Crate iou

Idiomatic Rust bindings to liburing.

This gives users an idiomatic Rust interface for interacting with the Linux kernel's io_uring interface for async IO. Despite being idiomatic Rust, this interface is still very low level and some fundamental operations remain unsafe.

The core entry point to the API is the IoUring type, which manages an io_uring object for interfacing with the kernel. Using this, users can submit IO events and wait for their completion.

It is also possible to "split" an IoUring instance into its constituent components - a SubmissionQueue, a CompletionQueue, and a Registrar - in order to operate on them separately without synchronization.

Submitting events

You can prepare new IO events using the SubmissionQueueEvent type. Once an event has been prepared, the next call to submit will submit that event. Eventually, those events will complete, and that a CompletionQueueEvent will appear on the completion queue indicating that the event is complete.

Preparing IO events is inherently unsafe, as you must guarantee that the buffers and file descriptors used for that IO are alive long enough for the kernel to perform the IO operation with them.

Timeouts

Some APIs allow you to time out a call into the kernel. It's important to note how this works with io_uring.

A timeout is submitted as an additional IO event which completes after the specified time. Therefore when you create a timeout, all that happens is that a completion event will appear after that specified time. This also means that when processing completion events, you need to be prepared for the possibility that the completion represents a timeout and not a normal IO event (CompletionQueueEvent has a method to check for this).

Structs

CompletionQueue	The queue of completed IO events.
CompletionQueueEvent	A completed IO event.
FsyncFlags
IoUring	The main interface to kernel IO using io_uring.
Registrar
SetupFlags	IoUring initialization flags for advanced use cases.
SubmissionFlags	SubmissionQueueEvent configuration flags.
SubmissionQueue	The queue of pending IO events.
SubmissionQueueEvent	A pending IO event.