Support counters in v7 UUIDs #755
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KodrAus
commented
May 13, 2024
| @@ -434,6 +478,10 @@ pub mod context { | |||
| // where the clock sequence doesn't change regardless of the timestamp | |||
| self.count.fetch_add(1, Ordering::AcqRel) & (u16::MAX >> 2) | |||
| } | |||
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| fn usable_bits(&self) -> usize { | |||
| 14 | |||
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We need to add another implementation here with a 42bit counter that's intended to be used by v7 UUIDs.
KodrAus
commented
May 13, 2024
| /// ```rust | ||
| /// # use uuid::{Uuid, Timestamp, Context}; | ||
| /// let context = Context::new(42); | ||
| /// let uuid1 = Uuid::new_v7(Timestamp::from_unix(&context, 1497624119, 1234)); |
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These examples should use Timestamp::from_unix_wide with a 42bit counter to steer users wanting counters in the right direction.
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For #717
This PR sketches out a solution to make the v7 support respect the input counter, while retaining existing semantics around filling with random data. It requires a bit of fudgery to keep compatibility with existing APIs, but I think the overall solution works out ok. I need to actually fill it all in fully and then explore ways to better integrate the existing
TimestampAPI, which may involve deprecating bits.The gist of it is to add a
usable_bitsmethod toClockSequence, so it can tell how many bits a given counter occupies. The UUID constructor can then do appropriate shifts and fill the rest with random bytes. That way a caller creating a v7 UUID can decide how many bits to dedicate to sequencing and how many to randomness.As part of this PR I'm expecting to find some solution to re-seeding sequences, which will probably remain an implementation detail of the given
ClockSequence.