RFR: 8319117: GrowableArray: Allow for custom initializer instead of copy constructor [v2]

[Quan Anh Mai]

On Tue, 31 Oct 2023 12:19:57 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi, 
>> 
>> When using at_put and at_put_grow you can provide a value which will be supplied to the constructor of each element. In other words, you can intialize each element through a copy constructor.
>> 
>> I suggest that we also provide a function equivalent where the function is provided a pointer to the memory to be initialized. This can be used for `NONCOPYABLE` classes, for example.
>> 
>> This is implemented using a SFINAE pattern because `nullptr` introduces ambiguity if you use static overload.
>> 
>> Currently running tier1-tier4.
>
> Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Use variadic templates for in-place construction
>  - Two tests

src/hotspot/share/utilities/growableArray.hpp line 405:

> 403:   void push(const E& elem) { append(elem); }
> 404: private:
> 405:   static void default_fill(E* ptr) {

This method is unused I believe

src/hotspot/share/utilities/growableArray.hpp line 410:

> 408: public:
> 409:   template<typename... Args >
> 410:   E at_grow(int i, Args... args) {

Should this be `Args&... args`? Also this method is returning a value instead of a reference, is it intentional?

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PR Review Comment: https://git.openjdk.org/jdk/pull/16409#discussion_r1377501493
PR Review Comment: https://git.openjdk.org/jdk/pull/16409#discussion_r1377501250