RFR: 8322809: SystemModulesMap::classNames and moduleNames arrays do not match the order

[Alan Bateman]

On Tue, 9 Jan 2024 00:17:48 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> One optimization of Jlink SystemModulesPlugin pre-resolves the module graph for modules with a main class.  It stores the name of the initial module and the generated `SystemModules` class name in two arrays that can be obtained from `SystemModulesMap::moduleNames` and `SystemModulesMap::classNames`.   The elements in the array returned by `classNames()` are supposed to correspond to the elements in the array returned by `moduleNames()`.    However, the implementation sorts both arrays by the value of the elements. 
> 
> This fix is simple and write the correct class names and not to sort the values separately.

Looks good, surprising we didn't notice this before now but perhaps not too common to have several modules in the run-time image with a main class. I assume you'll bump the copyright header of SystemModulesPlugin before integrating.

test/jdk/tools/jlink/plugins/SystemModuleDescriptors/ModuleMainClassTest.java line 59:

> 57:     private static final Path SRC_DIR = Paths.get(TEST_SRC, "src");
> 58:     private static final Path MODS_DIR = Paths.get("mods");
> 59:     private static final Path JMODS_DIR = Paths.get("jmods");

In passing, these can use Path.of if you want.

test/jdk/tools/jlink/plugins/SystemModuleDescriptors/src/com.foo/module-info.java line 25:

> 23: 
> 24: module com.foo {
> 25:     requires jdk.httpserver;

This `requires` means the run-time image created by the test will have 3 modules with main classes. It needs a minimum of 2 so this dependency is okay.

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Marked as reviewed by alanb (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17316#pullrequestreview-1810822187
PR Review Comment: https://git.openjdk.org/jdk/pull/17316#discussion_r1445883006
PR Review Comment: https://git.openjdk.org/jdk/pull/17316#discussion_r1445882416