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/*
Copyright (C) 2003 Nikolas Zimmermann <[email protected]>
This file is part of the KDE project
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
aint with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef T2P_CACHE_H
#define T2P_CACHE_H
#include <map>
#include <string>
#include <vector>
#include <iostream>
#include "myboost/shared_ptr.hpp"
namespace T2P
{
class CacheElement
{
public:
CacheElement(std::string key) : m_key(key), m_usage(0) { }
~CacheElement() { }
std::string key() const { return m_key; }
int usage() const { return m_usage; }
void incUsage() { m_usage++; }
private:
std::string m_key;
int m_usage;
};
template<typename T>
class Cache
{
public:
typedef myboost::shared_ptr<T> SharedT;
Cache(int maxSize = 10) : m_size(0), m_maxSize(maxSize) { }
~Cache() { clear(); }
// Number of elements in cache
int size() const { return m_size; }
// Maximum number of elements in cache
int maxSize() const { return m_maxSize; }
// Add new entry
void insert(const std::string &key, SharedT &value)
{
// TODO: Add real LRU logic, now i will just delete the less
// used item when inserting a new item would exceed maxSize
if(m_size == m_maxSize)
{
// Find less used item
typename std::map<SharedT, CacheElement *>::const_iterator it = m_cacheMap.begin();
int usage = (*it).second->usage(); std::string keyUsage = (*it).second->key();
for(it++; it != m_cacheMap.end(); ++it)
{
int curUsage = (*it).second->usage();
if(curUsage < usage)
{
usage = curUsage;
keyUsage = (*it).second->key();
}
}
// std::cout << "[CACHE] Removing less used element with key: " << keyUsage << " (Used " << usage << " times!)" << std::endl;
remove(keyUsage);
}
m_size++;
m_entries.push_back(value);
m_cacheMap[value] = new CacheElement(key);
}
// Remove single entry
void remove(const std::string &key)
{
for(typename std::vector<SharedT>::iterator it = m_entries.begin(); it != m_entries.end(); ++it)
{
SharedT cur = *it;
if(m_cacheMap[cur]->key() == key)
{
m_size--;
typename std::map<SharedT, CacheElement *>::iterator cacheElement = m_cacheMap.find(cur);
m_cacheMap.erase(cacheElement);
delete cacheElement->second;
m_entries.erase(it); // Only valid to write because we don't go on here!
break; // Otherwhise the iterators _may_ be invalid!
}
}
}
// Remove all entries
void clear()
{
m_size = 0;
m_entries.clear();
m_cacheMap.clear();
}
// Lookup entry
SharedT find(const std::string &key)
{
for(typename std::vector<SharedT>::const_iterator it = m_entries.begin(); it != m_entries.end(); ++it)
{
SharedT cur = *it;
if(m_cacheMap[cur]->key() == key)
{
m_cacheMap[cur]->incUsage();
return cur;
}
}
return SharedT();
}
void dump()
{
std::cout << "[CACHE] " << size() << " of " << maxSize() << " Objects in the cache." << std::endl;
for(typename std::vector<SharedT>::iterator it = m_entries.begin(); it != m_entries.end(); ++it)
{
SharedT cur = *it;
std::cout << "[CACHE] - " << m_cacheMap[cur]->key() << " -> " << cur << " (Usage: " << m_cacheMap[cur]->usage() << ")" << std::endl;
}
}
private:
std::vector<SharedT> m_entries;
std::map<SharedT, CacheElement *> m_cacheMap;
int m_size, m_maxSize;
};
}
#endif
// vim:ts=4:noet
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