CacheStorageMmap.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CacheStorage.h"
 
#if !UE_BUILD_SHIPPING
 
#include "Async/MappedFileHandle.h"
 
namespace StorageServer
{
    // Cache storage implemented via mmap-ing a file on platforms that support mmap
    class FCacheStorageMmap : public ICacheStorage
    {
    public:
        FCacheStorageMmap(const TCHAR* FileNamePrefix, const uint64 FileSize);
        virtual ~FCacheStorageMmap() override;
 
        virtual void Flush() override;
 
        virtual uint64 GetSize() const override {return TotalSize;}
 
        virtual void Invalidate(const uint64 Offset, const uint64 Size) override;
 
        virtual FIoBuffer Read(
            const uint64 Offset,
            const uint64 ReadSize,
            TOptional<FIoBuffer> OptDestination
        ) override;
 
        virtual void WriteAsync(
            const uint64 Offset,
            const void* Buffer,
            const uint64 WriteSize
        ) override;
 
    private:
        struct FBackingFile
        {
            TUniquePtr<IMappedFileHandle> FileHandle;
            TUniquePtr<IMappedFileRegion> FileRegion;
            uint8* MapPtr;
            uint64 MapSize;
 
            FBackingFile() = default;
            FBackingFile(FBackingFile&&) = default;
            FBackingFile(const FBackingFile&) = delete;
            FBackingFile& operator=(const FBackingFile&) = delete;
            ~FBackingFile()
            {
                // release region before file handle
                FileRegion.Reset();
                FileHandle.Reset();
                MapPtr = nullptr;
                MapSize = 0;
            }
        };
 
        TArray<FBackingFile> BackingFiles;
        uint64 TotalSize;
 
        bool IsValidRange(const uint64 Offset, const uint64 Size) const
        {
            return Offset + Size <= TotalSize;
        }
    };
}
 
#endif