JDK-8283415: Update java.lang.ref to use sealed classes

[jddarcy]

Another refactoring to use sealed classes where possible, this time in the java.lang.ref package.

Copyright dates will be updated, if needed, before a push.

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Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed
• Change requires a CSR request to be approved

Issues

• JDK-8283415: Update java.lang.ref to use sealed classes
• JDK-8283428: Update java.lang.ref to use sealed classes (CSR)

Reviewers

• Kim Barrett (@kimbarrett - Reviewer) ⚠️ Review applies to 8dc83e5
• Alan Bateman (@AlanBateman - Reviewer) ⚠️ Review applies to 8dc83e5

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/7874/head:pull/7874
$ git checkout pull/7874

Update a local copy of the PR:
$ git checkout pull/7874
$ git pull https://git.openjdk.java.net/jdk pull/7874/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 7874

View PR using the GUI difftool:
$ git pr show -t 7874

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/7874.diff

[bridgekeeper]

👋 Welcome back darcy! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@jddarcy The following label will be automatically applied to this pull request:

• core-libs

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 01: Full - Incremental (6382c607)
• 00: Full (8dc83e5f)

[kimbarrett]

Looks good.

[openjdk]

@jddarcy This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8283415: Update java.lang.ref to use sealed classes

Reviewed-by: kbarrett, alanb

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 12 new commits pushed to the master branch:

• 999da9b: 8282306: os::is_first_C_frame(frame*) crashes on invalid link access
• c4dc58e: 8283277: ISO 4217 Amendment 171 Update
• cb576da: 8283379: Memory leak in FileHeaderHelper
• 909986c: 8283217: Leak FcObjectSet in getFontConfigLocations() in fontpath.c
• b617f1d: 8283447: Remove unused LIR_Assembler::_bs
• eb4849e: 8283327: Add methods to save/restore registers when calling into the VM from C1/interpreter barrier code
• fd93015: 8283332: G1: Stricter assertion in G1BlockOffsetTablePart::forward_to_block_containing_addr
• ec62d90: 8283365: G1: Remove duplicate assertions in HeapRegion::oops_on_memregion_seq_iterate_careful
• e709cb0: 8283186: Explicitly pass a third temp register to MacroAssembler::store_heap_oop
• 83a1c90: 8282789: Create a regression test for the JTree usecase of JDK-4618767
• ... and 2 more: https://git.openjdk.java.net/jdk/compare/4df67426ed02f18af0757897acb28b636a317a91...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[AlanBateman]

/csr

[openjdk]

@AlanBateman has indicated that a compatibility and specification (CSR) request is needed for this pull request.
@jddarcy please create a CSR request for issue JDK-8283415. This pull request cannot be integrated until the CSR request is approved.

[jddarcy]

/csr

[jddarcy]

PS @AlanBateman and @kimbarrett , please also review the CSR https://bugs.openjdk.java.net/browse/JDK-8283428
Thanks.

[openjdk]

@jddarcy an approved CSR request is already required for this pull request.

[jddarcy]

/integrate

[openjdk]

Going to push as commit 14b9e80.
Since your change was applied there have been 14 commits pushed to the master branch:

• f4f8728: 8283097: Parallel: Move filler object logic inside PSPromotionLAB::unallocate_object
• 19d34bd: 8281879: Serial: Merge CardGeneration into TenuredGeneration
• 999da9b: 8282306: os::is_first_C_frame(frame*) crashes on invalid link access
• c4dc58e: 8283277: ISO 4217 Amendment 171 Update
• cb576da: 8283379: Memory leak in FileHeaderHelper
• 909986c: 8283217: Leak FcObjectSet in getFontConfigLocations() in fontpath.c
• b617f1d: 8283447: Remove unused LIR_Assembler::_bs
• eb4849e: 8283327: Add methods to save/restore registers when calling into the VM from C1/interpreter barrier code
• fd93015: 8283332: G1: Stricter assertion in G1BlockOffsetTablePart::forward_to_block_containing_addr
• ec62d90: 8283365: G1: Remove duplicate assertions in HeapRegion::oops_on_memregion_seq_iterate_careful
• ... and 4 more: https://git.openjdk.java.net/jdk/compare/4df67426ed02f18af0757897acb28b636a317a91...master

Your commit was automatically rebased without conflicts.

[openjdk]

@jddarcy Pushed as commit 14b9e80.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.