fuchsia_async

Trait ReadableHandle

Source 
pub trait ReadableHandle {
    // Required methods
    fn poll_readable(
        &self,
        cx: &mut Context<'_>,
    ) -> Poll<Result<ReadableState, Status>>;
    fn need_readable(&self, cx: &mut Context<'_>) -> Poll<Result<(), Status>>;
}
Expand description

A Handle that receives notifications when it is readable.

§Examples

loop {
    ready!(self.poll_readable(cx))?;
    match /* make read syscall */ {
        Err(zx::Status::SHOULD_WAIT) => ready!(self.need_readable(cx)?),
        status => return Poll::Ready(status),
    }
}

Required Methods§

Source

fn poll_readable( &self, cx: &mut Context<'_>, ) -> Poll<Result<ReadableState, Status>>

If the object is ready for reading, returns Ready with the readable state. If the implementor returns Pending, it should first ensure that need_readable is called.

This should be called in a poll function. If the syscall returns SHOULD_WAIT, you must call need_readable to schedule wakeup when the object is readable.

The returned ReadableState does not necessarily reflect an observed OBJECT_READABLE signal. We optimistically assume the object remains readable until need_readable is called.

Source

fn need_readable(&self, cx: &mut Context<'_>) -> Poll<Result<(), Status>>

Arranges for the current task to be woken when the object receives an OBJECT_READABLE or OBJECT_PEER_CLOSED signal. This can return Poll::Ready if the object has already been signaled in which case the waker will not be woken and it is the caller’s responsibility to not lose the signal.

Implementors§