tower-service-0.3.3/.cargo_vcs_info.json0000644000000001530000000000100136340ustar { "git": { "sha1": "646804d77eebf072dac180cb5e1256b9ee7e0229" }, "path_in_vcs": "tower-service" }tower-service-0.3.3/CHANGELOG.md000064400000000000000000000024741046102023000142450ustar 00000000000000# 0.3.2 - **all**: new functions const when possible ([#760]) - **documentation**: Clarify subtlety around cloning and readiness in the `Service` docs. ([#622]) - **documentation**: service: Call inner.poll_ready() in docs when cloning inner ([#679]) [#760]: https://github.com/tower-rs/tower/pull/760 [#622]: https://github.com/tower-rs/tower/pull/662 [#679]: https://github.com/tower-rs/tower/pull/679 # 0.3.1 (November 29, 2019) - Improve example in `Service` docs. ([#510]) [#510]: https://github.com/tower-rs/tower/pull/510 # 0.3.0 (November 29, 2019) - Update to `futures 0.3`. - Update documentation for `std::future::Future`. # 0.3.0-alpha.2 (September 30, 2019) - Documentation fixes. # 0.3.0-alpha.1 (Aug 20, 2019) * Switch to `std::future::Future` # 0.2.0 (Dec 12, 2018) * Change `Service`'s `Request` associated type to be a generic instead. * Before: ```rust impl Service for Client { type Request = HttpRequest; type Response = HttpResponse; // ... } ``` * After: ```rust impl Service for Client { type Response = HttpResponse; // ... } ``` * Remove `NewService`, use `tower_util::MakeService` instead. * Remove `Service::ready` and `Ready`, use `tower_util::ServiceExt` instead. # 0.1.0 (Aug 9, 2018) * Initial release tower-service-0.3.3/Cargo.toml0000644000000024450000000000100116400ustar # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies. # # If you are reading this file be aware that the original Cargo.toml # will likely look very different (and much more reasonable). # See Cargo.toml.orig for the original contents. [package] edition = "2018" name = "tower-service" version = "0.3.3" authors = ["Tower Maintainers "] build = false autobins = false autoexamples = false autotests = false autobenches = false description = """ Trait representing an asynchronous, request / response based, client or server. """ homepage = "https://github.com/tower-rs/tower" documentation = "https://docs.rs/tower-service/0.3.3" readme = "README.md" categories = [ "asynchronous", "network-programming", ] license = "MIT" repository = "https://github.com/tower-rs/tower" [lib] name = "tower_service" path = "src/lib.rs" [dependencies] [dev-dependencies.futures] version = "0.3.22" [dev-dependencies.http] version = "0.2" [dev-dependencies.tokio] version = "1.6.2" features = [ "macros", "time", ] [dev-dependencies.tower-layer] version = "0.3" tower-service-0.3.3/Cargo.toml.orig000064400000000000000000000014551046102023000153210ustar 00000000000000[package] name = "tower-service" # When releasing to crates.io: # - Update doc url # - Cargo.toml # - README.md # - Update CHANGELOG.md. # - Create "v0.2.x" git tag. version = "0.3.3" authors = ["Tower Maintainers "] license = "MIT" readme = "README.md" repository = "https://github.com/tower-rs/tower" homepage = "https://github.com/tower-rs/tower" documentation = "https://docs.rs/tower-service/0.3.3" description = """ Trait representing an asynchronous, request / response based, client or server. """ categories = ["asynchronous", "network-programming"] edition = "2018" [dependencies] [dev-dependencies] http = { workspace = true } tower-layer = { version = "0.3", path = "../tower-layer" } tokio = { workspace = true, features = ["macros", "time"] } futures = { workspace = true } tower-service-0.3.3/LICENSE000064400000000000000000000020461046102023000134340ustar 00000000000000Copyright (c) 2019 Tower Contributors Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. tower-service-0.3.3/README.md000064400000000000000000000043241046102023000137070ustar 00000000000000# Tower Service The foundational `Service` trait that [Tower] is based on. [![Crates.io][crates-badge]][crates-url] [![Documentation][docs-badge]][docs-url] [![Documentation (master)][docs-master-badge]][docs-master-url] [![MIT licensed][mit-badge]][mit-url] [![Build Status][actions-badge]][actions-url] [![Discord chat][discord-badge]][discord-url] [crates-badge]: https://img.shields.io/crates/v/tower-service.svg [crates-url]: https://crates.io/crates/tower-service [docs-badge]: https://docs.rs/tower-service/badge.svg [docs-url]: https://docs.rs/tower-service [docs-master-badge]: https://img.shields.io/badge/docs-master-blue [docs-master-url]: https://tower-rs.github.io/tower/tower_service [mit-badge]: https://img.shields.io/badge/license-MIT-blue.svg [mit-url]: LICENSE [actions-badge]: https://github.com/tower-rs/tower/workflows/CI/badge.svg [actions-url]:https://github.com/tower-rs/tower/actions?query=workflow%3ACI [discord-badge]: https://img.shields.io/discord/500028886025895936?logo=discord&label=discord&logoColor=white [discord-url]: https://discord.gg/EeF3cQw ## Overview The [`Service`] trait provides the foundation upon which [Tower] is built. It is a simple, but powerful trait. At its heart, `Service` is just an asynchronous function of request to response. ``` async fn(Request) -> Result ``` Implementations of `Service` take a request, the type of which varies per protocol, and returns a future representing the eventual completion or failure of the response. Services are used to represent both clients and servers. An *instance* of `Service` is used through a client; a server *implements* `Service`. By using standardizing the interface, middleware can be created. Middleware *implement* `Service` by passing the request to another `Service`. The middleware may take actions such as modify the request. [`Service`]: https://docs.rs/tower-service/latest/tower_service/trait.Service.html [Tower]: https://crates.io/crates/tower ## License This project is licensed under the [MIT license](LICENSE). ### Contribution Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tower by you, shall be licensed as MIT, without any additional terms or conditions. tower-service-0.3.3/src/lib.rs000064400000000000000000000323431046102023000143350ustar 00000000000000#![warn( missing_debug_implementations, missing_docs, rust_2018_idioms, unreachable_pub )] #![forbid(unsafe_code)] // `rustdoc::broken_intra_doc_links` is checked on CI //! Definition of the core `Service` trait to Tower //! //! The [`Service`] trait provides the necessary abstractions for defining //! request / response clients and servers. It is simple but powerful and is //! used as the foundation for the rest of Tower. use std::future::Future; use std::task::{Context, Poll}; /// An asynchronous function from a `Request` to a `Response`. /// /// The `Service` trait is a simplified interface making it easy to write /// network applications in a modular and reusable way, decoupled from the /// underlying protocol. It is one of Tower's fundamental abstractions. /// /// # Functional /// /// A `Service` is a function of a `Request`. It immediately returns a /// `Future` representing the eventual completion of processing the /// request. The actual request processing may happen at any time in the /// future, on any thread or executor. The processing may depend on calling /// other services. At some point in the future, the processing will complete, /// and the `Future` will resolve to a response or error. /// /// At a high level, the `Service::call` function represents an RPC request. The /// `Service` value can be a server or a client. /// /// # Server /// /// An RPC server *implements* the `Service` trait. Requests received by the /// server over the network are deserialized and then passed as an argument to the /// server value. The returned response is sent back over the network. /// /// As an example, here is how an HTTP request is processed by a server: /// /// ```rust /// # use std::pin::Pin; /// # use std::task::{Poll, Context}; /// # use std::future::Future; /// # use tower_service::Service; /// use http::{Request, Response, StatusCode}; /// /// struct HelloWorld; /// /// impl Service>> for HelloWorld { /// type Response = Response>; /// type Error = http::Error; /// type Future = Pin>>>; /// /// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll> { /// Poll::Ready(Ok(())) /// } /// /// fn call(&mut self, req: Request>) -> Self::Future { /// // create the body /// let body: Vec = "hello, world!\n" /// .as_bytes() /// .to_owned(); /// // Create the HTTP response /// let resp = Response::builder() /// .status(StatusCode::OK) /// .body(body) /// .expect("Unable to create `http::Response`"); /// /// // create a response in a future. /// let fut = async { /// Ok(resp) /// }; /// /// // Return the response as an immediate future /// Box::pin(fut) /// } /// } /// ``` /// /// # Client /// /// A client consumes a service by using a `Service` value. The client may /// issue requests by invoking `call` and passing the request as an argument. /// It then receives the response by waiting for the returned future. /// /// As an example, here is how a Redis request would be issued: /// /// ```rust,ignore /// let client = redis::Client::new() /// .connect("127.0.0.1:6379".parse().unwrap()) /// .unwrap(); /// /// let resp = client.call(Cmd::set("foo", "this is the value of foo")).await?; /// /// // Wait for the future to resolve /// println!("Redis response: {:?}", resp); /// ``` /// /// # Middleware / Layer /// /// More often than not, all the pieces needed for writing robust, scalable /// network applications are the same no matter the underlying protocol. By /// unifying the API for both clients and servers in a protocol agnostic way, /// it is possible to write middleware that provide these pieces in a /// reusable way. /// /// Take timeouts as an example: /// /// ```rust /// use tower_service::Service; /// use tower_layer::Layer; /// use futures::FutureExt; /// use std::future::Future; /// use std::task::{Context, Poll}; /// use std::time::Duration; /// use std::pin::Pin; /// use std::fmt; /// use std::error::Error; /// /// // Our timeout service, which wraps another service and /// // adds a timeout to its response future. /// pub struct Timeout { /// inner: T, /// timeout: Duration, /// } /// /// impl Timeout { /// pub const fn new(inner: T, timeout: Duration) -> Timeout { /// Timeout { /// inner, /// timeout /// } /// } /// } /// /// // The error returned if processing a request timed out /// #[derive(Debug)] /// pub struct Expired; /// /// impl fmt::Display for Expired { /// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { /// write!(f, "expired") /// } /// } /// /// impl Error for Expired {} /// /// // We can implement `Service` for `Timeout` if `T` is a `Service` /// impl Service for Timeout /// where /// T: Service, /// T::Future: 'static, /// T::Error: Into> + 'static, /// T::Response: 'static, /// { /// // `Timeout` doesn't modify the response type, so we use `T`'s response type /// type Response = T::Response; /// // Errors may be either `Expired` if the timeout expired, or the inner service's /// // `Error` type. Therefore, we return a boxed `dyn Error + Send + Sync` trait object to erase /// // the error's type. /// type Error = Box; /// type Future = Pin>>>; /// /// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll> { /// // Our timeout service is ready if the inner service is ready. /// // This is how backpressure can be propagated through a tree of nested services. /// self.inner.poll_ready(cx).map_err(Into::into) /// } /// /// fn call(&mut self, req: Request) -> Self::Future { /// // Create a future that completes after `self.timeout` /// let timeout = tokio::time::sleep(self.timeout); /// /// // Call the inner service and get a future that resolves to the response /// let fut = self.inner.call(req); /// /// // Wrap those two futures in another future that completes when either one completes /// // /// // If the inner service is too slow the `sleep` future will complete first /// // And an error will be returned and `fut` will be dropped and not polled again /// // /// // We have to box the errors so the types match /// let f = async move { /// tokio::select! { /// res = fut => { /// res.map_err(|err| err.into()) /// }, /// _ = timeout => { /// Err(Box::new(Expired) as Box) /// }, /// } /// }; /// /// Box::pin(f) /// } /// } /// /// // A layer for wrapping services in `Timeout` /// pub struct TimeoutLayer(Duration); /// /// impl TimeoutLayer { /// pub const fn new(delay: Duration) -> Self { /// TimeoutLayer(delay) /// } /// } /// /// impl Layer for TimeoutLayer { /// type Service = Timeout; /// /// fn layer(&self, service: S) -> Timeout { /// Timeout::new(service, self.0) /// } /// } /// ``` /// /// The above timeout implementation is decoupled from the underlying protocol /// and is also decoupled from client or server concerns. In other words, the /// same timeout middleware could be used in either a client or a server. /// /// # Backpressure /// /// Calling a `Service` which is at capacity (i.e., it is temporarily unable to process a /// request) should result in an error. The caller is responsible for ensuring /// that the service is ready to receive the request before calling it. /// /// `Service` provides a mechanism by which the caller is able to coordinate /// readiness. `Service::poll_ready` returns `Ready` if the service expects that /// it is able to process a request. /// /// # Be careful when cloning inner services /// /// Services are permitted to panic if `call` is invoked without obtaining `Poll::Ready(Ok(()))` /// from `poll_ready`. You should therefore be careful when cloning services for example to move /// them into boxed futures. Even though the original service is ready, the clone might not be. /// /// Therefore this kind of code is wrong and might panic: /// /// ```rust /// # use std::pin::Pin; /// # use std::task::{Poll, Context}; /// # use std::future::Future; /// # use tower_service::Service; /// # /// struct Wrapper { /// inner: S, /// } /// /// impl Service for Wrapper /// where /// S: Service + Clone + 'static, /// R: 'static, /// { /// type Response = S::Response; /// type Error = S::Error; /// type Future = Pin>>>; /// /// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll> { /// self.inner.poll_ready(cx) /// } /// /// fn call(&mut self, req: R) -> Self::Future { /// let mut inner = self.inner.clone(); /// Box::pin(async move { /// // `inner` might not be ready since its a clone /// inner.call(req).await /// }) /// } /// } /// ``` /// /// You should instead use [`std::mem::replace`] to take the service that was ready: /// /// ```rust /// # use std::pin::Pin; /// # use std::task::{Poll, Context}; /// # use std::future::Future; /// # use tower_service::Service; /// # /// struct Wrapper { /// inner: S, /// } /// /// impl Service for Wrapper /// where /// S: Service + Clone + 'static, /// R: 'static, /// { /// type Response = S::Response; /// type Error = S::Error; /// type Future = Pin>>>; /// /// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll> { /// self.inner.poll_ready(cx) /// } /// /// fn call(&mut self, req: R) -> Self::Future { /// let clone = self.inner.clone(); /// // take the service that was ready /// let mut inner = std::mem::replace(&mut self.inner, clone); /// Box::pin(async move { /// inner.call(req).await /// }) /// } /// } /// ``` pub trait Service { /// Responses given by the service. type Response; /// Errors produced by the service. type Error; /// The future response value. type Future: Future>; /// Returns `Poll::Ready(Ok(()))` when the service is able to process requests. /// /// If the service is at capacity, then `Poll::Pending` is returned and the task /// is notified when the service becomes ready again. This function is /// expected to be called while on a task. Generally, this can be done with /// a simple `futures::future::poll_fn` call. /// /// If `Poll::Ready(Err(_))` is returned, the service is no longer able to service requests /// and the caller should discard the service instance. /// /// Once `poll_ready` returns `Poll::Ready(Ok(()))`, a request may be dispatched to the /// service using `call`. Until a request is dispatched, repeated calls to /// `poll_ready` must return either `Poll::Ready(Ok(()))` or `Poll::Ready(Err(_))`. /// /// Note that `poll_ready` may reserve shared resources that are consumed in a subsequent /// invocation of `call`. Thus, it is critical for implementations to not assume that `call` /// will always be invoked and to ensure that such resources are released if the service is /// dropped before `call` is invoked or the future returned by `call` is dropped before it /// is polled. fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll>; /// Process the request and return the response asynchronously. /// /// This function is expected to be callable off task. As such, /// implementations should take care to not call `poll_ready`. /// /// Before dispatching a request, `poll_ready` must be called and return /// `Poll::Ready(Ok(()))`. /// /// # Panics /// /// Implementations are permitted to panic if `call` is invoked without /// obtaining `Poll::Ready(Ok(()))` from `poll_ready`. #[must_use = "futures do nothing unless you `.await` or poll them"] fn call(&mut self, req: Request) -> Self::Future; } impl<'a, S, Request> Service for &'a mut S where S: Service + 'a, { type Response = S::Response; type Error = S::Error; type Future = S::Future; fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll> { (**self).poll_ready(cx) } fn call(&mut self, request: Request) -> S::Future { (**self).call(request) } } impl Service for Box where S: Service + ?Sized, { type Response = S::Response; type Error = S::Error; type Future = S::Future; fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll> { (**self).poll_ready(cx) } fn call(&mut self, request: Request) -> S::Future { (**self).call(request) } }