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//! # Agnostik //! //! Agnostik is a layer between your application and the executor that is used to execute futures. //! It allows you to switch between the executors smoothly and without having to change much code. //! //! You can use agnostik in every library that requires an executor, but wants to let the user decide //! which executor should be used. You can also use agnostik in an application, if you plan to use multiple executors, //! or want to switch between executors. //! //! ## Features //! //! - Run futures and wait for them to finish //! - Spawn futures using the underlying executor //! - Spawn blocking tasks in threads that are able to execute blocking methods //! //! Every feature I just said, can be used with every executor provided by agnostik, or //! you can integrate your own executor with Agnostik. //! //! ## Get started //! //! Check the [tests](https://github.com/bastion-rs/agnostik/tree/master/tests) for simple examples. //! //! If you have [cargo-edit](https://github.com/killercup/cargo-edit) installed, you can just execute //! this: //! ```text //! cargo add agnostik //! ``` //! //! otherwise, add this to your Cargo.toml file //! ```text //! agnostik = "0.1.0" //! ``` //! //! ## Usage //! //! ### Switching executors //! //! You can choose the executor, by using cargo features. //! The default runtime is the `bastion-executor`. //! To use another executor you just have to disable the default features, and choose one of the valid features. //! Valid features are: //! - `runtime_bastion` (default) to use the [Bastion Executor](https://crates.io/crates/bastion-executor) //! - `runtime_tokio` to use the [Tokio](https://tokio.rs) runtime //! - `runtime_asyncstd` to use the [AsyncStd](https://async.rs) runtime //! - `runtime_nostd` (coming soon) to use Agnostik in a no_std environment //! //! E.g. to use the Tokio runtime, add the following line to your Cargo.toml //! ```text //! agnostik = { version = "0.1.0", default-features = false, features = ["runtime_tokio"]} //! ``` //! //! ### Examples //! //! Agnostiks API is very easy and only has a few methods to use. //! Here's an example with the bastion-executor. //! //! ```ignore //! use agnostik::prelude::*; //! //! fn main() { //! let runtime = Agnostik::bastion(); //! //! let future = runtime.spawn(async { //! println!("Hello from bastions executor!"); //! }) //! runtime.block_on(future) //! //! let future = runtime.spawn_blocking(|| { //! expensive_blocking_method(); //! }) //! runtime.block_on(future) //! } //! ``` //! //! There's also a global executor instance that can be used to spawn futures //! without creating and storing your own executor. //! //! ```ignore //! fn main() { //! let result = agnostik::block_on(async { //! agnostik::spawn(async { //! println!("Hello from bastion executor!"); //! 1 //! }) //! .await //! }); //! assert_eq!(result, 1); //! } //! ``` //! //! or use the attribute macros. //! //! ``` //! #[agnostik::main] //! async fn main() { //! println!("hello world"); //! } //! ``` //! //! If you want to use another exceutor, you just have to replace the `Agnostik::bastion()` //! method call, with the method that corresponds to your executor. //! //! Use //! - `Agnostik::bastion()` for bastion //! - `Agnostik::async_std()` for async std //! - `Agnostik::tokio()` for tokio. **Warning:** See "How to use tokio runtime" //! - `Agnostik::tokio_with_runtime(runtime)` if you want to use your own `tokio::runtime::Runtime` object. **Warning:** See "How to use tokio runtime" //! - `Agnostik::no_std()` (coming soon) to create an exeutor that works in a nostd environment //! //! ### How to use tokio runtime //! //! It's not supported to use the `tokio::main` macro together with agnostik, //! because Agnostik requires a `Runtime` object, which is created by calling `Runtime::new()`. //! If your are using the `tokio::main` macro, there will be a panic, because you can't create a runtime //! inside a runtime. //! //! Here's how to fix it: //! //! ```ignore //! use agnostik::prelude::*; //! //! #[tokio::main] //! async fn main() { //! let runtime = Agnostik::tokio(); //! //! let result = runtime.spawn(async_task()).await; //! //! println!("The result is {}", result) //! } //! ``` //! //! This would fail with a panic. //! How to do it correctly: //! //! ```ignore //! use agnostik::prelude::*; //! use tokio::runtime::Runtime; //! //! fn main() { //! // see tokio docs for more methods to create a runtime //! let runtime = Runtime::new().expect("Failed to create a runtime"); // 1 //! let runtime = Agnostik::tokio_with_runtime(runtime); // 2 //! //! let result = runtime.spawn(async_task()); //! let result = runtime.block_on(result); //! //! println!("The result is {}", result) //! } //! ``` //! //! You can replace 1 and 2 with `Agnostik::tokio()`, because this method call will //! create a Runtime object using `Runtime::new()`. #![deny(rust_2018_idioms, clippy::pedantic, warnings, missing_docs)] pub mod executor; pub mod join_handle; #[cfg(feature = "attributes")] pub use agnostik_attributes::{bench, main, test}; use join_handle::JoinHandle; #[allow(unused)] use once_cell::sync::Lazy; use std::future::Future; #[cfg(bastion)] static EXECUTOR: Lazy<executor::BastionExecutor> = Lazy::new(|| executor::BastionExecutor); #[cfg(async_std)] static EXECUTOR: Lazy<executor::AsyncStdExecutor> = Lazy::new(|| executor::AsyncStdExecutor); #[cfg(tokio)] static EXECUTOR: Lazy<executor::TokioExecutor> = Lazy::new(|| executor::TokioExecutor::new()); #[cfg(smol)] static EXECUTOR: Lazy<executor::SmolExecutor> = Lazy::new(|| executor::SmolExecutor); /// and wait for a future to finish. pub trait AgnostikExecutor { /// Spawns an asynchronous task using the underlying executor. fn spawn<F>(&self, future: F) -> JoinHandle<F::Output> where F: Future + Send + 'static, F::Output: Send + 'static; /// Runs the provided closure on a thread, which can execute blocking tasks asynchronously. fn spawn_blocking<F, T>(&self, task: F) -> JoinHandle<T> where F: FnOnce() -> T + Send + 'static, T: Send + 'static; /// Blocks until the future has finished. fn block_on<F>(&self, future: F) -> F::Output where F: Future + Send + 'static, F::Output: Send + 'static; } /// This trait represents an executor that is capable of spawning futures onto the same thread. pub trait LocalAgnostikExecutor: AgnostikExecutor { /// Spawns a future that doesn't implement [Send]. /// /// The spawned future will be executed on the same thread that called `spawn_local`. /// /// [Send]: https://doc.rust-lang.org/std/marker/trait.Send.html fn spawn_local<F>(&self, future: F) -> JoinHandle<F::Output> where F: Future + 'static, F::Output: 'static; } /// This struct doesn't have any functionality. /// It's only use is to have a nice API to create executors /// for different runtimes. pub struct Agnostik; impl Agnostik { /// Returns an [AgnostikExecutor], that will use [bastion-executor] to spawn futures. /// /// [bastion-executor]: https://docs.rs/bastion-executor /// [AgnostikExecutor]: ./trait.AgnostikExecutor.html #[cfg(bastion)] pub fn bastion() -> impl AgnostikExecutor { executor::BastionExecutor::new() } /// Returns an [LocalAgnostikExecutor], that will use the [AsyncStd] runtime to spawn futures. /// /// [AsyncStd]: https://docs.rs/async_std /// [LocalAgnostikExecutor]: ./trait.LocalAgnostikExecutor.html #[cfg(async_std)] pub fn async_std() -> impl LocalAgnostikExecutor { executor::AsyncStdExecutor::new() } /// Returns an [LocalAgnostikExecutor], that will use the [Tokio] runtime to spawn futures. /// /// **Attention:** This method will create a new [Runtime] object using the [Runtime::new] /// method and will panic if it fails to create the [Runtime] object. /// If you want to use your own [Runtime] object, use [tokio_with_runtime] instead. /// /// [Tokio]: https://docs.rs/tokio /// [Runtime]: https://docs.rs/tokio/0.2.13/tokio/runtime/struct.Runtime.html /// [Runtime::new]: https://docs.rs/tokio/0.2.13/tokio/runtime/struct.Runtime.html#method.new /// [tokio_with_runtime]: #method.tokio_with_runtime /// [LocalAgnostikExecutor]: ../trait.LocalAgnostikExecutor.html #[cfg(tokio)] pub fn tokio() -> impl LocalAgnostikExecutor { executor::TokioExecutor::new() } /// Returns an [LocalAgnostikExecutor], that will use the [Tokio] runtime to spawn futures. /// It will use the given [Runtime] object to spawn, and block_on futures. The spawn_blocking method /// will use the [tokio::task::spawn_blocking] method. /// /// [tokio::task::spawn_blocking]: https://docs.rs/tokio/0.2.13/tokio/task/fn.spawn_blocking.html /// [Tokio]: https://docs.rs/tokio /// [Runtime]: https://docs.rs/tokio/0.2.13/tokio/runtime/struct.Runtime.html /// [tokio_with_runtime]: ./fn.tokio_with_runtime.html /// [LocalAgnostikExecutor]: ../trait.LocalAgnostikExecutor.html #[cfg(tokio)] pub fn tokio_with_runtime( runtime: tokio_crate::runtime::Runtime, ) -> impl LocalAgnostikExecutor { executor::TokioExecutor::with_runtime(runtime) } /// Returns an [LocalAgnostikExecutor] that will use the [smol] runtime, to spawn and run futures. /// /// [smol]: https://docs.rs/smol /// [LocalAgnostikExecutor]: ../trait.LocalAgnostikExecutor.html #[cfg(smol)] pub fn smol() -> impl AgnostikExecutor { executor::SmolExecutor } } /// `spawn` will use the global executor instance, which is determined by the cargo features, /// to spawn the given future. pub fn spawn<F>(future: F) -> JoinHandle<F::Output> where F: Future + Send + 'static, F::Output: Send + 'static, { executor().spawn(future) } /// `spawn_blocking` will use the global executor instance, which is determined by the cargo features, /// to spawn the given blocking task. pub fn spawn_blocking<F, T>(task: F) -> JoinHandle<T> where F: FnOnce() -> T + Send + 'static, T: Send + 'static, { executor().spawn_blocking(task) } /// `block_on` will use the global executor instance, which is determined by the cargo features, /// to block until the given future has finished. pub fn block_on<F>(future: F) -> F::Output where F: Future + Send + 'static, F::Output: Send + 'static, { executor().block_on(future) } /// `spawn_local` will use the global executor instance, which is determined by the cargo features, /// to spawn a `!Send` future. #[cfg(spawn_local)] pub fn spawn_local<F>(future: F) -> JoinHandle<F::Output> where F: Future + 'static, F::Output: 'static, { executor().spawn_local(future) } /// This method will set the [`tokio Runtime`] in the global executor. /// /// [`tokio Runtime`]: https://docs.rs/tokio/0.2.21/tokio/runtime/struct.Runtime.html #[cfg(tokio)] pub fn set_runtime(runtime: tokio_crate::runtime::Runtime) { use std::any::Any; let executor = executor() as &dyn Any; match executor.downcast_ref::<executor::TokioExecutor>() { Some(executor) => executor.set_runtime(runtime), None => unreachable!(), } } /// Returns a reference to the global executor. #[cfg(not(local_spawn))] pub fn executor() -> &'static impl AgnostikExecutor { #[cfg(enable)] return &*EXECUTOR; #[cfg(not(enable))] { struct PanicExecutor; impl AgnostikExecutor for PanicExecutor { fn spawn<F>(&self, _: F) -> JoinHandle<F::Output> where F: Future + Send + 'static, F::Output: Send + 'static, { panic!("no runtime feature enabled.") } fn spawn_blocking<F, T>(&self, _: F) -> JoinHandle<T> where F: FnOnce() -> T + Send + 'static, T: Send + 'static, { panic!("no runtime feature enabled.") } fn block_on<F>(&self, _: F) -> F::Output where F: Future + Send + 'static, F::Output: Send + 'static, { panic!("no runtime feature enabled.") } } &PanicExecutor } } /// Returns a reference to the global executor #[cfg(local_spawn)] pub fn executor() -> &'static impl LocalAgnostikExecutor { &*EXECUTOR } /// A prelude for the agnostik crate. #[allow(unused)] pub mod prelude { pub use crate::{block_on, spawn, spawn_blocking}; pub use crate::{Agnostik, AgnostikExecutor, LocalAgnostikExecutor}; }