8316150: Refactor get chars and string size

[wenshao]

1. Reduce duplicate stringSize code
2. Move java.lang.StringLatin1.getChars to jdk.internal.util.DecimalDigits::getCharLatin1，not only java.lang, other packages also need to use this method

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Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed (2 reviews required, with at least 2 Reviewers)

Integration blocker

 ⚠️ Title mismatch between PR and JBS for issue JDK-8316150

Issue

• JDK-8316150: Refactor getChars and stringSize (Enhancement - P4) ⚠️ Title mismatch between PR and JBS.

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/15699/head:pull/15699
$ git checkout pull/15699

Update a local copy of the PR:
$ git checkout pull/15699
$ git pull https://git.openjdk.org/jdk.git pull/15699/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 15699

View PR using the GUI difftool:
$ git pr show -t 15699

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/15699.diff

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[bridgekeeper]

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[openjdk]

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

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• hotspot-compiler
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[mlbridge]

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[wenshao]

@cl4es can you help me to review this PR?

[AlanBateman]

/reviewers 2

[openjdk]

@AlanBateman
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).

[wenshao]

/label remove i18n

[openjdk]

@wenshao
The i18n label was successfully removed.

[wenshao]

/label remove hotspot-compiler

[openjdk]

@wenshao
The hotspot-compiler label was successfully removed.

[RogerRiggs]

There's a lot of duplication exposed here between the digits method and the getCharsLatin1 method that should be resolved.
Can the callers of getCharsLatin1 be converted to use digits?

We also should keep HexDigits and OctalDigits classes have a consistent API and functionality.

[openjdk]

@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 refactor_get_chars_and_string_size
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

[liach]

Since the current MethodHandle-based char putter can only put 1-byte at once, have you considered something like this:

// A replacement for setter MethodHandle, or VarHandle, to accept multiple value types
public interface DigitConsumer {
    void putChar(byte[] array, int index, byte value);
    // put 2 byte-sized chars at once, encoded little endian
    void putChar2(byte[] array, int index, short value);
    // you can add putChar4, putChar8, etc. if you need
}

and StringConcatHelper.selectPutChar will return a DigitConsumer instead of a MethodHandle.

Currently, you are allocating a new byte array for every number in the format, which I deem very inefficient.

[wenshao]

Since the current MethodHandle-based char putter can only put 1-byte at once, have you considered something like this:

// A replacement for setter MethodHandle, or VarHandle, to accept multiple value types
public interface DigitConsumer {
    void putChar(byte[] array, int index, byte value);
    // put 2 byte-sized chars at once, encoded little endian
    void putChar2(byte[] array, int index, short value);
    // you can add putChar4, putChar8, etc. if you need
}

and StringConcatHelper.selectPutChar will return a DigitConsumer instead of a MethodHandle.

Currently, you are allocating a new byte array for every number in the format, which I deem very inefficient.

Code based on MethodHandler is difficult to maintain and debug. We should remove the use of MethodHandle in FormatItem.

[ExE-Boss]

The throws Throwable declarations are no longer needed, as the prependers no longer depend on MethodHandles.

[RogerRiggs]

You could benefit from compiling and testing in your repo before committing; it would cut down on the spurious changes.
and/or (before pushing) squash the intermediate commits to a single commit with a salient comment.

[wenshao]

There are too many changes that need to be made to reduce the duplication of code in the digits method and the getCharsLatin1.

Can we temporarily allow duplicate code for digits and getCharLatin1? Revert changes related to FormatItem. After this PR is completed, submit a new PR to change FormatItem and reduce duplicate code.

[wenshao]

There's a lot of duplication exposed here between the digits method and the getCharsLatin1 method that should be resolved. Can the callers of getCharsLatin1 be converted to use digits?

We also should keep HexDigits and OctalDigits classes have a consistent API and functionality.

Changes related to FormatItem have been reverted because too many changes were made. The duplicate code of getChars and digits will be solved with another PR later.

[AlanBateman]

/reviewers 2 reviewer

[openjdk]

@AlanBateman
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 2 Reviewers).

[bridgekeeper]

@wenshao 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!

[bridgekeeper]

@wenshao This pull request has been inactive for more than 8 weeks and will now be automatically closed. If you would like to continue working on this pull request in the future, feel free to reopen it! This can be done using the /open pull request command.