:
            raise ValueError("invalid message type: %r" % (msg, ))

    def serve(self, timeout=1, wait_for_lock=True):  # serving
        """Serves a single request or reply that arrives within the given
        time frame (default is 1 sec). Note that the dispatching of a request
        might trigger multiple (nested) requests, thus this function may be
        reentrant.

        :returns: ``True`` if a request or reply were received, ``False``
                  otherwise.
        """
        timeout = Timeout(timeout)
        with self._recv_event:
            if not self._recvlock.acquire(False):
                return wait_for_lock and self._recv_event.wait(
                    timeout.timeleft())
        try:
            data = self._channel.poll(timeout) and self._channel.recv()
            if not data:
                return False
        except EOFError:
            self.close()
            raise
        finally:
            self._recvlock.release()
            with self._recv_event:
                self._recv_event.notify_all()
        self._dispatch(data)
        return True

    def poll(self, timeout=0):  # serving
        """Serves a single transaction, should one arrives in the given
        interval. Note that handling a request/reply may trigger nested
        requests, which are all part of a single transaction.

        :returns: ``True`` if a transaction was served, ``False`` otherwise"""
        return self.serve(timeout, False)

    def serve_all(self):  # serving
        """Serves all requests and replies for as long as the connection is
        alive."""
        try:
            while not self.closed:
                self.serve(None)
        except (socket.error, select_error, IOError):
            if not self.closed:
                raise
        except EOFError:
            pass
        finally:
            self.close()

    def serve_threaded(self, thread_count=10):  # serving
        """Serves all requests and replies for as long as the connection is alive.

        CAVEAT: using non-immutable types that require a netref to be constructed to serve a request,
        or invoking anything else that performs a sync_request, may timeout due to the sync_request reply being
        received by another thread serving the connection. A more conventional approach where each client thread
        opens a new connection would allow `ThreadedServer` to naturally avoid such multiplexing issues and
        is the preferred approach for threading procedures that invoke sync_request. See issue #345
        """
        def _thread_target():
            try:
                while True:
                    self.serve(None)
            except (socket.error, select_error, IOError):
                if not self.closed:
                    raise
            except EOFError:
                pass

        try:
            threads = [spawn(_thread_target) for _ in range(thread_count)]

            for thread in threads:
                thread.join()
        finally:
            self.close()

    def poll_all(self, timeout=0):  # serving
        """Serves all requests and replies that arrive within the given interval.

        :returns: ``True`` if at least a single transaction was served, ``False`` otherwise
        """
        at_least_once = False
        timeout = Timeout(timeout)
        try:
            while True:
                if self.poll(timeout):
                    at_least_once = True
                if timeout.expired():
                    break
        except EOFError:
            pass
        return at_least_once

    def sync_request(self, handler, *args):  # serving
        """requests, sends a synchronous request (waits for the reply to arrive)

        :raises: any exception that the requets may be generated
        :returns: the result of the request
        """
        timeout = self._config["sync_request_timeout"]
        return self.async_request(handler, *args, timeout=timeout).value

    def _async_request(self, handler, args=(),
                       callback=(lambda a, b: None)):  # serving
        seq = self._get_seq_id()
        self._request_callbacks[seq] = callback
        try:
            self._send(consts.MSG_REQUEST, seq, (handler, self._box(args)))
        except Exception:
            # TODO: review test_remote_exception, logging exceptions show attempt to write on closed stream
            # depending on the case, the MSG_REQUEST may or may not have been sent completely
            # so, pop the callback and raise to keep response integrity is consistent
            self._request_callbacks.pop(seq, None)
            raise

    def async_request(self, handler, *args, **kwargs):  # serving
        """Send an asynchronous request (does not wait for it to finish)

        :returns: an :class:`rpyc.core.async_.AsyncResult` object, which will
                  eventually hold the result (or exception)
        """
        timeout = kwargs.pop("timeout", None)
        if kwargs:
            raise TypeError("got unexpected keyword argument(s) %s" %
                            (list(kwargs.keys()), ))
        res = AsyncResult(self)
        self._async_request(handler, args, res)
        if timeout is not None:
            res.set_expiry(timeout)
        return res

    @property
    def root(self):  # serving
        """Fetches the root object (service) of the other party"""
        if self._remote_root is None:
            self._remote_root = self.sync_request(consts.HANDLE_GETROOT)
        return self._remote_root

    def _check_attr(self, obj, name, perm):  # attribute access
        config = self._config
        if not config[perm]:
            raise AttributeError("cannot access %r" % (name, ))
        prefix = config["allow_exposed_attrs"] and config["exposed_prefix"]
        plain = config["allow_all_attrs"]
        plain |= config["allow_exposed_attrs"] and name.startswith(prefix)
        plain |= config["allow_safe_attrs"] and name in config["safe_attrs"]
        plain |= config["allow_public_attrs"] and not name.startswith("_")
        has_exposed = prefix and hasattr(obj, prefix + name)
        if plain and (not has_exposed or hasattr(obj, name)):
            return name
        if has_exposed:
            return prefix + name
        if plain:
            return name  # chance for better traceback
        raise AttributeError("cannot access %r" % (name, ))

    def _access_attr(self, obj, name, args, overrider, param,
                     default):  # attribute access
        if is_py_3k:
            if type(name) is bytes:
                name = str(name, "utf8")
            elif type(name) is not str:
                raise TypeError("name must be a string")
        else:
            if type(name) not in (str, unicode):  # noqa
                raise TypeError("name must be a string")
            name = str(name)  # IronPython issue #10 + py3k issue
        accessor = getattr(type(obj), overrider, None)
        if accessor is None:
            accessor = default
            name = self._check_attr(obj, name, param)
        return accessor(obj, name, *args)

    @classmethod
    def _request_handlers(cls):  # request handlers
        return {
            consts.HANDLE_PING: cls._handle_ping,
            consts.HANDLE_CLOSE: cls._handle_close,
            consts.HANDLE_GETROOT: cls._handle_getroot,
            consts.HANDLE_GETATTR: cls._handle_getattr,
            consts.HANDLE_DELATTR: cls._handle_delattr,
            consts.HANDLE_SETATTR: cls._handle_setattr,
            consts.HANDLE_CALL: cls._handle_call,
            consts.HANDLE_CALLATTR: cls._handle_callattr,
            consts.HANDLE_REPR: cls._handle_repr,
            consts.HANDLE_STR: cls._handle_str,
            consts.HANDLE_CMP: cls._handle_cmp,
            consts.HANDLE_HASH: cls._handle_hash,
            consts.HANDLE_INSTANCECHECK: cls._handle_instancecheck,
            consts.HANDLE_DIR: cls._handle_dir,
            consts.HANDLE_PICKLE: cls._handle_pickle,
            consts.HANDLE_DEL: cls._handle_del,
            consts.HANDLE_INSPECT: cls._handle_inspect,
            consts.HANDLE_BUFFITER: cls._handle_buffiter,
            consts.HANDLE_OLDSLICING: cls._handle_oldslicing,
            consts.HANDLE_CTXEXIT: cls._handle_ctxexit,
        }

    def _handle_ping(self, data):  # request handler
        return data

    def _handle_close(self):  # request handler
        self._cleanup()

    def _handle_getroot(self):  # request handler
        return self._local_root

    def _handle_del(self, obj, count=1):  # request handler
        self._local_objects.decref(get_id_pack(obj), count)

    def _handle_repr(self, obj):  # request handler
        return repr(obj)

    def _handle_str(self, obj):  # request handler
        return str(obj)

    def _handle_cmp(self, obj, other, op='__cmp__'):  # request handler
        # cmp() might enter recursive resonance... so use the underlying type and return cmp(obj, other)
        try:
            return self._access_attr(type(obj), op, (), "_rpyc_getattr",
                                     "allow_getattr", getattr)(obj, other)
        except Exception:
            raise

    def _handle_hash(self, obj):  # request handler
        return hash(obj)

    def _handle_call(self, obj, args, kwargs=()):  # request handler
        return obj(*args, **dict(kwargs))

    def _handle_dir(self, obj):  # request handler
        return tuple(dir(obj))

    def _handle_inspect(self, id_pack):  # request handler
        if hasattr(self._local_objects[id_pack], '____conn__'):
            # When RPyC is chained (RPyC over RPyC), id_pack is cached in local objects as a netref
            # since __mro__ is not a safe attribute the request is forwarded using the proxy connection
            # see issue #346 or tests.test_rpyc_over_rpyc.Test_rpyc_over_rpyc
            conn = self._local_objects[id_pack].____conn__
            return conn.sync_request(consts.HANDLE_INSPECT, id_pack)
        else:
            return tuple(
                get_methods(netref.LOCAL_ATTRS, self._local_objects[id_pack]))

    def _handle_getattr(self, obj, name):  # request handler
        return self._access_attr(obj, name, (), "_rpyc_getattr",
                                 "allow_getattr", getattr)

    def _handle_delattr(self, obj, name):  # request handler
        return self._access_attr(obj, name, (), "_rpyc_delattr",
                                 "allow_delattr", delattr)

    def _handle_setattr(self, obj, name, value):  # request handler
        return self._access_attr(obj, name, (value, ), "_rpyc_setattr",
                                 "allow_setattr", setattr)

    def _handle_callattr(self, obj, name, args, kwargs=()):  # request handler
        obj = self._handle_getattr(obj, name)
        return self._handle_call(obj, args, kwargs)

    def _handle_ctxexit(self, obj, exc):  # request handler
        if exc:
            try:
                raise exc
            except Exception:
                exc, typ, tb = sys.exc_info()
        else:
            typ = tb = None
        return self._handle_getattr(obj, "__exit__")(exc, typ, tb)

    def _handle_instancecheck(self, obj, other_id_pack):
        # TODOs:
        #  + refactor cache instancecheck/inspect/class_factory
        #  + improve cache docs

        if hasattr(obj, '____conn__'):  # keep unwrapping!
            # When RPyC is chained (RPyC over RPyC), id_pack is cached in local objects as a netref
            # since __mro__ is not a safe attribute the request is forwarded using the proxy connection
            # relates to issue #346 or tests.test_netref_hierachy.Test_Netref_Hierarchy.test_StandardError
            conn = obj.____conn__
            return conn.sync_request(consts.HANDLE_INSPECT, id_pack)
        # Create a name pack which would be familiar here and see if there is a hit
        other_id_pack2 = (other_id_pack[0], other_id_pack[1], 0)
        if other_id_pack[0] in netref.builtin_classes_cache:
            cls = netref.builtin_classes_cache[other_id_pack[0]]
            other = cls(self, other_id_pack)
        elif other_id_pack2 in self._netref_classes_cache:
            cls = self._netref_classes_cache[other_id_pack2]
            other = cls(self, other_id_pack2)
        else:  # might just have missed cache, FIX ME
            return False
        return isinstance(other, obj)

    def _handle_pickle(self, obj, proto):  # request handler
        if not self._config["allow_pickle"]:
            raise ValueError("pickling is disabled")
        return bytes(pickle.dumps(obj, proto))

    def _handle_buffiter(self, obj, count):  # request handler
        return tuple(itertools.islice(obj, count))

    def _handle_oldslicing(self, obj, attempt, fallback, start, stop,
                           args):  # request handler
        try:
            # first try __xxxitem__
            getitem = self._handle_getattr(obj, attempt)
            return getitem(slice(start, stop), *args)
        except Exception:
            # fallback to __xxxslice__. see issue #41
            if stop is None:
                stop = maxint
            getslice = self._handle_getattr(obj, fallback)
            return getslice(start, stop, *args)