CombinedResource no longer deduplicates the same jar

[anetaporebska]

Jetty version(s)

12.1.9

Jetty Environment

HTTP version

Java version/vendor (use: java -version)
openjdk 25.0.3-ea

OS type/version
Ubuntu 26.04

Description

After the FileSystemPool deprecation in PR #14826, ResourceFactory.newClassLoaderResource(...) can return a multi-member CombinedResource whose members all point at the same jar entry. CombinedResource.gatherUniqueFlatResourceList no longer collapses them because PathResource.equals now returns false for what is effectively the same path but on different filesystems because of MountedPathResourceFactory.newFileSystem(...).

Affected code

• org.eclipse.jetty.util.resource.ResourceFactory#newClassLoaderResource(String, boolean)
• org.eclipse.jetty.util.resource.CombinedResource#gatherUniqueFlatResourceList(List)

How to reproduce?

Setup: any classpath where the same resource is visible through more than one classloader in newClassLoaderResource's search order (context CL, ResourceFactory.class CL, optionally system CL)

Easily reproduces with swagger-ui webjar.

        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-util</artifactId>
            <version>12.1.9</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>swagger-ui</artifactId>
            <version>5.32.5</version>
        </dependency>

        System.out.println("jetty-util " + ResourceFactory.class.getPackage().getImplementationVersion());

        try (ResourceFactory.Closeable rf = ResourceFactory.closeable()) {
            Resource r = rf.newClassLoaderResource("META-INF/resources/webjars/swagger-ui");

            System.out.println("class: " + r.getClass().getSimpleName());
            System.out.println("getURI(): " + r.getURI());

            if (r instanceof CombinedResource combined && combined.getResources().size() >= 2) {
                Resource a = combined.getResources().get(0);
                Resource b = combined.getResources().get(1);
                System.out.println("members: " + combined.getResources().size());
                System.out.println("a.getURI().equals(b.getURI())                              = " + a.getURI().equals(b.getURI()));
                System.out.println("a.getPath().getFileSystem() == b.getPath().getFileSystem() = " + (a.getPath().getFileSystem() == b.getPath().getFileSystem()));
                System.out.println("a.getPath().equals(b.getPath())                            = " + a.getPath().equals(b.getPath()));
                System.out.println("a.equals(b)                                                = " + a.equals(b));
            }

12.1.8 output

  jetty-util 12.1.8
  class: MountedPathResource
  getURI(): jar:file:///home/aneta/.m2/repository/org/webjars/swagger-ui/5.32.5/swagger-ui-5.32.5.jar!/META-INF/resources/webjars/swagger-ui/

12.1.9 output

  jetty-util 12.1.9
  class: CombinedResource
  getURI(): null
  members: 2
  a.getURI().equals(b.getURI())                              = true
  a.getPath().getFileSystem() == b.getPath().getFileSystem() = false
  a.getPath().equals(b.getPath())                            = false
  a.equals(b)                                                = false

[joakime]

The same jar:file:///path/to/foo.jar!/content/inside.txt from different ResourceFactory calls are different Path objects with different FileSystem instances.

Not sure it's safe to de-duplicate based on the Path alone.