"""The RPyC protocol
"""
import sys
import itertools
import socket
import time  # noqa: F401
import gc  # noqa: F401

from threading import Lock, Condition
from rpyc.lib import spawn, Timeout, get_methods, get_id_pack
from rpyc.lib.compat import pickle, next, maxint, select_error, acquire_lock  # noqa: F401
from rpyc.lib.colls import WeakValueDict, RefCountingColl
from rpyc.core import consts, brine, vinegar, netref
from rpyc.core.async_ import AsyncResult


class PingError(Exception):
    """The exception raised should :func:`Connection.ping` fail"""
    pass


DEFAULT_CONFIG = dict(
    # ATTRIBUTES
    allow_safe_attrs=True,
    allow_exposed_attrs=True,
    allow_public_attrs=False,
    allow_all_attrs=False,
    safe_attrs=set(['__abs__', '__add__', '__and__', '__bool__', '__cmp__', '__contains__',
                    '__delitem__', '__delslice__', '__div__', '__divmod__', '__doc__',
                    '__eq__', '__float__', '__floordiv__', '__ge__', '__getitem__',
                    '__getslice__', '__gt__', '__hash__', '__hex__', '__iadd__', '__iand__',
                    '__idiv__', '__ifloordiv__', '__ilshift__', '__imod__', '__imul__',
                    '__index__', '__int__', '__invert__', '__ior__', '__ipow__', '__irshift__',
                    '__isub__', '__iter__', '__itruediv__', '__ixor__', '__le__', '__len__',
                    '__long__', '__lshift__', '__lt__', '__mod__', '__mul__', '__ne__',
                    '__neg__', '__new__', '__nonzero__', '__oct__', '__or__', '__pos__',
                    '__pow__', '__radd__', '__rand__', '__rdiv__', '__rdivmod__', '__repr__',
                    '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__',
                    '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__',
                    '__rxor__', '__setitem__', '__setslice__', '__str__', '__sub__',
                    '__truediv__', '__xor__', 'next', '__length_hint__', '__enter__',
                    '__exit__', '__next__', ]),
    exposed_prefix="exposed_",
    allow_getattr=True,
    allow_setattr=False,
    allow_delattr=False,
    # EXCEPTIONS
    include_local_traceback=True,
    include_local_version=True,
    instantiate_custom_exceptions=False,
    import_custom_exceptions=False,
    instantiate_oldstyle_exceptions=False,  # which don't derive from Exception
    propagate_SystemExit_locally=False,  # whether to propagate SystemExit locally or to the other party
    propagate_KeyboardInterrupt_locally=True,  # whether to propagate KeyboardInterrupt locally or to the other party
    log_exceptions=True,
    # MISC
    allow_pickle=False,
    connid=None,
    credentials=None,
    endpoints=None,
    logger=None,
    sync_request_timeout=30,
    before_closed=None,
    close_catchall=False,
)
"""
The default configuration dictionary of the protocol. You can override these parameters
by passing a different configuration dict to the :class:`Connection` class.

.. note::
   You only need to override the parameters you want to change. There's no need
   to repeat parameters whose values remain unchanged.

=======================================  ================  =====================================================
Parameter                                Default value     Description
=======================================  ================  =====================================================
``allow_safe_attrs``                     ``True``          Whether to allow the use of *safe* attributes
                                                           (only those listed as ``safe_attrs``)
``allow_exposed_attrs``                  ``True``          Whether to allow exposed attributes
                                                           (attributes that start with the ``exposed_prefix``)
``allow_public_attrs``                   ``False``         Whether to allow public attributes
                                                           (attributes that don't start with ``_``)
``allow_all_attrs``                      ``False``         Whether to allow all attributes (including private)
``safe_attrs``                           ``set([...])``    The set of attributes considered safe
``exposed_prefix``                       ``"exposed_"``    The prefix of exposed attributes
``allow_getattr``                        ``True``          Whether to allow getting of attributes (``getattr``)
``allow_setattr``                        ``False``         Whether to allow setting of attributes (``setattr``)
``allow_delattr``                        ``False``         Whether to allow deletion of attributes (``delattr``)
``allow_pickle``                         ``False``         Whether to allow the use of ``pickle``

``include_local_traceback``              ``True``          Whether to include the local traceback
                                                           in the remote exception
``instantiate_custom_exceptions``        ``False``         Whether to allow instantiation of
                                                           custom exceptions (not the built in ones)
``import_custom_exceptions``             ``False``         Whether to allow importing of
                                                           exceptions from not-yet-imported modules
``instantiate_oldstyle_exceptions``      ``False``         Whether to allow instantiation of exceptions
                                                           which don't derive from ``Exception``. This
                                                           is not applicable for Python 3 and later.
``propagate_SystemExit_locally``         ``False``         Whether to propagate ``SystemExit``
                                                           locally (kill the server) or to the other
                                                           party (kill the client)
``propagate_KeyboardInterrupt_locally``  ``False``         Whether to propagate ``KeyboardInterrupt``
                                                           locally (kill the server) or to the other
                                                           party (kill the client)
``logger``                               ``None``          The logger instance to use to log exceptions
                                                           (before they are sent to the other party)
                                                           and other events. If ``None``, no logging takes place.

``connid``                               ``None``          **Runtime**: the RPyC connection ID (used
                                                           mainly for debugging purposes)
``credentials``                          ``None``          **Runtime**: the credentails object that was returned
                                                           by the server's :ref:`authenticator <api-authenticators>`
                                                           or ``None``
``endpoints``                            ``None``          **Runtime**: The connection's endpoints. This is a tuple
                                                           made of the local socket endpoint (``getsockname``) and the
                                                           remote one (``getpeername``). This is set by the server
                                                           upon accepting a connection; client side connections
                                                           do no have this configuration option set.

``sync_request_timeout``                 ``30``            Default timeout for waiting results
=======================================  ================  =====================================================
"""


_connection_id_generator = itertools.count(1)


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):  # IO
        """closes the connection, releasing all held resources"""
        if self._closed:
            return
        try:
            self._closed = True
            if self._config.get("before_closed"):
                self._config["before_closed"](self.root)
            self._async_request(consts.HANDLE_CLOSE)
        except EOFError:
            pass
        except Exception:
            if not self._config["close_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 type(name) is bytes:
            name = str(name, "utf8")
        elif type(name) is not str:
            raise TypeError("name must be a string")
        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, other_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)
