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Allow errors (#26)

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This changes error model to actually allow errors. I think if we're going to use this for things like tonic's route we need a more flexible error handling model. The same `handle_error` adaptors are still there but services aren't required to have `Infallible` as their error type. The error type is simply propagated all the way through.
This commit is contained in:
David Pedersen
2021-07-05 16:18:39 +02:00
committed by GitHub
parent 3fc7f1880f
commit c4d266e94d
7 changed files with 312 additions and 154 deletions
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src/lib.rs
+14 -21
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@@ -304,17 +304,17 @@
//!
//! ## Error handling
//!
//! awebframework requires all errors to be handled. That is done by using
//! [`std::convert::Infallible`] as the error type in all its [`Service`]
//! implementations.
//! Handlers created from async functions must always produce a response, even
//! when returning a `Result<T, E>` the error type must implement
//! [`IntoResponse`]. In practice this makes error handling very perdictable and
//! easier to reason about.
//!
//! For handlers created from async functions this is works automatically since
//! handlers must return something that implements
//! [`IntoResponse`](response::IntoResponse), even if its a `Result`.
//!
//! However middleware might add new failure cases that has to be handled. For
//! that awebframework provides a [`handle_error`](handler::Layered::handle_error)
//! combinator:
//! However when applying middleware, or embedding other tower services, errors
//! might happen. For example [`Timeout`] will return an error if the timeout
//! elapses. By default these errors will be propagated all the way up to hyper
//! where the connection will be closed. If that isn't desireable you can call
//! [`handle_error`](handler::Layered::handle_error) to handle errors from
//! adding a middleware to a handler:
//!
//! ```rust,no_run
//! use awebframework::prelude::*;
@@ -488,7 +488,6 @@
//! "/static/Cargo.toml",
//! service::get(
//! ServeFile::new("Cargo.toml")
//! // Errors must be handled
//! .handle_error(|error: std::io::Error| { /* ... */ })
//! )
//! );
@@ -508,7 +507,6 @@
//! use awebframework::{prelude::*, routing::BoxRoute, body::{Body, BoxBody}};
//! use tower_http::services::ServeFile;
//! use http::Response;
//! use std::convert::Infallible;
//!
//! fn api_routes() -> BoxRoute<Body> {
//! route("/users", get(|_: Request<Body>| async { /* ... */ })).boxed()
@@ -527,7 +525,6 @@
//! use awebframework::{prelude::*, service::ServiceExt, routing::nest};
//! use tower_http::services::ServeDir;
//! use http::Response;
//! use std::convert::Infallible;
//! use tower::{service_fn, BoxError};
//!
//! let app = nest(
@@ -558,6 +555,8 @@
//! [tokio]: http://crates.io/crates/tokio
//! [hyper]: http://crates.io/crates/hyper
//! [feature flags]: https://doc.rust-lang.org/cargo/reference/features.html#the-features-section
//! [`IntoResponse`]: crate::response::IntoResponse
//! [`Timeout`]: tower::timeout::Timeout
#![doc(html_root_url = "https://docs.rs/tower-http/0.1.0")]
#![warn(
@@ -609,12 +608,12 @@
use self::body::Body;
use http::Request;
use routing::{EmptyRouter, Route};
use std::convert::Infallible;
use tower::Service;
#[macro_use]
pub(crate) mod macros;
mod buffer;
mod util;
pub mod body;
@@ -661,12 +660,6 @@ pub mod prelude {
/// `service` is the [`Service`] that should receive the request if the path
/// matches `description`.
///
/// Note that `service`'s error type must be [`Infallible`] meaning you must
/// handle all errors. If you're creating handlers from async functions that is
/// handled automatically but if you're routing to some other [`Service`] you
/// might need to use [`handle_error`](service::ServiceExt::handle_error) to map
/// errors into responses.
///
/// # Examples
///
/// ```rust
@@ -688,7 +681,7 @@ pub mod prelude {
/// Panics if `description` doesn't start with `/`.
pub fn route<S, B>(description: &str, service: S) -> Route<S, EmptyRouter>
where
S: Service<Request<B>, Error = Infallible> + Clone,
S: Service<Request<B>> + Clone,
{
use routing::RoutingDsl;