Merge pull request #234 from nrc/guide-async

async/await chapter

Author: nrc

examples/Cargo.toml

@@ -1,6 +1,9 @@
 [workspace]
 members = [
   "hello-world",
+  "hello-world-sleep",
+  "hello-world-spawn",
+  "hello-world-join",
   "01_02_why_async",
   "01_04_async_await_primer",
   "02_02_future_trait",

examples/hello-world-join/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "hello-world-join"
+version = "0.1.0"
+authors = ["Nicholas Cameron <nrc@ncameron.org>"]
+edition = "2021"
+
+[dependencies]
+tokio = { version = "1.40.0", features = ["full"] }

examples/hello-world-join/src/main.rs

@@ -0,0 +1,23 @@
+use tokio::{spawn, time::{sleep, Duration}};
+
+async fn say_hello() {
+    // Wait for a while before printing to make it a more interesting race.
+    sleep(Duration::from_millis(100)).await;
+    println!("hello");
+}
+
+async fn say_world() {
+    sleep(Duration::from_millis(100)).await;
+    println!("world");
+}
+
+#[tokio::main]
+async fn main() {
+    let handle1 = spawn(say_hello());
+    let handle2 = spawn(say_world());
+    
+    let _ = handle1.await;
+    let _ = handle2.await;
+
+    println!("!");
+}

examples/hello-world-sleep/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "hello-world-sleep"
+version = "0.1.0"
+authors = ["Nicholas Cameron <nrc@ncameron.org>"]
+edition = "2021"
+
+[dependencies]
+tokio = { version = "1.40.0", features = ["full"] }

examples/hello-world-sleep/src/main.rs

@@ -0,0 +1,20 @@
+use std::io::{stdout, Write};
+use tokio::time::{sleep, Duration};
+
+async fn say_hello() {
+    print!("hello, ");
+    // Flush stdout so we see the effect of the above `print` immediately.
+    stdout().flush().unwrap();
+}
+
+async fn say_world() {
+    println!("world!");
+}
+
+#[tokio::main]
+async fn main() {
+    say_hello().await;
+    // An async sleep function, puts the current task to sleep for 1s.
+    sleep(Duration::from_millis(1000)).await;
+    say_world().await;
+}

examples/hello-world-spawn/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "hello-world-spawn"
+version = "0.1.0"
+authors = ["Nicholas Cameron <nrc@ncameron.org>"]
+edition = "2021"
+
+[dependencies]
+tokio = { version = "1.40.0", features = ["full"] }

examples/hello-world-spawn/src/main.rs

@@ -0,0 +1,20 @@
+use tokio::{spawn, time::{sleep, Duration}};
+
+async fn say_hello() {
+    // Wait for a while before printing to make it a more interesting race.
+    sleep(Duration::from_millis(100)).await;
+    println!("hello");
+}
+
+async fn say_world() {
+    sleep(Duration::from_millis(100)).await;
+    println!("world!");
+}
+
+#[tokio::main]
+async fn main() {
+    spawn(say_hello());
+    spawn(say_world());
+    // Wait for a while to give the tasks time to run.
+    sleep(Duration::from_millis(1000)).await;
+}

src/SUMMARY.md

@@ -11,6 +11,7 @@
 
 - [Introduction](part-guide/intro.md)
 - [Concurrent programming](part-guide/concurrency.md)
+- [Async and Await](part-guide/async-await.md)
 
 # Part 2: reference