/****************************************************************************
 *   This file is part of the aGrUM/pyAgrum library.                        *
 *                                                                          *
 *   Copyright (c) 2005-2026 by                                             *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *                                                                          *
 *   The aGrUM/pyAgrum library is free software; you can redistribute it    *
 *   and/or modify it under the terms of either :                           *
 *                                                                          *
 *    - the GNU Lesser General Public License as published by               *
 *      the Free Software Foundation, either version 3 of the License,      *
 *      or (at your option) any later version,                              *
 *    - the MIT license (MIT),                                              *
 *    - or both in dual license, as here.                                   *
 *                                                                          *
 *   (see https://agrum.gitlab.io/articles/dual-licenses-lgplv3mit.html)    *
 *                                                                          *
 *   This aGrUM/pyAgrum library is distributed in the hope that it will be  *
 *   useful, but WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,          *
 *   INCLUDING BUT NOT LIMITED TO THE WARRANTIES MERCHANTABILITY or FITNESS *
 *   FOR A PARTICULAR PURPOSE  AND NONINFRINGEMENT. IN NO EVENT SHALL THE   *
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,        *
 *   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR  *
 *   OTHER DEALINGS IN THE SOFTWARE.                                        *
 *                                                                          *
 *   See LICENCES for more details.                                         *
 *                                                                          *
 *   SPDX-FileCopyrightText: Copyright 2005-2026                            *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *   SPDX-License-Identifier: LGPL-3.0-or-later OR MIT                      *
 *                                                                          *
 *   Contact  : info_at_agrum_dot_org                                       *
 *   homepage : http://agrum.gitlab.io                                      *
 *   gitlab   : https://gitlab.com/agrumery/agrum                           *
 *                                                                          *
 ****************************************************************************/


/** @file
 * @brief A scheduler that executes available operators in parallel
 *
 * @author Christophe GONZALES(@AMU) and Pierre-Henri WUILLEMIN(@LIP6)
 */

#ifndef GUM_SCHEDULER_PARALLEL_H
#define GUM_SCHEDULER_PARALLEL_H

#include <algorithm>
#include <atomic>
#include <chrono>
#include <memory>
#include <mutex>
#include <thread>
#include <vector>

#include <agrum/agrum.h>

#include <agrum/base/core/priorityQueue.h>
#include <agrum/base/core/threads/threadExecutor.h>
#include <agrum/base/graphicalModels/inference/scheduler/schedulerSequential.h>

#include <condition_variable>

namespace gum {

  /**
   * @class SchedulerParallel
   * @brief A scheduler that executes available operators in parallel
   * @headerfile schedulerParallel.h <agrum/base/graphicalModels/inference/scheduler/schedulerParallel.h>
   */
  class SchedulerParallel: public Scheduler {
    public:
    // ############################################################################
    /// @name Constructors / Destructors
    // ############################################################################
    /// @{

    /// default constructor
    explicit SchedulerParallel(Size max_nb_threads = 0, double max_megabyte_memory = 0.0);

    /// copy constructor
    SchedulerParallel(const SchedulerParallel& from);

    /// move constructor
    SchedulerParallel(SchedulerParallel&& from);

    /// virtual copy constructor
    [[nodiscard]] SchedulerParallel* clone() const final;

    /// destructor
    ~SchedulerParallel() override;

    /// @}

    // ############################################################################
    /// @name Accessors/Modifiers
    // ############################################################################
    /// @{

    /// sets the number of threads that can be used by the scheduler
    /**
     * @param nb the number of threads used for executing schedules. If this
     * number is set to 0, then it is defaulted to aGrUM's number of threads
     */
    void setNumberOfThreads(Size nb) final;

    /// sets an upper bound on the memory consumption admissible
    /**
     * @param megabytes the number of megabytes that can be used for the
     * execution of the schedule. If this number is equal to 0, then no
     * memory limit is applied.
     */
    void setMaxMemory(double megabytes) final;

    /// execute all the operations of a given schedule
    void execute(Schedule&) final;

    /** @brief returns an estimation of the number of elementary operations
     * needed to perform a given schedule */
    double nbOperations(const Schedule&) final;

    /// returns the memory consumption used during the execution of a schedule
    /** Actually, this function does not return a precise account of the memory
     * used to perform the schedule but a rough estimate based on the sizes
     * of the tables involved in the schedule.
     * @return a pair of memory consumption: the first one is the maximum
     * amount of memory used during the execution of the Schedule and the second
     * one is the amount of memory still used at the end of the execution of
     * the schedule */
    std::pair< double, double > memoryUsage(const Schedule&) final;

    /// @}


    private:
    /// a scheduler used for computing the number of operations and memory usage
    SchedulerSequential _sequential_scheduler_;
  };

} /* namespace gum */

// include the inlined functions if necessary
#ifndef GUM_NO_INLINE
#  include <agrum/base/graphicalModels/inference/scheduler/schedulerParallel_inl.h>
#endif /* GUM_NO_INLINE */

#endif /* GUM_SCHEDULER_PARALLEL_H */
