e699d46534
## Motivation The `futures` crate's [`compat` module][futures-compat] provides interoperability between `futures` 0.1 and `std::future` _future types_ (e.g. implementing `std::future::Future` for a type that implements the `futures` 0.1 `Future` trait). However, this on its own is insufficient to run code written against `tokio` 0.1 on a `tokio` 0.2 runtime, if that code also relies on `tokio`'s runtime services. If legacy tasks are executed that rely on `tokio::timer`, perform IO using `tokio`'s reactor, or call `tokio::spawn`, those API calls will fail unless there is also a runtime compatibility layer. ## Solution As proposed in #1549, this branch introduces a new `tokio-compat` crate, with implementations of the thread pool and current-thread runtimes that are capable of running both tokio 0.1 and tokio 0.2 tasks. The compat runtime creates a background thread that runs a `tokio` 0.1 timer and reactor, and sets itself as the `tokio` 0.1 executor as well as the default 0.2 executor. This allows 0.1 futures that use 0.1 timer, reactor, and executor APIs may run alongside `std::future` tasks on the 0.2 runtime. ### Examples Spawning both `tokio` 0.1 and `tokio` 0.2 futures: ```rust use futures_01::future::lazy; tokio_compat::run(lazy(|| { // spawn a `futures` 0.1 future using the `spawn` function from the // `tokio` 0.1 crate: tokio_01::spawn(lazy(|| { println!("hello from tokio 0.1!"); Ok(()) })); // spawn an `async` block future on the same runtime using `tokio` // 0.2's `spawn`: tokio_02::spawn(async { println!("hello from tokio 0.2!"); }); Ok(()) })) ``` Futures on the compat runtime can use `timer` APIs from both 0.1 and 0.2 versions of `tokio`: ```rust use std::time::{Duration, Instant}; use futures_01::future::lazy; use tokio_compat::prelude::*; tokio_compat::run_03(async { // Wait for a `tokio` 0.1 `Delay`... let when = Instant::now() + Duration::from_millis(10); tokio_01::timer::Delay::new(when) // convert the delay future into a `std::future` that we can `await`. .compat() .await .expect("tokio 0.1 timer should work!"); println!("10 ms have elapsed"); // Wait for a `tokio` 0.2 `Delay`... let when = Instant::now() + Duration::from_millis(20); tokio_02::timer::delay(when).await; println!("20 ms have elapsed"); }); ``` ## Future Work This is just an initial implementation of a `tokio-compat` crate; there are more compatibility layers we'll want to provide before that crate is complete. For example, we should also provide compatibility between `tokio` 0.2's `AsyncRead` and `AsyncWrite` traits and the `futures` 0.1 and `futures` 0.3 versions of those traits. In #1549, @carllerche also suggests that the `compat` crate provide reimplementations of APIs that were removed from `tokio` 0.2 proper, such as the `tcp::Incoming` future. Additionally, there is likely extra work required to get the `tokio-threadpool` 0.1 `blocking` APIs to work on the compat runtime. This will be addressed in a follow-up PR. Fixes: #1605 Fixes: #1552 Refs: #1549 [futures-compat]: https://rust-lang-nursery.github.io/futures-api-docs/0.3.0-alpha.19/futures/compat/index.html
Tokio
NOTE: Tokio's master is currently undergoing heavy development. This branch and the alpha releases will see API breaking changes and there are currently significant performance regressions that still need to be fixed before the final release. Use the v0.1.x branch for stable releases.
A runtime for writing reliable, asynchronous, and slim applications with the Rust programming language. It is:
-
Fast: Tokio's zero-cost abstractions give you bare-metal performance.
-
Reliable: Tokio leverages Rust's ownership, type system, and concurrency model to reduce bugs and ensure thread safety.
-
Scalable: Tokio has a minimal footprint, and handles backpressure and cancellation naturally.
Website | Guides | API Docs | Chat
Overview
Tokio is an event-driven, non-blocking I/O platform for writing asynchronous applications with the Rust programming language. At a high level, it provides a few major components:
- A multithreaded, work-stealing based task scheduler.
- A reactor backed by the operating system's event queue (epoll, kqueue, IOCP, etc...).
- Asynchronous TCP and UDP sockets.
These components provide the runtime components necessary for building an asynchronous application.
Example
A basic TCP echo server with Tokio:
use tokio::net::TcpListener;
use tokio::prelude::*;
use std::net::SocketAddr;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let addr = "127.0.0.1:8080".parse::<SocketAddr>()?;
let mut listener = TcpListener::bind(&addr).await?;
loop {
let (mut socket, _) = listener.accept().await?;
tokio::spawn(async move {
let mut buf = [0; 1024];
// In a loop, read data from the socket and write the data back.
loop {
let n = match socket.read(&mut buf).await {
// socket closed
Ok(n) if n == 0 => return,
Ok(n) => n,
Err(e) => {
println!("failed to read from socket; err = {:?}", e);
return;
}
};
// Write the data back
if let Err(e) = socket.write_all(&buf[0..n]).await {
println!("failed to write to socket; err = {:?}", e);
return;
}
}
});
}
}
More examples can be found here. Note that the master branch
is currently being updated to use async / await. The examples are
not fully ported. Examples for stable Tokio can be found
here.
Getting Help
First, see if the answer to your question can be found in the Guides or the API documentation. If the answer is not there, there is an active community in the Tokio Gitter channel. We would be happy to try to answer your question. Last, if that doesn't work, try opening an issue with the question.
Contributing
🎈 Thanks for your help improving the project! We are so happy to have you! We have a contributing guide to help you get involved in the Tokio project.
Related Projects
In addition to the crates in this repository, the Tokio project also maintains several other libraries, including:
-
tracing(formerlytokio-trace): A framework for application-level tracing and async-aware diagnostics. -
mio: A low-level, cross-platform abstraction over OS I/O APIs that powerstokio. -
bytes: Utilities for working with bytes, including efficient byte buffers.
Supported Rust Versions
Tokio is built against the latest stable, nightly, and beta Rust releases. The minimum version supported is the stable release from three months before the current stable release version. For example, if the latest stable Rust is 1.29, the minimum version supported is 1.26. The current Tokio version is not guaranteed to build on Rust versions earlier than the minimum supported version.
License
This project is licensed under the MIT license.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tokio by you, shall be licensed as MIT, without any additional terms or conditions.