I built the same basic thing a year ago (using libevent for php, same general API as node.js) for a particular project.

https://github.com/hinathan/edges-php#summary

For some these php-but-like-node.js projects are abominations but there are a few reasonable use cases.

Of course the vast majority of php and the php 'class library' isn't appropriate for this programming model but neither was most of the existing js corpus before people built an ecosystem around node.js.