RHIDescriptorAllocator.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Containers/Array.h"
#include "HAL/CriticalSection.h"
#include "RHIDefinitions.h"
#include "Stats/Stats.h"
 
struct FRHIDescriptorAllocatorRange
{
    FRHIDescriptorAllocatorRange(uint32 InFirst, uint32 InLast) : First(InFirst), Last(InLast) {}
    uint32 First;
    uint32 Last;
};
 
struct FRHIDescriptorAllocation
{
    FRHIDescriptorAllocation(uint32 InStartIndex, uint32 InCount)
        : StartIndex(InStartIndex)
        , Count(InCount)
    {
    }
 
    uint32 StartIndex = 0;
    uint32 Count = 0;
};
 
class FRHIDescriptorAllocator
{
public:
    RHICORE_API FRHIDescriptorAllocator();
    RHICORE_API FRHIDescriptorAllocator(uint32 InNumDescriptors, TConstArrayView<TStatId> InStats);
    RHICORE_API ~FRHIDescriptorAllocator();
 
    RHICORE_API void Init(uint32 InNumDescriptors, TConstArrayView<TStatId> InStats);
    RHICORE_API void Shutdown();
 
    RHICORE_API TOptional<FRHIDescriptorAllocation> ResizeGrowAndAllocate(uint32 NewCapacity, uint32 NumAllocations);
 
    RHICORE_API TOptional<FRHIDescriptorAllocation> Allocate(uint32 NumDescriptors);
    RHICORE_API void Free(FRHIDescriptorAllocation Allocation);
 
    RHICORE_API FRHIDescriptorHandle Allocate(ERHIDescriptorType InType);
    RHICORE_API void Free(FRHIDescriptorHandle InHandle);
 
    // Get the range of allocated descriptors. Useful for determining the smallest range to copy between heaps.
    RHICORE_API bool GetAllocatedRange(FRHIDescriptorAllocatorRange& OutRange);
 
    uint32 GetCapacity() const { return Capacity; }
 
private:
 
    RHICORE_API TOptional<FRHIDescriptorAllocation> AllocateInternal(uint32 NumDescriptors);
 
    void RecordAlloc(uint32 Count)
    {
#if STATS
        for (TStatId Stat : Stats)
        {
            INC_DWORD_STAT_BY_FName(Stat.GetName(), Count);
        }
#endif
    }
 
    void RecordFree(uint32 Count)
    {
#if STATS
        for (TStatId Stat : Stats)
        {
            DEC_DWORD_STAT_BY_FName(Stat.GetName(), Count);
        }
#endif
    }
 
    TArray<FRHIDescriptorAllocatorRange> Ranges;
    uint32 Capacity = 0;
 
    FCriticalSection CriticalSection;
 
#if STATS
    TArray<TStatId> Stats;
#endif
};
 
 
class FRHIHeapDescriptorAllocator : protected FRHIDescriptorAllocator
{
public:
    FRHIHeapDescriptorAllocator() = delete;
    RHICORE_API FRHIHeapDescriptorAllocator(ERHIDescriptorTypeMask InTypeMask, uint32 InDescriptorCount, TConstArrayView<TStatId> InStats);
 
    RHICORE_API FRHIDescriptorHandle Allocate(ERHIDescriptorType InType);
    RHICORE_API void Free(FRHIDescriptorHandle InHandle);
 
    RHICORE_API TOptional<FRHIDescriptorAllocation> Allocate(uint32 NumDescriptors);
    RHICORE_API void Free(FRHIDescriptorAllocation Allocation);
 
    using FRHIDescriptorAllocator::GetAllocatedRange;
    using FRHIDescriptorAllocator::GetCapacity;
    using FRHIDescriptorAllocator::ResizeGrowAndAllocate;
 
    ERHIDescriptorTypeMask GetTypeMask() const
    {
        return TypeMask;
    }
 
    bool HandlesAllocation(ERHIDescriptorType InType) const
    {
        return EnumHasAnyFlags(GetTypeMask(), RHIDescriptorTypeMaskFromType(InType));
    }
 
    bool HandlesAllocations(ERHIDescriptorTypeMask InTypeMask) const
    {
        return EnumHasAllFlags(GetTypeMask(), InTypeMask);
    }
 
private:
    const ERHIDescriptorTypeMask TypeMask;
};
 
class FRHIOffsetHeapDescriptorAllocator : protected FRHIHeapDescriptorAllocator
{
public:
    FRHIOffsetHeapDescriptorAllocator() = delete;
    RHICORE_API FRHIOffsetHeapDescriptorAllocator(ERHIDescriptorTypeMask InTypeMask, uint32 InDescriptorCount, uint32 InHeapOffset, TConstArrayView<TStatId> InStats);
 
    RHICORE_API FRHIDescriptorHandle Allocate(ERHIDescriptorType InType);
    RHICORE_API void Free(FRHIDescriptorHandle InHandle);
 
    using FRHIHeapDescriptorAllocator::GetCapacity;
    using FRHIHeapDescriptorAllocator::GetTypeMask;
    using FRHIHeapDescriptorAllocator::HandlesAllocation;
 
private:
    // Offset from start of heap we belong to
    const uint32 HeapOffset;
};
 
#if UE_ENABLE_INCLUDE_ORDER_DEPRECATED_IN_5_4
#include "RHIDefinitions.h"
#endif