first thoughts about cache

cache.hpp

@@ -0,0 +1,114 @@
+// 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