nb-executor

This crate provides an async executor with the following features:

• #![no_std], does not depend on alloc.

• #![forbid(unsafe_code)].

• Runs a single future on the current thread of execution. Concurrency can be achieved with multiplexers such as futures::join!(). The executor itself is !Send + !Sync.

• A Sync-friendly, atomic 32-bit event mask is shared between the executor and all external event sources. Users define an event set (with, for example, bitflags) to make the event mask meaningful.

• Wakeups correspond to edge-triggered signals. A shared reference to the event mask is sufficient to raise a signal.

• Async code can drive non-blocking poll functions with a given signal mask. The poll function is attempted whenever any of the signals in the mask is raised until it resolves to its output. This is the primary mechanism for performing asynchronous work.

• The future is polled only if an intersection exists between the current event mask and the combined signal mask. Likewise, a poll function won't be attempted if there is no intersection between its signal mask and a snapshot of the event mask taken just before polling the "root" future.

• When further progress is presumed not to be currently possible, a user-provided park function is invoked. This function may enter an event-free context and then verify whether there is in fact no work to do right now. it may then suspend the executor in some particular way, such as a WFI/WFE-style operation on embedded firmware or std::thread::park() on hosted systems.

• A no-op waker is used by default. It can be replaced for another one that cooperates with the park function.

License

nb-executor is licensed under Apache-2.0.

Contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in nb-executor by you shall be under the terms and conditions of the Apache-2.0 license, without any additional terms or conditions.