8268764: Use Long.hashCode() instead of int-cast where applicable

[stsypanov]

In some JDK classes there's still the following hashCode() implementation:

long objNum;

public int hashCode() {
    return (int) objNum;
}

This outdated expression should be replaced with Long.hashCode(long) as it

• uses all bits of the original value, does not discard any information upfront. For example, depending on how you are generating the IDs, the upper bits could change more frequently (or the opposite).

• does not introduce any bias towards values with more ones (zeros), as it would be the case if the two halves were combined with an OR (AND) operation.

See https://stackoverflow.com/a/4045083

This is related to #4309

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8268764: Use Long.hashCode() instead of int-cast where applicable

Reviewers

• Kevin Walls (@kevinjwalls - Committer) ⚠️ Review applies to 932c26a
• Phil Race (@prrace - Reviewer)
• Alexander Zuev (@azuev-java - Reviewer)
• Sergey Bylokhov (@mrserb - Reviewer)

Reviewing

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[bridgekeeper]

👋 Welcome back stsypanov! 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]

@stsypanov The following labels will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 03: Full - Incremental (20ad76be)
• 02: Full - Incremental (932c26ad)
• 01: Full - Incremental (12a1d3ac)
• 00: Full (27233ae1)

[kevinjwalls]

The changes look good to me, we have done the same thing elsewhere. This changes things in different functional areas, which is maybe unusual, but seems fine for a small change as long as nobody objects.

Some of the files also need a (C) year update.

[stsypanov]

Hi Kevin, thanks for review! I've updated copy-right year

[kevinjwalls]

OK, one more (C) in src/jdk.jdi/share/classes/com/sun/tools/jdi/ReferenceTypeImpl.java and done. 8-)
Needs a second Review before integrating, thanks.

[stsypanov]

Right, done!

[stsypanov]

/integrate

[openjdk]

@stsypanov This PR has not yet been marked as ready for integration.

[prrace]

Speaking only to the media classes in the desktop module (you'll need approval from others for the other cases),
I can't think of any actual problem this will create, but honestly I can't see any actual value in it either.

[openjdk]

⚠️ @stsypanov the full name on your profile does not match the author name in this pull requests' HEAD commit. If this pull request gets integrated then the author name from this pull requests' HEAD commit will be used for the resulting commit. If you wish to push a new commit with a different author name, then please run the following commands in a local repository of your personal fork:

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[openjdk]

@stsypanov 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:

8268764: Use Long.hashCode() instead of int-cast where applicable

Reviewed-by: kevinw, prr, kizune, serb

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 1209 new commits pushed to the master branch:

• a5f09d1: 8275031: runtime/ErrorHandling/MachCodeFramesInErrorFile.java fails when hsdis is present
• ef0922e: 8274560: JFR: Add test for OldObjectSample event when using Shenandoah
• 1e30695: 8274466: G1: use field directly rather than method in G1CollectorState::in_mixed_phase
• dd93c6e: 8272167: AbsPathsInImage.java should skip *.dSYM directories
• 829dea4: 8274945: Cleanup unnecessary calls to Throwable.initCause() in java.desktop
• 75f5145: 8274925: Shenandoah: shenandoah/TestAllocHumongousFragment.java test failed on lock rank check
• 83c3771: 8273881: Metaspace: test repeated deallocations
• 3f01d03: 8275021: Test serviceability/sa/TestJmapCore.java fails with: java.io.IOException: Stack frame 0x4 not found
• 3f07337: 8273614: Shenandoah: intermittent timeout with ConcurrentGCBreakpoint tests
• 0d80f6c: 8274379: Allow process of unsafe access errors in check_special_condition_for_native_trans
• ... and 1199 more: https://git.openjdk.java.net/jdk/compare/a0f32cb1406e4957e84befd9b68444adb662bd13...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@kevinjwalls, @prrace, @azuev-java, @mrserb) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[prrace]

/reviewers 3

[openjdk]

@prrace
The number of required reviews for this PR is now set to 3 (with at least 1 of role reviewers).

[bridgekeeper]

@stsypanov This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[stsypanov]

Let's wait, bridgekeeper.

[bridgekeeper]

@stsypanov This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[stsypanov]

Let's wait, bridgekeeper.

[stsypanov]

/integrate

[openjdk]

@stsypanov
Your change (at version 20ad76b) is now ready to be sponsored by a Committer.

[mrserb]

/sponsor

[openjdk]

Going to push as commit 124f823.
Since your change was applied there have been 1223 commits pushed to the master branch:

• 8657f77: 8271514: support JFR use of new ThreadsList::Iterator
• b8bd259: 8271737: Only normalize the cached user.dir property once
• 89999f7: 8275131: Exceptions after a touchpad gesture on macOS
• 07b1f1c: 8274548: (fc) FileChannel gathering write fails with IOException "Invalid argument" on macOS 11.6
• f623460: 8274911: testlibrary_tests/ir_framework/tests/TestIRMatching.java fails with "java.lang.RuntimeException: Should have thrown exception"
• e393c5e: 8275074: Cleanup unused code in JFR LeakProfiler
• e16b93a: 8274770: [PPC64] resolve_jobject needs a generic implementation to support load barriers
• 1ab6414: 8275051: Shenandoah: Correct ordering of requested gc cause and gc request flag
• b460d6d: 8275091: /src/jdk.management.jfr/share/classes/module-info.java has non-canonical order
• d04d4ee: 8274894: Use Optional.empty() instead of ofNullable(null) in HttpResponse.BodySubscribers.discarding
• ... and 1213 more: https://git.openjdk.java.net/jdk/compare/a0f32cb1406e4957e84befd9b68444adb662bd13...master

Your commit was automatically rebased without conflicts.

[openjdk]

@mrserb @stsypanov Pushed as commit 124f823.

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