threadpool.h

/** ThreadPool
 * (C) Madura. A
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General
 * Public License along with this program; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02111-1307, USA.
 */

#pragma once

#include <atomic>
#include <functional>
#include <thread>
#include <vector>

#include "runnable.h"

namespace vrok {
class ThreadPool {
private:
    struct ThreadData {
        int thread_id;
        std::vector<std::vector<Runnable *>> *runnables;
        std::atomic<bool> work;
    };
    std::vector<std::thread *> _threads;
    std::vector<std::vector<Runnable *>> _runnables;
    std::vector<ThreadData *> _thread_data;

public:
    // the container type,
    // Dedicated - only work on a dedicated thread
    // Any - work on any idling thread
    enum SchedMode { Dedicated, Any };
    // Best - wake up as soon as possible
    // Lazy - schedule in to a free thread, if not run
    // for along time (>5 sec) schedule in to a new
    // thread
    enum WakeUpMode { Best, Lazy };
    ThreadPool(size_t thread_count);
    bool RegisterWork(size_t thread_id, Runnable *runnable);
    void StopThreads();
    void CreateThreads();
    void JoinThreads();
    ~ThreadPool();

    static void Work(ThreadData *th);
};
}