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113 lines
3.7 KiB
Python
113 lines
3.7 KiB
Python
# (c) 2014, Brian Coca, Josh Drake, et al
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#
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# This file is part of Ansible
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#
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# Ansible is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Ansible is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
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from __future__ import absolute_import
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import collections
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# FIXME: can we store these as something else before we ship it?
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import cPickle
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import sys
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import time
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from ansible import constants as C
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from ansible.cache.base import BaseCacheModule
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try:
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from redis import StrictRedis
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except ImportError:
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print "The 'redis' Python module is required for the redis fact cache"
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sys.exit(1)
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class PickledRedis(StrictRedis):
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"""
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A subclass of StrictRedis that uses the pickle module to store and load
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representations of the provided values.
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"""
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def get(self, name):
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pickled_value = super(PickledRedis, self).get(name)
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if pickled_value is None:
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return None
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return cPickle.loads(pickled_value)
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def set(self, name, value, *args, **kwargs):
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return super(PickledRedis, self).set(name, cPickle.dumps(value), *args, **kwargs)
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def setex(self, name, time, value):
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return super(PickledRedis, self).setex(name, time, cPickle.dumps(value))
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class CacheModule(BaseCacheModule):
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"""
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A caching module backed by redis.
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Keys are maintained in a zset with their score being the timestamp
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when they are inserted. This allows for the usage of 'zremrangebyscore'
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to expire keys. This mechanism is used or a pattern matched 'scan' for
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performance.
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"""
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def __init__(self, *args, **kwargs):
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if C.CACHE_PLUGIN_CONNECTION:
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connection = C.CACHE_PLUGIN_CONNECTION.split(':')
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else:
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connection = []
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self._timeout = C.CACHE_PLUGIN_TIMEOUT
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self._prefix = C.CACHE_PLUGIN_PREFIX
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self._cache = PickledRedis(*connection)
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self._keys_set = 'ansible_cache_keys'
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def _make_key(self, key):
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return "{}{}".format(self._prefix, key)
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def get(self, key):
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value = self._cache.get(self._make_key(key))
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# guard against the key not being removed from the zset;
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# this could happen in cases where the timeout value is changed
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# between invocations
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if value is None:
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self.delete(key)
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raise KeyError
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return value
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def set(self, key, value):
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if self._timeout > 0: # a timeout of 0 is handled as meaning 'never expire'
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self._cache.setex(self._make_key(key), self._timeout, value)
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else:
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self._cache.set(self._make_key(key), value)
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self._cache.zadd(self._keys_set, time.time(), key)
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def _expire_keys(self):
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if self._timeout > 0:
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expiry_age = time.time() - self._timeout
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self._cache.zremrangebyscore(self._keys_set, 0, expiry_age)
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def keys(self):
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self._expire_keys()
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return self._cache.zrange(self._keys_set, 0, -1)
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def contains(self, key):
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self._expire_keys()
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return (self._cache.zrank(self._keys_set, key) >= 0)
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def delete(self, key):
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self._cache.delete(self._make_key(key))
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self._cache.zrem(self._keys_set, key)
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def flush(self):
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for key in self.keys():
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self.delete(key)
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