可以将2D字节数组制成一个巨大的连续字节数组吗？

Question

我在内存中有一个非常大的2D字节数组,

byte MyBA = new byte[int.MaxValue][10];

有什么方法(可能是不安全的)我可以欺骗C#认为这是一个巨大的连续字节数组？我想这样做,以便我可以将它传递给a MemoryStream然后a BinaryReader.

MyReader = new BinaryReader(MemoryStream(*MyBA)) //Syntax obviously made-up here

Answer 1

我不相信.NET提供了这个,但实现自己的实现System.IO.Stream,无缝切换后备阵列应该相当容易.以下是(未经测试的)基础知识:

public class MultiArrayMemoryStream: System.IO.Stream
{
    byte[][] _arrays;
    long _position;
    int _arrayNumber;
    int _posInArray;

    public MultiArrayMemoryStream(byte[][] arrays){
        _arrays = arrays;
        _position = 0;
        _arrayNumber = 0;
        _posInArray = 0;
    }

    public override int Read(byte[] buffer, int offset, int count){
        int read = 0;
        while(read<count){
            if(_arrayNumber>=_arrays.Length){
                return read;
            }
            if(count-read <= _arrays[_arrayNumber].Length - _posInArray){
                Buffer.BlockCopy(_arrays[_arrayNumber], _posInArray, buffer, offset+read, count-read);
                _posInArray+=count-read;
                            _position+=count-read;
                read=count;
            }else{
                Buffer.BlockCopy(_arrays[_arrayNumber], _posInArray, buffer, offset+read, _arrays[_arrayNumber].Length - _posInArray);
                read+=_arrays[_arrayNumber].Length - _posInArray;
                            _position+=_arrays[_arrayNumber].Length - _posInArray;
                _arrayNumber++;
                _posInArray=0;
            }
        }
        return count;
    }

    public override long Length{
        get {
            long res = 0;
            for(int i=0;i<_arrays.Length;i++){
                res+=_arrays[i].Length;
            }
            return res;
        }
    }

    public override long Position{
        get { return _position; }
        set { throw new NotSupportedException(); }
    }

    public override bool CanRead{
        get { return true; }
    }

    public override bool CanSeek{
        get { return false; }
    }

    public override bool CanWrite{
        get { return false; }
    }

    public override void Flush(){
    }

    public override void Seek(long offset, SeekOrigin origin){
        throw new NotSupportedException();
    }

    public override void SetLength(long value){
        throw new NotSupportedException();
    }

    public override void Write(byte[] buffer, int offset, int count){
        throw new NotSupportedException();
    }       
}

要解决的2 ^ 31字节的大小,限制的另一种方式是UnmanagedMemoryStream,它实现System.IO.Stream对非托管内存缓冲器(这可能是一样大的操作系统支持)的顶部.像这样的东西可能有效(未经测试):

var fileStream = new FileStream("data", 
  FileMode.Open, 
  FileAccess.Read, 
  FileShare.Read, 
  16 * 1024, 
  FileOptions.SequentialScan);
long length = fileStream.Length;
IntPtr buffer = Marshal.AllocHGlobal(new IntPtr(length));
var memoryStream = new UnmanagedMemoryStream((byte*) buffer.ToPointer(), length, length, FileAccess.ReadWrite);
fileStream.CopyTo(memoryStream);
memoryStream.Seek(0, SeekOrigin.Begin);
// work with the UnmanagedMemoryStream
Marshal.FreeHGlobal(buffer);