RFR: 8378759: Make ZipFile.CleanableResource.inflaterCache field final [v2]

[Chen Liang]

On Thu, 26 Feb 2026 13:39:51 GMT, Eirik Bjørsnøs <eirbjo at openjdk.org> wrote:

>> Please review this cleanup PR where we simplify synchronization on ZipFile's inflater cache.
>> 
>> Currently, the `ZipFile.CleanableResource.inflaterCache` field is non-final, is used in synchronization and is set to `null` to indicate a closed inflater cache. This complicates the state considerations for synchronization, requiring double-checking that the cache does not close under us. Generally, correctness of synchronizing on a non-final field which can also be null is hard to reason about.
>> 
>> This PR marks the `inflaterCache` field as `final` and introduces a boolean flag field to model the closed state explicitly. This allows synchronization to be simplified, double-checking to be removed and the closed state to be more obvious. If we want the future ZipFile to be less mutable, this is one step in that direction.
>> 
>> Cleanup refactoring, `noreg-cleanup`
>
> Eirik Bjørsnøs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reduce memory retained by a closed ZipFile

Old code ensured getInflater can fail properly when inflaterCache is null. This safety is lost in your refactor.

src/java.base/share/classes/java/util/zip/ZipFile.java line 736:

> 734:                 if (inflaterCacheClosed) {
> 735:                     // inflaters cache already closed - just end it.
> 736:                     inf.end();

In your new code, we always need to get the inflaterCache monitor to end an inflator when the cache is closed. Could be a regression.

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PR Review: https://git.openjdk.org/jdk/pull/29937#pullrequestreview-3861810399
PR Review Comment: https://git.openjdk.org/jdk/pull/29937#discussion_r2859749076