mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-13 01:41:59 +00:00
67 lines
2.0 KiB
C++
67 lines
2.0 KiB
C++
//
|
|
// UniqueExpireCache.h
|
|
//
|
|
// Library: Foundation
|
|
// Package: Cache
|
|
// Module: UniqueExpireCache
|
|
//
|
|
// Definition of the UniqueExpireCache class.
|
|
//
|
|
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
|
|
// and Contributors.
|
|
//
|
|
// SPDX-License-Identifier: BSL-1.0
|
|
//
|
|
|
|
|
|
#ifndef Foundation_UniqueExpireCache_INCLUDED
|
|
#define Foundation_UniqueExpireCache_INCLUDED
|
|
|
|
|
|
#include "Poco/AbstractCache.h"
|
|
#include "Poco/UniqueExpireStrategy.h"
|
|
|
|
|
|
namespace Poco
|
|
{
|
|
|
|
|
|
template <class TKey, class TValue, class TMutex = FastMutex, class TEventMutex = FastMutex>
|
|
class UniqueExpireCache : public AbstractCache<TKey, TValue, UniqueExpireStrategy<TKey, TValue>, TMutex, TEventMutex>
|
|
/// An UniqueExpireCache caches entries for a given time amount. In contrast
|
|
/// to ExpireCache which only allows to set a per cache expiration value, it allows to define
|
|
/// expiration per CacheEntry.
|
|
/// Each TValue object must thus offer the following method:
|
|
///
|
|
/// const Poco::Timestamp& getExpiration() const;
|
|
///
|
|
/// which returns the absolute timepoint when the entry will be invalidated.
|
|
/// Accessing an object will NOT update this absolute expire timepoint.
|
|
/// You can use the Poco::ExpirationDecorator to add the getExpiration
|
|
/// method to values that do not have a getExpiration function.
|
|
///
|
|
/// Be careful when using an UniqueExpireCache. A cache is often used
|
|
/// like cache.has(x) followed by cache.get x). Note that it could happen
|
|
/// that the "has" call works, then the current execution thread gets descheduled, time passes,
|
|
/// the entry gets invalid, thus leading to an empty SharedPtr being returned
|
|
/// when "get" is invoked.
|
|
{
|
|
public:
|
|
UniqueExpireCache()
|
|
: AbstractCache<TKey, TValue, UniqueExpireStrategy<TKey, TValue>, TMutex, TEventMutex>(UniqueExpireStrategy<TKey, TValue>())
|
|
{
|
|
}
|
|
|
|
~UniqueExpireCache() { }
|
|
|
|
private:
|
|
UniqueExpireCache(const UniqueExpireCache & aCache);
|
|
UniqueExpireCache & operator=(const UniqueExpireCache & aCache);
|
|
};
|
|
|
|
|
|
} // namespace Poco
|
|
|
|
|
|
#endif // Foundation_UniqueExpireCache_INCLUDED
|