docs(examples): Update web_api example to use async await

messense · seanmonstar · commit 524a453b6fe1 · 2019-07-16T10:08:22.000-07:00
diff --git a/examples_disabled/web_api.rs b/examples_disabled/web_api.rs
@@ -1,64 +1,60 @@
+#![feature(async_await)]
 #![deny(warnings)]
-extern crate futures;
 extern crate hyper;
 extern crate pretty_env_logger;
 extern crate serde_json;
 
-use futures::{future, Future, Stream};
-
 use hyper::{Body, Chunk, Client, Method, Request, Response, Server, StatusCode, header};
 use hyper::client::HttpConnector;
-use hyper::service::service_fn;
+use hyper::service::{service_fn, make_service_fn};
+use futures_util::{TryStreamExt};
+
+type GenericError = Box<dyn std::error::Error + Send + Sync>;
 
 static NOTFOUND: &[u8] = b"Not Found";
 static URL: &str = "http://127.0.0.1:1337/json_api";
 static INDEX: &[u8] = b"<a href=\"test.html\">test.html</a>";
 static POST_DATA: &str = r#"{"original": "data"}"#;
 
-type GenericError = Box<dyn std::error::Error + Send + Sync>;
-type ResponseFuture = Box<dyn Future<Item=Response<Body>, Error=GenericError> + Send>;
-
-fn client_request_response(client: &Client<HttpConnector>) -> ResponseFuture {
+async fn client_request_response(client: &Client<HttpConnector>)
+    -> Result<Response<Body>, GenericError>
+{
      let req = Request::builder()
          .method(Method::POST)
          .uri(URL)
          .header(header::CONTENT_TYPE, "application/json")
          .body(POST_DATA.into())
          .unwrap();
 
-     Box::new(client.request(req).from_err().map(|web_res| {
-         // Compare the JSON we sent (before) with what we received (after):
-         let body = Body::wrap_stream(web_res.into_body().map(|b| {
-             Chunk::from(format!("<b>POST request body</b>: {}<br><b>Response</b>: {}",
-                                 POST_DATA,
-                                 std::str::from_utf8(&b).unwrap()))
-         }));
+     let web_res = client.request(req).await?;
+    // Compare the JSON we sent (before) with what we received (after):
+    let body = Body::wrap_stream(web_res.into_body().map_ok(|b| {
+        Chunk::from(format!("<b>POST request body</b>: {}<br><b>Response</b>: {}",
+                            POST_DATA,
+                            std::str::from_utf8(&b).unwrap()))
+    }));
 
-         Response::new(body)
-     }))
+    Ok(Response::new(body))
 }
 
-fn api_post_response(req: Request<Body>) -> ResponseFuture {
+async fn api_post_response(req: Request<Body>)
+    -> Result<Response<Body>, GenericError>
+{
     // A web api to run against
-    Box::new(req.into_body()
-        .concat2() // Concatenate all chunks in the body
-        .from_err()
-        .and_then(|entire_body| {
-            // TODO: Replace all unwraps with proper error handling
-            let str = String::from_utf8(entire_body.to_vec())?;
-            let mut data : serde_json::Value = serde_json::from_str(&str)?;
-            data["test"] = serde_json::Value::from("test_value");
-            let json = serde_json::to_string(&data)?;
-            let response = Response::builder()
-                .status(StatusCode::OK)
-                .header(header::CONTENT_TYPE, "application/json")
-                .body(Body::from(json))?;
-            Ok(response)
-        })
-    )
+    let entire_body = req.into_body().try_concat().await?;
+    // TODO: Replace all unwraps with proper error handling
+    let str = String::from_utf8(entire_body.to_vec())?;
+    let mut data : serde_json::Value = serde_json::from_str(&str)?;
+    data["test"] = serde_json::Value::from("test_value");
+    let json = serde_json::to_string(&data)?;
+    let response = Response::builder()
+        .status(StatusCode::OK)
+        .header(header::CONTENT_TYPE, "application/json")
+        .body(Body::from(json))?;
+    Ok(response)
 }
 
-fn api_get_response() -> ResponseFuture {
+async fn api_get_response() -> Result<Response<Body>, GenericError> {
     let data = vec!["foo", "bar"];
     let res = match serde_json::to_string(&data) {
         Ok(json) => {
@@ -74,59 +70,62 @@ fn api_get_response() -> ResponseFuture {
                 .unwrap()
         }
     };
-
-    Box::new(future::ok(res))
+    Ok(res)
 }
 
-fn response_examples(req: Request<Body>, client: &Client<HttpConnector>) -> ResponseFuture {
+async fn response_examples(req: Request<Body>, client: &Client<HttpConnector>)
+    -> Result<Response<Body>, GenericError>
+{
     match (req.method(), req.uri().path()) {
         (&Method::GET, "/") | (&Method::GET, "/index.html") => {
             let body = Body::from(INDEX);
-            Box::new(future::ok(Response::new(body)))
+            Ok(Response::new(body))
         },
         (&Method::GET, "/test.html") => {
-           client_request_response(client)
+           client_request_response(client).await
         },
         (&Method::POST, "/json_api") => {
-            api_post_response(req)
+            api_post_response(req).await
         },
         (&Method::GET, "/json_api") => {
-            api_get_response()
+            api_get_response().await
         }
         _ => {
             // Return 404 not found response.
             let body = Body::from(NOTFOUND);
-            Box::new(future::ok(Response::builder()
-                                         .status(StatusCode::NOT_FOUND)
-                                         .body(body)
-                                         .unwrap()))
+            Ok(Response::builder()
+                        .status(StatusCode::NOT_FOUND)
+                        .body(body)
+                        .unwrap())
         }
     }
 }
 
-fn main() {
+#[hyper::rt::main]
+async fn main() -> Result<(), GenericError> {
     pretty_env_logger::init();
 
     let addr = "127.0.0.1:1337".parse().unwrap();
 
-    hyper::rt::run(future::lazy(move || {
-        // Share a `Client` with all `Service`s
-        let client = Client::new();
+    // Share a `Client` with all `Service`s
+    let client = Client::new();
 
-        let new_service = move || {
-            // Move a clone of `client` into the `service_fn`.
-            let client = client.clone();
-            service_fn(move |req| {
+    let new_service = make_service_fn(move |_| {
+        // Move a clone of `client` into the `service_fn`.
+        let client = client.clone();
+        async {
+            Ok::<_, GenericError>(service_fn(move |req| {
                 response_examples(req, &client)
-            })
-        };
+            }))
+        }
+    });
 
-        let server = Server::bind(&addr)
-            .serve(new_service)
-            .map_err(|e| eprintln!("server error: {}", e));
+    let server = Server::bind(&addr)
+        .serve(new_service);
 
-        println!("Listening on http://{}", addr);
+    println!("Listening on http://{}", addr);
 
-        server
-    }));
+    server.await?;
+
+    Ok(())
 }
