[−][src]Trait ringbahn::Drive

pub trait Drive {
    fn poll_prepare<'cx>(
        self: Pin<&mut Self>, 
        ctx: &mut Context<'cx>, 
        prepare: impl FnOnce(SubmissionQueueEvent, &mut Context<'cx>) -> Completion<'cx>
    ) -> Poll<Completion<'cx>>;

    fn poll_submit(
        self: Pin<&mut Self>, 
        ctx: &mut Context, 
        eager: bool
    ) -> Poll<Result<usize>>;
}

Implemented by drivers for io-uring.

The type that implements Drive is used to prepare and submit IO events to an io-uring instance. Paired with a piece of code which processes completions, it can run IO on top of io-uring.

Required methods

fn poll_prepare<'cx>(
    self: Pin<&mut Self>,
    ctx: &mut Context<'cx>,
    prepare: impl FnOnce(SubmissionQueueEvent, &mut Context<'cx>) -> Completion<'cx>
) -> Poll<Completion<'cx>>

Prepare an event on the submission queue.

The implementer is responsible for provisioning an iou::SubmissionQueueEvent from the submission queue. Once an SQE is available, the implementer should pass it to the prepare callback, which constructs a Completion, and return that Completion to the caller.

If the driver is not ready to recieve more events, it can return Poll::Pending. If it does, it must register a waker to wake the task when more events can be prepared, otherwise this method will not be called again. This allows the driver to implement backpressure.

Drivers which call prepare but do not return the completion it gives are incorrectly implemented. This will lead ringbahn to panic.

fn poll_submit(
    self: Pin<&mut Self>,
    ctx: &mut Context,
    eager: bool
) -> Poll<Result<usize>>

Submit all of the events on the submission queue.

The implementer is responsible for determining how and when these events are submitted to the kernel to complete. The eager argument is a hint indicating whether the caller would prefer to see events submitted eagerly, but the implementation is not obligated to follow this hint.

If the implementation is not ready to submit, but wants to be called again to try later, it can return Poll::Pending. If it does, it must register a waker to wake the task when it would be appropriate to try submitting again.

It is also valid not to submit an event but not to register a waker to try again, in which case the appropriate response would be to return Ok(0). This indicates to the caller that the submission step is complete, whether or not actual IO was performed.

Loading content...

Implementors

impl<'_> Drive for DemoDriver<'_>[src]

Loading content...