DatabaseConnectionPool.h

/*
╔══════════════════════════════════════════════════════════════════════════════╗
║                        SIMPLY POWERFUL TOOLKIT (SPTK)                        ║
╟──────────────────────────────────────────────────────────────────────────────╢
║  copyright            © 1999-2022 Alexey Parshin. All rights reserved.       ║
║  email                alexeyp@gmail.com                                      ║
╚══════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────────────────────────────────────────────────┐
│   This library is free software; you can redistribute it and/or modify it    │
│   under the terms of the GNU Library General Public License as published by  │
│   the Free Software Foundation; either version 2 of the License, or (at your │
│   option) any later version.                                                 │
│                                                                              │
│   This library 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 Library   │
│   General Public License for more details.                                   │
│                                                                              │
│   You should have received a copy of the GNU Library General Public License  │
│   along with this library; if not, write to the Free Software Foundation,    │
│   Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.               │
│                                                                              │
│   Please report all bugs and problems to alexeyp@gmail.com.                  │
└──────────────────────────────────────────────────────────────────────────────┘
*/
 
#pragma once
 
#include <sptk5/CaseInsensitiveCompare.h>
#include <sptk5/db/AutoDatabaseConnection.h>
#include <sptk5/db/DatabaseConnectionString.h>
#include <sptk5/db/PoolDatabaseConnection.h>
#include <sptk5/threads/SynchronizedList.h>
#include <sptk5/threads/SynchronizedQueue.h>
 
namespace sptk {
 
using CreateDriverInstance = PoolDatabaseConnection*(const char* connectString, size_t connectTimeoutSeconds);
 
using DestroyDriverInstance = void(PoolDatabaseConnection*);
 
#ifdef WIN32
using DriverHandle = HMODULE;
 
#else
using DriverHandle = uint8_t*;
 
#endif
 
struct SP_EXPORT DatabaseDriver {
    DriverHandle m_handle;
 
    CreateDriverInstance* m_createConnection;
 
    DestroyDriverInstance* m_destroyConnection;
};
 
class SP_EXPORT DatabaseConnectionPool
    : public DatabaseConnectionString
    , public std::mutex
{
    friend class AutoDatabaseConnection;
 
public:
    DatabaseConnectionPool(const String& connectionString, unsigned maxConnections = 100, std::chrono::seconds connectionTimeout = std::chrono::seconds(60));
 
    [[nodiscard]] DatabaseConnection getConnection();
 
    std::chrono::seconds connectionTimeout() const
    {
        return m_connectionTimeout;
    }
 
protected:
    void load();
 
    [[nodiscard]] SPoolDatabaseConnection createConnection();
 
    void releaseConnection(const SPoolDatabaseConnection& connection);
 
private:
    DatabaseDriver* m_driver {nullptr};
 
    CreateDriverInstance* m_createConnection {nullptr};
 
    DestroyDriverInstance* m_destroyConnection {nullptr};
 
    size_t m_maxConnections;
    SynchronizedQueue<SPoolDatabaseConnection> m_pool;       
    SynchronizedList<SPoolDatabaseConnection> m_connections; 
    std::chrono::seconds m_connectionTimeout;                
};
 
} // namespace sptk