base.h

/*
 * LMDB Abstraction Layer.
 * Copyright (C) 2023  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/>.
 */
 
#pragma once
 
#include <map>
#include <set>
#include <string>
#include <optional>
#include <limits>
#include <cstdint>
#include <mutex>
 
#include <QString>
#include <QStandardPaths>
#include <QDir>
 
#include <lmdb.h>
 
#include "exceptions.h"
 
namespace LMDBAL {
 
class StorageCommon;
class Transaction;
class WriteTransaction;
class Session;
 
template<class T>
class Serializer;
 
template <class K, class V>
class Storage;
 
template <class K, class V>
class Cache;
 
typedef MDB_txn* TransactionID;                         
typedef uint32_t SizeType;                              
 
class Base {
    friend class StorageCommon;
    friend class Transaction;
    friend class WriteTransaction;
    friend class Session;
 
public:
    Base(const QString& name, uint16_t mapSize = 10);
    ~Base();
 
    Session open();
    bool opened() const;
    bool removeDirectory();
    QString createDirectory();
    QString getName() const;
    QString getPath() const;
    void drop();
 
    Transaction beginReadOnlyTransaction() const;
    WriteTransaction beginTransaction();
 
    template <class K, class V>
    LMDBAL::Storage<K, V>* addStorage(const std::string& storageName, bool duplicates = false);
 
    template <class K, class V>
    LMDBAL::Cache<K, V>* addCache(const std::string& storageName);
 
    template <class K, class V>
    LMDBAL::Storage<K, V>* getStorage(const std::string& storageName);
 
    template <class K, class V>
    LMDBAL::Cache<K, V>* getCache(const std::string& storageName);
 
private:
    typedef std::map<std::string, LMDBAL::StorageCommon *> Storages;    
    typedef std::map<TransactionID, Transaction*> Transactions;         
    typedef std::set<Session*> Sessions;                                
 
    void commitTransaction(TransactionID id);
    void abortTransaction(TransactionID id) const;
    TransactionID beginReadOnlyTransaction(const std::string& storageName) const;
    TransactionID beginTransaction(const std::string& storageName) const;
    void commitTransaction(TransactionID id, const std::string& storageName);
    void abortTransaction(TransactionID id, const std::string& storageName) const;
 
    TransactionID beginPrivateReadOnlyTransaction(const std::string& storageName) const;
    TransactionID beginPrivateTransaction(const std::string& storageName) const;
    void commitPrivateTransaction(TransactionID id, const std::string& storageName);
    void abortPrivateTransaction(TransactionID id, const std::string& storageName) const;
 
    void registerSession(Session* session);
    void unregisterSession(Session* session);
    void replaceSession(Session* closing, Session* opening);
 
    void activate();
    void deactivate();
 
private:
    std::string name;                                           
    Sessions sessions;                                          
    uint16_t size;                                              
    MDB_env* environment;                                       
    Storages storages;                                          
    mutable Transactions transactions;                          
    std::mutex mutex;                                           
 
    inline static const std::string emptyName = "";             
};
 
}
#include "operators.hpp"

template <class K, class V>
LMDBAL::Storage<K, V>* LMDBAL::Base::addStorage(const std::string& storageName, bool duplicates) {
    if (opened())
        throw Opened(name, "add storage " + storageName);
 
    auto storage = new Storage<K, V>(this, storageName, duplicates);
    std::pair<Storages::const_iterator, bool> pair = storages.emplace(storageName, static_cast<StorageCommon *>(storage));
    if (!pair.second)
        throw StorageDuplicate(name, storageName);
 
    return storage;
}

template<class K, class V>
LMDBAL::Cache<K, V> * LMDBAL::Base::addCache(const std::string& storageName) {
    if (opened())
        throw Opened(name, "add cache " + storageName);
 
    auto cache = new Cache<K, V>(this, storageName, false);
    std::pair<Storages::const_iterator, bool> pair = storages.emplace(storageName, static_cast<StorageCommon *>(cache));
    if (!pair.second)
        throw StorageDuplicate(name, storageName);
 
    return cache;
}

template <class K, class V>
LMDBAL::Storage<K, V>* LMDBAL::Base::getStorage(const std::string& storageName) {
    return static_cast<Storage<K, V>*>(storages.at(storageName));
}

template <class K, class V>
LMDBAL::Cache<K, V>* LMDBAL::Base::getCache(const std::string& storageName) {
    return static_cast<Cache<K, V>*>(storages.at(storageName));
}