mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-04 13:32:13 +00:00
143 lines
3.0 KiB
C++
143 lines
3.0 KiB
C++
//
|
|
// LRUStrategy.h
|
|
//
|
|
// $Id: //poco/1.4/Foundation/include/Poco/LRUStrategy.h#1 $
|
|
//
|
|
// Library: Foundation
|
|
// Package: Cache
|
|
// Module: LRUStrategy
|
|
//
|
|
// Definition of the LRUStrategy class.
|
|
//
|
|
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
|
|
// and Contributors.
|
|
//
|
|
// SPDX-License-Identifier: BSL-1.0
|
|
//
|
|
|
|
|
|
#ifndef Foundation_LRUStrategy_INCLUDED
|
|
#define Foundation_LRUStrategy_INCLUDED
|
|
|
|
|
|
#include "Poco/KeyValueArgs.h"
|
|
#include "Poco/ValidArgs.h"
|
|
#include "Poco/AbstractStrategy.h"
|
|
#include "Poco/EventArgs.h"
|
|
#include "Poco/Exception.h"
|
|
#include <list>
|
|
#include <map>
|
|
#include <cstddef>
|
|
|
|
|
|
namespace Poco {
|
|
|
|
|
|
template <class TKey, class TValue>
|
|
class LRUStrategy: public AbstractStrategy<TKey, TValue>
|
|
/// An LRUStrategy implements least recently used cache replacement.
|
|
{
|
|
public:
|
|
typedef std::list<TKey> Keys;
|
|
typedef typename Keys::iterator Iterator;
|
|
typedef typename Keys::const_iterator ConstIterator;
|
|
typedef std::map<TKey, Iterator> KeyIndex;
|
|
typedef typename KeyIndex::iterator IndexIterator;
|
|
typedef typename KeyIndex::const_iterator ConstIndexIterator;
|
|
|
|
public:
|
|
LRUStrategy(std::size_t size):
|
|
_size(size)
|
|
{
|
|
if (_size < 1) throw InvalidArgumentException("size must be > 0");
|
|
}
|
|
|
|
~LRUStrategy()
|
|
{
|
|
}
|
|
|
|
void onAdd(const void*, const KeyValueArgs <TKey, TValue>& args)
|
|
{
|
|
_keys.push_front(args.key());
|
|
std::pair<IndexIterator, bool> stat = _keyIndex.insert(std::make_pair(args.key(), _keys.begin()));
|
|
if (!stat.second)
|
|
{
|
|
stat.first->second = _keys.begin();
|
|
}
|
|
}
|
|
|
|
void onRemove(const void*, const TKey& key)
|
|
{
|
|
IndexIterator it = _keyIndex.find(key);
|
|
|
|
if (it != _keyIndex.end())
|
|
{
|
|
_keys.erase(it->second);
|
|
_keyIndex.erase(it);
|
|
}
|
|
}
|
|
|
|
void onGet(const void*, const TKey& key)
|
|
{
|
|
// LRU: in case of an hit, move to begin
|
|
IndexIterator it = _keyIndex.find(key);
|
|
|
|
if (it != _keyIndex.end())
|
|
{
|
|
_keys.splice(_keys.begin(), _keys, it->second); //_keys.erase(it->second)+_keys.push_front(key);
|
|
it->second = _keys.begin();
|
|
}
|
|
}
|
|
|
|
void onClear(const void*, const EventArgs& args)
|
|
{
|
|
_keys.clear();
|
|
_keyIndex.clear();
|
|
}
|
|
|
|
void onIsValid(const void*, ValidArgs<TKey>& args)
|
|
{
|
|
if (_keyIndex.find(args.key()) == _keyIndex.end())
|
|
{
|
|
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!
|
|
std::size_t curSize = _keyIndex.size();
|
|
|
|
if (curSize < _size)
|
|
{
|
|
return;
|
|
}
|
|
|
|
std::size_t diff = curSize - _size;
|
|
Iterator it = --_keys.end(); //--keys can never be invoked on an empty list due to the minSize==1 requirement of LRU
|
|
std::size_t i = 0;
|
|
|
|
while (i++ < diff)
|
|
{
|
|
elemsToRemove.insert(*it);
|
|
if (it != _keys.begin())
|
|
{
|
|
--it;
|
|
}
|
|
}
|
|
}
|
|
|
|
protected:
|
|
std::size_t _size; /// Number of keys the cache can store.
|
|
Keys _keys;
|
|
KeyIndex _keyIndex; /// For faster access to _keys
|
|
};
|
|
|
|
|
|
} // namespace Poco
|
|
|
|
|
|
#endif // Foundation_LRUStrategy_INCLUDED
|