async-local-executor 0.4.0

Lightweight executor for building single-threaded async runtimes.
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# async-local-executor   [![Action Badge]][actions] [![Version Badge]][crates.io] [![License Badge]][license] [![Docs Badge]][docs]

[Version Badge]: https://img.shields.io/crates/v/async-local-executor.svg
[crates.io]: https://crates.io/crates/async-local-executor
[Action Badge]: https://github.com/JayceFayne/async-local-executor/workflows/Rust/badge.svg
[actions]: https://github.com/JayceFayne/async-local-executor/actions
[License Badge]: https://img.shields.io/crates/l/async-local-executor.svg
[license]: https://github.com/JayceFayne/async-local-executor/blob/master/LICENSE.md
[Docs Badge]: https://docs.rs/async-local-executor/badge.svg
[docs]: https://docs.rs/async-local-executor

Lightweight executor for building single-threaded async runtimes.

## Why?

This crate provides an `Executor` for spawning and executing `!Send` futures without locks. It is meant to be integrated into an existing event loop and driven by that event loop whenever tasks need to make progress.

## Usage

Examples of how to use the library can be found [here](./examples).
A short example of building a runtime on top of `Executor` is shown below.

```rust
use async_io::Timer;
use async_local_executor::{spawn_local, Executor, run_ready_tasks, exit};
use std::sync::mpsc;
use std::time::Duration;
use std::thread;

pub fn block_on<F>(future: F) -> F::Output
where
    F: IntoFuture + 'static,
{
    let thread = thread::current();
    let mut executor = Executor::new(move || thread.unpark());
    let _guard = executor.enter();
    let main = spawn_local(async move {
        let result = future.await;
        exit();
        result
    });
    loop {
        run_ready_tasks();
        if let Some(result) = main.result() {
            return result;
        }
        thread::park();
    }
}

fn main() {
    let res = block_on(async {
        spawn_local(async {
            for _ in 0..10 {
                println!("Hello, again!");
                Timer::after(Duration::from_secs(1)).await;
            }
        });
        for _ in 0..3 {
            println!("Hello, world!");
            Timer::after(Duration::from_secs(1)).await;
        }
        1
    });
    assert_eq!(res, 1);
}

```

This is basically the implementation of [block_on](https://github.com/JayceFayne/async-local-executor/blob/master/src/lib.rs#L39)

## Contributing

If you find any errors in async-local-executor or just want to add a new feature feel free to [submit a PR](https://github.com/jaycefayne/async-local-executor/pulls).