Hi Bruno, > On Jun 17, 2016, at 03:49, Bruno Bonacci <bruno.bona...@gmail.com> wrote: > > Hi Max, > > That's a interesting library thanks. > > Does the library guarantee monotonically increasing IDs? Eg protection > against clock reset and other clock fluctuations?
Like the Erlang implementation, Flake asks the user to call an init function—this writes out the last known timestamp to disk in a separate thread. Next time the Flake process is run, it compares the current time to the time written to disk and throws an exception if time seems to moving in the wrong direction. Apart from that, the generation function does a comparison of timestamps as well, again throwing an exception if the last known timestamp as compared to the current is in the future. These are the same guarantees that Boundary’s implementation seems to make with what I believe is a slight improvement on the persisted timer (writing out the actual Flake timestamp instead of just an arbitrary interval). > Another thing I've noticed is that you are using (System/currentTimeMillis) > to get the wall clock on every generation. > > (System/currentTimeMillis) causes a low level system call which in turn > causes a context switch. > > Maybe one way to improve could be use a initial (System/currentTimeMillis) on > the first init! and then > use System/nanoTime to calculate the time elapsed from the init. > The advantage would be that System/nanoTime runs in the UserSpace (not Kernel > Space) and it doesn't require > a system call (so no context switch). > > This could really help the case of a bulk production of IDs and any other > burst situation. I really like this idea. I’m certainly open to pull requests if you wanted to take a stab at it otherwise I may try my hand at making this improvement. :) > > Bruno > > > On Friday, June 3, 2016 at 4:40:26 PM UTC+1, Max Countryman wrote: > Hi Mark, > > I haven’t done any benchmarking comparing Flakes to UUIDs. However the > primary benefit of flake IDs, over a traditional UUID, e.g. UUID-1, is flakes > do not require coordination (i.e. to avoid clock-skew and duplicate IDs), > provide k-ordering (UUID-1’s bit ordering breaks this), and use the standard > Unix epoch. It would be interesting to compare performance, but the features > of flakes are certainly their primary selling points. > > > Max > >> On Jun 2, 2016, at 20:38, Mark Engelberg <mark.en...@gmail.com >> <javascript:>> wrote: >> >> This is interesting. Is it faster than uuid for generation and/or comparing >> for equality? >> >> On Thu, Jun 2, 2016 at 6:03 PM, Max Countryman <ma...@me.com <javascript:>> >> wrote: >> Hi, >> >> I’m happy to announce a new release of Flake, the decentralized, k-ordered >> unique ID generator. >> >> Flake 0.4.0 includes a number of important breaking changes, but by far the >> most important is dropping `generate` in favor of `generate!` which now >> returns a ByteBuffer. Previously `generate` returned a BigInteger, however >> this arbitrarily limits how an application can handle IDs and goes against >> the spirit of the Erlang implementation. In order to maintain backwards >> compatibility, a helper `flake->bigint` was added to the core namespace. >> Applications which already consume flakes should update their calls to >> `generate` so they are `generate!` and wrap them with `flake->bigint` if >> BigIntegers are desirable or already used. >> >> Github: https://github.com/maxcountryman/flake >> <https://github.com/maxcountryman/flake> >> Changes: https://github.com/maxcountryman/flake/blob/master/CHANGELOG.md >> <https://github.com/maxcountryman/flake/blob/master/CHANGELOG.md> >> >> Thanks! >> >> >> Max >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com <javascript:> >> Note that posts from new members are moderated - please be patient with your >> first post. >> To unsubscribe from this group, send email to >> clojure+u...@googlegroups.com <javascript:> >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> <http://groups.google.com/group/clojure?hl=en> >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. >> >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com <javascript:> >> Note that posts from new members are moderated - please be patient with your >> first post. >> To unsubscribe from this group, send email to >> clojure+u...@googlegroups.com <javascript:> >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> <http://groups.google.com/group/clojure?hl=en> >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with your > first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > <http://groups.google.com/group/clojure?hl=en> > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com > <mailto:clojure+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
