connection_manager.h

#ifndef _CONNECTION_MANAGER_H
#define _CONNECTION_MANAGER_H
/*
 * Fledge storage service.
 *
 * Copyright (c) 2017 OSisoft, LLC
 *
 * Released under the Apache 2.0 Licence
 *
 * Author: Mark Riddoch
 */

#include <plugin_api.h>
#include <list>
#include <mutex>

class Connection;

class ConnectionManager {
    public:
        static ConnectionManager  *getInstance();
        void                      growPool(unsigned int);
        unsigned int              shrinkPool(unsigned int);
        Connection                *allocate();
        void                      release(Connection *);
        void              shutdown();
        void              setError(const char *, const char *, bool);
        PLUGIN_ERROR          *getError()
                      {
                        return &lastError;
                      }
        void              setMaxReadingRows(long rows)
                      {
                          m_maxReadingRows = rows;
                      }

    private:
        ConnectionManager();
        static ConnectionManager     *instance;
        std::list<Connection *>      idle;
        std::list<Connection *>      inUse;
        std::mutex                   idleLock;
        std::mutex                   inUseLock;
        std::mutex                   errorLock;
        PLUGIN_ERROR             lastError;
        bool                 m_logSQL;
        long                 m_maxReadingRows;
};

#endif