The code has a nice explanation of the workaround they need to resort to to ensure a monotonic time source.
https://doc.rust-lang.org/src/std/time.rs.html#157 // And here we come upon a sad state of affairs. The whole point of // `Instant` is that it's monotonically increasing. We've found in the // wild, however, that it's not actually monotonically increasing for // one reason or another. These appear to be OS and hardware level bugs, // and there's not really a whole lot we can do about them. Here's a // taste of what we've found: // // * #48514 - OpenBSD, x86_64 // * #49281 - linux arm64 and s390x // * #51648 - windows, x86 // * #56560 - windows, x86_64, AWS // * #56612 - windows, x86, vm (?) // * #56940 - linux, arm64 // * https://bugzilla.mozilla.org/show_bug.cgi?id=1487778 - a similar // Firefox bug // // It simply seems that this it just happens so that a lot in the wild // we're seeing panics across various platforms where consecutive calls // to `Instant::now`, such as via the `elapsed` function, are panicking // as they're going backwards. Placed here is a last-ditch effort to try // to fix things up. We keep a global "latest now" instance which is // returned instead of what the OS says if the OS goes backwards. // // To hopefully mitigate the impact of this though a few platforms are // whitelisted as "these at least haven't gone backwards yet". In other words, 60% of the time it works every time. -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to mechanical-sympathy+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
