linux-io-uring 0.1.0

The `io_uring` library for Rust.
Documentation 
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use linux_io_uring::{ opcode, IoUring };


#[test]
fn test_basic() -> anyhow::Result<()> {
    let mut ring = IoUring::new(4)?;

    // nop
    let entry = opcode::Nop::new()
        .build()
        .user_data(0x42);

    unsafe {
        ring.submission()
            .available()
            .push(entry)
            .ok()
            .expect("squeue is full");
    }

    ring.submit_and_wait(1)?;

    let cqe = ring.completion()
        .available()
        .next()
        .expect("cqueue is empty");

    assert_eq!(cqe.user_data(), 0x42);

    Ok(())
}

#[test]
fn test_sq_full() -> anyhow::Result<()> {
    let mut ring = IoUring::new(4)?;

    for _ in 0..4 {
        unsafe {
            ring.submission()
                .available()
                .push(opcode::Nop::new().build())
                .ok()
                .expect("squeue is full");
        }
    }

    unsafe {
        let ret = ring.submission()
            .available()
            .push(opcode::Nop::new().build());

        assert!(ret.is_err());
    }

    assert!(ring.submission().is_full());
    assert_eq!(ring.submission().len(), 4);

    assert!(ring.submission().available().is_full());
    assert_eq!(ring.submission().available().len(), 4);

    Ok(())
}

#[cfg(feature = "unstable")]
#[test]
fn test_cq_overflow() -> anyhow::Result<()> {
    let mut ring = IoUring::new(4)?;

    if ring.params().is_feature_nodrop() {
        // fill cq
        for _ in 0..2 {
            for _ in 0..4 {
                unsafe {
                    ring.submission()
                        .available()
                        .push(opcode::Nop::new().build())
                        .ok()
                        .expect("squeue is full");
                }
            }

            ring.submit()?;
        }

        assert_eq!(ring.completion().len(), 8);
        assert!(ring.completion().is_full());

        // overflow cq
        for _ in 0..4 {
            unsafe {
                ring.submission()
                    .available()
                    .push(opcode::Nop::new().build())
                    .ok()
                    .expect("squeue is full");
            }
        }

        ring.submit()?;

        assert_eq!(ring.completion().len(), 8);
        assert!(ring.completion().is_full());
        assert_eq!(ring.completion().overflow(), 0);

        // cq busy
        unsafe {
            ring.submission()
                .available()
                .push(opcode::Nop::new().build())
                .ok()
                .expect("squeue is full");
        }

        let err = ring.submit().unwrap_err();
        assert_eq!(err.raw_os_error(), Some(libc::EBUSY));
        assert_eq!(ring.completion().len(), 8);
        assert!(ring.completion().is_full());
        assert_eq!(ring.completion().overflow(), 0);

        // release cq
        ring.completion().available().take(4).for_each(drop);
        assert_eq!(ring.completion().len(), 4);

        unsafe {
            ring.submission()
                .available()
                .push(opcode::Nop::new().build())
                .ok()
                .expect("squeue is full");
        }

        ring.submit()?;

        // fill again
        assert_eq!(ring.completion().len(), 8);
    } else {
        todo!("5.4 kernel");
    }

    Ok(())
}