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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");
}
}