diff --git a/__concurrent/async_study/examples/stream.rs b/__concurrent/async_study/examples/stream.rs
new file mode 100644
index 0000000..2becc30
--- /dev/null
+++ b/__concurrent/async_study/examples/stream.rs
@@ -0,0 +1,98 @@
+use std::future::Future;
+use std::io::{self, ErrorKind};
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use std::time::Duration;
+
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt, ReadBuf};
+use tokio::sync::mpsc::{channel, Receiver, Sender};
+use tokio::time::sleep;
+
+#[tokio::main]
+async fn main() {
+    let (sender, receiver) = channel::<StreamMessage>(512);
+    let stream = Stream { sender, receiver };
+    let (mut s, mut w) = tokio::io::split(stream);
+
+    let t = tokio::spawn(async move {
+        let mut buf = Vec::<u8>::with_capacity(1024);
+        loop {
+            match s.read_buf(&mut buf).await {
+                Ok(len) => println!("Len: {}, Buf: {:?}", len, &buf[..len]),
+                Err(e) => {
+                    println!("Err: {:?}", e);
+                    if e.to_string().contains("broken pipe") {
+                        break;
+                    }
+                }
+            }
+        }
+    });
+
+    sleep(Duration::from_secs(1)).await;
+    let _ = w.write_all(b"hello world").await;
+    sleep(Duration::from_secs(1)).await;
+    let _ = w.write_all(b"hello world").await;
+    sleep(Duration::from_secs(1)).await;
+    let _ = w.write_all(b"hello world").await;
+    let a = tokio::join!(w.shutdown());
+    let b = tokio::join!(t);
+    println!("{:?}, {:?}", a, b)
+}
+
+#[derive(Debug)]
+enum StreamMessage {
+    Data(Vec<u8>),
+    Flush,
+    Close,
+}
+
+struct Stream {
+    sender: Sender<StreamMessage>,
+    receiver: Receiver<StreamMessage>,
+}
+
+impl AsyncRead for Stream {
+    fn poll_read(mut self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
+        let m = self.receiver.poll_recv(cx);
+        match m {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(m_opt) => match m_opt {
+                None => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, "broken pipe"))),
+                Some(StreamMessage::Close) => {
+                    self.receiver.close();
+                    Poll::Ready(Ok(()))
+                }
+                Some(StreamMessage::Flush) => Poll::Ready(Ok(())),
+                Some(StreamMessage::Data(mm)) => {
+                    buf.put_slice(mm.as_slice());
+                    Poll::Ready(Ok(()))
+                }
+            }
+        }
+    }
+}
+
+impl AsyncWrite for Stream {
+    fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<io::Result<usize>> {
+        pool_send(self, cx, StreamMessage::Data(Vec::from(buf)), buf.len())
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        pool_send(self, cx, StreamMessage::Flush, ())
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        pool_send(self, cx, StreamMessage::Close, ())
+    }
+}
+
+fn pool_send<R>(s: Pin<&mut Stream>, cx: &mut Context<'_>, stream_message: StreamMessage, r: R) -> Poll<io::Result<R>> {
+    let fut = s.sender.send(stream_message);
+    tokio::pin!( fut);
+    match fut.poll(cx) {
+        Poll::Pending => Poll::Pending,
+        Poll::Ready(Ok(_)) => Poll::Ready(Ok(r)),
+        Poll::Ready(Err(e)) => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, e.to_string()))),
+    }
+}
\ No newline at end of file
diff --git a/__concurrent/async_study/src/main.rs b/__concurrent/async_study/src/main.rs
index 2becc30..e68090e 100644
--- a/__concurrent/async_study/src/main.rs
+++ b/__concurrent/async_study/src/main.rs
@@ -9,90 +9,11 @@ use tokio::sync::mpsc::{channel, Receiver, Sender};
 use tokio::time::sleep;
 
 #[tokio::main]
-async fn main() {
-    let (sender, receiver) = channel::<StreamMessage>(512);
-    let stream = Stream { sender, receiver };
-    let (mut s, mut w) = tokio::io::split(stream);
-
-    let t = tokio::spawn(async move {
-        let mut buf = Vec::<u8>::with_capacity(1024);
-        loop {
-            match s.read_buf(&mut buf).await {
-                Ok(len) => println!("Len: {}, Buf: {:?}", len, &buf[..len]),
-                Err(e) => {
-                    println!("Err: {:?}", e);
-                    if e.to_string().contains("broken pipe") {
-                        break;
-                    }
-                }
-            }
-        }
-    });
-
-    sleep(Duration::from_secs(1)).await;
-    let _ = w.write_all(b"hello world").await;
-    sleep(Duration::from_secs(1)).await;
-    let _ = w.write_all(b"hello world").await;
-    sleep(Duration::from_secs(1)).await;
-    let _ = w.write_all(b"hello world").await;
-    let a = tokio::join!(w.shutdown());
-    let b = tokio::join!(t);
-    println!("{:?}, {:?}", a, b)
-}
+async fn main() {}
 
 #[derive(Debug)]
-enum StreamMessage {
-    Data(Vec<u8>),
-    Flush,
-    Close,
+enum StreamPackage {
+    Data(u64, Vec<u8>),
+    Flush(u64),
+    Close(u64),
 }
-
-struct Stream {
-    sender: Sender<StreamMessage>,
-    receiver: Receiver<StreamMessage>,
-}
-
-impl AsyncRead for Stream {
-    fn poll_read(mut self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
-        let m = self.receiver.poll_recv(cx);
-        match m {
-            Poll::Pending => Poll::Pending,
-            Poll::Ready(m_opt) => match m_opt {
-                None => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, "broken pipe"))),
-                Some(StreamMessage::Close) => {
-                    self.receiver.close();
-                    Poll::Ready(Ok(()))
-                }
-                Some(StreamMessage::Flush) => Poll::Ready(Ok(())),
-                Some(StreamMessage::Data(mm)) => {
-                    buf.put_slice(mm.as_slice());
-                    Poll::Ready(Ok(()))
-                }
-            }
-        }
-    }
-}
-
-impl AsyncWrite for Stream {
-    fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<io::Result<usize>> {
-        pool_send(self, cx, StreamMessage::Data(Vec::from(buf)), buf.len())
-    }
-
-    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
-        pool_send(self, cx, StreamMessage::Flush, ())
-    }
-
-    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
-        pool_send(self, cx, StreamMessage::Close, ())
-    }
-}
-
-fn pool_send<R>(s: Pin<&mut Stream>, cx: &mut Context<'_>, stream_message: StreamMessage, r: R) -> Poll<io::Result<R>> {
-    let fut = s.sender.send(stream_message);
-    tokio::pin!( fut);
-    match fut.poll(cx) {
-        Poll::Pending => Poll::Pending,
-        Poll::Ready(Ok(_)) => Poll::Ready(Ok(r)),
-        Poll::Ready(Err(e)) => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, e.to_string()))),
-    }
-}
\ No newline at end of file