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https://github.com/VCMP-SqMod/SqMod.git
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4a6bfc086c
Switched to POCO library for unified platform/library interface. Deprecated the external module API. It was creating more problems than solving. Removed most built-in libraries in favor of system libraries for easier maintenance. Cleaned and secured code with help from static analyzers.
133 lines
3.1 KiB
C++
133 lines
3.1 KiB
C++
//
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// ExpireStrategy.h
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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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// SPDX-License-Identifier: BSL-1.0
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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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typename TimeIndex::value_type tiValue(now, args.key());
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IndexIterator it = _keyIndex.insert(tiValue);
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typename Keys::value_type kValue(args.key(), it);
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std::pair<Iterator, bool> stat = _keys.insert(kValue);
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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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else //not found: probably removed by onReplace
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args.invalidate();
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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 // Foundation_ExpireStrategy_INCLUDED
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