Configuration cache support for SourceSetHelper.findFileInResource

src/main/java/net/fabricmc/loom/extension/LoomFilesBaseImpl.java

@@ -40,11 +40,7 @@ public LoomFilesBaseImpl() { }
 
 	private static File createFile(File parent, String child) {
 		File file = new File(parent, child);
-
-		if (!file.exists()) {
-			file.mkdirs();
-		}
-
+		file.mkdirs();
 		return file;
 	}
 

src/main/java/net/fabricmc/loom/util/gradle/GradleUtils.java

@@ -24,9 +24,11 @@
 
 package net.fabricmc.loom.util.gradle;
 
+import java.io.File;
 import java.util.function.Consumer;
 
 import org.gradle.api.Project;
+import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.invocation.Gradle;
 import org.gradle.api.provider.Provider;
 
@@ -78,4 +80,12 @@ public static Provider<Boolean> getBooleanPropertyProvider(Project project, Stri
 	public static boolean getBooleanProperty(Project project, String key) {
 		return getBooleanPropertyProvider(project, key).getOrElse(false);
 	}
+
+	// A hack to include the given file in the configuration cache input
+	// this ensures that configuration cache is invalidated when the file changes
+	public static File configurationInputFile(Project project, File file) {
+		final RegularFileProperty property = project.getObjects().fileProperty();
+		property.set(file);
+		return property.getAsFile().get();
+	}
 }

src/main/java/net/fabricmc/loom/util/gradle/SourceSetHelper.java

@@ -241,8 +241,14 @@ public static File findFileInResource(SourceSet sourceSet, String path) {
 		final LoomGradleExtension extension = LoomGradleExtension.get(project);
 
 		if (extension.isConfigurationCacheActive()) {
-			// TODO config cache, figure this out
-			project.getLogger().warn("Unable to find resource ({}) in source set ({}) when configuration cache is active", path, sourceSet.getName());
+			for (File rootDir: sourceSet.getResources().getSrcDirs()) {
+				final File file = GradleUtils.configurationInputFile(project, new File(rootDir, path));
+
+				if (file.exists()) {
+					return file;
+				}
+			}
+
 			return null;
 		}
 

src/test/groovy/net/fabricmc/loom/test/integration/ConfigurationCacheTest.groovy

@@ -30,6 +30,7 @@ import spock.lang.Unroll
 import net.fabricmc.loom.test.util.GradleProjectTestTrait
 
 import static net.fabricmc.loom.test.LoomTestConstants.PRE_RELEASE_GRADLE
+import static net.fabricmc.loom.test.LoomTestConstants.STANDARD_TEST_VERSIONS
 import static org.gradle.testkit.runner.TaskOutcome.FAILED
 
 class ConfigurationCacheTest extends Specification implements GradleProjectTestTrait {
@@ -60,4 +61,75 @@ class ConfigurationCacheTest extends Specification implements GradleProjectTestT
 		"jar"                     | _
 		"check"                   | _
 	}
+
+	// Test GradleUtils.configurationInputFile invalidates the cache when the file changes
+	@Unroll
+	def "File input (#version)"() {
+		setup:
+		def gradle = gradleProject(project: "minimalBase", version: version)
+		gradle.buildGradle << """
+            dependencies {
+                minecraft 'com.mojang:minecraft:1.20.4'
+                mappings 'net.fabricmc:yarn:1.20.4+build.3:v2'
+                modImplementation 'net.fabricmc:fabric-loader:0.15.6'
+            }
+
+			abstract class TestTask extends DefaultTask {
+				@Input
+				abstract Property<String> getModVersion()
+
+				@TaskAction
+				void run() {
+					println "Version: " + modVersion.get()
+				}
+			}
+
+			println "Configuring task testTask"
+            tasks.register('testTask', TestTask) {
+            	modVersion.set(loom.getModVersion()) // loom.getModVersion() returns a String
+			}
+            """.stripIndent()
+
+		def fabricModJson = new File(gradle.projectDir, "src/main/resources/fabric.mod.json")
+		fabricModJson.parentFile.mkdirs()
+		fabricModJson.text = fmj("1.0.0")
+
+		when:
+		def result = gradle.run(task: "testTask", configurationCache: true)
+		def result2 = gradle.run(task: "testTask", configurationCache: true)
+		fabricModJson.text = fmj("2.0.0")
+		def result3 = gradle.run(task: "testTask", configurationCache: true)
+
+		then:
+		// Test that the cache is created
+		result.task(":testTask").outcome != FAILED
+		result.output.contains("Calculating task graph as no cached configuration is available for tasks: testTask")
+		result.output.contains("Configuring task testTask")
+		result.output.contains("Version: 1.0.0")
+
+		// Test that the cache is reused when nothing has changed
+		result2.task(":testTask").outcome != FAILED
+		!result2.output.contains("Calculating task graph")
+		!result2.output.contains("Configuring task testTask")
+		result2.output.contains("Version: 1.0.0")
+
+		// Test that the cache is invalidated when the file changes
+		result3.task(":testTask").outcome != FAILED
+		result3.output.contains("Calculating task graph as configuration cache cannot be reused because file 'src/main/resources/fabric.mod.json' has changed.".replace("/", File.separator))
+		result3.output.contains("Configuring task testTask")
+		result3.output.contains("Version: 2.0.0")
+
+		where:
+		version << STANDARD_TEST_VERSIONS
+	}
+
+	static def fmj(String version) {
+		return """
+		{
+			"schemaVersion": 1,
+			"id": "test",
+			"version": "${version}"
+		}
+		"""
+	}
 }