io_uring Go

WORK IN PROGRESS This library adds support for io_uring for Go. This library is similar to liburing. If you want to contribute feel free to send PRs or emails, there's plenty of things that need cleaned up.

General Steps

1. Create the io_uring buffers
2. Setup mmap for both ring buffers
3. Submit requests, this is done through another system call.

Interacting with the Submit/Completion Queues

The submission and completion queues are both mmap'd as slices, the question then becomes how to design an efficient API that is also able to interact with many of the standard library interfaces. One choice is to run a background goroutine that manages all operations with the queues and use channels for enqueuing requests. The downside of this approach is that are outstanding issues with the design of channels may make it suboptimal for high throughput IO.

liburing uses memory barriers for interacting appropriately with the submission/completion queues of io_uring. One problem with the memory model of Go is that it uses weak atomics which can make it difficult to use sync/atomic in all situations. If certain IO operations are to be carriered out in a specific order then this becomes a real challenge.

The current approach is to use a FSM that uses atomics for synchronization. Once a ring is "filled" (no writes occuring to any memory locations in the mmap'd sumission queue) then the ring may be submitted. This design is not final and this library is far from ready for general use.

Example

Here is a minimal example to get started:

package main

import (
	"log"
	"os"

	"github.com/hodgesds/iouring-go"
)

func main() {
	r, err := iouring.New(1024)
	if err != nil {
		log.Fatal(err)
	}

	// Open a file for registring with the ring.
	f, err := os.OpenFile("hello.txt", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0755)
	if err != nil {
		log.Fatal(err)
	}

	// Register the file with the ring, which returns an io.WriteCloser.
	rw, err := r.FileReadWriter(f)
	if err != nil {
		log.Fatal(err)
	}

	if _, err := rw.Write([]byte("hello io_uring!")); err != nil {
		log.Fatal(err)
	}
}

Other References

https://cor3ntin.github.io/posts/iouring/

https://github.com/google/vectorio

https://github.com/shuveb/io_uring-by-example/blob/master/02_cat_uring/main.c

https://golang.org/pkg/syscall/#Iovec