# (c) 2014, Brian Coca, Josh Drake, et al
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import sys
import time
import json
from ansible import constants as C
from ansible.errors import AnsibleError
from ansible.plugins.cache.base import BaseCacheModule
try:
from redis import StrictRedis
except ImportError:
raise AnsibleError("The 'redis' python module is required for the redis fact cache, 'pip install redis'")
[docs]class CacheModule(BaseCacheModule):
"""
A caching module backed by redis.
Keys are maintained in a zset with their score being the timestamp
when they are inserted. This allows for the usage of 'zremrangebyscore'
to expire keys. This mechanism is used or a pattern matched 'scan' for
performance.
"""
def __init__(self, *args, **kwargs):
if C.CACHE_PLUGIN_CONNECTION:
connection = C.CACHE_PLUGIN_CONNECTION.split(':')
else:
connection = []
self._timeout = float(C.CACHE_PLUGIN_TIMEOUT)
self._prefix = C.CACHE_PLUGIN_PREFIX
self._cache = StrictRedis(*connection)
self._keys_set = 'ansible_cache_keys'
def _make_key(self, key):
return self._prefix + key
[docs] def get(self, key):
value = self._cache.get(self._make_key(key))
# guard against the key not being removed from the zset;
# this could happen in cases where the timeout value is changed
# between invocations
if value is None:
self.delete(key)
raise KeyError
return json.loads(value)
[docs] def set(self, key, value):
value2 = json.dumps(value)
if self._timeout > 0: # a timeout of 0 is handled as meaning 'never expire'
self._cache.setex(self._make_key(key), int(self._timeout), value2)
else:
self._cache.set(self._make_key(key), value2)
self._cache.zadd(self._keys_set, time.time(), key)
def _expire_keys(self):
if self._timeout > 0:
expiry_age = time.time() - self._timeout
self._cache.zremrangebyscore(self._keys_set, 0, expiry_age)
[docs] def keys(self):
self._expire_keys()
return self._cache.zrange(self._keys_set, 0, -1)
[docs] def contains(self, key):
self._expire_keys()
return (self._cache.zrank(self._keys_set, key) >= 0)
[docs] def delete(self, key):
self._cache.delete(self._make_key(key))
self._cache.zrem(self._keys_set, key)
[docs] def flush(self):
for key in self.keys():
self.delete(key)
[docs] def copy(self):
# TODO: there is probably a better way to do this in redis
ret = dict()
for key in self.keys():
ret[key] = self.get(key)
return ret
def __getstate__(self):
return dict()
def __setstate__(self, data):
self.__init__()