Implement Some Tokio Tutorials

Tutorial/Delay.rs

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+#![allow(non_snake_case)]
+
+use std::sync::Arc;
+use std::thread;
+use std::time::{Duration, Instant};
+use tokio::sync::Notify;
+
+async fn delay(dur: Duration) {
+    let when = Instant::now() + dur;
+    let notify = Arc::new(Notify::new());
+    let notify2 = notify.clone();
+
+    thread::spawn(move || {
+        let now = Instant::now();
+
+        if now < when {
+            thread::sleep(when - now);
+        }
+
+        notify2.notify_one();
+    });
+
+    notify.notified().await;
+}