RFR: JDK-8318563: GetClassFields should not use random access to field

[Serguei Spitsyn]

On Wed, 13 Dec 2023 21:32:50 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> FieldStream/FilteredFieldStream classes from reflectionUtils.hpp iterate class fields in the reverse order and use field indexes to access instead of forward iteration. This is performance ineffective (see [JDK-8317692](https://bugs.openjdk.org/browse/JDK-8317692) for details).
> The change introduces new class FilteredJavaFieldStream as a replacement for FilteredFieldStream.
> It uses the same FilteredField/FilteredFieldsMap stuff as FilteredJavaFieldStream does.
> 
> FieldStream/FilteredFieldStream are still used by heap walking API, will be cleaned by [JDK-8317636](https://bugs.openjdk.org/browse/JDK-8317636)
> 
> Testing:
> - tier1..3
> - all tests which calls GetClassFields: open/test/hotspot/jtreg/serviceability/jvmti,open/test/hotspot/jtreg/vmTestbase/nsk/jvmti/GetClassFields,open/test/hotspot/jtreg/vmTestbase/nsk/jvmti/IterateThroughHeap,open/test/hotspot/jtreg/vmTestbase/nsk/jvmti/unit/IsSynthetic
> including
>   - test/hotspot/jtreg/vmTestbase/nsk/jvmti/GetClassFields/getclfld007.java - tests that GetClassFields returns fields in correct order;
>   - test/hotspot/jtreg/serviceability/jvmti/GetClassFields/FilteredFields/FilteredFieldsTest.java - test that GetClassFields filters out field like reflection.

This looks good in general. Will make one more pass tomorrow.

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PR Comment: https://git.openjdk.org/jdk/pull/17094#issuecomment-1855032678