2006-10-23 17:48:43 +02:00
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//
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// ExpireStrategy.h
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//
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2008-01-29 10:06:52 +01:00
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// $Id: //poco/svn/Foundation/include/Poco/ExpireStrategy.h#3 $
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2006-10-23 17:48:43 +02:00
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//
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// Library: Foundation
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// Package: Cache
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// Module: ExpireStrategy
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//
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// Definition of the ExpireStrategy 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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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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#ifndef Foundation_ExpireStrategy_INCLUDED
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#define Foundation_ExpireStrategy_INCLUDED
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#include "Poco/KeyValueArgs.h"
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#include "Poco/ValidArgs.h"
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#include "Poco/AbstractStrategy.h"
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#include "Poco/Bugcheck.h"
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#include "Poco/Timestamp.h"
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#include "Poco/EventArgs.h"
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#include <set>
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#include <map>
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namespace Poco {
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template <
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class TKey,
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class TValue
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>
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class ExpireStrategy: public AbstractStrategy<TKey, TValue>
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/// An ExpireStrategy implements time based expiration of cache entries
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{
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public:
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typedef std::multimap<Timestamp, TKey> TimeIndex;
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typedef typename TimeIndex::iterator IndexIterator;
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typedef typename TimeIndex::const_iterator ConstIndexIterator;
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typedef std::map<TKey, IndexIterator> Keys;
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typedef typename Keys::iterator Iterator;
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public:
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ExpireStrategy(Timestamp::TimeDiff expireTimeInMilliSec): _expireTime(expireTimeInMilliSec * 1000)
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/// Create an expire strategy. Note that the smallest allowed caching time is 25ms.
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/// Anything lower than that is not useful with current operating systems.
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{
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if (_expireTime < 25000) throw InvalidArgumentException("expireTime must be at least 25 ms");
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}
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~ExpireStrategy()
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{
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}
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void onAdd(const void*, const KeyValueArgs <TKey, TValue>& args)
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{
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Timestamp now;
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2007-05-05 15:15:55 +02:00
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IndexIterator it = _keyIndex.insert(typename TimeIndex::value_type(now, args.key()));
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std::pair<Iterator, bool> stat = _keys.insert(typename Keys::value_type(args.key(), it));
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2006-10-23 17:48:43 +02:00
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if (!stat.second)
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{
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_keyIndex.erase(stat.first->second);
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stat.first->second = it;
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}
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}
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void onRemove(const void*, const TKey& key)
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{
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Iterator it = _keys.find(key);
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if (it != _keys.end())
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{
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_keyIndex.erase(it->second);
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_keys.erase(it);
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}
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}
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void onGet(const void*, const TKey& key)
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{
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// get triggers no changes in an expire
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}
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void onClear(const void*, const EventArgs& args)
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{
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_keys.clear();
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_keyIndex.clear();
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}
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void onIsValid(const void*, ValidArgs<TKey>& args)
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{
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Iterator it = _keys.find(args.key());
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if (it != _keys.end())
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{
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if (it->second->first.isElapsed(_expireTime))
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{
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args.invalidate();
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}
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}
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2008-01-29 10:06:52 +01:00
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else //not found: probably removed by onReplace
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args.invalidate();
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2006-10-23 17:48:43 +02:00
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}
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void onReplace(const void*, std::set<TKey>& elemsToRemove)
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{
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// Note: replace only informs the cache which elements
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// it would like to remove!
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// it does not remove them on its own!
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IndexIterator it = _keyIndex.begin();
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while (it != _keyIndex.end() && it->first.isElapsed(_expireTime))
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{
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elemsToRemove.insert(it->second);
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++it;
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}
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}
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protected:
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Timestamp::TimeDiff _expireTime;
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Keys _keys; /// For faster replacement of keys, the iterator points to the _keyIndex map
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TimeIndex _keyIndex; /// Maps time to key value
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};
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} // namespace Poco
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#endif
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