This is a useful data structure for its niche where accuracy doesn't matter and most events will be canceled, but I would not use this article to learn about it.

This does remind me of some thoughts on what a timer API should look like - there needs to be a distinction between "fire-and-forget so never cancel", "owned but cancellation is rare", "owned and cancellation is common". I've almost exclusively used the first two; for rare cancellations you can rely a lot on amortized constant overhead, or use bubbling, or use precise tracked cancellation.

... this is one case when I utilized C++ nontrivial move constructors to their fullest extent, something which Rust chooses to make utterly impossible.