EventLoopHandle.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreTypes.h"
#include "Containers/UnrealString.h"
#include "Templates/Atomic.h"
 
namespace UE::EventLoop {
 
template <typename Traits>
struct TResourceHandle final
{
    enum EGenerateNewHandleType
    {
        GenerateNewHandle
    };
 
    TResourceHandle()
        : ID(0)
    {
    }
 
    explicit TResourceHandle(EGenerateNewHandleType)
        : ID(GenerateNewID())
    {
    }
 
    bool IsValid() const
    {
        return ID > 0;
    }
 
    void Invalidate()
    {
        ID = 0;
    }
 
    bool operator==(const TResourceHandle& Other) const
    {
        return ID == Other.ID;
    }
 
    bool operator!=(const TResourceHandle& Other) const
    {
        return ID != Other.ID;
    }
 
    friend inline uint32 GetTypeHash(const TResourceHandle& InHandle)
    {
        return GetTypeHash(InHandle.ID);
    }
 
    FString ToString() const
    {
        return IsValid() ? FString::Printf(TEXT("%s:%llu"), Traits::Name, ID) : FString::Printf(TEXT("%s:<invalid>"), Traits::Name);
    }
 
    static const TCHAR* GetTypeName()
    {
        return Traits::Name;
    }
 
private:
    static uint64 GenerateNewID()
    {
        // Just increment a counter to generate an ID.
        uint64 Result = NextID++;
 
        // Check for the next-to-impossible event that we wrap round to 0, because we reserve 0 for null delegates.
        if (Result == 0)
        {
            // Increment it again - it might not be zero, so don't just assign it to 1.
            Result = ++NextID;
        }
 
        return Result;
    }
 
    static TAtomic<uint64> NextID;
 
    uint64 ID;
};
 
template <typename Traits>
TAtomic<uint64> TResourceHandle<Traits>::NextID = 1;
 
/* UE::EventLoop */ }