Fix vectored IO for TcpStream

Implements `Write::poll_write_vectored` and `Read::poll_read_vectored` on `TcpStream` using the vectored IO methods on the underlying stream. Previously, the trait's default implementation was used, which just called `poll_write` and `poll_read` once for each `IoSlice`.

src/net/tcp/stream.rs

@@ -307,6 +307,14 @@ impl Read for &TcpStream {
  ) -> Poll<io::Result<usize>> {
  Pin::new(&mut &*self.watcher).poll_read(cx, buf)
  }
+
+ fn poll_read_vectored(
+ self: Pin<&mut Self>,
+ cx: &mut Context<'_>,
+ bufs: &mut [IoSliceMut<'_>],
+ ) -> Poll<io::Result<usize>> {
+ Pin::new(&mut &*self.watcher).poll_read_vectored(cx, bufs)
+ }
 }
 
 impl Write for TcpStream {
@@ -344,6 +352,14 @@ impl Write for &TcpStream {
  Pin::new(&mut &*self.watcher).poll_write(cx, buf)
  }
 
+ fn poll_write_vectored(
+ self: Pin<&mut Self>,
+ cx: &mut Context<'_>,
+ bufs: &[IoSlice<'_>],
+ ) -> Poll<io::Result<usize>> {
+ Pin::new(&mut &*self.watcher).poll_write_vectored(cx, bufs)
+ }
+
  fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
  Pin::new(&mut &*self.watcher).poll_flush(cx)
  }