78 lines
3.0 KiB
Python
78 lines
3.0 KiB
Python
# Copyright 2014 Mirantis Inc
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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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"""dogpile.cache backend that uses Memcached connection pool"""
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import functools
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from dogpile.cache.backends import memcached as memcached_backend
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from oslo_cache import _memcache_pool
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# Helper to ease backend refactoring
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class ClientProxy(object):
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def __init__(self, client_pool):
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self.client_pool = client_pool
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def _run_method(self, __name, *args, **kwargs):
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with self.client_pool.acquire() as client:
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return getattr(client, __name)(*args, **kwargs)
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def __getattr__(self, name):
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return functools.partial(self._run_method, name)
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class PooledMemcachedBackend(memcached_backend.MemcachedBackend):
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"""Memcached backend that does connection pooling.
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This memcached backend only allows for reuse of a client object,
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prevents too many client object from being instantiated, and maintains
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proper tracking of dead servers so as to limit delays when a server
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(or all servers) become unavailable.
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This backend doesn't allow to load balance things between servers.
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Memcached isn't HA. Values aren't automatically replicated between servers
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unless the client went out and wrote the value multiple time.
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The memcache server to use is determined by `python-memcached` itself by
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picking the host to use (from the given server list) based on a key hash.
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"""
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# Composed from GenericMemcachedBackend's and MemcacheArgs's __init__
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def __init__(self, arguments):
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super(PooledMemcachedBackend, self).__init__(arguments)
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self.client_pool = _memcache_pool.MemcacheClientPool(
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self.url,
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arguments={
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'dead_retry': arguments.get('dead_retry', 5 * 60),
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'socket_timeout': arguments.get('socket_timeout', 3.0),
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'server_max_value_length':
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arguments.get('server_max_value_length'),
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'flush_on_reconnect': arguments.get('pool_flush_on_reconnect',
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False),
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},
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maxsize=arguments.get('pool_maxsize', 10),
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unused_timeout=arguments.get('pool_unused_timeout', 60),
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conn_get_timeout=arguments.get('pool_connection_get_timeout', 10),
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)
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# Since all methods in backend just call one of methods of client, this
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# lets us avoid need to hack it too much
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@property
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def client(self):
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return ClientProxy(self.client_pool)
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