5517ccb63e
CacheIsolatingProxy was in the tests, but it should be available to applications since it's useful to use in their own tests when setting up the environment for caching. Change-Id: If88e8026494dffbf74674aa72964552943ef0d1d
71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
# Copyright 2013 Metacloud
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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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, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Items useful for external testing."""
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import copy
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from dogpile.cache import proxy
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from oslo_cache import core as cache
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__all__ = [
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'CacheIsolatingProxy',
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]
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NO_VALUE = cache.NO_VALUE
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def _copy_value(value):
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if value is not NO_VALUE:
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value = copy.deepcopy(value)
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return value
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# NOTE(morganfainberg): WARNING - It is not recommended to use the Memory
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# backend for dogpile.cache in a real deployment under any circumstances. The
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# backend does no cleanup of expired values and therefore will leak memory. The
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# backend is not implemented in a way to share data across processes (e.g.
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# Keystone in HTTPD. This proxy is a hack to get around the lack of isolation
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# of values in memory. Currently it blindly stores and retrieves the values
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# from the cache, and modifications to dicts/lists/etc returned can result in
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# changes to the cached values. In short, do not use the dogpile.cache.memory
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# backend unless you are running tests or expecting odd/strange results.
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class CacheIsolatingProxy(proxy.ProxyBackend):
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"""Proxy that forces a memory copy of stored values.
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The default in-memory cache-region does not perform a copy on values it
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is meant to cache. Therefore if the value is modified after set or after
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get, the cached value also is modified. This proxy does a copy as the last
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thing before storing data.
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In your application's tests, you'll want to set this as a proxy for the
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in-memory cache, like this::
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self.config_fixture.config(
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group='cache',
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backend='dogpile.cache.memory',
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enabled=True,
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proxies=['oslo_cache.testing.CacheIsolatingProxy'])
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"""
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def get(self, key):
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return _copy_value(self.proxied.get(key))
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def set(self, key, value):
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self.proxied.set(key, _copy_value(value))
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