initial commit

exercises/08_futures/02_spawn/Cargo.toml

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+[package]
+name = "spawn"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.83"
+tokio = { version = "1", features = ["full"] }

exercises/08_futures/02_spawn/src/lib.rs

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+use tokio::net::TcpListener;
+
+// TODO: write an echo server that accepts TCP connections on two listeners, concurrently.
+//  Multiple connections (on the same listeners) should be processed concurrently.
+//  The received data should be echoed back to the client.
+pub async fn echoes(first: TcpListener, second: TcpListener) -> Result<(), anyhow::Error> {
+    todo!()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::net::SocketAddr;
+    use std::panic;
+    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    use tokio::task::JoinSet;
+
+    async fn bind_random() -> (TcpListener, SocketAddr) {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let addr = listener.local_addr().unwrap();
+        (listener, addr)
+    }
+
+    #[tokio::test]
+    async fn test_echo() {
+        let (first_listener, first_addr) = bind_random().await;
+        let (second_listener, second_addr) = bind_random().await;
+        tokio::spawn(echoes(first_listener, second_listener));
+
+        let requests = vec!["hello", "world", "foo", "bar"];
+        let mut join_set = JoinSet::new();
+
+        for request in requests.clone() {
+            for addr in [first_addr, second_addr] {
+                join_set.spawn(async move {
+                    let mut socket = tokio::net::TcpStream::connect(addr).await.unwrap();
+                    let (mut reader, mut writer) = socket.split();
+
+                    // Send the request
+                    writer.write_all(request.as_bytes()).await.unwrap();
+                    // Close the write side of the socket
+                    writer.shutdown().await.unwrap();
+
+                    // Read the response
+                    let mut buf = Vec::with_capacity(request.len());
+                    reader.read_to_end(&mut buf).await.unwrap();
+                    assert_eq!(&buf, request.as_bytes());
+                });
+            }
+        }
+
+        while let Some(outcome) = join_set.join_next().await {
+            if let Err(e) = outcome {
+                if let Ok(reason) = e.try_into_panic() {
+                    panic::resume_unwind(reason);
+                }
+            }
+        }
+    }
+}