Utilize a child-first strategy for resource loading (#6414)

* Utilize a child-first strategy for resource loading

* Add override annotations as desired by the review-bot

Author: shanman190

rewrite-core/src/main/java/org/openrewrite/marketplace/RecipeClassLoader.java

@@ -17,14 +17,13 @@
 
 import org.jspecify.annotations.Nullable;
 
+import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.file.Path;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Objects;
+import java.util.*;
 import java.util.stream.Stream;
 
 import static java.util.Collections.emptyList;
@@ -129,6 +128,27 @@ protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundE
         }
     }
 
+    @Override
+    public @Nullable URL getResource(String name) {
+        Objects.requireNonNull(name);
+        URL url = findResource(name);
+        if (url == null) {
+            return parent.getResource(name);
+        }
+        return url;
+    }
+
+    @Override
+    public Enumeration<URL> getResources(String name) throws IOException {
+        Objects.requireNonNull(name);
+        @SuppressWarnings("unchecked")
+        Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
+        tmp[0] = findResources(name);
+        tmp[1] = parent.getResources(name);
+
+        return new CompoundEnumeration<>(tmp);
+    }
+
     private boolean shouldDelegateToParent(String className) {
         // Check additional delegations first (can be overridden)
         for (String prefix : getAdditionalParentDelegatedPackages()) {
@@ -208,3 +228,39 @@ public static URL[] getUrls(@Nullable Path recipeJar, List<Path> classpath) {
                 .toArray(URL[]::new);
     }
 }
+
+/*
+ * A utility class that will enumerate over an array of enumerations.
+ * @see java.lang.CompoundEnumeration
+ */
+final class CompoundEnumeration<E> implements Enumeration<E> {
+    private final Enumeration<E>[] enums;
+    private int index;
+
+    public CompoundEnumeration(Enumeration<E>[] enums) {
+        this.enums = enums;
+    }
+
+    private boolean next() {
+        while (index < enums.length) {
+            if (enums[index] != null && enums[index].hasMoreElements()) {
+                return true;
+            }
+            index++;
+        }
+        return false;
+    }
+
+    @Override
+    public boolean hasMoreElements() {
+        return next();
+    }
+
+    @Override
+    public E nextElement() {
+        if (!next()) {
+            throw new NoSuchElementException();
+        }
+        return enums[index].nextElement();
+    }
+}

rewrite-core/src/test/java/org/openrewrite/marketplace/RecipeClassLoaderTest.java

@@ -16,15 +16,22 @@
 package org.openrewrite.marketplace;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.openrewrite.Recipe;
 import org.openrewrite.config.ClasspathScanningLoader;
 import org.openrewrite.config.Environment;
 import org.openrewrite.config.RecipeDescriptor;
+import org.openrewrite.internal.StringUtils;
 
 import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
+import java.util.Enumeration;
 import java.util.List;
 import java.util.Properties;
 
@@ -77,4 +84,83 @@ void loadRecipeWithIsolatedClassLoader() {
           .as("Recipe should be loaded through RecipeClassLoader for isolation")
           .isInstanceOf(RecipeClassLoader.class);
     }
+
+    @Test
+    void resourcesShouldBeChildLoaded(@TempDir Path tempDir) throws IOException {
+        Path lib1 = tempDir.resolve("lib1");
+        Files.createDirectories(lib1);
+        Path file1 = lib1.resolve("rewrite.txt");
+        Files.write(file1, "file1".getBytes());
+        Path lib2 = tempDir.resolve("lib2");
+        Files.createDirectories(lib2);
+        Path file2 = lib2.resolve("rewrite.txt");
+        Files.write(file2, "file2".getBytes());
+
+        try (URLClassLoader urlClassLoader = new URLClassLoader(new URL[]{lib1.toUri().toURL()})) {
+            try (RecipeClassLoader classLoader = new RecipeClassLoader(new URL[]{lib2.toUri().toURL()}, urlClassLoader)) {
+                String text = StringUtils.readFully(classLoader.getResourceAsStream("rewrite.txt"));
+                assertThat(text).isEqualTo("file2");
+            }
+        }
+    }
+
+    @Test
+    void resourcesShouldFindFromParentLast(@TempDir Path tempDir) throws IOException {
+        Path lib1 = tempDir.resolve("lib1");
+        Files.createDirectories(lib1);
+        Path file1 = lib1.resolve("rewrite.txt");
+        Files.write(file1, "file1".getBytes());
+        Path lib2 = tempDir.resolve("lib2");
+        Files.createDirectories(lib2);
+
+        try (URLClassLoader urlClassLoader = new URLClassLoader(new URL[]{lib1.toUri().toURL()})) {
+            try (RecipeClassLoader classLoader = new RecipeClassLoader(new URL[]{lib2.toUri().toURL()}, urlClassLoader)) {
+                String text = StringUtils.readFully(classLoader.getResourceAsStream("rewrite.txt"));
+                assertThat(text).isEqualTo("file1");
+            }
+        }
+    }
+
+    @Test
+    void allResourcesShouldFindFromChildFirst(@TempDir Path tempDir) throws IOException {
+        Path lib1 = tempDir.resolve("lib1");
+        Files.createDirectories(lib1);
+        Path file1 = lib1.resolve("rewrite.txt");
+        Files.write(file1, "file1".getBytes());
+        Path lib2 = tempDir.resolve("lib2");
+        Files.createDirectories(lib2);
+        Path file2 = lib2.resolve("rewrite.txt");
+        Files.write(file2, "file2".getBytes());
+
+        try (URLClassLoader urlClassLoader = new URLClassLoader(new URL[]{lib1.toUri().toURL()})) {
+            try (RecipeClassLoader classLoader = new RecipeClassLoader(new URL[]{lib2.toUri().toURL()}, urlClassLoader)) {
+                Enumeration<URL> resources = classLoader.getResources("rewrite.txt");
+                assertThat(resources.hasMoreElements()).isTrue();
+                assertThat(resources.nextElement().toString()).contains("lib2/rewrite.txt");
+                assertThat(resources.hasMoreElements()).isTrue();
+                assertThat(resources.nextElement().toString()).contains("lib1/rewrite.txt");
+                assertThat(resources.hasMoreElements()).isFalse();
+            }
+        }
+    }
+
+    @Test
+    void allResourcesShouldFindFromParentLast(@TempDir Path tempDir) throws IOException {
+        Path lib1 = tempDir.resolve("lib1");
+        Files.createDirectories(lib1);
+        Path file1 = lib1.resolve("rewrite.txt");
+        Files.write(file1, "file1".getBytes());
+        Path lib2 = tempDir.resolve("lib2");
+        Files.createDirectories(lib2);
+
+        try (URLClassLoader urlClassLoader = new URLClassLoader(new URL[]{lib1.toUri().toURL()})) {
+            try (RecipeClassLoader classLoader = new RecipeClassLoader(new URL[]{lib2.toUri().toURL()}, urlClassLoader)) {
+                Enumeration<URL> resources = classLoader.getResources("rewrite.txt");
+                assertThat(resources.hasMoreElements()).isTrue();
+                assertThat(resources.nextElement().toString()).contains("lib1/rewrite.txt");
+                assertThat(resources.hasMoreElements()).isFalse();
+
+            }
+        }
+    }
 }