return 数据作为互操作 C++ 的数组的更快方法

Question

这是从非托管 C++ 代码编组结构数组的一个非常干净和不错的解决方案。就简单性而言，它是最完美的解决方案，我花了一段时间才达到理解这个概念的水平，所以在几行代码中，正如你所看到的 C# Main()，我有一个填充数组结构准备 'harvested'..

typedef struct {
int Id;
BSTR StrVal;
}Package;

extern "C" __declspec(dllexport) void dodata(int requestedLength,int StringSize, Package **Packs){

    int count;
    count=0;
    *Packs = (Package*)LocalAlloc(0, requestedLength * sizeof(Package));
    Package *Cur = *Packs;
    while(count!= requestedLength)
    {
        Cur[count].StrVal = NULL;
        Cur[count].Id = count;
        Cur[count].StrVal=SysAllocString(L"abcdefghij");
        Cur[count].StrVal[StringSize-1]=count+'0';

    ++count;

    }

}

C#

[DllImport(@"ExportStructArr.dll", CallingConvention = CallingConvention.Cdecl), SuppressUnmanagedCodeSecurity]
public static extern void dodata(int requestedLength, int StringSize, out IntPtr csPkPtr);


[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct csPk
{
    public int V;
    [MarshalAsAttribute(UnmanagedType.BStr, SizeConst = 10)]
    public string testStr;
}

static void Main(string[] args){

    int ArrL = 16000;
    csPk[] Cpk = new csPk[ArrL];
    IntPtr CpkPtr = IntPtr.Zero;
    int szPk = Marshal.SizeOf(typeof(csPk));
    dodata(ArrL, 10, out CpkPtr);
}

现在我要做的就是:

        for (int i = 0; i < Cpk.Length; i++)
        {
            Cpk[i] = (csPk)Marshal.PtrToStructure(new IntPtr(CpkPtr.ToInt32() + (szPk * i)), typeof(csPk));
        }

如您所见，解决方案非常简单问题是对数据使用不安全或任何类型的转换，甚至下降到字节...

我如何优化它以更好地返回数据？

编辑：

链接我试图从这里的其他答案中学习：

来自Hans Passant的回答
来自AbdElRaheim的回答
回答来自supercat

也试过 google : wikipedia , a github post by stephentoub

Answer 1

这是一个完整的极速填充对象列表的解决方案，我已尽力而为我很乐意提出意见和建议。

c++

typedef struct _DataPacket
{
    BSTR buffer;
    UINT size;
} DataPacket;

extern "C" __declspec(dllexport)  void GetPacksUnsafe( int size, DataPacket** DpArray )
{
    int szr = size;int count=0;
    *DpArray = (DataPacket*)CoTaskMemAlloc( szr * sizeof( DataPacket ));

    if ( DpArray != NULL )
    {
        DataPacket* CurPack = *DpArray;

        for ( int i = 0; i < szr; i++, CurPack++ )
        {
            CurPack->size = i;
            CurPack->buffer = SysAllocString(L"SomeText00");
            CurPack->buffer[9]=i+'0';   

        }
    }
}

C#

    [DllImport(@"ExportStructArr.dll", CallingConvention = CallingConvention.Cdecl), SuppressUnmanagedCodeSecurity]
    public static extern void GetPacksUnsafe(int size, PackU** outPackUArr);

    [StructLayout(LayoutKind.Sequential)]
    public unsafe struct PackU
    {
        public char* StrVal;
        public int IntVal;
    }


    public static unsafe List<PackU> PopulateLstPackU(int ArrL)
    {
        PackU* PackUArrOut;
        List<PackU> RtLstPackU = new List<PackU>(ArrL);
        GetPacksUnsafe(ArrL, &PackUArrOut);
        PackU* CurrentPack = PackUArrOut;
        for (int i = 0; i < ArrL; i++, CurrentPack++)
        {
            RtLstPackU.Add(new PackU(){ StrVal = CurrentPack->StrVal, IntVal=CurrentPack->IntVal});
        }
        Marshal.FreeCoTaskMem((IntPtr)PackUArrOut);

        for (int i = 0; i < 10; i++)
        {
            Console.WriteLine("{0}", new string(RtLstPackU[i].StrVal));
        }
        return RtLstPackU;
    }

使用代码尽可能简单

    static unsafe void Main(string[] args)
    {
        int ArrL = 100000;
        List<PackU> LstPackU;
        LstPackU = PopulateLstPackU(ArrL);
    }

你有一个像子弹一样快的自定义数据列表..

编辑

使用指针而不是字符串：

typedef struct _DataPackCharPnt
{
    char* buffer;
    UINT IntVal;
} DataPackCharPnt;


extern "C" __declspec(dllexport)  void GetPacksPnt( int size, DataPackCharPnt** DpArrPnt )
{

    int count = 0;
    int TmpStrSize = 10;
    *DpArrPnt = (DataPackCharPnt*)CoTaskMemAlloc( size * sizeof( DataPackCharPnt ));
    DataPackCharPnt* CurPackPnt = *DpArrPnt;
    char dummyStringDataObject[]= "abcdefgHi";
    for ( int i = 0; i < size; i++,CurPackPnt++ )
    {

        dummyStringDataObject[9] = i+'0';
        CurPackPnt->IntVal=i;
        CurPackPnt->buffer = (char*)malloc(sizeof(char)*TmpStrSize);
        strcpy(CurPackPnt->buffer, dummyStringDataObject);

    }
}

将填充 100k 元素所需的时间从 11 毫秒减少到 7 毫秒

我可以省略创建 buffer 的任何部分吗？

dummyStringDataObject的职责是模拟工作，比如说获取文件名然后用它的值设置缓冲区，所以除了这个额外的时间，这是这个函数的全部目的，return 一些未知的字符串值和长度...

能再优化一下吗？

return 数据作为互操作 C++ 的数组的更快方法

faster way to return data as an array interoping c++

c#

c++

arrays

performance

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