barrier.cpp

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#include "benchmark/barrier.h"
 
#include <cassert>
 
namespace CppBenchmark {
 
Barrier::Barrier(int threads) noexcept : _counter(threads), _generation(0), _threads(threads)
{
    assert((threads > 0) && "Barrier threads counter must be greater than zero!");
}
 
bool Barrier::Wait() noexcept
{
    std::unique_lock<std::mutex> lock(_mutex);
 
    // Remember the current barrier generation
    int generation = _generation;
 
    // Decrease the count of waiting threads
    if (--_counter == 0)
    {
        // Increase the current barrier generation
        ++_generation;
 
        // Reset waiting threads counter
        _counter = _threads;
 
        // Notify all waiting threads
        _cond.notify_all();
 
        // Notify the last thread that reached the barrier
        return true;
    }
 
    // Wait for the next barrier generation
    _cond.wait(lock, [&, this]() { return generation != _generation; });
 
    // Notify each of remaining threads
    return false;
}
 
} // namespace CppBenchmark