RFR: 8364544: Extract the checks of AtomicXxxFieldUpdater into a common place [v3]

[Steve Armstrong]

On Tue, 25 Nov 2025 03:56:10 GMT, Steve Armstrong <duke at openjdk.org> wrote:

>> The three AtomicXxxFieldUpdater classes (AtomicIntegerFieldUpdater, AtomicLongFieldUpdater, and AtomicReferenceFieldUpdater) contain duplicate field validation and access checking logic in their constructors and helper methods.
>> 
>> This change extracts the common validation and utility methods into a new package-private class FieldUpdaterUtil to eliminate code duplication and improve maintainability.
>> 
>> Changes:
>> - Added new FieldUpdaterUtil class with static utility methods:
>>   * validateField() - validates field type, volatile, and static checks
>>   * computeAccessClass() - determines correct class for access checks
>>   * isSamePackage() - checks if two classes are in same package
>>   * isAncestor() - checks classloader delegation chain
>> 
>> - Updated AtomicIntegerFieldUpdater to use FieldUpdaterUtil
>>   * Simplified constructor to use validateField() and computeAccessClass()
>>   * Removed duplicate isAncestor() and isSamePackage() methods
>> 
>> - Updated AtomicLongFieldUpdater to use FieldUpdaterUtil
>>   * Simplified constructor to use validateField() and computeAccessClass()
>>   * Removed duplicate isAncestor() and isSamePackage() methods
>> 
>> - Updated AtomicReferenceFieldUpdater to use FieldUpdaterUtil
>>   * Simplified constructor to use validateField() and computeAccessClass()
>>   * Removed duplicate isAncestor() and isSamePackage() methods
>> 
>> Existing tests in test/jdk/java/util/concurrent/tck and test/jdk/java/util/concurrent/atomic verify that the refactoring preserves the original behavior.
>
> Steve Armstrong has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
> 
>   Refactor FieldUpdaterUtil API based on review feedback
>   
>   Simplified the API by combining field lookup and validation into a
>   single findValidatedField() method, eliminating the need for the
>   redundant FieldAndModifiers record since Field already provides
>   getModifiers(). This makes the API more ergonomic and the caller
>   code more concise.

Thanks for catching that! Fixed the try-catch block - validation exceptions are now thrown directly. Couldn't run the full test suite locally due to Xcode requirements, but verified the fix logic with a standalone test.

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PR Comment: https://git.openjdk.org/jdk/pull/28464#issuecomment-3573721117