Struct hyper::ffi::hyper_waker

pub struct hyper_waker { /* private fields */ }

Available on crate feature ffi and hyper_unstable_ffi only.

A waker that is saved and used to waken a pending task.

This is provided to hyper_io’s read and write callbacks via hyper_context and hyper_context_waker.

When nonblocking I/O in one of those callbacks can’t make progress (returns EAGAIN or EWOULDBLOCK), the callback has to return to avoid blocking the executor. But it also has to arrange to get called in the future when more data is available. That’s the role of the async context and the waker. The waker can be used to tell the executor “this task is ready to make progress.”

The read or write callback, upon finding it can’t make progress, must get a waker from the context (hyper_context_waker), arrange for that waker to be called in the future, and then return HYPER_POLL_PENDING.

The arrangements for the waker to be called in the future are up to the application, but usually it will involve one big select(2) loop that checks which FDs are ready, and a correspondence between FDs and waker objects. For each FD that is ready, the corresponding waker must be called. Then hyper_executor_poll must be called. That will cause the executor to attempt to make progress on each woken task.

Corresponding Rust type: https://doc.rust-lang.org/std/task/struct.Waker.html