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67 lines
2.0 KiB
C++
67 lines
2.0 KiB
C++
//
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// UniqueExpireCache.h
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//
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// Library: Foundation
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// Package: Cache
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// Module: UniqueExpireCache
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//
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// Definition of the UniqueExpireCache class.
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//
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// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_UniqueExpireCache_INCLUDED
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#define Foundation_UniqueExpireCache_INCLUDED
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#include "Poco/AbstractCache.h"
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#include "Poco/UniqueExpireStrategy.h"
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namespace Poco
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{
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template <class TKey, class TValue, class TMutex = FastMutex, class TEventMutex = FastMutex>
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class UniqueExpireCache : public AbstractCache<TKey, TValue, UniqueExpireStrategy<TKey, TValue>, TMutex, TEventMutex>
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/// An UniqueExpireCache caches entries for a given time amount. In contrast
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/// to ExpireCache which only allows to set a per cache expiration value, it allows to define
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/// expiration per CacheEntry.
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/// Each TValue object must thus offer the following method:
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///
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/// const Poco::Timestamp& getExpiration() const;
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///
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/// which returns the absolute timepoint when the entry will be invalidated.
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/// Accessing an object will NOT update this absolute expire timepoint.
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/// You can use the Poco::ExpirationDecorator to add the getExpiration
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/// method to values that do not have a getExpiration function.
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///
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/// Be careful when using an UniqueExpireCache. A cache is often used
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/// like cache.has(x) followed by cache.get x). Note that it could happen
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/// that the "has" call works, then the current execution thread gets descheduled, time passes,
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/// the entry gets invalid, thus leading to an empty SharedPtr being returned
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/// when "get" is invoked.
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{
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public:
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UniqueExpireCache()
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: AbstractCache<TKey, TValue, UniqueExpireStrategy<TKey, TValue>, TMutex, TEventMutex>(UniqueExpireStrategy<TKey, TValue>())
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{
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}
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~UniqueExpireCache() { }
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private:
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UniqueExpireCache(const UniqueExpireCache & aCache);
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UniqueExpireCache & operator=(const UniqueExpireCache & aCache);
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};
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} // namespace Poco
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#endif // Foundation_UniqueExpireCache_INCLUDED
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