8315968: Move java.util.Digits to jdk.internal.util and refactor to reduce duplication #15651

wenshao · 2023-09-10T16:15:01Z

java.util.DecimalDigits::DIGITS and java.lang.StringLatin1.PACKED_DIGITS are duplicates, We need to move java.util.Digits/OctalDigits/DecimalDigits/HexDigits to the jdk.internal.util package, and modify these classes to public class, so that classes in other packages can also access them.

DecimalDigits::DIGITS provides a new digitPair static method, used to replace StringLatin1.PACKED_DIGITS access.

In order to be consistent with the original StringLatin1.PACKED_DIGITS, OctalDigits::DIGITS and DecimalDigits::DIGITS are modified to little-endian. HexDigits::DIGITS will also be modified after PR #14745 is merged.

These changes will be used by PR #15658 #15555

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Issue

JDK-8315968: Move java.util.Digits to jdk.internal.util and refactor to reduce duplication (Enhancement - P4)

Reviewers

Roger Riggs (@RogerRiggs - Reviewer)
Chen Liang (@liach - Author) ⚠️ Review applies to 27174f45
Claes Redestad (@cl4es - Reviewer)

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bridgekeeper · 2023-09-10T16:16:26Z

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openjdk · 2023-09-10T16:18:05Z

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mlbridge · 2023-09-10T16:22:13Z

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RogerRiggs · 2023-09-10T16:39:03Z

Instead of packing more stuff into SharedSecrets, how about moving some common utilities into package jdk.internal.util or a new package jdk.internal.string.
For example, Digits, HexDigits, DecimalDigits, OctalDigits.
That would make access better without the overhead shared secrets.

cl4es · 2023-09-10T17:25:27Z

Yes, moving java.util.Digits to jdk.internal.util was what I had in mind, too. SharedSecrets are only necessary when we have things that need to stay package-private, such as member functions on String. Static utilities like this are generally easier to maintain when they are public but in a non-exported package like jdk.internal.util.

RogerRiggs

This would cleaner and easier to review, if you moved the classes together and did not refactor the functions. Only include the dependencies. Update the functions in a separate PR. (We can retitle the issue to match).

src/java.base/share/classes/java/lang/Long.java

src/java.base/share/classes/java/util/Digits.java

src/java.base/share/classes/java/lang/Integer.java

src/java.base/share/classes/jdk/internal/util/DecimalDigits.java

liach

In short: I suggest splitting the change of moving getChars stringSize into another patch; they are sufficiently distinct and can shrink this PR's size by a half at least.

总结：推荐这个PR专门处理移除StringLatin1.PACKED_DIGITS字段和Digits移包。
迁移getChars和stringSize分另外一个补丁。这两个内容唯一共通点是StringLatin1.getChars有些冲突，但是除此之外没必要两个补丁合并，大幅增加代码改动，难review，回滚和git blame，比如这个补丁里面Long AbstractStringBuilder等一堆改动实际上是这两个method，和PACKED_DIGITS无关。

src/java.base/share/classes/jdk/internal/util/DecimalDigits.java

src/java.base/share/classes/jdk/internal/util/OctalDigits.java

liach · 2023-09-11T14:28:28Z

src/java.base/share/classes/jdk/internal/util/DecimalDigits.java

+     * wins. The iteration results are also routinely inlined in the generated
+     * code after loop unrolling.
+     */
+    public static int stringSize(int x) {


I suggest splitting the moves of stringSize getChars into a new PR dependent on this one; your future date and time optimizations can depend on that one, which exposes stringSize.

Having the DecimalDigits package move and stringSize getChars moves together complicates the file changes, and it's hard to detect if there's any accidental typo/malicious code in the new additions.

If this PR is split into two PRs, the other two PRs I submitted #15658 #15555 cannot be based on this PR.

I agree, do the package move separate from the refactoring.
The other PRs can wait a bit or be committed as is and take part in the refactoring later.
One step at a time please.

Refactoring of stringSize has been restored

src/java.base/share/classes/java/lang/StringUTF16.java

src/java.base/share/classes/java/lang/StringLatin1.java

openjdk · 2023-09-11T15:42:13Z

@wenshao this pull request can not be integrated into master due to one or more merge conflicts. To resolve these merge conflicts and update this pull request you can run the following commands in the local repository for your personal fork:

git checkout reduce_duplicate
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push

src/java.base/share/classes/jdk/internal/util/OctalDigits.java

RogerRiggs · 2023-09-11T18:57:58Z

src/java.base/share/classes/jdk/internal/util/DecimalDigits.java

+     * wins. The iteration results are also routinely inlined in the generated
+     * code after loop unrolling.
+     */
+    public static int stringSize(int x) {


I agree, do the package move separate from the refactoring.
The other PRs can wait a bit or be committed as is and take part in the refactoring later.
One step at a time please.

RogerRiggs · 2023-09-11T18:58:56Z

src/java.base/share/classes/jdk/internal/util/DecimalDigits.java

@@ -0,0 +1,294 @@
+/*


Can git be convinced to show this as a rename instead of a delete and add?
The history will be cleaner.

I just looked it up and git actually doesn't have commands for renames like hg, but rather decides if something is a delete+add or a rename based on the amount of changes. Too many changes and it'll automatically look like a remove+add.

Which is yet another argument for splitting up this in multiple PRs. One to move, one to refactor.

Refactoring of stringSize has been restored, the problem of 'delete & add' has been resolved

src/java.base/share/classes/jdk/internal/util/OctalDigits.java

openjdk · 2023-09-11T23:22:46Z

@wenshao Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

openjdk · 2023-09-11T23:45:00Z

@wenshao Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

openjdk · 2023-09-11T23:54:42Z

@wenshao Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

openjdk · 2023-09-12T00:01:09Z

@wenshao Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

cl4es · 2023-09-12T10:11:53Z

Running some additional testing. This mostly looks fine.

One issue is that you're swapping the byte-order in DecimalDigits::DIGITS but not in OctalDigits and HexDigits. I think we need to keep these internally consistent to avoid surprises.

I also would like to see performance numbers of the byte order swap evaluated in isolation. I suspect the real effect is small and might be due to JIT noise rather than a real effect, and that this swap got rushed in without solid evidence that it helps.

If there's no significant performance difference I would prefer if we kept DecimalDigits::DIGITS big-endian encoded - which is more intuitive to most - and adjust code depending on DecimalDigits::digitPair to use ByteArray rather than ByteArrayLittleEndian.

cl4es · 2023-09-12T10:42:59Z

If there's no significant performance difference I would prefer if we kept DecimalDigits::DIGITS big-endian encoded - which is more intuitive to most - and adjust code depending on DecimalDigits::digitPair to use ByteArray rather than ByteArrayLittleEndian.

Just a datapoint but when I test implementing HexFormat::toHexDigits using either ByteArray or ByteArrayLittleEndian then the difference is in the noise:

Name                           Cnt  Base   Error   Test   Error  Unit   Diff%
HexFormatBench.toHexDigitsLong  15 1,950 ± 0,012  1,941 ± 0,016 us/op    0,5% (p = 0,081 )

wenshao · 2023-09-12T13:24:56Z

Running some additional testing. This mostly looks fine.

One issue is that you're swapping the byte-order in DecimalDigits::DIGITS but not in OctalDigits and HexDigits. I think we need to keep these internally consistent to avoid surprises.

I also would like to see performance numbers of the byte order swap evaluated in isolation. I suspect the real effect is small and might be due to JIT noise rather than a real effect, and that this swap got rushed in without solid evidence that it helps.

If there's no significant performance difference I would prefer if we kept DecimalDigits::DIGITS big-endian encoded - which is more intuitive to most - and adjust code depending on DecimalDigits::digitPair to use ByteArray rather than ByteArrayLittleEndian.

I prefer to use little endian, most environments are little endian. Changes to HexDigit will have to wait until #PR 14745 is merged.

RogerRiggs · 2023-09-12T13:49:09Z

Please update this PR title and description to indicate this refactoring to move to jdk.internal.util.
I can update the Jira title and description to match after that.

wenshao · 2023-09-12T14:13:06Z

Please update this PR title and description to indicate this refactoring to move to jdk.internal.util. I can update the Jira title and description to match after that.

The title has been updated, please help update the title of JIRA

RogerRiggs · 2023-09-12T14:16:27Z

The title has been updated, please help update the title of JIRA

The description needs an update too.

liach · 2023-09-12T14:24:38Z

I have updated the JBS bug title and explicitly stated the actions in this patch:

Move Digits to jdk.internal.util
Keep the tables in DecimalDigits and access via a new digitPair static method
Change the DecimalDigits' table to be LE (instead of BE) and update implementation

wenshao · 2023-09-12T14:51:47Z

The title has been updated, please help update the title of JIRA

The description needs an update too.

The description has also been updated

cl4es · 2023-09-12T15:32:40Z

I prefer to use little endian, most environments are little endian. Changes to HexDigit will have to wait until #PR 14745 is merged.

I don't have a very strong opinion except that we should be consistent across these related implementations. If you could either include OctalDigits changes in #14745 or prepare a separate PR for it I'm OK with this.

openjdk · 2023-09-12T15:57:19Z

⚠️ @wenshao 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:

$ git checkout reduce_duplicate
$ git commit --author='Preferred Full Name <[email protected]>' --allow-empty -m 'Update full name'
$ git push

openjdk · 2023-09-12T15:57:20Z

@wenshao 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:

8315968: Move java.util.Digits to jdk.internal.util and refactor to reduce duplication

Reviewed-by: rriggs, liach, redestad

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:

d75d977: 8285447: StackWalker minimal batch size should be optimized for getCallerClass
fc3e826: 8314832: Few runtime/os tests ignore vm flags
347beb2: 8315998: Remove dead ClassLoaderDataGraphKlassIteratorStatic
50158f3: 8316002: Remove unnecessary seen_dead_loader in ClassLoaderDataGraph::do_unloading
6f2684b: 8315948: JDK-8315818 broke Xcomp on libgraal
8b4f9a8: 8315990: Amend problemlisted tests to proper position
455c471: 8313277: Resolve multiple definition of 'normalize' when statically linking JDK native libraries with user code
3b422d0: 8316094: Problemlist compiler/rangechecks/TestRangeCheckHoistingScaledIV.java
f55e799: 8316038: Fix doc typos in java.io.Console and java.util.Scanner
9480078: 8315550: G1: Fix -Wconversion warnings in g1NUMA
... and 2 more: https://git.openjdk.org/jdk/compare/d0be73a78038faf9509623bc4ba71eb4385cd645...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 (@RogerRiggs, @cl4es) 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).

RogerRiggs

Thanks for the updates.

wenshao · 2023-09-12T16:31:38Z

/integrate

openjdk · 2023-09-12T16:33:52Z

@wenshao
Your change (at version c68c4e8) is now ready to be sponsored by a Committer.

cl4es · 2023-09-12T16:34:31Z

/sponsor

openjdk · 2023-09-12T16:35:09Z

Going to push as commit e084516.
Since your change was applied there have been 12 commits pushed to the master branch:

d75d977: 8285447: StackWalker minimal batch size should be optimized for getCallerClass
fc3e826: 8314832: Few runtime/os tests ignore vm flags
347beb2: 8315998: Remove dead ClassLoaderDataGraphKlassIteratorStatic
50158f3: 8316002: Remove unnecessary seen_dead_loader in ClassLoaderDataGraph::do_unloading
6f2684b: 8315948: JDK-8315818 broke Xcomp on libgraal
8b4f9a8: 8315990: Amend problemlisted tests to proper position
455c471: 8313277: Resolve multiple definition of 'normalize' when statically linking JDK native libraries with user code
3b422d0: 8316094: Problemlist compiler/rangechecks/TestRangeCheckHoistingScaledIV.java
f55e799: 8316038: Fix doc typos in java.io.Console and java.util.Scanner
9480078: 8315550: G1: Fix -Wconversion warnings in g1NUMA
... and 2 more: https://git.openjdk.org/jdk/compare/d0be73a78038faf9509623bc4ba71eb4385cd645...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-09-12T16:35:20Z

@cl4es @wenshao Pushed as commit e084516.

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

openjdk bot added the rfr Pull request is ready for review label Sep 10, 2023

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8315999: Improve Date toString performance #15658

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wenshao force-pushed the reduce_duplicate branch from 0395293 to 6cc34be Compare September 11, 2023 23:22

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rebase & resolve DecimalDigits delete and add

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little-endian

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rebase PR openjdk#15651 last version

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wenshao changed the title ~~8315968: Consolidate java.util.Digits and StringLatin1::PACKED_DIGITS~~ 8315968: Move java.util.Digits to jdk.internal.util and refactor Sep 12, 2023

openjdk bot changed the title ~~8315968: Move java.util.Digits to jdk.internal.util and refactor~~ 8315968: Move java.util.Digits to jdk.internal.util and refactor Sep 12, 2023

wenshao changed the title ~~8315968: Move java.util.Digits to jdk.internal.util and refactor~~ 8315968: Move java.util.Digits to jdk.internal.util and refactor to reduce duplication Sep 12, 2023

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8315968: Move java.util.Digits to jdk.internal.util and refactor to reduce duplication #15651

8315968: Move java.util.Digits to jdk.internal.util and refactor to reduce duplication #15651

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