Trait fuchsia_async::WritableHandle

pub trait WritableHandle {
    // Required methods
    fn poll_writable(
        &self,
        cx: &mut Context<'_>
    ) -> Poll<Result<WritableState, Status>>;
    fn need_writable(&self, cx: &mut Context<'_>) -> Poll<Result<(), Status>>;
}

A Handle that receives notifications when it is writable.

Examples

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

Required Methods

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

If the object is ready for writing, returns Ready with the writable state. If the implementor returns Pending, it should first ensure that need_writable is called.

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

The returned WritableState does not necessarily reflect an observed OBJECT_WRITABLE signal. We optimistically assume the object remains writable until need_writable is called.

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

Arranges for the current task to be woken when the object receives an OBJECT_WRITABLE 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

impl WritableHandle for Socket

impl<T> WritableHandle for RWHandle<T>

where T: AsHandleRef,