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//! Defines types for a middleware pipeline pub mod chain; pub mod set; pub mod single; use log::trace; use std::pin::Pin; use crate::handler::HandlerFuture; use crate::middleware::chain::{MiddlewareChain, NewMiddlewareChain}; use crate::middleware::NewMiddleware; use crate::state::{request_id, State}; /// When using middleware, one or more `Middleware` are combined to form a `Pipeline`. /// `Middleware` are invoked strictly in the order they're added to the `Pipeline`. /// /// At `Request` dispatch time, the `Middleware` are created from the `NewMiddleware` values given /// to the `PipelineBuilder`, and combined with a `Handler` created from the `NewHandler` provided /// to `Pipeline::call`. These `Middleware` and `Handler` values are used for a single `Request`. /// /// # Examples /// /// ```rust /// # extern crate gotham; /// # #[macro_use] /// # extern crate gotham_derive; /// # extern crate hyper; /// # extern crate mime; /// # /// # use std::pin::Pin; /// # /// # use gotham::helpers::http::response::create_response; /// # use gotham::state::State; /// # use gotham::handler::HandlerFuture; /// # use gotham::middleware::Middleware; /// # use gotham::pipeline::new_pipeline; /// # use gotham::pipeline::single::*; /// # use gotham::router::builder::*; /// # use gotham::test::TestServer; /// # use hyper::{Body, Response, StatusCode}; /// # /// #[derive(StateData)] /// struct MiddlewareData { /// vec: Vec<i32> /// } /// /// #[derive(NewMiddleware, Copy, Clone)] /// struct MiddlewareOne; /// /// impl Middleware for MiddlewareOne { /// // Implementation elided. /// // Appends `1` to `MiddlewareData.vec` /// # fn call<Chain>(self, mut state: State, chain: Chain) -> Pin<Box<HandlerFuture>> /// # where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static /// # { /// # state.put(MiddlewareData { vec: vec![1] }); /// # chain(state) /// # } /// } /// /// #[derive(NewMiddleware, Copy, Clone)] /// struct MiddlewareTwo; /// /// impl Middleware for MiddlewareTwo { /// // Implementation elided. /// // Appends `2` to `MiddlewareData.vec` /// # fn call<Chain>(self, mut state: State, chain: Chain) -> Pin<Box<HandlerFuture>> /// # where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static /// # { /// # state.borrow_mut::<MiddlewareData>().vec.push(2); /// # chain(state) /// # } /// } /// /// #[derive(NewMiddleware, Copy, Clone)] /// struct MiddlewareThree; /// /// impl Middleware for MiddlewareThree { /// // Implementation elided. /// // Appends `3` to `MiddlewareData.vec` /// # fn call<Chain>(self, mut state: State, chain: Chain) -> Pin<Box<HandlerFuture>> /// # where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static /// # { /// # state.borrow_mut::<MiddlewareData>().vec.push(3); /// # chain(state) /// # } /// } /// /// fn handler(state: State) -> (State, Response<Body>) { /// let body = { /// let data = state.borrow::<MiddlewareData>(); /// format!("{:?}", data.vec) /// }; /// /// let res = create_response(&state, /// StatusCode::OK, /// mime::TEXT_PLAIN, /// body); /// /// (state, res) /// } /// /// fn main() { /// let (chain, pipelines) = single_pipeline( /// new_pipeline() /// .add(MiddlewareOne) /// .add(MiddlewareTwo) /// .add(MiddlewareThree) /// .build() /// ); /// /// let router = build_router(chain, pipelines, |route| { /// route.get("/").to(handler); /// }); /// /// let test_server = TestServer::new(router).unwrap(); /// let response = test_server.client().get("http://example.com/").perform().unwrap(); /// assert_eq!(response.status(), StatusCode::OK); /// assert_eq!(response.read_utf8_body().unwrap(), "[1, 2, 3]"); /// } /// ``` pub struct Pipeline<T> where T: NewMiddlewareChain, { chain: T, } /// Represents an instance of a `Pipeline`. Returned from `Pipeline::construct()`. struct PipelineInstance<T> where T: MiddlewareChain, { chain: T, } impl<T> Pipeline<T> where T: NewMiddlewareChain, { /// Constructs an instance of this `Pipeline` by creating all `Middleware` instances required /// to serve a request. If any middleware fails creation, its error will be returned. fn construct(&self) -> anyhow::Result<PipelineInstance<T::Instance>> { Ok(PipelineInstance { chain: self.chain.construct()?, }) } } impl<T> PipelineInstance<T> where T: MiddlewareChain, { /// Serves a request using this `PipelineInstance`. Requests that pass through all `Middleware` /// will be served with the `f` function. fn call<F>(self, state: State, f: F) -> Pin<Box<HandlerFuture>> where F: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static, { trace!("[{}] calling middleware", request_id(&state)); self.chain.call(state, f) } } /// Begins defining a new pipeline. /// /// See `PipelineBuilder` for information on using `new_pipeline()`. pub fn new_pipeline() -> PipelineBuilder<()> { trace!(" starting pipeline construction"); // See: `impl NewMiddlewareChain for ()` PipelineBuilder { t: () } } /// Constructs a pipeline from a single middleware. pub fn single_middleware<M>(m: M) -> Pipeline<(M, ())> where M: NewMiddleware, M::Instance: Send + 'static, { new_pipeline().add(m).build() } /// Allows a pipeline to be defined by adding `NewMiddleware` values, and building a `Pipeline`. /// /// # Examples /// /// ```rust /// # extern crate gotham; /// # #[macro_use] /// # extern crate gotham_derive; /// # /// # use std::pin::Pin; /// # /// # use gotham::state::State; /// # use gotham::handler::HandlerFuture; /// # use gotham::middleware::Middleware; /// # use gotham::pipeline::new_pipeline; /// # /// # #[derive(NewMiddleware, Copy, Clone)] /// # struct MiddlewareOne; /// # /// # #[derive(NewMiddleware, Copy, Clone)] /// # struct MiddlewareTwo; /// # /// # #[derive(NewMiddleware, Copy, Clone)] /// # struct MiddlewareThree; /// # /// # impl Middleware for MiddlewareOne { /// # fn call<Chain>(self, state: State, chain: Chain) -> Pin<Box<HandlerFuture>> /// # where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static /// # { /// # chain(state) /// # } /// # } /// # /// # impl Middleware for MiddlewareTwo { /// # fn call<Chain>(self, state: State, chain: Chain) -> Pin<Box<HandlerFuture>> /// # where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static /// # { /// # chain(state) /// # } /// # } /// # /// # impl Middleware for MiddlewareThree { /// # fn call<Chain>(self, state: State, chain: Chain) -> Pin<Box<HandlerFuture>> /// # where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static /// # { /// # chain(state) /// # } /// # } /// # /// # fn main() { /// new_pipeline() /// .add(MiddlewareOne) /// .add(MiddlewareTwo) /// .add(MiddlewareThree) /// .build(); /// # } /// ``` /// /// The pipeline defined here is invoked in this order: /// /// `(&mut state)` → `MiddlewareOne` → `MiddlewareTwo` → `MiddlewareThree` → /// `handler` (provided later, when building the router) pub struct PipelineBuilder<T> where T: NewMiddlewareChain, { t: T, } impl<T> PipelineBuilder<T> where T: NewMiddlewareChain, { /// Builds a `Pipeline`, which contains all middleware in the order provided via `add` and is /// ready to process requests via a `NewHandler` provided to `Pipeline::call`. pub fn build(self) -> Pipeline<T> where T: NewMiddlewareChain, { Pipeline { chain: self.t } } /// Adds a `NewMiddleware` which will create a `Middleware` during request dispatch. pub fn add<M>(self, m: M) -> PipelineBuilder<(M, T)> where M: NewMiddleware, M::Instance: Send + 'static, Self: Sized, { // "cons" the most recently added `NewMiddleware` onto the front of the list. This is // essentially building an HList-style tuple in reverse order. So for a call like: // // new_pipeline().add(MiddlewareOne).add(MiddlewareTwo).add(MiddlewareThree) // // The resulting `PipelineBuilder` will be: // // PipelineBuilder { t: (MiddlewareThree, (MiddlewareTwo, (MiddlewareOne, ()))) } // // An empty `PipelineBuilder` is represented as: // // PipelineBuilder { t: () } trace!(" adding middleware to pipeline"); PipelineBuilder { t: (m, self.t) } } } #[cfg(test)] mod tests { use super::*; use futures::prelude::*; use hyper::{Body, Response, StatusCode}; use crate::handler::Handler; use crate::middleware::Middleware; use crate::state::StateData; use crate::test::TestServer; fn handler(state: State) -> (State, Response<Body>) { let number = state.borrow::<Number>().value; ( state, Response::builder() .status(StatusCode::OK) .body(format!("{}", number).into()) .unwrap(), ) } #[derive(Clone)] struct Number { value: i32, } impl NewMiddleware for Number { type Instance = Number; fn new_middleware(&self) -> anyhow::Result<Number> { Ok(self.clone()) } } impl Middleware for Number { fn call<Chain>(self, mut state: State, chain: Chain) -> Pin<Box<HandlerFuture>> where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static, Self: Sized, { state.put(self.clone()); chain(state) } } impl StateData for Number {} struct Addition { value: i32, } impl NewMiddleware for Addition { type Instance = Addition; fn new_middleware(&self) -> anyhow::Result<Addition> { Ok(Addition { ..*self }) } } impl Middleware for Addition { fn call<Chain>(self, mut state: State, chain: Chain) -> Pin<Box<HandlerFuture>> where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + Send + 'static, Self: Sized, { state.borrow_mut::<Number>().value += self.value; chain(state) } } struct Multiplication { value: i32, } impl NewMiddleware for Multiplication { type Instance = Multiplication; fn new_middleware(&self) -> anyhow::Result<Multiplication> { Ok(Multiplication { ..*self }) } } impl Middleware for Multiplication { fn call<Chain>(self, mut state: State, chain: Chain) -> Pin<Box<HandlerFuture>> where Chain: FnOnce(State) -> Pin<Box<HandlerFuture>> + 'static, Self: Sized, { state.borrow_mut::<Number>().value *= self.value; chain(state) } } #[test] fn pipeline_ordering_test() { let test_server = TestServer::new(|| { let pipeline = new_pipeline() .add(Number { value: 0 }) // 0 .add(Addition { value: 1 }) // 1 .add(Multiplication { value: 2 }) // 2 .add(Addition { value: 1 }) // 3 .add(Multiplication { value: 2 }) // 6 .add(Addition { value: 2 }) // 8 .add(Multiplication { value: 3 }) // 24 .build(); Ok(move |state| match pipeline.construct() { Ok(p) => p.call(state, |state| handler.handle(state)), Err(e) => future::err((state, e.into())).boxed(), }) }) .unwrap(); let response = test_server .client() .get("http://localhost/") .perform() .unwrap(); let buf = response.read_body().unwrap(); assert_eq!(buf.as_slice(), b"24"); } }