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squawk/core/storage/cache.hpp

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// 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 CORE_CACHE_HPP
#define CORE_CACHE_HPP
#include "cache.h"
template <class K, class V>
Core::Cache<K, V>::Cache(const QString& name):
storage(name),
cache(new std::map<K, V> ()),
abscent(new std::set<K> ()) {}
template <class K, class V>
Core::Cache<K, V>::~Cache() {
close();
delete cache;
delete abscent;
}
template <class K, class V>
void Core::Cache<K, V>::open() {
storage.open();}
template <class K, class V>
void Core::Cache<K, V>::close() {
storage.close();}
template <class K, class V>
void Core::Cache<K, V>::addRecord(const K& key, const V& value) {
storage.addRecord(key, value);
cache->insert(std::make_pair(key, value));
abscent->erase(key);
}
template <class K, class V>
V Core::Cache<K, V>::getRecord(const K& key) const {
typename std::map<K, V>::const_iterator itr = cache->find(key);
if (itr == cache->end()) {
if (abscent->count(key) > 0) {
throw Archive::NotFound(std::to_string(key), storage.getName().toStdString());
}
try {
V value = storage.getRecord(key);
itr = cache->insert(std::make_pair(key, value)).first;
} catch (const Archive::NotFound& error) {
abscent->insert(key);
throw error;
}
}
return itr->second;
}
template<class K, class V>
bool Core::Cache<K, V>::checkRecord(const K& key) const {
typename std::map<K, V>::const_iterator itr = cache->find(key);
if (itr != cache->end())
return true;
if (abscent->count(key) > 0)
return false;
try {
V value = storage.getRecord(key);
itr = cache->insert(std::make_pair(key, value)).first;
} catch (const Archive::NotFound& error) {
return false;
}
return true;
}
template<class K, class V>
void Core::Cache<K, V>::changeRecord(const K& key, const V& value) {
storage.changeRecord(key, value); //there is a non straightforward behaviour: if there was no element at the sorage it will be added
cache->at(key) = value;
abscent->erase(key); //so... this line here is to make it coherent with the storage
}
template<class K, class V>
void Core::Cache<K, V>::removeRecord(const K& key) {
storage.removeRecord(key);
cache->erase(key);
abscent->insert(key);
}
#endif //CORE_CACHE_HPP