lmdbal/cache.hpp

// Squawk messenger. 
// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
// 
// 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 DATABASE_CACHE_HPP
#define DATABASE_CACHE_HPP

#include "cache.h"
#include "exceptions.h"

template<class K, class V>
DataBase::Cache<K, V>::Cache(const std::string& p_name, DataBase* parent):
    DataBase::Table<K, V>(p_name, parent),
    mode(Mode::nothing),
    cache(new std::map<K, V>()),
    abscent(new std::set<K>())
{
}

template<class K, class V>
DataBase::Cache<K, V>::~Cache() {
    delete cache;
    delete abscent;
}

template<class K, class V>
void DataBase::Cache<K, V>::addRecord(const K& key, const V& value) {
    if (!DataBase::Table<K, V>::db->opened) {
        throw Closed("addRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    if (cache->count(key) > 0) {
        throw Exist(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    Table<K, V>::addRecord(key, value);
    cache->insert(std::make_pair(key, value));
}



template<class K, class V>
void DataBase::Cache<K, V>::changeRecord(const K& key, const V& value) {
    if (!DataBase::Table<K, V>::db->opened) {
        throw Closed("changeRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    typename std::map<K, V>::iterator itr = cache->find(key);
    if (itr == cache->end() || abscent->count(key) > 0) {
        throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    try {
        Table<K, V>::changeRecord(key, value);
        itr->second = value;
    } catch (const NotFound& error) {
        abscent->insert(key);
        throw error;
    }
}

template<class K, class V>
V DataBase::Cache<K, V>::getRecord(const K& key) const {
    if (!DataBase::Table<K, V>::db->opened) {
        throw Closed("getRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    typename std::map<K, V>::const_iterator itr = cache->find(key);
    if (itr != cache->end()) {
        return itr->second;
    }

    if (abscent->count(key) == 0) {
        throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    try {
        V value = Table<K, V>::getRecord(key);
        cache->insert(std::make_pair(key, value));
        return value;
    } catch (const NotFound& error) {
        abscent->insert(key);
        throw error;
    }
}

template<class K, class V>
void DataBase::Cache<K, V>::removeRecord(const K& key) {
    if (!DataBase::Table<K, V>::db->opened) {
        throw Closed("removeRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    typename std::pair<typename std::set<K>::const_iterator, bool> pair = abscent->insert(key);
    if (!pair.second) {
        throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
    }

    cache->erase(key);
    Table<K, V>::removeRecord(key);
}

#endif //DATABASE_CACHE_HPP