Will throw an exception if generating more than 65,535 flakes in a millisecond

[danielcompton]

While it is very unlikely to happen, if 65,535 flakes are generated in a millisecond, then an exception will be thrown. Would it be better to check this and wait until the start of the next millisecond to generate the next flake?

I'm not 100% sure this is even an issue, if the caller is aware that this may throw an exception then they could prepare for it and catch it to retry.

(PartialFlake. (System/currentTimeMillis) (p/inc (Short/MAX_VALUE)))
IllegalArgumentException Value out of range for short: 32768  clojure.lang.RT.shortCast (RT.java:1040)

[xpe]

@danielcompton I skimmed the code, but I'm not sure which exception you are talking about. Would you mind pointing it out?

My thoughts on your note: Your suggestion sounds reasonable, but the current implementation sounds reasonable too. My guess is that if "overflow" happens, it probably is truly exceptional -- and an application would want to know about it and fail. The alternative is wait a millisecond -- but if you are making a system writing that many ID's, milliseconds may matter -- and you might end up with a backlog. Better to fail fast and let the application figure out what to do.

P.S. Just as a reference, from http://boundary.com/blog/2012/01/12/flake-a-decentralized-k-ordered-unique-id-generator-in-erlang/

This means that each server can produce 2^16 – 1 unique ids per millisecond without overflow.

[danielcompton]

@xpe that exception doesn't happen in the code, I made it happen by simulating what would happen if we were to inc a flake which had Short/MAX_VALUE as it's sequence value.

I agree 65,000 flakes/millisecond is a lot, it's equivalent to 65 million flakes/second.

[maxcountryman]

@danielcompton my feeling is, as @xpe mentioned, it's better to allow the application to decide how to handle this situation.

[danielcompton]

@maxcountryman is it worth documenting it as an extremely unlikely edge case then?

[maxcountryman]

Sure, more documentation couldn't hurt.