Add second subsystem to basic usage example, as it was unclear in the…

… example that the start function could be called multiple times

examples/01_normal_shutdown.rs

@@ -1,13 +1,10 @@
 //! This example demonstrates the basic usage pattern of this crate.
 //!
-//! It shows that a subsystem gets started, and when the program
-//! gets shut down (by pressing Ctrl-C), the subsystem gets shut down
+//! It shows that subsystems get started, and when the program
+//! gets shut down (by pressing Ctrl-C), the subsystems get shut down
 //! gracefully.
 //!
-//! In this case, the subsystem is an async function.
-//! This crate supports async functions and async coroutines.
-//!
-//! If custom arguments for the subsystem coroutine are required,
+//! If custom arguments for the subsystem coroutines are required,
 //! a struct has to be used instead, as seen in other examples.
 
 use anyhow::Result;
@@ -19,11 +16,20 @@ async fn subsys1(subsys: SubsystemHandle) -> Result<()> {
     log::info!("Subsystem1 started.");
     subsys.on_shutdown_requested().await;
     log::info!("Shutting down Subsystem1 ...");
-    sleep(Duration::from_millis(500)).await;
+    sleep(Duration::from_millis(400)).await;
     log::info!("Subsystem1 stopped.");
     Ok(())
 }
 
+async fn subsys2(subsys: SubsystemHandle) -> Result<()> {
+    log::info!("Subsystem2 started.");
+    subsys.on_shutdown_requested().await;
+    log::info!("Shutting down Subsystem2 ...");
+    sleep(Duration::from_millis(500)).await;
+    log::info!("Subsystem2 stopped.");
+    Ok(())
+}
+
 #[tokio::main]
 async fn main() -> Result<()> {
     // Init logging
@@ -32,6 +38,7 @@ async fn main() -> Result<()> {
     // Create toplevel
     Toplevel::new()
         .start("Subsys1", subsys1)
+        .start("Subsys2", subsys2)
         .catch_signals()
         .handle_shutdown_requests(Duration::from_millis(1000))
         .await