Wheels Within Wheels

Exhibit A: Hashed and Hierarchical Timing Wheels: Efficient Data Structures for Implementing a Timer Facility, by George Varghese and Tony Lauck, originally in SOSP '87 and later reappeared in 1996 when network protocol research had caught up to it.

Exhibit B: An implementation of hierarchical timing wheels for the fleshy-ape platform, due to David Allen (2002).


(I haven't actually read Getting Things Done, but I have friends who swear by it, some of whom talk to me about it, to which I tend to wind up responding with “oh, that's just locality of reference” or similar.)