dope-core 0.12.0

The manifold runtime
Documentation 
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use io_uring::IoUring;
use io_uring::squeue::Entry;

use crate::backend::uring::sqe::Sqe;
use crate::driver::PushError;
use crate::io::fd::FdSlot;
use libc::SHUT_RDWR;

pub(crate) enum Submission {}

impl Submission {
    pub(crate) fn push_once(ring: &mut IoUring, entry: &Entry) -> Result<(), PushError> {
        // SAFETY: the live ring copies the entry; Sqe/RawSqe proves its resources live.
        unsafe { ring.submission().push(entry) }.map_err(|_| PushError)
    }

    pub(crate) fn push(ring: &mut IoUring, entry: &Entry) -> Result<(), PushError> {
        // SAFETY: the live ring copies the entry; Sqe/RawSqe proves its resources live.
        if unsafe { ring.submission().push(entry) }.is_ok() {
            return Ok(());
        }
        ring.submit().map_err(|_| PushError)?;
        // SAFETY: as above; submit only frees queue capacity.
        unsafe { ring.submission().push(entry) }.map_err(|_| PushError)
    }

    pub(crate) fn try_close(ring: &mut IoUring, slot: FdSlot) -> bool {
        let shut = Sqe::shutdown_linked_at(slot, SHUT_RDWR);
        let close = Sqe::close_at(slot);
        let entries = [shut.entry().clone(), close.entry().clone()];
        // SAFETY: the ring copies a linked pair retaining only a live fixed slot.
        unsafe { ring.submission().push_multiple(&entries) }.is_ok()
    }
}