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"""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 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
|
