MetalRHIRenderQuery.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    MetalRHIRenderQuery.h: Metal RHI Render Query Definitions.
=============================================================================*/
 
#pragma once
 
#include "MetalRHIPrivate.h"
#include "RHIResources.h"
#include "MetalSubmission.h"
 
//------------------------------------------------------------------------------
 
#pragma mark - Metal RHI Private Query Buffer Forward Declarations
 
 
class FMetalRHICommandContext;
class FMetalQueryBufferPool;
class FMetalQueryResult;
class FMetalDevice;
class FMetalBuffer;
typedef TSharedPtr<FMetalBuffer, ESPMode::ThreadSafe> FMetalBufferPtr;
 
//------------------------------------------------------------------------------
 
#pragma mark - Metal RHI Private Query Buffer Resource Class -
 
 
class FMetalQueryBuffer : public FRHIResource
{
public:
    FMetalQueryBuffer(FMetalQueryBufferPool* Pool, FMetalBufferPtr InBuffer);
    virtual ~FMetalQueryBuffer();
 
    uint64 GetResult(uint32 Offset);
 
    FMetalQueryBufferPool* Pool;
    FMetalBufferPtr Buffer;
    uint32 WriteOffset;
};
 
typedef TRefCountPtr<FMetalQueryBuffer> FMetalQueryBufferRef;
 
//------------------------------------------------------------------------------
 
#pragma mark - Metal RHI Private Query Buffer Pool Class -
 
 
class FMetalQueryBufferPool
{
public:
    enum
    {
        EQueryBufferAlignment = 8,
        EQueryResultMaxSize   = 8
    };
 
    // Disallow a default constructor
    FMetalQueryBufferPool() = delete;
 
    FMetalQueryBufferPool(FMetalDevice& InDevice);
    ~FMetalQueryBufferPool();
 
    void Allocate(FMetalQueryResult& NewQuery);
    
    FMetalQueryBufferRef AcquireQueryBuffer(uint32_t NumOcclusionQueries);
    FMetalQueryBufferRef GetCurrentQueryBuffer();
    void ReleaseCurrentQueryBuffer();
    void ReleaseQueryBuffer(FMetalBufferPtr Buffer);
 
    uint32_t BufferSize = 0;
    
    FMetalQueryBufferRef CurrentBuffer;
    TArray<FMetalBufferPtr> Buffers;
    FMetalDevice& Device;
};
 
 
//------------------------------------------------------------------------------
 
#pragma mark - Metal RHI Private Query Result Class -
 
 
class FMetalQueryResult
{
public:
    FMetalQueryResult() = default;
    ~FMetalQueryResult() = default;
 
    void Reset();
    uint64 GetResult();
 
    FMetalQueryBufferRef SourceBuffer = nullptr;
    uint32 Offset = 0;
    bool bCompleted = false;
    bool bBatchFence = false;
};
 
 
//------------------------------------------------------------------------------
 
#pragma mark - Metal RHI Render Query Class -
 
class FMetalRHIRenderQuery : public FRHIRenderQuery
{
    friend class FMetalDynamicRHI;
public:
    FMetalRHIRenderQuery(FMetalDevice& MetalDevice, ERenderQueryType InQueryType);
    virtual ~FMetalRHIRenderQuery();
 
    void Begin_TopOfPipe();
    void End_TopOfPipe();
    
    void Begin(FMetalRHICommandContext* Context);
 
    void End(FMetalRHICommandContext* Context);
 
    void SampleOcclusionResult();
    
    bool GetResult(uint64& OutNumPixels, bool bWait, uint32 GPUIndex);
 
private:
    FMetalDevice& Device;
    
    // The type of query
    ERenderQueryType Type;
 
    // Query buffer allocation details as the buffer is already set on the command-encoder
    FMetalQueryResult Buffer;
 
    // Query result.
    volatile uint64 Result;
 
    // Result availability - if not set the first call to acquire it will read the buffer & cache
    std::atomic<bool> bAvailable;
 
    // Signaled when the result is available. Nullptr if the query has never been used.
    FMetalSyncPointRef SyncPoint;
    
    // Temporary
    FMetalCommandBuffer* CommandBuffer = nullptr;
};