Source code for taskflow.types.cache

# -*- coding: utf-8 -*-

#    Copyright (C) 2014 Yahoo! Inc. 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.

import threading

from oslo_utils import reflection
import six


[docs]class ExpiringCache(object): """Represents a thread-safe time-based expiring cache. NOTE(harlowja): the values in this cache must have a expired attribute that can be used to determine if the key and associated value has expired or if it has not. """ def __init__(self): self._data = {} self._lock = threading.Lock() def __setitem__(self, key, value): """Set a value in the cache.""" with self._lock: self._data[key] = value def __len__(self): """Returns how many items are in this cache.""" return len(self._data)
[docs] def get(self, key, default=None): """Retrieve a value from the cache (returns default if not found).""" return self._data.get(key, default)
def __getitem__(self, key): """Retrieve a value from the cache.""" return self._data[key] def __delitem__(self, key): """Delete a key & value from the cache.""" with self._lock: del self._data[key]
[docs] def clear(self, on_cleared_callback=None): """Removes all keys & values from the cache.""" cleared_items = [] with self._lock: if on_cleared_callback is not None: cleared_items.extend(six.iteritems(self._data)) self._data.clear() if on_cleared_callback is not None: arg_c = len(reflection.get_callable_args(on_cleared_callback)) for (k, v) in cleared_items: if arg_c == 2: on_cleared_callback(k, v) else: on_cleared_callback(v)
[docs] def cleanup(self, on_expired_callback=None): """Delete out-dated keys & values from the cache.""" with self._lock: expired_values = [(k, v) for k, v in six.iteritems(self._data) if v.expired] for (k, _v) in expired_values: del self._data[k] if on_expired_callback is not None: arg_c = len(reflection.get_callable_args(on_expired_callback)) for (k, v) in expired_values: if arg_c == 2: on_expired_callback(k, v) else: on_expired_callback(v)