8302603: Use Set.of in java.nio.charset.Charset #12570

Glavo · 2023-02-15T09:42:53Z

A small patch, using Set.of instead of Collections.unmodifiableSet() of Charset#aliasSet.

The alias should not be null, and the aliasSet is an immutable copy, so it is safe to use Set.of.

I have investigated all charsets, most of charsets have no more than 4 aliases, and the maximum is only 17.

In this case, the performance difference between immutable sets and HashSet can be ignored, and the memory footprint of immutable sets is smaller.

I need someone to help me open an Issue on JBS. Thank you very much.

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Issue

JDK-8302603: Use Set.of in java.nio.charset.Charset

Reviewers

Sergey Tsypanov (@stsypanov - Author) ⚠️ Review applies to f28a3f1b
Alan Bateman (@AlanBateman - Reviewer)
Naoto Sato (@naotoj - Reviewer)

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bridgekeeper · 2023-02-15T09:43:49Z

👋 Welcome back Glavo! 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 · 2023-02-15T09:46:29Z

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

nio

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naotoj · 2023-02-15T19:25:20Z

Good cleanup. Filed an issue: https://bugs.openjdk.org/browse/JDK-8302603

Glavo · 2023-02-15T21:05:11Z

Good cleanup. Filed an issue: https://bugs.openjdk.org/browse/JDK-8302603

Thank you!

mlbridge · 2023-02-15T21:09:44Z

Webrevs

AlanBateman · 2023-02-16T08:03:21Z

src/java.base/share/classes/java/nio/charset/Charset.java

-            hs.add(aliases[i]);
-        aliasSet = Collections.unmodifiableSet(hs);
+        if (aliasSet == null)
+            aliasSet = Set.of(aliases);


Given that this is racy then it might be better to use a local and avoid someone reading this code puzzling over whether it can return null, e.g.

Set<String> aliasSet = this.aliasSet; if (aliasSet == null) { this.aliasSet = aliasSet = Set.of(aliases); }

You can also drop explicitly initialising it null at line 670.

I have updated the code.

I have updated the code.

Thanks for the update. I think it looks okay although "as" looks a bit strange here, I think I would use aliasSet or something better.

I have updated the code.

Thanks for the update. I think it looks okay although "as" looks a bit strange here, I think I would use aliasSet or something better.

Well, the name as is a bit strange. I didn't use the name aliasSet because I didn't want to shadow the field.

Now I simply name it set. I think this name is clear enough in this context.

stsypanov

LGTM

openjdk · 2023-02-20T19:21:04Z

@Glavo 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:

8302603: Use Set.of in java.nio.charset.Charset

Reviewed-by: stsypanov, alanb, naoto

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 99 new commits pushed to the master branch:

10b4cc9: 8301627: System.exit and Runtime.exit debug logging
db483a3: 8302320: AsyncGetCallTrace obtains too few frames in sanity test
02eb240: 8302846: IGV: Zoom stuck when zooming out on large graphs
92dfa11: 8302863: Speed up String::encodeASCII using countPositives
8b20aa9: 8302981: Fix a typo in the doc comment for java.lang.Record.equals
644fe0a: 8302837: Kernel32.cpp array memory release invokes undefined behaviour
60e6378: 8302977: ZGC: Doesn't support gc/TestVerifySubSet.java
fef1910: 8299777: Test runtime/NMT/BaselineWithParameter.java timed out
622f560: 8302886: Parallel: Remove unimplemented methods in ParCompactionManager
9fd77c7: 8302868: Serial: Remove CardTableRS::initialize
... and 89 more: https://git.openjdk.org/jdk/compare/46bcc4901ea66589ec4c6904f8bab9156422312a...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 (@AlanBateman, @naotoj) 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).

Glavo · 2023-02-20T19:45:25Z

/integrate

openjdk · 2023-02-20T19:47:17Z

@Glavo
Your change (at version fdb423d) is now ready to be sponsored by a Committer.

stsypanov · 2023-02-21T07:43:00Z

/sponsor

openjdk · 2023-02-21T07:43:27Z

@stsypanov Only Committers are allowed to sponsor changes.

AlanBateman · 2023-02-21T07:46:23Z

I can sponsor but I'm giving maintainers in this area, e.g. @naotoj, a chance to comment.

naotoj

LGTM. Thanks for the fix! I will sponsor it.

naotoj · 2023-02-21T17:33:56Z

/sponsor

openjdk · 2023-02-21T17:36:05Z

Going to push as commit 5489c82.
Since your change was applied there have been 99 commits pushed to the master branch:

10b4cc9: 8301627: System.exit and Runtime.exit debug logging
db483a3: 8302320: AsyncGetCallTrace obtains too few frames in sanity test
02eb240: 8302846: IGV: Zoom stuck when zooming out on large graphs
92dfa11: 8302863: Speed up String::encodeASCII using countPositives
8b20aa9: 8302981: Fix a typo in the doc comment for java.lang.Record.equals
644fe0a: 8302837: Kernel32.cpp array memory release invokes undefined behaviour
60e6378: 8302977: ZGC: Doesn't support gc/TestVerifySubSet.java
fef1910: 8299777: Test runtime/NMT/BaselineWithParameter.java timed out
622f560: 8302886: Parallel: Remove unimplemented methods in ParCompactionManager
9fd77c7: 8302868: Serial: Remove CardTableRS::initialize
... and 89 more: https://git.openjdk.org/jdk/compare/46bcc4901ea66589ec4c6904f8bab9156422312a...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-02-21T17:36:22Z

@naotoj @Glavo Pushed as commit 5489c82.

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

Use Set.of in Charset

f28a3f1

openjdk bot added the nio nio-dev@openjdk.org label Feb 15, 2023

Glavo changed the title ~~Use Set.of in java.nio.charset.Charset~~ 8302603: Use Set.of in java.nio.charset.Charset Feb 15, 2023

openjdk bot added the rfr Pull request is ready for review label Feb 15, 2023

AlanBateman reviewed Feb 16, 2023

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stsypanov approved these changes Feb 16, 2023

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Glavo added 2 commits February 21, 2023 01:50

update

0eea8b8

update

fdb423d

AlanBateman approved these changes Feb 20, 2023

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openjdk bot added the ready Pull request is ready to be integrated label Feb 20, 2023

openjdk bot added the sponsor Pull request is ready to be sponsored label Feb 20, 2023

naotoj approved these changes Feb 21, 2023

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openjdk bot added the integrated Pull request has been integrated label Feb 21, 2023

openjdk bot closed this Feb 21, 2023

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review sponsor Pull request is ready to be sponsored labels Feb 21, 2023

Glavo deleted the charset-aliases branch February 21, 2023 18:16

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8302603: Use Set.of in java.nio.charset.Charset #12570

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8302603: Use Set.of in java.nio.charset.Charset #12570

8302603: Use Set.of in java.nio.charset.Charset #12570

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