router.to_async(), simple async/.await examples

Cargo.toml

@@ -58,6 +58,7 @@ members = [
     "examples/handlers/request_data",
     "examples/handlers/stateful",
     "examples/handlers/simple_async_handlers",
+    "examples/handlers/simple_async_handlers_await",
     "examples/handlers/async_handlers",
     "examples/handlers/form_urlencoded",
     "examples/handlers/multipart",

examples/handlers/README.md

@@ -18,6 +18,7 @@ We recommend reviewing our handler examples in the order shown below:
 1. [Request Data](request_data) - Accessing common request information
 1. [Stateful Handlers](stateful) - Keeping state in a handler
 1. [Simple Async Handlers](simple_async_handlers) - Async Request Handlers 101
+1. [Simple Async Handlers (.await version)](simple_async_handlers_await) - Request Handlers that use async/.await
 1. [Async Handlers](async_handlers) - More complicated async request handlers
 
 ## Help

examples/handlers/simple_async_handlers/README.md

@@ -24,6 +24,9 @@ find yourself doing lots of CPU/memory intensive operations on the web server,
 then futures are probably not going to help your performance, and you might be
 better off spawning a new thread per request.
 
+If you came here looking for an example that uses async/.await, please read
+[Async Request Handlers (.await version)](../simple_async_handlers).
+
 ## Running
 
 From the `examples/handlers/async_handlers` directory:

examples/handlers/simple_async_handlers_await/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "gotham_examples_handlers_simple_async_handlers_await"
+description = "An example that does asynchronous work before responding"
+version = "0.0.0"
+authors = ["David Laban <alsuren@gmail.com>"]
+publish = false
+edition = "2018"
+
+[dependencies]
+gotham = { path = "../../../gotham" }
+gotham_derive = { path = "../../../gotham_derive" }
+
+mime = "0.3"
+futures = "0.3.1"
+serde = "1.0"
+serde_derive = "1.0"
+tokio = "0.2.9"

examples/handlers/simple_async_handlers_await/README.md

@@ -0,0 +1,49 @@
+# Async Request Handlers (.await version)
+
+The idea of async handlers has already been introduced by the post_handler example in
+[Request Data](../request_data), which waits for the POST body asyncronously, and resolves
+the response future once it has processed the body. The combinator-based version
+of this example can be found at [Async Request Handlers](../simple_async_handlers).
+
+This example has exactly the same behavior and API as the combinator-based version,
+and it can be used as a reference when converting your code to use async/await.
+
+## Running
+
+From the `examples/handlers/async_handlers` directory:
+
+```
+Terminal 1:
+   Compiling gotham_examples_handlers_simple_async_handlers v0.0.0 (file:///.../gotham/examples/handlers/simple_async_handlers)
+    Finished dev [unoptimized + debuginfo] target(s) in 8.19 secs
+     Running `.../gotham/target/debug/gotham_examples_handlers_simple_async_handlers`
+Listening for requests at http://127.0.0.1:7878
+sleep for 5 seconds once: starting
+sleep for 5 seconds once: finished
+sleep for one second 5 times: starting
+sleep for one second 5 times: finished
+
+Terminal 2:
+$ curl 'http://127.0.0.1:7878/sleep?seconds=5'
+slept for 5 seconds
+$ curl 'http://127.0.0.1:7878/loop?seconds=5'
+slept for 1 seconds
+slept for 1 seconds
+slept for 1 seconds
+slept for 1 seconds
+slept for 1 seconds
+```
+
+## License
+
+Licensed under your option of:
+
+* [MIT License](../../LICENSE-MIT)
+* [Apache License, Version 2.0](../../LICENSE-APACHE)
+
+## Community
+
+The following policies guide participation in our project and our community:
+
+* [Code of conduct](../../CODE_OF_CONDUCT.md)
+* [Contributing](../../CONTRIBUTING.md)

examples/handlers/simple_async_handlers_await/src/main.rs

@@ -0,0 +1,162 @@
+//! A basic example showing the request components
+
+use futures::prelude::*;
+use std::pin::Pin;
+use std::time::{Duration, Instant};
+
+use gotham::hyper::{Body, StatusCode};
+
+use gotham::handler::HandlerResult;
+use gotham::helpers::http::response::create_response;
+use gotham::router::builder::DefineSingleRoute;
+use gotham::router::builder::{build_simple_router, DrawRoutes};
+use gotham::router::Router;
+use gotham::state::{FromState, State};
+use gotham_derive::{StateData, StaticResponseExtender};
+use serde_derive::Deserialize;
+
+use tokio::time::delay_until;
+
+type SleepFuture = Pin<Box<dyn Future<Output = Vec<u8>> + Send>>;
+
+#[derive(Deserialize, StateData, StaticResponseExtender)]
+struct QueryStringExtractor {
+    seconds: u64,
+}
+
+/// Sneaky hack to make tests take less time. Nothing to see here ;-).
+#[cfg(not(test))]
+fn get_duration(seconds: u64) -> Duration {
+    Duration::from_secs(seconds)
+}
+#[cfg(test)]
+fn get_duration(seconds: u64) -> Duration {
+    Duration::from_millis(seconds)
+}
+/// All this function does is return a future that resolves after a number of
+/// seconds, with a Vec<u8> that tells you how long it slept for.
+///
+/// Note that it does not block the thread from handling other requests, because
+/// it returns a `Future`, which will be managed by the tokio reactor, and
+/// called back once the timeout has expired.
+///
+/// Vec<u8> is chosen because it is one of the things that you need to resolve
+/// a HandlerFuture and respond to a request.
+///
+/// Most things that you call to access remote services (e.g databases and
+/// web apis) can be coerced into returning futures that yield useful data,
+/// so the patterns that you learn in this example should be applicable to
+/// real world problems.
+fn sleep(seconds: u64) -> SleepFuture {
+    let when = Instant::now() + get_duration(seconds);
+    let delay = delay_until(when.into()).map(move |_| {
+        format!("slept for {} seconds\n", seconds)
+            .as_bytes()
+            .to_vec()
+    });
+
+    delay.boxed()
+}
+
+/// This handler sleeps for the requested number of seconds, using the `sleep()`
+/// helper method, above.
+async fn sleep_handler(mut state: State) -> HandlerResult {
+    let seconds = QueryStringExtractor::take_from(&mut state).seconds;
+    println!("sleep for {} seconds once: starting", seconds);
+    // Here, we call the sleep function and turn its old-style future into
+    // a new-style future. Note that this step doesn't block: it just sets
+    // up the timer so that we can use it later.
+    let sleep_future = sleep(seconds);
+
+    // Here is where the serious sleeping happens. We yield execution of
+    // this block until sleep_future is resolved.
+    // The Ok("slept for x seconds") value is stored in result.
+    let data = sleep_future.await;
+
+    // Here, we convert the result from `sleep()` into the form that Gotham
+    // expects: `state` is owned by this block so we need to return it.
+    // We also convert any errors that we have into the form that Hyper
+    // expects, using the helper from IntoHandlerError.
+    let res = create_response(&state, StatusCode::OK, mime::TEXT_PLAIN, data);
+    println!("sleep for {} seconds once: finished", seconds);
+    Ok((state, res))
+}
+
+/// It calls sleep(1) as many times as needed to make the requested duration.
+///
+/// Notice how much easier it is to read than the version in
+/// `simple_async_handlers`.
+async fn loop_handler(mut state: State) -> HandlerResult {
+    let seconds = QueryStringExtractor::take_from(&mut state).seconds;
+    println!("sleep for one second {} times: starting", seconds);
+
+    // The code within this block reads exactly like syncronous code.
+    // This is the style that you should aim to write your business
+    // logic in.
+    let mut accumulator = Vec::new();
+    for _ in 0..seconds {
+        let body = sleep(1).await;
+        accumulator.extend(body)
+    }
+
+    let res = create_response(
+        &state,
+        StatusCode::OK,
+        mime::TEXT_PLAIN,
+        Body::from(accumulator),
+    );
+    println!("sleep for one second {} times: finished", seconds);
+    Ok((state, res))
+}
+
+/// Create a `Router`.
+fn router() -> Router {
+    build_simple_router(|route| {
+        route
+            .get("/sleep")
+            .with_query_string_extractor::<QueryStringExtractor>()
+            .to_async(sleep_handler);
+        route
+            .get("/loop")
+            .with_query_string_extractor::<QueryStringExtractor>()
+            .to_async(loop_handler);
+    })
+}
+
+/// Start a server and use a `Router` to dispatch requests.
+pub fn main() {
+    let addr = "127.0.0.1:7878";
+    println!("Listening for requests at http://{}", addr);
+    gotham::start(addr, router())
+}
+
+#[cfg(test)]
+mod tests {
+    use gotham::test::TestServer;
+
+    use super::*;
+
+    fn assert_returns_ok(url_str: &str, expected_response: &str) {
+        let test_server = TestServer::new(router()).unwrap();
+        let response = test_server.client().get(url_str).perform().unwrap();
+
+        assert_eq!(response.status(), StatusCode::OK);
+        assert_eq!(
+            &String::from_utf8(response.read_body().unwrap()).unwrap(),
+            expected_response
+        );
+    }
+
+    #[test]
+    fn sleep_says_how_long_it_slept_for() {
+        assert_returns_ok("http://localhost/sleep?seconds=2", "slept for 2 seconds\n");
+    }
+
+    #[test]
+    fn loop_breaks_the_time_into_one_second_sleeps() {
+        assert_returns_ok(
+            "http://localhost/loop?seconds=2",
+            "slept for 1 seconds\nslept for 1 seconds\n",
+        );
+    }
+}

gotham/src/handler/mod.rs

@@ -23,12 +23,14 @@ pub mod assets;
 
 pub use self::error::{HandlerError, IntoHandlerError};
 
+/// A type alias for the results returned by async fns that can be passed to to_async.
+pub type HandlerResult = std::result::Result<(State, Response<Body>), (State, HandlerError)>;
+
 /// A type alias for the trait objects returned by `HandlerService`.
 ///
 /// When the `Future` resolves to an error, the `(State, HandlerError)` value is used to generate
 /// an appropriate HTTP error response.
-pub type HandlerFuture =
-    dyn Future<Output = std::result::Result<(State, Response<Body>), (State, HandlerError)>> + Send;
+pub type HandlerFuture = dyn Future<Output = HandlerResult> + Send;
 
 /// A `Handler` is an asynchronous function, taking a `State` value which represents the request
 /// and related runtime state, and returns a future which resolves to a response.

gotham/src/router/builder/single.rs

@@ -4,14 +4,17 @@ use std::panic::RefUnwindSafe;
 
 use crate::extractor::{PathExtractor, QueryStringExtractor};
 use crate::handler::assets::{DirHandler, FileHandler, FileOptions, FilePathExtractor};
-use crate::handler::{Handler, NewHandler};
+use crate::handler::{Handler, HandlerResult, NewHandler};
 use crate::pipeline::chain::PipelineHandleChain;
 use crate::router::builder::{
     ExtendRouteMatcher, ReplacePathExtractor, ReplaceQueryStringExtractor, SingleRouteBuilder,
 };
 use crate::router::route::dispatch::DispatcherImpl;
 use crate::router::route::matcher::RouteMatcher;
 use crate::router::route::{Delegation, Extractors, RouteImpl};
+use crate::state::State;
+use core::future::Future;
+use futures::FutureExt;
 
 /// Describes the API for defining a single route, after determining which request paths will be
 /// dispatched here. The API here uses chained function calls to build and add the route into the
@@ -106,6 +109,54 @@ pub trait DefineSingleRoute {
     where
         H: Handler + RefUnwindSafe + Copy + Send + Sync + 'static;
 
+    /// Similar to `to`, but accepts an `async fn`
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # extern crate gotham;
+    /// # extern crate hyper;
+    /// #
+    /// # use hyper::{Body, Response, StatusCode};
+    /// # use gotham::handler::HandlerResult;
+    /// # use gotham::state::State;
+    /// # use gotham::router::Router;
+    /// # use gotham::router::builder::*;
+    /// # use gotham::pipeline::new_pipeline;
+    /// # use gotham::pipeline::single::*;
+    /// # use gotham::middleware::session::NewSessionMiddleware;
+    /// # use gotham::test::TestServer;
+    /// #
+    /// async fn my_handler(state: State) -> HandlerResult {
+    ///     // Handler implementation elided.
+    /// #   Ok((state, Response::builder().status(StatusCode::ACCEPTED).body(Body::empty()).unwrap()))
+    /// }
+    /// #
+    /// # fn router() -> Router {
+    /// #   let (chain, pipelines) = single_pipeline(
+    /// #       new_pipeline().add(NewSessionMiddleware::default()).build()
+    /// #   );
+    ///
+    /// build_router(chain, pipelines, |route| {
+    ///     route.get("/request/path").to_async(my_handler);
+    /// })
+    /// #
+    /// # }
+    /// #
+    /// # fn main() {
+    /// #   let test_server = TestServer::new(router()).unwrap();
+    /// #   let response = test_server.client()
+    /// #       .get("https://example.com/request/path")
+    /// #       .perform()
+    /// #       .unwrap();
+    /// #   assert_eq!(response.status(), StatusCode::ACCEPTED);
+    /// # }
+    /// ```
+    fn to_async<H, Fut>(self, handler: H)
+    where
+        Self: Sized,
+        H: (FnOnce(State) -> Fut) + RefUnwindSafe + Copy + Send + Sync + 'static,
+        Fut: Future<Output = HandlerResult> + Send + 'static;
     /// Directs the route to the given `NewHandler`. This gives more control over how `Handler`
     /// values are constructed.
     ///
@@ -471,6 +522,15 @@ where
         self.to_new_handler(move || Ok(handler))
     }
 
+    fn to_async<H, Fut>(self, handler: H)
+    where
+        Self: Sized,
+        H: (FnOnce(State) -> Fut) + RefUnwindSafe + Copy + Send + Sync + 'static,
+        Fut: Future<Output = HandlerResult> + Send + 'static,
+    {
+        self.to_new_handler(move || Ok(move |s: State| handler(s).boxed()))
+    }
+
     fn to_new_handler<NH>(self, new_handler: NH)
     where
         NH: NewHandler + 'static,