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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Super simple fake memcache client."""
from oslo.config import cfg
from openstack.common import timeutils
memcache_opts = [
cfg.ListOpt('memcached_servers',
default=None,
help='Memcached servers or None for in process cache.'),
]
CONF = cfg.CONF
CONF.register_opts(memcache_opts)
def get_client(memcached_servers=None):
client_cls = Client
if not memcached_servers:
memcached_servers = CONF.memcached_servers
if memcached_servers:
try:
import memcache
client_cls = memcache.Client
except ImportError:
pass
return client_cls(memcached_servers, debug=0)
class Client(object):
"""Replicates a tiny subset of memcached client interface."""
def __init__(self, *args, **kwargs):
"""Ignores the passed in args."""
self.cache = {}
def get(self, key):
"""Retrieves the value for a key or None.
This expunges expired keys during each get.
"""
now = timeutils.utcnow_ts()
for k in self.cache.keys():
(timeout, _value) = self.cache[k]
if timeout and now >= timeout:
del self.cache[k]
return self.cache.get(key, (0, None))[1]
def set(self, key, value, time=0, min_compress_len=0):
"""Sets the value for a key."""
timeout = 0
if time != 0:
timeout = timeutils.utcnow_ts() + time
self.cache[key] = (timeout, value)
return True
def add(self, key, value, time=0, min_compress_len=0):
"""Sets the value for a key if it doesn't exist."""
if self.get(key) is not None:
return False
return self.set(key, value, time, min_compress_len)
def incr(self, key, delta=1):
"""Increments the value for a key."""
value = self.get(key)
if value is None:
return None
new_value = int(value) + delta
self.cache[key] = (self.cache[key][0], str(new_value))
return new_value
def delete(self, key, time=0):
"""Deletes the value associated with a key."""
if key in self.cache:
del self.cache[key]
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