LINK and his friends

[quininer]

@CarterLi mentioned that we can use a token to link entry together.

link(|link| {
    let buf = fd.read(buf, link)?;
    fd.write(buf, link)?;

    Ok(())
}).await?;

Ergonomics and securing shared buffers are design challenges.

[CarterLi]

bad english ;)

[CarterLi]

Ok(())

why two left parentheses?

[quininer]

This is Result<(), _>.

[quininer]

https://github.com/carterli/liburing4cpp#carefully-use-iosqe_io_link

Never use IOSQE_IO_LINK for RECV-SEND chain because you can't control the number of bytes to send (a short read for RECV is NOT considered an error. I don't know why).

Indeed, it makes things more complicated. :(

[CarterLi]

link(|link| {
    let buf = fd.read(buf, link)?;
    fd.write(buf, link)?;

    Ok(())
}).await?;

This design may not be user-friendly.

A function named when_all ( or Promise.all in JavaScript ) returns an promise of array (Promise<int[]>) which holds all results of all futures/promises that the function is awaited, because all results can be useful for the user.

For example:

when_all([
    poll(fd, LINK),
    read(fd, buf, bufsize, LINK),
    write(fd, buf, bufsize),
]).await

Should return ( JS, don't know how to write it in rust )

[
    poll_mask_on_success,
    bytes_read_or_errno_on_error,
    bytes_written_or_ecanceled_if_canceled,
]

Users may test if the last result equals -ECANCELED to see if an short read is detected, and resubmit the write operation.

// JS too
if (result[2] === -ECANCELED) {
    await write(fd, buf, result[1]);
}

[quininer]

This is a bit complicated and has no obvious benefits. close it temporarily.