feat: works

__concurrent/async_study/Cargo.lock

@@ -6,6 +6,7 @@ version = 3
 name = "async_study"
 version = "0.1.0"
 dependencies = [
+ "futures-util",
  "tokio",
 ]
 
@@ -27,6 +28,30 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "futures-core"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c09fd04b7e4073ac7156a9539b57a484a8ea920f79c7c675d05d289ab6110d3"
+
+[[package]]
+name = "futures-task"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57c66a976bf5909d801bbef33416c41372779507e7a6b3a5e25e4749c58f776a"
+
+[[package]]
+name = "futures-util"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8b7abd5d659d9b90c8cba917f6ec750a74e2dc23902ef9cd4cc8c8b22e6036a"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "pin-project-lite",
+ "pin-utils",
+]
+
 [[package]]
 name = "hermit-abi"
 version = "0.1.19"
@@ -143,6 +168,12 @@ version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e280fbe77cc62c91527259e9442153f4688736748d24660126286329742b4c6c"
 
+[[package]]
+name = "pin-utils"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.36"

__concurrent/async_study/Cargo.toml

@@ -7,3 +7,4 @@ edition = "2021"
 
 [dependencies]
 tokio = { version = "1.0", features = ["full"] }
+futures-util = { version = "0.3", default-features = false }

__concurrent/async_study/src/main.rs

@@ -1,3 +1,102 @@
-fn main() {
-    println!("Hello, world!");
+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::<Vec<u8>>(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)
 }
+
+struct Stream {
+    sender: Sender<Vec<u8>>,
+    receiver: Receiver<Vec<u8>>,
+}
+
+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(mm) => {
+                    if "close".as_bytes().to_vec() == mm {
+                        self.receiver.close();
+                    }
+                    Poll::Ready(Ok(buf.put_slice(mm.as_slice())))
+                }
+            }
+        }
+    }
+}
+
+impl AsyncWrite for Stream {
+    fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<io::Result<usize>> {
+        let mut fut = self.sender.send(Vec::from(buf));
+        let fut = unsafe { Pin::new_unchecked(&mut fut) }; // SAFE??
+        match fut.poll(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(Ok(_)) => Poll::Ready(Ok(buf.len())),
+            Poll::Ready(Err(e)) => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, e.to_string()))),
+        }
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        // NEED FLUSH?
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        // let mut fut = self.sender.send("close".as_bytes().to_vec());
+        // let fut = unsafe { Pin::new_unchecked(&mut fut) }; // SAFE??
+        // match fut.poll(cx) {
+        //     Poll::Pending => Poll::Pending,
+        //     Poll::Ready(Ok(_)) => Poll::Ready(Ok(())),
+        //     Poll::Ready(Err(e)) => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, e.to_string()))),
+        // }
+        let mut fut = self.sender.send("close".as_bytes().to_vec());
+        tokio::pin!( fut);
+        match fut.poll(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(Ok(_)) => Poll::Ready(Ok(())),
+            Poll::Ready(Err(e)) => Poll::Ready(Err(io::Error::new(ErrorKind::BrokenPipe, e.to_string()))),
+        }
+        // Poll::Ready(Ok(()))
+    }
+}