Update the guide for async-related API changes.

site/guide/10-pastebin.md

@@ -216,10 +216,11 @@ For the `upload` route, we'll need to `use` a few items:
 
 ```rust
 use std::io;
-use std::path::Path;
+use std::path::PathBuf;
 
 use rocket::Data;
 use rocket::http::RawStr;
+use rocket::response::Debug;
 ```
 
 The [Data](@api/rocket/data/struct.Data.html) structure is key
@@ -279,7 +280,7 @@ fn upload(paste: Data) -> Result<String, Debug<std::io::Error>> {
     let url = format!("{host}/{id}\n", host = "http://localhost:8000", id = id);
 
     // Write the paste out to the file and return the URL.
-    paste.stream_to_file(Path::new(&filename))?;
+    paste.stream_to_file(PathBuf::from(filename)).await?;
     Ok(url)
 }
 ```

site/guide/4-requests.md

@@ -412,7 +412,7 @@ imply, a request guard protects a handler from being called erroneously based on
 information contained in an incoming request. More specifically, a request guard
 is a type that represents an arbitrary validation policy. The validation policy
 is implemented through the [`FromRequest`] trait. Every type that implements
-`FromRequest` is a request guard.
+`FromRequest` (or the related [`FromRequestAsync`]) is a request guard.
 
 Request guards appear as inputs to handlers. An arbitrary number of request
 guards can appear as arguments in a route handler. Rocket will automatically
@@ -444,6 +444,7 @@ more about request guards and implementing them, see the [`FromRequest`]
 documentation.
 
 [`FromRequest`]: @api/rocket/request/trait.FromRequest.html
+[`FromRequestAsync`]: @api/rocket/request/trait.FromRequestAsync.html
 [`Cookies`]: @api/rocket/http/enum.Cookies.html
 
 ### Custom Guards

site/guide/5-responses.md

@@ -299,8 +299,8 @@ library. Among these are:
 The `Stream` type deserves special attention. When a large amount of data needs
 to be sent to the client, it is better to stream the data to the client to avoid
 consuming large amounts of memory. Rocket provides the [`Stream`] type, making
-this easy. The `Stream` type can be created from any `Read` type. For example,
+this easy. The `Stream` type can be created from any `AsyncRead` type. For
-to stream from a local Unix stream, we might write:
+example, to stream from a local Unix stream, we might write:
 
 ```rust
 # #[macro_use] extern crate rocket;

site/guide/6-state.md

@@ -203,6 +203,7 @@ request-local state to implement request timing.
 [`FromRequest` request-local state]: @api/rocket/request/trait.FromRequest.html#request-local-state
 [`Fairing`]: @api/rocket/fairing/trait.Fairing.html#request-local-state
 
+<!-- TODO.async: rewrite? -->
 ## Databases
 
 Rocket includes built-in, ORM-agnostic support for databases. In particular,

site/guide/7-fairings.md

@@ -175,7 +175,8 @@ impl Fairing for Counter {
         };
     }
 
-    fn on_response(&self, request: &Request, response: &mut Response) {
+    fn on_response<'a>(&'a self, request: &'a Request<'_>, response: &'a mut Response<'_>) -> BoxFuture<'a, ()> {
+        Box::pin(async move {
             // Don't change a successful user's response, ever.
             if response.status() != Status::NotFound {
                 return
@@ -191,6 +192,7 @@ impl Fairing for Counter {
                 response.set_header(ContentType::Plain);
                 response.set_sized_body(Cursor::new(body));
             }
+        })
     }
 }
 ```
@@ -220,9 +222,9 @@ rocket::ignite()
     .attach(AdHoc::on_launch("Launch Printer", |_| {
         println!("Rocket is about to launch! Exciting! Here we go...");
     }))
-    .attach(AdHoc::on_request("Put Rewriter", |req, _| {
+    .attach(AdHoc::on_request("Put Rewriter", |req, _| Box::pin(async move {
         req.set_method(Method::Put);
-    }));
+    })));
 ```
 
 [`AdHoc`]: @api/rocket/fairing/struct.AdHoc.html

site/guide/8-testing.md

@@ -103,7 +103,7 @@ use rocket::http::{ContentType, Status};
 
 let rocket = rocket::ignite().mount("/", routes![hello]);
 let client = Client::new(rocket).expect("valid rocket instance");
-let mut response = client.get("/").dispatch();
+let mut response = client.get("/").dispatch().await;
 
 assert_eq!(response.status(), Status::Ok);
 assert_eq!(response.content_type(), Some(ContentType::Plain));
@@ -167,7 +167,13 @@ You can also move the body of the `test` module into its own file, say
 
 ### Testing
 
-To test our "Hello, world!" application, we first create a `Client` for our
+First, note the `#[rocket::async_test]` attribute. Rust does not support `async
+fn` for tests, so an asynchronous runtime needs to be set up. In most
+applications this is done by `launch()`, but we are deliberately not calling
+that in tests! Instead, we use `#[rocket::async_test]`, which runs the test
+inside a runtime.
+
+To test our "Hello, world!" application, we create a `Client` for our
 `Rocket` instance. It's okay to use methods like `expect` and `unwrap` during
 testing: we _want_ our tests to panic when something goes wrong.
 
@@ -211,7 +217,7 @@ use rocket::http::{ContentType, Status};
 # let mut response = client.get("/").dispatch();
 
 assert_eq!(response.status(), Status::Ok);
-assert_eq!(response.body_string(), Some("Hello, world!".into()));
+assert_eq!(response.body_string().await, Some("Hello, world!".into()));
 ```
 
 That's it! Altogether, this looks like:
@@ -242,9 +248,9 @@ mod test {
     # */ pub
     fn hello_world() {
         let client = Client::new(rocket()).expect("valid rocket instance");
-        let mut response = client.get("/").dispatch();
+        let mut response = client.get("/").dispatch().await;
         assert_eq!(response.status(), Status::Ok);
-        assert_eq!(response.body_string(), Some("Hello, world!".into()));
+        assert_eq!(response.body_string().await, Some("Hello, world!".into()));
     }
 }