I would keep the JDK source. My reasoning being: 1. Users that want to use java.util.Random would not be able to use some or all of the RNG Utils code as the later will probably relay on RandomSource instances.
2. With LCGs the current Random implementation provided by Oracle could possibly be emulated by commons-rng. However, there is no guarantee the current implementation is used by all JDKs. Also, there a no guarantee the Oracle implement doesn't change in future versions of their JDK and change to something that can not be emulated by commons-rng. So, to give users more flexibility in choosing a RandomSource and to be resilient to Random change, I feel the JDK source is beneficial. Brent On Mon, Sep 26, 2016 at 11:33 AM, Gilles <gil...@harfang.homelinux.org> wrote: > Hi. > > Reviving this thread following a new feature request: > https://issues.apache.org/jira/browse/RNG-19 > > IMHO, the request departs from the initial goal (and, hence > the design "requirements" on which the current code is based). > > As I suggested previously on this list, I'm going to request > a new "git" repository for implementing utilities based on > random generators. > > First candidates are: > * Non-uniform deviates (i.e. the samplers now defined in > Commons Math's "o.a.c.math4.distribution" package), > * Shuffling algorithm (cf. Commons Math's "o.a.c.m.MathArrays"), > * Data generation (e.g. random strings, currently defined in > Commons Math's "o.a.c.m.random.RandomUtils"), > * Syntactic sugar (e.g. strongly-type factory methods, as > suggested by Emmanuel during the RC1 vote), > * Bridge/wrappers (as suggested by Emmanuel in RNG-19, on JIRA). > > Thus, "RNG Utils" would have a much less tightened scope, allowing > for experimenting with user-requested codes.[1][2] > > Independently, I'm also wondering about removing the "JDK" element > from the "o.a.c.rng.RandomSource" enum. > Rationale is that this RNG should not be used.[3] > Once the LCG family of generators is available[4], the algorithm > provided by the JDK can be emulated.[5] > > WDYT? > > > Regards, > Gilles > > [1] Thus avoiding any impact on the stability of "Commons RNG" as a > simple, no-dependency, repository of PRNG algorithms ported to > Java (and usable as such). > [2] I'd also suggest to copy/move to that new component the related > utilities currently defined in Commons Lang. > [3] Users that _want_ to use "java.util.Random" for some reason will > probably be better off using it directly. > [4] https://issues.apache.org/jira/browse/RNG-16 > [5] To be confirmed by a unit test... > > > On Wed, 21 Sep 2016 17:27:35 +0200, Emmanuel Bourg wrote: > >> Le 21/09/2016 à 14:46, Gilles a écrit : >> >> If we want "Commons RNG" to be a repository of all >>> generators that exist out there, irrespective of their >>> known weaknesses, it's fine; but we should be careful to >>> not let casual users just pick one of the implementations >>> on the premise that the library focuses on high quality >>> generators. >>> >> >> I think it's fine to have weaker implementations as long as they are >> properly documented with the necessary warnings. There aren't that many >> algorithms anyway, we'll quickly have the interesting ones. >> >> >> I have no issue with adding any new implementation,[4] >>> on the conditions that it comes with >>> 1. a unit test where the output (say, a few hundred >>> numbers) of "Commons RNG" is compared against a >>> "reference" implementation,[5] >>> 2. the outputs of the "RandomStressTester"[6] piping >>> from the "Dieharder" and "TU01/BigCrush" actual >>> stress test suites.[7] >>> >> >> Sounds fair >> >> >> [1] Emmanuel, if you don't mind, we'd thus set the JIRA >>> issue "type" to "wish" rather than "improvement". >>> >> >> As you want, that doesn't make a big difference. It could even qualify >> for the "New Feature" type. >> >> [2] https://xkcd.com/221/ >>> >> >> Now I'm tempted to implement a XKCDRandomGenerator just for fun :) >> >> [3] Up to now, I had assumed that no known-to-be-bad >>> generators would be part of "Commons RNG" (except >>> "JDK", for reference purposes). >>> >> >> Note that as time goes some generators will be supplanted by better >> ones, so Commons RNG will inevitably contain implementations weaker than >> the then current state of the art. >> >> [4] It is not a problem to wait another couple of weeks >>> for the additional code, before releasing 1.0. >>> >> >> Ok, I can try implementing LCGs then. >> >> Emmanuel Bourg >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >> For additional commands, e-mail: dev-h...@commons.apache.org >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > >
