topical media & game development
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lib-of-vs-libs-Poco-include-Poco-UniqueExpireCache.h / h



  //
  // UniqueExpireCache.h
  //
  // Id: //poco/1.3/Foundation/include/Poco/UniqueExpireCache.h#2 
  //
  // Library: Foundation
  // Package: Cache
  // Module:  UniqueExpireCache
  //
  // Definition of the UniqueExpireCache class.
  //
  // Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
  // and Contributors.
  //
  // Permission is hereby granted, free of charge, to any person or organization
  // obtaining a copy of the software and accompanying documentation covered by
  // this license (the "Software") to use, reproduce, display, distribute,
  // execute, and transmit the Software, and to prepare derivative works of the
  // Software, and to permit third-parties to whom the Software is furnished to
  // do so, all subject to the following:
  // 
  // The copyright notices in the Software and this entire statement, including
  // the above license grant, this restriction and the following disclaimer,
  // must be included in all copies of the Software, in whole or in part, and
  // all derivative works of the Software, unless such copies or derivative
  // works are solely in the form of machine-executable object code generated by
  // a source language processor.
  // 
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
  // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
  // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  // DEALINGS IN THE SOFTWARE.
  //
  
  ifndef  Foundation_UniqueExpireCache_INCLUDED
  define  Foundation_UniqueExpireCache_INCLUDED
  
  include "Poco/AbstractCache.h"
  include "Poco/UniqueExpireStrategy.h"
  
  namespace Poco {
  
  template <class TKey, class TValue> 
  class UniqueExpireCache: public AbstractCache<TKey, TValue, UniqueExpireStrategy<TKey, TValue> >
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> >(UniqueExpireStrategy<TKey, TValue>()) { } 

          ~UniqueExpireCache()
          {
          }
  
  private:
          UniqueExpireCache(const UniqueExpireCache& aCache);
          UniqueExpireCache& operator = (const UniqueExpireCache& aCache);
  };
  
  } // namespace Poco
  
  endif
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 04/09/2009

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