8293920: G1: Add index based heap region iteration

[albertnetymk]

Simple change of introducing a new iterate method. It's dead code for now, and will be used soon in JDK-8293210.

Test: hotspot_gc

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8293920: G1: Add index based heap region iteration

Reviewers

• Thomas Schatzl (@tschatzl - Reviewer)
• Kim Barrett (@kimbarrett - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/10301/head:pull/10301
$ git checkout pull/10301

Update a local copy of the PR:
$ git checkout pull/10301
$ git pull https://git.openjdk.org/jdk pull/10301/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 10301

View PR using the GUI difftool:
$ git pr show -t 10301

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/10301.diff

[bridgekeeper]

👋 Welcome back ayang! 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]

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

• hotspot-gc

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

• 00: Full (033c8f71)

[tschatzl]

I was hoping that somehow there could be a solution with somewhat less code duplication (but also not overdoing with lots of additional boilerplate to make that possible), but I have no good idea either.
Lgtm.

[openjdk]

@albertnetymk 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:

8293920: G1: Add index based heap region iteration

Reviewed-by: tschatzl, kbarrett

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 5 new commits pushed to the master branch:

• f42caef: 8293550: Optionally add get-task-allow entitlement to macos binaries
• 5feca68: 8293840: RISC-V: Remove cbuf parameter from far_call/far_jump/trampoline_call
• 39cd163: 8293578: Duplicate ldc generated by javac
• 7765942: 8290367: Update default value and extend the scope of com.sun.jndi.ldap.object.trustSerialData system property
• 11e7d53: 8293819: sun/util/logging/PlatformLoggerTest.java failed with "RuntimeException: Retrieved backing PlatformLogger level null is not the expected CONFIG"

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[kimbarrett]

I was hoping that somehow there could be a solution with somewhat less code duplication (but also not overdoing with lots of additional boilerplate to make that possible), but I have no good idea either. Lgtm.

I thought about some ways to reduce the code duplication. But maybe the solution in the long run is to transform uses of HeapRegionClosure into uses of HeapRegionIndexClosure? There needs to be some convenient way to do the index->region lookup by the closures though. Making each of them reimplement would not be good. We can clean this up once we have a better idea of how many of each use-case we really have.

[kimbarrett]

Looks good.

[albertnetymk]

Thanks for the review.

/integrate

[openjdk]

Going to push as commit a93cf92.
Since your change was applied there have been 22 commits pushed to the master branch:

• 36c9034: 8293808: mscapi destroyKeyContainer enhance KeyStoreException: Access is denied exception
• cbd0688: 8293851: hs_err should print more stack in hex dump
• 04d7b7d: 8293503: gc/metaspace/TestMetaspacePerfCounters.java#Epsilon-64 failed assertGreaterThanOrEqual: expected MMM >= NNN
• d77c464: 8293891: gc/g1/mixedgc/TestOldGenCollectionUsage.java (still) assumes that GCs take 1ms minimum
• d7c1a76: 8293861: G1: Disable preventive GCs by default
• 43f7f47: 8293499: Provide jmod --compress option
• 26e08cf: 8293844: C2: Verify Location::{oop,normal} types in PhaseOutput::FillLocArray
• 357a2cc: 8293937: x86: Drop LP64 conditions from clearly x86_32 code
• b1ed40a: 8293466: libjsig should ignore non-modifying sigaction calls
• b6ff8fa: 8292073: NMT: remove unused constructor parameter from MallocHeader
• ... and 12 more: https://git.openjdk.org/jdk/compare/141d5f5deec488531e410af875c781f4b70490da...master

Your commit was automatically rebased without conflicts.

[openjdk]

@albertnetymk Pushed as commit a93cf92.

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