RFR: 8332586: Avoid cloning empty arrays in java.lang.reflect.{Method,Constructor}

[Aleksey Shipilev]

On Wed, 22 May 2024 14:32:23 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Thanks.  Unfortunately the variable `cloneArray` is actually a method parameter, and most of the callers pass in `false` - so using this utility method to control cloning would actually introduce cloning in several places where it is explicitly avoided.  We may get a performance gain by modifying `Class.getInterfaces()` directly (the sole caller that passes `true`) then eliminating the parameter, then modifying each caller, etc. but that feels like a separate change inspired by this one.
>> 
>> Thoughts?
>
> Why can't you do something like this:
> 
> return cloneArray ? ReflectionFactory.copyClasses(interfaces) : interfaces;
> 
> 
> Alternatively, your proposal is a good one too; we can rename this `getInterfaces(boolean)` to `getInterfacesShared()` (like `getSharedEnumConstants()`) and move this copy operation to `getInterfaces()` as you suggest.

I really see no reason to try and save on re-use of this one-line method for _everything_. In fact, I do not quite see a very compelling reason to even have the utility method. Sharing the code between `Method` and `Constructor` is clean enough and provides a good balance between reuse and cleanliness. Everything else can have the copy of the method definition, if needed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19327#discussion_r1610112885