610df5e87d
* don't load every possible answer, only do what is needed * cache instance data for a given address for a 15 seconds using either memcache or fake memcache (in-memory). This means only a single queue/db lookup for multiple calls to metadata service * add cache expirey to fake memcache (don't grow forever) and move it to nova.common.memorycache Addresses Bug #851159 Change-Id: Icf794156e055b18915b8b5be9ba2ab97d2338bbe
65 lines
2.1 KiB
Python
65 lines
2.1 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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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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"""Super simple fake memcache client."""
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from nova import utils
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class Client(object):
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"""Replicates a tiny subset of memcached client interface."""
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def __init__(self, *args, **kwargs):
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"""Ignores the passed in args."""
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self.cache = {}
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def get(self, key):
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"""Retrieves the value for a key or None.
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this expunges expired keys during each get"""
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for k in self.cache.keys():
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(timeout, _value) = self.cache[k]
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if timeout and utils.utcnow_ts() >= timeout:
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del self.cache[k]
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return self.cache.get(key, (0, None))[1]
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def set(self, key, value, time=0, min_compress_len=0):
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"""Sets the value for a key."""
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timeout = 0
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if time != 0:
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timeout = utils.utcnow_ts() + time
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self.cache[key] = (timeout, value)
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return True
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def add(self, key, value, time=0, min_compress_len=0):
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"""Sets the value for a key if it doesn't exist."""
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if not self.get(key) is None:
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return False
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return self.set(key, value, time, min_compress_len)
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def incr(self, key, delta=1):
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"""Increments the value for a key."""
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value = self.get(key)
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if value is None:
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return None
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new_value = int(value) + delta
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self.cache[key] = (self.cache[key][0], str(new_value))
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return new_value
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