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70 lines
2.5 KiB
Python
70 lines
2.5 KiB
Python
# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com>
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# Copyright 2012 Citrix Systems, Inc. Licensed under the
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# Apache License, Version 2.0 (the "License"); you may not use this
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# file except in compliance with the License. Citrix Systems, Inc.
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# reserves all rights not expressly granted by the License.
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# You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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# Automatically generated by addcopyright.py at 04/03/2012
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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"""
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Resource manager.
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"""
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import weakref
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class ResourceManager (object):
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"""
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A registry of objects and resources that should be closed when those
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objects are deleted.
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This is meant to be a safer alternative to python's C{__del__} method,
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which can cause reference cycles to never be collected. Objects registered
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with the ResourceManager can be collected but still free resources when
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they die.
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Resources are registered using L{register}, and when an object is garbage
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collected, each registered resource is closed by having its C{close()}
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method called. Multiple resources may be registered per object, but a
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resource will only be closed once, even if multiple objects register it.
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(The last object to register it wins.)
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"""
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def __init__(self):
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self._table = {}
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def register(self, obj, resource):
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"""
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Register a resource to be closed with an object is collected.
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When the given C{obj} is garbage-collected by the python interpreter,
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the C{resource} will be closed by having its C{close()} method called.
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Any exceptions are ignored.
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@param obj: the object to track
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@type obj: object
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@param resource: the resource to close when the object is collected
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@type resource: object
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"""
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def callback(ref):
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try:
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resource.close()
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except:
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pass
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del self._table[id(resource)]
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# keep the weakref in a table so it sticks around long enough to get
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# its callback called. :)
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self._table[id(resource)] = weakref.ref(obj, callback)
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# singleton
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ResourceManager = ResourceManager()
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