blob: 4703b348f7f4d7e13f6ff06f9112938d5b301046 [file] [log] [blame]
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
from __future__ import absolute_import
from cproton import pn_incref, pn_decref, \
pn_py2void, pn_void2py, \
pn_record_get, pn_record_def, pn_record_set, \
from ._exceptions import ProtonException
class EmptyAttrs:
def __contains__(self, name):
return False
def __getitem__(self, name):
raise KeyError(name)
def __setitem__(self, name, value):
raise TypeError("does not support item assignment")
EMPTY_ATTRS = EmptyAttrs()
class Wrapper(object):
""" Wrapper for python objects that need to be stored in event contexts and be retrived again from them
Quick note on how this works:
The actual *python* object has only 3 attributes which redirect into the wrapped C objects:
_impl The wrapped C object itself
_attrs This is a special pn_record_t holding a PYCTX which is a python dict
every attribute in the python object is actually looked up here
_record This is the C record itself (so actually identical to _attrs really but
a different python type
Because the objects actual attributes are stored away they must be initialised *after* the wrapping
is set up. This is the purpose of the _init method in the wrapped object. Wrapper.__init__ will call
eht subclass _init to initialise attributes. So they *must not* be initialised in the subclass __init__
before calling the superclass (Wrapper) __init__ or they will not be accessible from the wrapper at all.
def __init__(self, impl_or_constructor, get_context=None):
init = False
if callable(impl_or_constructor):
# we are constructing a new object
impl = impl_or_constructor()
if impl is None:
self.__dict__["_impl"] = impl
self.__dict__["_attrs"] = EMPTY_ATTRS
self.__dict__["_record"] = None
raise ProtonException(
"Wrapper failed to create wrapped object. Check for file descriptor or memory exhaustion.")
init = True
# we are wrapping an existing object
impl = impl_or_constructor
if get_context:
record = get_context(impl)
attrs = pn_void2py(pn_record_get(record, PYCTX))
if attrs is None:
attrs = {}
pn_record_def(record, PYCTX, PN_PYREF)
pn_record_set(record, PYCTX, pn_py2void(attrs))
init = True
init = False
record = None
self.__dict__["_impl"] = impl
self.__dict__["_attrs"] = attrs
self.__dict__["_record"] = record
if init:
def __getattr__(self, name):
attrs = self.__dict__["_attrs"]
if name in attrs:
return attrs[name]
raise AttributeError(name + " not in _attrs")
def __setattr__(self, name, value):
if hasattr(self.__class__, name):
object.__setattr__(self, name, value)
attrs = self.__dict__["_attrs"]
attrs[name] = value
def __delattr__(self, name):
attrs = self.__dict__["_attrs"]
if attrs:
del attrs[name]
def __hash__(self):
return hash(addressof(self._impl))
def __eq__(self, other):
if isinstance(other, Wrapper):
return addressof(self._impl) == addressof(other._impl)
return False
def __ne__(self, other):
if isinstance(other, Wrapper):
return addressof(self._impl) != addressof(other._impl)
return True
def __del__(self):
def __repr__(self):
return '<%s.%s 0x%x ~ 0x%x>' % (self.__class__.__module__,
id(self), addressof(self._impl))
PYCTX = int(pn_py2void(Wrapper))
addressof = int