RFR: 8311170: Simplify and modernize equals and hashCode in security area [v9]

[Pavel Rappo]

On Mon, 17 Jul 2023 12:23:17 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

>> The original code calculated `(37 ** nameValue.length)*(37+oid.hashCode)+Arrays.hashCode`; since you already dropped the multiplication, you can also drop the addition.
>
> Thanks for noticing this difference!
> 
> Yes, the initial value would've been exponentiated (^ or ** in your notation). However, I note that the original code computed this:
> 
> if nameValue.length > 0
> 
>     (37^nameValue.length) * oid.hashCode() + 37 + Arrays.hashCode(nameValue)
> 
> otherwise
> 
>     37 + oid.hashCode()
> 
> Well, it would've computed that, had the multiplier constant been 37 in Arrays.hashCode, which it is not; it's 31.
> 
> Since we cannot achieve absolute fidelity with the old code, I suggest we do this instead, what do you think?
> 
>         public int hashCode() {
>         if (myhash == -1) {
>             myhash = Arrays.deepHashCode(new Object[]{oid, nameValue});
>         }
>         return myhash;

Correction. If the multiplier were 31, then it would've been this:

    return ( 30 + oid.hashCode() ) * 31**nameValue.length + Arrays.hashCode(nameValue);
              ^                       ^

@djelinski, do you think we should use this instead?

    return Arrays.deepHashCode(new Object[]{oid, nameValue});

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PR Review Comment: https://git.openjdk.org/jdk/pull/14738#discussion_r1265737576