34b358a137
Instead of using a reader/writer lock in the cache types just take advantage of the fact that single, non-mutating operations on dictionaries are thread-safe in python. This means we can remove the need to have simple read-only operations using read-locks and can just use a simpler lock around write-operations or around read/write operations that span multiple dictionary operations (like iteration). Change-Id: I4679275d7fe25fac12a6b05e8aa38da95649f4f6
72 lines
2.3 KiB
Python
72 lines
2.3 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2014 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import threading
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import six
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from taskflow.utils import reflection
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class ExpiringCache(object):
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"""Represents a thread-safe time-based expiring cache.
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NOTE(harlowja): the values in this cache must have a expired attribute that
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can be used to determine if the key and associated value has expired or if
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it has not.
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"""
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def __init__(self):
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self._data = {}
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self._lock = threading.Lock()
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def __setitem__(self, key, value):
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"""Set a value in the cache."""
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with self._lock:
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self._data[key] = value
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def __len__(self):
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"""Returns how many items are in this cache."""
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return len(self._data)
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def get(self, key, default=None):
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"""Retrieve a value from the cache (returns default if not found)."""
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return self._data.get(key, default)
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def __getitem__(self, key):
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"""Retrieve a value from the cache."""
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return self._data[key]
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def __delitem__(self, key):
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"""Delete a key & value from the cache."""
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with self._lock:
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del self._data[key]
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def cleanup(self, on_expired_callback=None):
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"""Delete out-dated keys & values from the cache."""
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with self._lock:
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expired_values = [(k, v) for k, v in six.iteritems(self._data)
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if v.expired]
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for (k, _v) in expired_values:
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del self._data[k]
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if on_expired_callback is not None:
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arg_c = len(reflection.get_callable_args(on_expired_callback))
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for (k, v) in expired_values:
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if arg_c == 2:
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on_expired_callback(k, v)
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else:
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on_expired_callback(v)
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