JDK-8374395 : Improve MemoryUsage.toString() and constructor error messages for better clarity

[thswlsqls]

Summary

MemoryUsage.toString() now displays "N/A" for undefined init and max values (-1) instead of "-1(-1K)".

This addresses the first of three issues in JDK-8374395.

Description

When init or max is -1 (undefined), toString() outputs "-1(-1K)". The Javadoc states that -1 means undefined, but the output does not clearly indicate this.

toString() checks if init or max equals -1 and outputs "init = N/A" or "max = N/A" respectively. Output format for valid values remains unchanged.

Added test cases to the existing jtreg test file. All tests pass.

Bug-ID : JDK-8374395

https://bugs.java.com/bugdatabase/view_bug?bug_id=JDK-8374395

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Progress

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Issue

• JDK-8374395: Improve MemoryUsage.toString() and constructor error messages for better clarity (Enhancement - P3)

Reviewing

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[bridgekeeper]

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[openjdk]

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (413e3c12)
• 00: Full (479857d0)

[AlanBateman]

This addresses the first of three issues in JDK-8374395.

Note that you can't use the same JBS issue for different PRs/commits. If there are other changes proposed then they will need their own JBS issues. If this issue is only for changing MemoryUsage::toString then it should be renamed as it is confusing to see "constructor error messages" in the title when there is no change to the constructor.

MemoryUsage's methods are specified to return -1 for undefined so I don't think it's too surprising that the toString method includes "-1" values.

BTW: test/jdk/java/lang/management/MemoryUsage would be a better place for unit tests for this API.

[openjdk]

@thswlsqls core-libs has been added to this pull request based on files touched in new commit(s).

[thswlsqls]

@AlanBateman Thanks for the review. Addressed.

Would it be possible to review this PR for the first issue of JDK-8374395 only?
Should I create separate JBS issues for the remaining two?

[AlanBateman]

/label remove core-libs

[openjdk]

@AlanBateman
The core-libs label was successfully removed.

[thswlsqls]

/integrate

[openjdk]

@thswlsqls This pull request has not yet been marked as ready for integration.

[kevinjwalls]

When init or max is -1 (undefined), MemoryUsage.toString() outputs "-1(-1K)", which is confusing. While Javadoc states that -1 means undefined, the output does not clearly indicate this, making it difficult for users to distinguish undefined values from actual negative values.

Hi. When does this happen? When is a MemoryUsage created with init or max as -1 ? When is it then printed using toString() for a user to understand, and when would the user then have to distinguish between the -1 which suggests a problem, and "actual negative values"?