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https://issues.apache.org/jira/browse/RNG-192?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18073532#comment-18073532
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Alex Herbert commented on RNG-192:
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This also affects abstract classes:
||Abstract base||Derived classes||
|AbstractPcg6432|PcgXshRr32; PcgXshRs32|
|AbstractXoRoShiRo64|XoRoShiRo64Star; XoRoShiRo64StarStar|
|AbstractXoShiRo128|XoShiRo128Plus; XoShiRo128PlusPlus; XoShiRo128StarStar|
|AbstractXoRoShiRo1024|XoRoShiRo1024PlusPlus; XoRoShiRo1024Star;
XoRoShiRo1024StarStar|
|AbstractXoRoShiRo128|XoRoShiRo128Plus; XoRoShiRo128PlusPlus; XoRoShiRo128Star|
|AbstractXoShiRo256|XoShiRo256Plus; XoShiRo256PlusPlus; XoShiRo256StarStar|
|AbstractXoShiRo512|XoShiRo512Plus; XoShiRo512PlusPlus; XoShiRo512StarStar|
> Remove use of overriddable instance method for state initialisation
> -------------------------------------------------------------------
>
> Key: RNG-192
> URL: https://issues.apache.org/jira/browse/RNG-192
> Project: Commons RNG
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.6
> Reporter: Alex Herbert
> Priority: Trivial
>
> The {{org.apache.commons.rng.core.BaseProvider}} provides methods to fill a
> state array using a seed array:
> {code:java}
> protected void fillState(int[] state, int[] seed)
> protected void fillState(long[] state, long[] seed)
> {code}
> If the seed is not long enough then it is extended using a random generator.
> The method is used in the constructor by:
> * DotyHumphreySmallFastCounting32
> * KISSRandom
> * MultiplyWithCarry256
> * DotyHumphreySmallFastCounting64
> * PcgRxsMXs64
> * XorShift1024Star
> This generates a compile time warning on JDK 21+: "possible 'this' escape
> before subclass is fully initialized". This is due to this feature:
> [JDK-8299995: Add lint check for calling overridable methods from a
> constructor|https://bugs.openjdk.org/browse/JDK-8299995]
> Since the method is a non-final protected instance method it is possible for
> the method to be overridden by sub-classes to alter construction behaviour.
> h2. Solution
> Unexpected behaviour of partially initialised classes can be avoided by
> altering the constructors to call the alternative seeding methods in the
> {{BaseProvider}} to extend an input seed:
> {code:java}
> protected static long[] extendSeed(long[] seed, int length)
> protected static int[] extendSeed(int[] seed, int length)
> {code}
> This will introduce a behavioural change to the listed RNGs when used with a
> seed that does not fill the entire state of the generator:
> Use of a fixed seed will change the output sequence. This may effect code
> that relies on certain output, for example unit tests on pseudorandom data.
> Use of a random seed will continue to output a random sequence from the
> generator.
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