feat(net): allow peek TcpStream (#974)

* feat: allow peek from TcpStream

* test: updated unit test for TcpStream peek.

* test: updated unit test for TcpStream peek

* docs: make method description succint

* fix: make implementation simplier

* docs: fix platform specific info

Co-authored-by: Yuyi Wang <Strawberry_Str@hotmail.com>

---------

Co-authored-by: Yuyi Wang <Strawberry_Str@hotmail.com>

Author: ararog

compio-net/src/tcp.rs

@@ -447,6 +447,14 @@ impl TcpStream {
             )
             .await
     }
+
+    /// Peeks at data from this socket without consuming it
+    ///
+    /// ## Platform-specific
+    /// * Windows: this method may work, but is not ensured by Microsoft.
+    pub async fn peek<T: IoBufMut>(&self, buffer: T) -> BufResult<usize, T> {
+        self.inner.recv(buffer, RecvFlags::PEEK).await
+    }
 }
 
 impl AsyncRead for TcpStream {

compio-net/tests/incoming.rs

@@ -27,6 +27,8 @@ async fn incoming_tcp() {
 
     for i in 0..2 {
         let mut client = TcpStream::connect(&addr).await.unwrap();
+        let (_, text) = client.peek([0u8; 8]).await.unwrap();
+        assert_eq!(text, format!("Hello, {}", i).as_bytes());
         let (_, text) = client.read_exact([0u8; 8]).await.unwrap();
         assert_eq!(text, format!("Hello, {}", i).as_bytes());
         client.write_all(text).await.unwrap();