RFR: 8332086: Remove the usage of ServiceLoader in j.u.r.RandomGeneratorFactory

[Jaikiran Pai]

On Mon, 13 May 2024 08:47:50 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

> All random number generator algorithms are implemented in module `java.base`. The usage of `ServiceLoader` in `j.u.r.RandomGeneratorFactory` is no longer needed.

src/java.base/share/classes/java/util/random/RandomGeneratorFactory.java line 190:

> 188:                 if (properties == null) {  // double-checking idiom
> 189:                     RandomGeneratorProperties props = rgClass.getDeclaredAnnotation(RandomGeneratorProperties.class);
> 190:                     Objects.requireNonNull(props, rgClass + " missing annotation");

Hello Raffaello, with the `RandomGenerator` implementations now all residing within the java.base module, I think an additional advantage of that is that, it will now allow us to remove this internal `RandomGeneratorProperties` annotation and thus this reflection code.

I think one way to do that would be something like this within this `RandomGeneratorFactory` class itself: 


private record RandomGenEntry(Class<?> randomGenClass, int i, int j,
                              int k, int equiDistribution, boolean stochastic,
                              boolean hardware) {

}

private static final Map<String, RandomGenEntry> FACTORY_MAP = ... // construct the map


where the `FACTORY_MAP` will be keyed to the alogrithm and the value will be a record which holds these additional details about the `RandomGenerator`. 
This current PR is about getting rid of ServiceLoader usage. So if you want to remove the usage of this annotation and reflection is a separate PR that's fine with me. Furthermore, although I don't see the necessity of an annotation for what we are doing here, if you think that the removal of the annotation and reflection isn't worth doing, that is OK too.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19212#discussion_r1598417990