io_timeouted - Man Page
return a file descriptor over deadline
io_timeouted returns the next file descriptor that is past it's deadline. If no descriptors are past their deadlines, it returns -1.
After io_timeouted() returned -1, you should wait a second before calling it again. Checking for connections past their deadline involves walking through the whole data structure, which may thrash the CPU cache needlessly. Treat it as an expensive operation.