Use istype() when checking if canned object is a dict

Using istype(canned, dict) instead of isinstance(canned, dict) ensures that dict subclasses retain their type during unserialization. This also agrees with the implementation of serialize_object().

IPython/kernel/zmq/serialize.py

@@ -1,198 +1,198 b''
 """serialization utilities for apply messages
 
 Authors:
 
 * Min RK
 """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 try:
     import cPickle
     pickle = cPickle
 except:
     cPickle = None
     import pickle
 
 
 # IPython imports
 from IPython.utils import py3compat
 from IPython.utils.data import flatten
 from IPython.utils.pickleutil import (
     can, uncan, can_sequence, uncan_sequence, CannedObject,
     istype, sequence_types,
 )
 
 if py3compat.PY3:
     buffer = memoryview
 
 #-----------------------------------------------------------------------------
 # Serialization Functions
 #-----------------------------------------------------------------------------
 
 # default values for the thresholds:
 MAX_ITEMS = 64
 MAX_BYTES = 1024
 
 def _extract_buffers(obj, threshold=MAX_BYTES):
     """extract buffers larger than a certain threshold"""
     buffers = []
     if isinstance(obj, CannedObject) and obj.buffers:
         for i,buf in enumerate(obj.buffers):
             if len(buf) > threshold:
                 # buffer larger than threshold, prevent pickling
                 obj.buffers[i] = None
                 buffers.append(buf)
             elif isinstance(buf, buffer):
                 # buffer too small for separate send, coerce to bytes
                 # because pickling buffer objects just results in broken pointers
                 obj.buffers[i] = bytes(buf)
     return buffers
 
 def _restore_buffers(obj, buffers):
     """restore buffers extracted by """
     if isinstance(obj, CannedObject) and obj.buffers:
         for i,buf in enumerate(obj.buffers):
             if buf is None:
                 obj.buffers[i] = buffers.pop(0)
 
 def serialize_object(obj, buffer_threshold=MAX_BYTES, item_threshold=MAX_ITEMS):
     """Serialize an object into a list of sendable buffers.
     
     Parameters
     ----------
     
     obj : object
         The object to be serialized
     buffer_threshold : int
         The threshold (in bytes) for pulling out data buffers
         to avoid pickling them.
     item_threshold : int
         The maximum number of items over which canning will iterate.
         Containers (lists, dicts) larger than this will be pickled without
         introspection.
     
     Returns
     -------
     [bufs] : list of buffers representing the serialized object.
     """
     buffers = []
     if istype(obj, sequence_types) and len(obj) < item_threshold:
         cobj = can_sequence(obj)
         for c in cobj:
             buffers.extend(_extract_buffers(c, buffer_threshold))
     elif istype(obj, dict) and len(obj) < item_threshold:
         cobj = {}
         for k in sorted(obj.iterkeys()):
             c = can(obj[k])
             buffers.extend(_extract_buffers(c, buffer_threshold))
             cobj[k] = c
     else:
         cobj = can(obj)
         buffers.extend(_extract_buffers(cobj, buffer_threshold))
 
     buffers.insert(0, pickle.dumps(cobj,-1))
     return buffers
 
 def unserialize_object(buffers, g=None):
     """reconstruct an object serialized by serialize_object from data buffers.
     
     Parameters
     ----------
     
     bufs : list of buffers/bytes
     
     g : globals to be used when uncanning
     
     Returns
     -------
     
     (newobj, bufs) : unpacked object, and the list of remaining unused buffers.
     """
     bufs = list(buffers)
     pobj = bufs.pop(0)
     if not isinstance(pobj, bytes):
         # a zmq message
         pobj = bytes(pobj)
     canned = pickle.loads(pobj)
     if istype(canned, sequence_types) and len(canned) < MAX_ITEMS:
         for c in canned:
             _restore_buffers(c, bufs)
         newobj = uncan_sequence(canned, g)
-    elif isinstance(canned, dict) and len(canned) < MAX_ITEMS:
+    elif istype(canned, dict) and len(canned) < MAX_ITEMS:
         newobj = {}
         for k in sorted(canned.iterkeys()):
             c = canned[k]
             _restore_buffers(c, bufs)
             newobj[k] = uncan(c, g)
     else:
         _restore_buffers(canned, bufs)
         newobj = uncan(canned, g)
     
     return newobj, bufs
 
 def pack_apply_message(f, args, kwargs, buffer_threshold=MAX_BYTES, item_threshold=MAX_ITEMS):
     """pack up a function, args, and kwargs to be sent over the wire
     
     Each element of args/kwargs will be canned for special treatment,
     but inspection will not go any deeper than that.
     
     Any object whose data is larger than `threshold`  will not have their data copied
     (only numpy arrays and bytes/buffers support zero-copy)
     
     Message will be a list of bytes/buffers of the format:
     
     [ cf, pinfo, <arg_bufs>, <kwarg_bufs> ]
     
     With length at least two + len(args) + len(kwargs)
     """
     
     arg_bufs = flatten(serialize_object(arg, buffer_threshold, item_threshold) for arg in args)
     
     kw_keys = sorted(kwargs.keys())
     kwarg_bufs = flatten(serialize_object(kwargs[key], buffer_threshold, item_threshold) for key in kw_keys)
     
     info = dict(nargs=len(args), narg_bufs=len(arg_bufs), kw_keys=kw_keys)
     
     msg = [pickle.dumps(can(f),-1)]
     msg.append(pickle.dumps(info, -1))
     msg.extend(arg_bufs)
     msg.extend(kwarg_bufs)
     
     return msg
 
 def unpack_apply_message(bufs, g=None, copy=True):
     """unpack f,args,kwargs from buffers packed by pack_apply_message()
     Returns: original f,args,kwargs"""
     bufs = list(bufs) # allow us to pop
     assert len(bufs) >= 2, "not enough buffers!"
     if not copy:
         for i in range(2):
             bufs[i] = bufs[i].bytes
     f = uncan(pickle.loads(bufs.pop(0)), g)
     info = pickle.loads(bufs.pop(0))
     arg_bufs, kwarg_bufs = bufs[:info['narg_bufs']], bufs[info['narg_bufs']:]
     
     args = []
     for i in range(info['nargs']):
         arg, arg_bufs = unserialize_object(arg_bufs, g)
         args.append(arg)
     args = tuple(args)
     assert not arg_bufs, "Shouldn't be any arg bufs left over"
     
     kwargs = {}
     for key in info['kw_keys']:
         kwarg, kwarg_bufs = unserialize_object(kwarg_bufs, g)
         kwargs[key] = kwarg
     assert not kwarg_bufs, "Shouldn't be any kwarg bufs left over"
     
     return f,args,kwargs