submitted 1.2.0

Foundation/include/Poco/ExpireStrategy.h

@@ -0,0 +1,150 @@
+//
+// ExpireStrategy.h
+//
+// $Id: //poco/1.2/Foundation/include/Poco/ExpireStrategy.h#1 $
+//
+// Library: Foundation
+// Package: Cache
+// Module:  ExpireStrategy
+//
+// Definition of the ExpireStrategy 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_ExpireStrategy_INCLUDED
+#define  Foundation_ExpireStrategy_INCLUDED
+
+
+#include "Poco/KeyValueArgs.h"
+#include "Poco/ValidArgs.h"
+#include "Poco/AbstractStrategy.h"
+#include "Poco/Bugcheck.h"
+#include "Poco/Timestamp.h"
+#include "Poco/EventArgs.h"
+#include <set>
+#include <map>
+
+
+namespace Poco {
+
+
+template < 
+	class TKey,
+	class TValue
+> 
+class ExpireStrategy: public AbstractStrategy<TKey, TValue>
+	/// An ExpireStrategy implements time based ecpiration of cache entries
+{
+public:
+	typedef std::multimap<Timestamp, TKey>     TimeIndex;
+	typedef typename TimeIndex::iterator       IndexIterator;
+	typedef typename TimeIndex::const_iterator ConstIndexIterator;
+	typedef std::map<TKey, IndexIterator>	   Keys;
+	typedef typename Keys::iterator            Iterator;
+
+public:
+	ExpireStrategy(Timestamp::TimeDiff expireTimeInMilliSec): _expireTime(expireTimeInMilliSec * 1000)
+		/// Create an expire strategy. Note that the smallest allowed caching time is 25ms.
+		/// Anything lower than that is not useful with current operating systems.
+	{
+		if (_expireTime < 25000) throw InvalidArgumentException("expireTime must be at least 25 ms");  
+	}
+
+	virtual ~ExpireStrategy()
+	{
+	}
+
+	void onAdd(const void*, const KeyValueArgs <TKey, TValue>& args)
+	{
+		Timestamp now;
+		IndexIterator it = _keyIndex.insert(std::make_pair(now, args.key()));
+		std::pair < Iterator, bool > stat = _keys.insert(std::make_pair(args.key(), it));
+		if (!stat.second)
+		{
+			_keyIndex.erase(stat.first->second);
+			stat.first->second = it;
+		}
+	}
+
+	void onRemove(const void*, const TKey& key)
+	{
+		Iterator it = _keys.find(key);
+		if (it != _keys.end ())
+		{
+			_keyIndex.erase(it->second);
+			_keys.erase(it);
+		}
+	}
+
+	void onGet(const void*, const TKey& key)
+	{
+		// get triggers no changes in an expire
+	}
+
+	void onClear(const void*, const EventArgs& args)
+	{
+		_keys.clear();
+		_keyIndex.clear();
+	}
+		
+	void onIsValid(const void*, ValidArgs<TKey>& args)
+	{
+		Iterator it = _keys.find(args.key());
+		if (it != _keys.end ())
+		{
+			if (it->second->first.isElapsed(_expireTime))
+			{
+				args.invalidate();
+			}
+		}
+	}
+
+	void onReplace(const void*, std::set<TKey>& elemsToRemove)
+	{
+		// Note: replace only informs the cache which elements
+		// it would like to remove!
+		// it does not remove them on its own!
+		IndexIterator it = _keyIndex.begin();
+		while (it != _keyIndex.end() && it->first.isElapsed(_expireTime))
+		{
+			elemsToRemove.insert(it->second);
+			++it;
+		}
+	}
+
+protected:
+	Timestamp::TimeDiff _expireTime;
+	Keys      _keys;     /// For faster replacement of keys, the iterator points to the _keyIndex map
+	TimeIndex _keyIndex; /// Maps time to key value
+};
+
+
+} // namespace Poco
+
+
+#endif