Class ThreadLocal

Source/Engine/Threading/ThreadLocal.h:16–158

/// </summary>
template<typename T, int32 MaxThreads = (PLATFORM_THREADS_LIMIT >= 16 ? PLATFORM_THREADS_LIMIT : 16)>
class ThreadLocal
{
protected:
    static_assert(TIsPODType<T>::Value, "Only POD types are supported");

    struct Bucket
    {
        volatile int64 ThreadID;
        T Value;
    };

    Bucket _staticBuckets[MaxThreads];
#if THREAD_LOCAL_USE_DYNAMIC_BUCKETS
    Bucket* _dynamicBuckets = nullptr;
    constexpr static int32 DynamicMaxThreads = 1024;
#endif

public:
    ThreadLocal()
    {
        Platform::MemoryClear(_staticBuckets, sizeof(_staticBuckets));
    }

#if THREAD_LOCAL_USE_DYNAMIC_BUCKETS
    ~ThreadLocal()
    {
        Platform::Free(_dynamicBuckets);
    }
#endif

public:
    FORCE_INLINE T& Get()
    {
        return GetBucket().Value;
    }

    FORCE_INLINE void Set(const T& value)
    {
        GetBucket().Value = value;
    }

    int32 Count() const
    {
        int32 result = 0;
        for (int32 i = 0; i < MaxThreads; i++)
        {
            if (Platform::AtomicRead((int64 volatile*)&_staticBuckets[i].ThreadID) != 0)
                result++;
        }
#if THREAD_LOCAL_USE_DYNAMIC_BUCKETS
        if (auto dynamicBuckets = (Bucket*)Platform::AtomicRead((intptr volatile*)&_dynamicBuckets))
        {
            for (int32 i = 0; i < DynamicMaxThreads; i++)
            {
                if (Platform::AtomicRead((int64 volatile*)&dynamicBuckets[i].ThreadID) != 0)
                    result++;
            }
        }