#core #futures #stateless #async-await #task #bypass

nightly core-futures-stateless

Workaround for no_std async-await that doesn’t store task contexts

1 unstable release

0.1.0 Jul 26, 2019


Used in lpc11xx-async-hal

MIT license

5KB
63 lines

NOTE: This is a WORKAROUND crate to bypass current standard library limitations. It will not be required in the future!

This crate is a libcore wrapper inspired from here which allows using #![feature(async_await)] in some restricted #![no_std] environments such as microcontrollers. In the current implementation the task::Context is a dummy context which does nothing and is not stored anywhere, so this crate is only useful if futures are woken up out-of-band e.g. through some interrupt request. For instance on Cortex-M the PendSV exception can be used to that effect.

A proper implementation would emulate thread-local-storage but I haven't needed this yet, and likely won't for as long as this workaround is needed.

Usage

Put the following in your Cargo.toml to override libcore:

[dependencies.core]
package = "core-futures-stateless"
version = "0.1.0"

This crate also exposes an additional non-core method task::stateless_waker() which will create a stateless task::Waker (with no behaviour) that your executor can use to poll futures. This method can easily be implemented outside this crate but is provided for convenience and to reduce code size.

No runtime deps