https://github.com/smol-rs/async-io

Async I/O and timers
https://github.com/smol-rs/async-io

async rust

Last synced: about 1 year ago
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Async I/O and timers

• Host: GitHub
• URL: https://github.com/smol-rs/async-io
• Owner: smol-rs
• License: apache-2.0
• Created: 2020-06-28T20:16:29.000Z (almost 6 years ago)
• Default Branch: master
• Last Pushed: 2025-04-07T02:53:57.000Z (about 1 year ago)
• Last Synced: 2025-04-22T10:00:05.309Z (about 1 year ago)
• Topics: async, rust
• Language: Rust
• Homepage:
• Size: 439 KB
• Stars: 497
• Watchers: 10
• Forks: 69
• Open Issues: 15
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE-APACHE

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README

          
# async-io

[![Build](https://github.com/smol-rs/async-io/actions/workflows/ci.yml/badge.svg)](

https://github.com/smol-rs/async-io/actions)

[![License](https://img.shields.io/badge/license-Apache--2.0_OR_MIT-blue.svg)](

https://github.com/smol-rs/async-io)

[![Cargo](https://img.shields.io/crates/v/async-io.svg)](

https://crates.io/crates/async-io)

[![Documentation](https://docs.rs/async-io/badge.svg)](

https://docs.rs/async-io)

Async I/O and timers.

This crate provides two tools:

* `Async`, an adapter for standard networking types (and [many other] types) to use in

  async programs.

* `Timer`, a future that expires at a point in time.

For concrete async networking types built on top of this crate, see [`async-net`].

[many other]: https://github.com/smol-rs/async-io/tree/master/examples

[`async-net`]: https://docs.rs/async-net

## Implementation

The first time `Async` or `Timer` is used, a thread named "async-io" will be spawned.

The purpose of this thread is to wait for I/O events reported by the operating system, and then

wake appropriate futures blocked on I/O or timers when they can be resumed.

To wait for the next I/O event, the "async-io" thread uses [epoll] on Linux/Android/illumos,

[kqueue] on macOS/iOS/BSD, [event ports] on illumos/Solaris, and [IOCP] on Windows. That

functionality is provided by the [`polling`] crate.

However, note that you can also process I/O events and wake futures on any thread using the

`block_on()` function. The "async-io" thread is therefore just a fallback mechanism

processing I/O events in case no other threads are.

[epoll]: https://en.wikipedia.org/wiki/Epoll

[kqueue]: https://en.wikipedia.org/wiki/Kqueue

[event ports]: https://illumos.org/man/port_create

[IOCP]: https://learn.microsoft.com/en-us/windows/win32/fileio/i-o-completion-ports

[`polling`]: https://docs.rs/polling

## Examples

Connect to `example.com:80`, or time out after 10 seconds.

```rust

use async_io::{Async, Timer};

use futures_lite::{future::FutureExt, io};

use std::net::{TcpStream, ToSocketAddrs};

use std::time::Duration;

let addr = "example.com:80".to_socket_addrs()?.next().unwrap();

let stream = Async::::connect(addr).or(async {

    Timer::after(Duration::from_secs(10)).await;

    Err(io::ErrorKind::TimedOut.into())

})

.await?;

```

## License

Licensed under either of

 * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)

 * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.

#### Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted

for inclusion in the work by you, as defined in the Apache-2.0 license, shall be

dual licensed as above, without any additional terms or conditions.