tracktion_RealTimeSpinLock.h

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 /*
    ,--.                     ,--.     ,--.  ,--.
  ,-'  '-.,--.--.,--,--.,---.|  |,-.,-'  '-.`--' ,---. ,--,--,      Copyright 2024
  '-.  .-'|  .--' ,-.  | .--'|     /'-.  .-',--.| .-. ||      \   Tracktion Software
    |  |  |  |  \ '-'  \ `--.|  \  \  |  |  |  |' '-' '|  ||  |       Corporation
    `---' `--'   `--`--'`---'`--'`--' `---' `--' `---' `--''--'    www.tracktion.com
 
    Tracktion Engine uses a GPL/commercial licence - see LICENCE.md for details.
*/
 
#pragma once
 
#if JUCE_INTEL
 #include <emmintrin.h>
#endif
 
namespace tracktion { inline namespace graph
{
 
class RealTimeSpinLock
{
public:
    void lock() noexcept
    {
        for (;;)
        {
            for (int i = 0; i < 5; ++i)
                if (try_lock())
                    return;
 
            for (int i = 0; i < 10; ++i)
            {
                #if JUCE_INTEL
                 _mm_pause();
                #else
                 __asm__ __volatile__ ("yield");
                #endif
 
                if (try_lock())
                    return;
            }
        }
    }
 
    void unlock() noexcept
    {
        flag.clear (std::memory_order_release);
    }
 
    bool try_lock() noexcept
    {
        return ! flag.test_and_set (std::memory_order_acquire);
    }
 
private:
    std::atomic_flag flag = ATOMIC_FLAG_INIT;
};
 
}}