[jdk8u-dev] RFR: 8071507: (ref) Clear phantom reference as soft and weak references do

[Andrew John Hughes]

On Mon, 1 Aug 2022 16:30:17 GMT, Poonam Bajaj <poonam at openjdk.org> wrote:

> Backport of 8071507 and 8143847 from jdk8u-ri to jdk8u-dev.
> 
>     8071507: (ref) Clear phantom reference as soft and weak references do
>     8143847: Remove REF_CLEANER reference category
> 
> With these changes, phantom references are automatically cleared by the garbage collector like soft and weak references.
> 
> The changes are clean backport apart from a little manual adjustment for the hunk at line 246 in referenceProcessor.cpp.

Is there a reason for backporting two changes in one PR? I see this was done in 8u42 as well. It makes it harder to review than necessary, notably where the two change the same code in `referenceProcessor.cpp`.

Also, SKARA does not appear to be picking this up as a backport, as the "Backport <commit>" style was not used (https://wiki.openjdk.org/display/SKARA/Backports). Ideally it would refer to the changeset in 8u42, [ad6cdea5ae385623afa86251a8278c9c5274f4c1](https://git.openjdk.java.net/jdk8u-ri/commit/ad6cdea5ae385623afa86251a8278c9c5274f4c1), but it may have to be one of the three original changesets from jdk

In the code itself, three files are missing copyright header changes where they are newer than the current version: `referenceProcessor.hpp`, `referenceProcessor.cpp" and `referenceType.hpp`.  8143847 bumps all of these to 2016 and this change should do the same. The other files already have a newer copyright year than in 8143847.

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Changes requested by andrew (Reviewer).

PR: https://git.openjdk.org/jdk8u-dev/pull/94