I get where you're coming from, I think the way I'd think about it would be a little different. The interruptible part is semi-specific to sleep. I'd want predicable naming for syscalls first and foremost. So something like libc_sleep(). (libc_open(), etc would follow too) This makes is more obvious you're dealing with a pretty raw api. But otherwise agree. I haven't written any PHP in nearly 20 years, so I completely forget: is sleep() pretty typical of how PHP treats these syscalls?