UnixPlatformManualResetEvent.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Misc/MonotonicTime.h"
 
#include <atomic>
 
namespace UE::HAL::Private
{
 
class FUnixManualResetEvent
{
public:
    FUnixManualResetEvent() = default;
    FUnixManualResetEvent(const FUnixManualResetEvent&) = delete;
    FUnixManualResetEvent& operator=(const FUnixManualResetEvent&) = delete;
 
    inline void Reset()
    {
        State.store(0, std::memory_order_relaxed);
    }
 
    inline bool Poll()
    {
        return !!State.load(std::memory_order_acquire);
    }
 
    inline void Wait()
    {
        if (!State.load(std::memory_order_acquire))
        {
            WaitSlow();
        }
    }
 
    inline bool WaitFor(FMonotonicTimeSpan WaitTime)
    {
        return State.load(std::memory_order_acquire) || WaitForSlow(WaitTime);
    }
 
    inline bool WaitUntil(FMonotonicTimePoint WaitTime)
    {
        return State.load(std::memory_order_acquire) || WaitUntilSlow(WaitTime);
    }
 
    void Notify();
 
private:
    void WaitSlow();
    bool WaitForSlow(FMonotonicTimeSpan WaitTime);
    bool WaitUntilSlow(FMonotonicTimePoint WaitTime);
 
    // 0 = Reset, 1 = Notified
    std::atomic<uint32> State = 0;
};
 
} // UE::HAL::Private