#ifndef DBAPI_DRIVER___DBAPI_POOL_BALANCER__HPP
#define DBAPI_DRIVER___DBAPI_POOL_BALANCER__HPP

/*  $Id: dbapi_pool_balancer.hpp 610945 2020-06-25 18:31:37Z ivanov $
 * ===========================================================================
 *
 *                            PUBLIC DOMAIN NOTICE
 *               National Center for Biotechnology Information
 *
 *  This software/database is a "United States Government Work" under the
 *  terms of the United States Copyright Act.  It was written as part of
 *  the author's official duties as a United States Government employee and
 *  thus cannot be copyrighted.  This software/database is freely available
 *  to the public for use. The National Library of Medicine and the U.S.
 *  Government have not placed any restriction on its use or reproduction.
 *
 *  Although all reasonable efforts have been taken to ensure the accuracy
 *  and reliability of the software and data, the NLM and the U.S.
 *  Government do not and cannot warrant the performance or results that
 *  may be obtained by using this software or data. The NLM and the U.S.
 *  Government disclaim all warranties, express or implied, including
 *  warranties of performance, merchantability or fitness for any particular
 *  purpose.
 *
 *  Please cite the author in any work or product based on this material.
 *
 * ===========================================================================
 *
 * Author:  Aaron Ucko
 *
 */

/// @file dbapi_pool_balancer.hpp
/// Help distribute connections within a pool across servers.

#include <dbapi/driver/impl/dbapi_driver_utils.hpp>

/** @addtogroup DBAPI
 *
 * @{
 */

BEGIN_NCBI_SCOPE

class CDBPoolBalancer : public CObject
{
public:
    CDBPoolBalancer(const string& service_name,
                    const string& pool_name,
                    const IDBServiceMapper::TOptions& options,
                    I_DriverContext* driver_ctx = nullptr);

    TSvrRef GetServer(CDB_Connection** conn, const CDBConnParams* params);

private:
    struct SEndpointInfo {
        SEndpointInfo()
            : effective_ranking(0.0), ideal_count(0.0), actual_count(0U),
              penalty_level(0U)
            { }
        
        CRef<CDBServerOption>  ref;
        double                 effective_ranking;
        double                 ideal_count;
        unsigned int           actual_count;
        unsigned int           penalty_level;
    };
    typedef map<impl::TEndpointKey, SEndpointInfo> TEndpoints;

    impl::TEndpointKey x_NameToKey(CTempString& name) const;
    
    TEndpoints        m_Endpoints;
    multiset<double>  m_Rankings;
    I_DriverContext*  m_DriverCtx;
    unsigned int      m_TotalCount;
};

END_NCBI_SCOPE

/* @} */

#endif  /* DBAPI_DRIVER___DBAPI_POOL_BALANCER__HPP */
