Jakub Zelenka has submitted an early PHP RFC covering IO hooks and operations. The proposal is documented at https://wiki.php.net/rfc/io_hooks and is now open for technical discussion.

The design depends on the recently introduced Polling API Additions RFC. If the proposal is accepted, follow-up support for the Ring API is planned. A working proof of concept integrates the related parts in PHP source pull request 23997. Zelenka notes that the API can still change.