dispatch-pool.h

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Author: Liam White
 * Copyright (C) 2024 Authors
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */
 
#ifndef INKSCAPE_DISPLAY_DISPATCH_POOL_H
#define INKSCAPE_DISPLAY_DISPATCH_POOL_H
 
#include <condition_variable>
#include <functional>
#include <mutex>
#include <thread>
#include <vector>
 
namespace Inkscape {
 
class dispatch_pool
{
public:
    using global_id = int;
    using local_id = int;
    using dispatch_func = std::function<void(global_id, local_id)>;
 
    explicit dispatch_pool(int size);
    ~dispatch_pool();
 
    void dispatch(int count, dispatch_func function);
 
    template <typename F>
    void dispatch_threshold(int count, bool threshold, F &&function)
    {
        if (threshold) {
            dispatch(count, std::forward<F>(function));
        } else {
            for (auto i = global_id{}; i < global_id{count}; i++) {
                function(i, local_id{});
            }
        }
    }
 
    int size() const
    {
        // The calling thread participates in the dispatch
        return _threads.size() + 1;
    }
 
private:
    void thread_func(local_id id);
    void execute_batch(std::unique_lock<std::mutex> &lk, local_id id, int thread_count);
 
private:
    global_id _available_work{};
    global_id _completed_work{};
    global_id _target_work{};
    bool _shutdown{};
 
    std::mutex _dispatch_lock;
    std::mutex _lock;
    std::condition_variable _available_cv;
    std::condition_variable _completed_cv;
    dispatch_func _function;
    std::vector<std::thread> _threads;
};
 
} // namespace Inkscape
 
#endif // INKSCAPE_DISPLAY_DISPATCH_POOL_H
 
/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
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