kicad/include/database/database_cache.h

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/*
* This program source code file is part of KiCad, a free EDA CAD application.
*
* Copyright (C) 2022 Jon Evans <jon@craftyjon.com>
* Copyright (C) 2022 KiCad Developers, see AUTHORS.txt for contributors.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at your
* option) any later version.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef KICAD_DATABASE_CACHE_H
#define KICAD_DATABASE_CACHE_H
#include <chrono>
#include <list>
#include <string>
#include <unordered_map>
#include <database/database_connection.h>
template<typename CacheValueType>
class DATABASE_CACHE
{
public:
typedef std::pair<std::string, std::pair<time_t, CacheValueType>> CACHE_ENTRY;
typedef std::unordered_map<std::string, typename std::list<CACHE_ENTRY>::iterator> CACHE_TYPE;
typedef typename CACHE_TYPE::const_iterator CACHE_CITER;
typedef CacheValueType CACHE_VALUE;
DATABASE_CACHE( size_t aMaxSize, time_t aMaxAge ) :
m_maxSize( aMaxSize ),
m_maxAge( aMaxAge )
{}
void Put( const std::string& aQuery, const CacheValueType& aResult )
{
auto it = m_cache.find( aQuery );
time_t time = std::chrono::system_clock::to_time_t( std::chrono::system_clock::now() );
m_cacheMru.push_front( std::make_pair( aQuery,
std::make_pair( time, aResult ) ) );
if( it != m_cache.end() )
{
m_cacheMru.erase( it->second );
m_cache.erase( it );
}
m_cache[aQuery] = m_cacheMru.begin();
if( m_cache.size() > m_maxSize )
{
auto last = m_cacheMru.end();
last--;
m_cache.erase( last->first );
m_cacheMru.pop_back();
}
}
bool Get( const std::string& aQuery, CacheValueType& aResult )
{
auto it = m_cache.find( aQuery );
if( it == m_cache.end() )
return false;
time_t time = std::chrono::system_clock::to_time_t( std::chrono::system_clock::now() );
if( time - it->second->second.first > m_maxAge )
{
m_cacheMru.erase( it->second );
m_cache.erase( it );
return false;
}
m_cacheMru.splice( m_cacheMru.begin(), m_cacheMru, it->second );
aResult = it->second->second.second;
return true;
}
void SetMaxSize( size_t aMaxSize ) { m_maxSize = aMaxSize; }
void SetMaxAge( time_t aMaxAge ) { m_maxAge = aMaxAge; }
private:
size_t m_maxSize;
time_t m_maxAge;
std::list<CACHE_ENTRY> m_cacheMru;
CACHE_TYPE m_cache;
};
#endif //KICAD_DATABASE_CACHE_H