On Thu, 30 Apr 2026 12:42:12 GMT, David Beaumont <[email protected]> wrote:
>> Implementation of preview-mode support for jimage modules file, migrated >> from Valhalla related work (see JDK-8352750). >> >> This PR (the first of several) migrates work from Valhalla (lworld) to the >> JDK mainline repository in relation to "preview mode" support. It affects >> the creation and reading of the jimage file, both in Java >> (BasicImageReader/ImageReader) and C++ (imageFile.xpp/jimage.xpp). >> >> Preview mode is a mechanism by which alternate version of JDK class files >> and resources can be made available for class loading and reflection when >> the '--enable-preview' flag is passed to the runtime. >> >> Alternate classes/resource appear in each module under the: >> >> /<module>/META-INF/preview/<path-to>/<resource-or-class> >> >> and replace the original: >> >> /<module>/<path-to>/<resource-or-class> >> >> files when preview mode is enabled. >> >> While initially useful for Valhalla work, this mechanism will be used for >> other cases where preview features (in the JEP 12 sense) require alternate >> classes/resources to be provided. None of the changes in this (or the >> follow-up PRs) are Valhalla specific. >> >> In this PR: >> * the writing of jimage files is modified to recognize and handle preview >> mode paths >> * flags in the jimage file are added or modified to support preview mode >> efficiently >> * (C++) the class loader is modified to permit reading preview versions of >> classes >> * (Java) the image reader and associated JRT file-system classes are >> modified to permit reading preview files >> * unit tests are added to ensure preview mode works as expected when enabled >> * (temporary) any code calling into the affected API (other than tests) >> specifies that preview mode is disabled >> >> Future PRs will add the plumbing to enable preview mode correctly, but with >> the PR there should be no observable change in behaviour (especially since >> no preview classes or resources are being supplied at this point). >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > David Beaumont has updated the pull request with a new target base due to a > merge or a rebase. The pull request now contains 22 commits: > > - Merge branch 'master' into jimage_preview_mode > - fix test failure in linkable image > - update test with correct dep > - Fix issue with resource lookup in ImageReader > - Merge branch 'master' into jimage_preview_mode > - High level test for preview mode > - renaming based on feedback > - Rename ModuleReference to ModuleLink > - tweak comments > - Feedback changes > - ... and 12 more: https://git.openjdk.org/jdk/compare/c8bb46be...7f17aa52 I went through the JRTArchive changes and `jlink` classes and associated tests. This looks fine to me. Impressive work. ------------- Marked as reviewed by sgehwolf (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/29414#pullrequestreview-4237659356
