initial commit

+ some reasearch on returning error when using async task

src/main.rs

@@ -0,0 +1,46 @@
+use std::fmt;
+use std::error::Error;
+use tokio::signal::unix::{signal, SignalKind};
+use tokio::select;
+use tokio::task::{self, JoinHandle};
+
+#[derive(Debug,Clone)]
+struct InvalidState;
+
+impl fmt::Display for InvalidState {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "cannot recover the state")
+    }
+}
+
+impl Error for InvalidState {}
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn Error>> {
+
+    let sighandler: JoinHandle<Result<(), Box<dyn Error + Send + Sync>>> = task::spawn(async {
+        let mut sigint = signal(SignalKind::interrupt())?; 
+        let mut sigterm = signal(SignalKind::terminate())?;
+        let mut sigchld = signal(SignalKind::child())?;
+        select! {
+            _ = sigint.recv() => {
+                println!("got SIGINT");
+            },
+            _ = sigterm.recv() => {
+                println!("got SIGTERM");
+                return Err(InvalidState.into());
+            },
+            _ = sigchld.recv() => {
+                // return Err(())
+            },
+        }
+
+        Ok(())
+    });
+
+    if let Err(v) = sighandler.await? {
+        return Err(v as Box<dyn Error>)
+    }
+
+    Ok(())
+}