Throttle.cpp

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/*
 * Copyright (c) 2015-2018, EPFL/Blue Brain Project
 *
 * Responsible Author: Daniel.Nachbaur@epfl.ch
 *
 * This file is part of Blue Brain BioExplorer <https://github.com/BlueBrain/BioExplorer>
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 3.0 as published
 * by the Free Software Foundation.
 *
 * This library 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 library; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#include "Throttle.h"
 
namespace core
{
namespace
{
using namespace std::chrono;
auto now()
{
    return high_resolution_clock::now();
}
auto elapsedSince(const time_point<high_resolution_clock>& last)
{
    return duration_cast<milliseconds>(now() - last).count();
}
} // namespace
 
void Throttle::operator()(const Throttle::Function& fn, const int64_t wait)
{
    operator()(fn, fn, wait);
}
 
void Throttle::operator()(const Throttle::Function& fn,
                          const Throttle::Function& later, const int64_t wait)
{
    time_point last;
    {
        std::lock_guard<std::mutex> lock(_mutex);
        last = _last;
    }
    if (_haveLast && (elapsedSince(last) <= wait))
    {
        _timeout.clear();
        auto delayed = [&_last = _last, &mutex = _mutex, later] {
            std::lock_guard<std::mutex> lock(mutex);
            later();
            _last = now();
        };
        _timeout.set(delayed, wait);
    }
    else
    {
        fn();
        _haveLast = true;
        std::lock_guard<std::mutex> lock(_mutex);
        _last = now();
    }
}
} // namespace core