c# - static extern void Buffer.InternalBlockCopy 是 .NET Framework 的一部分吗？

Question

我研究如何FileStream is implemented in C#在 Read(..) 方法中我可以看到:

n = ReadCore(_buffer, 0, _bufferSize);
...
Buffer.InternalBlockCopy(_buffer, _readPos, array, offset, n);
...

其中 Buffer.InternalBlockCopy 指向 buffer.cs 中的定义(如下) . BlockCopy 方法被定义为静态外部。这个方法在哪里定义的？它是.NET 的一部分？它是托管的还是 native 的？

[System.Runtime.InteropServices.ComVisible(true)]
public static class Buffer
{
    // Copies from one primitive array to another primitive array without
    // respecting types.  This calls memmove internally.  The count and 
    // offset parameters here are in bytes.  If you want to use traditional
    // array element indices and counts, use Array.Copy.
    [System.Security.SecuritySafeCritical]  // auto-generated
    [ResourceExposure(ResourceScope.None)]
    [MethodImplAttribute(MethodImplOptions.InternalCall)]
    public static extern void BlockCopy(Array src, int srcOffset,
        Array dst, int dstOffset, int count);
..
}

Answer 1

嗯，extern keyword意味着该方法是在 C# 代码之外定义的，而

[MethodImplAttribute(MethodImplOptions.InternalCall)]

表示它调用公共(public)语言运行时中定义的方法。

在 MethodImplOptions docs 之后:

The call is internal, that is, it calls a method that is implemented within the common language runtime.