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#
# Copyright 2022 Red Hat, Inc
#
# 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.
"""Simple wrapper for oslo_cache."""
import uuid
from oslo_cache import core as cache
from oslo_cache import exception
from oslo_log import log
from oslo_utils.secretutils import md5
# Default cache expiration period
CACHE_DURATION = 86400
NAME_ENCODED = __name__.encode('utf-8')
CACHE_NAMESPACE = uuid.UUID(
bytes=md5(NAME_ENCODED, usedforsecurity=False).digest()
)
LOG = log.getLogger(__name__)
class CacheClient(object):
def __init__(self, region):
self.region = region
def get(self, key):
value = self.region.get(key)
if value == cache.NO_VALUE:
return None
return value
def set(self, key, value):
return self.region.set(key, value)
def delete(self, key):
return self.region.delete(key)
def get_client(conf):
cache.configure(conf)
if 'cache' in conf.keys() and conf.cache.enabled:
region = get_cache_region(conf)
if region:
return CacheClient(region)
def get_cache_region(conf):
# Set expiration time to default CACHE_DURATION if missing in conf
if not conf.cache.expiration_time:
conf.cache.expiration_time = CACHE_DURATION
try:
region = cache.create_region()
cache.configure_cache_region(conf, region)
cache.key_mangler = cache_key_mangler
return region
except exception.ConfigurationError as e:
LOG.error("failed to configure oslo_cache. %s", str(e))
LOG.warning("using keystone to identify names from polled samples")
def cache_key_mangler(key):
"""Construct an opaque cache key."""
return uuid.uuid5(CACHE_NAMESPACE, key).hex
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