Add a lock file around building the loom cache. Regenerate if the lock file exists.

This helps to ensure that failed or canceled builds do not cause the cache to be left in an undetectable invalid state.

src/main/java/net/fabricmc/loom/LoomGradleExtension.java

@@ -109,4 +109,8 @@ public interface LoomGradleExtension extends LoomGradleExtensionAPI {
 	void addTransitiveAccessWideners(List<AccessWidenerFile> accessWidenerFiles);
 
 	DownloadBuilder download(String url);
+
+	boolean refreshDeps();
+
+	void setRefreshDeps(boolean refreshDeps);
 }

src/main/java/net/fabricmc/loom/LoomGradlePlugin.java

@@ -48,7 +48,6 @@ import net.fabricmc.loom.task.LoomTasks;
 import net.fabricmc.loom.util.LibraryLocationLogger;
 
 public class LoomGradlePlugin implements BootstrappedPlugin {
-	public static boolean refreshDeps;
 	public static final Gson GSON = new GsonBuilder().setPrettyPrinting().create();
 	public static final ObjectMapper OBJECT_MAPPER = new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
 	public static final String LOOM_VERSION = Objects.requireNonNullElse(LoomGradlePlugin.class.getPackage().getImplementationVersion(), "0.0.0+unknown");
@@ -66,12 +65,6 @@ public class LoomGradlePlugin implements BootstrappedPlugin {
 		project.getLogger().lifecycle("Fabric Loom: " + LOOM_VERSION);
 		LibraryLocationLogger.logLibraryVersions();
 
-		refreshDeps = project.getGradle().getStartParameter().isRefreshDependencies() || Boolean.getBoolean("loom.refresh");
-
-		if (refreshDeps) {
-			project.getLogger().lifecycle("Refresh dependencies is in use, loom will be significantly slower.");
-		}
-
 		// Apply default plugins
 		project.apply(ImmutableMap.of("plugin", "java-library"));
 		project.apply(ImmutableMap.of("plugin", "eclipse"));

src/main/java/net/fabricmc/loom/api/mappings/layered/MappingContext.java

@@ -57,4 +57,6 @@ public interface MappingContext {
 	Logger getLogger();
 
 	DownloadBuilder download(String url);
+
+	boolean refreshDeps();
 }

src/main/java/net/fabricmc/loom/configuration/CompileConfiguration.java

@@ -24,7 +24,11 @@
 
 package net.fabricmc.loom.configuration;
 
+import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
 
 import org.gradle.api.NamedDomainObjectProvider;
@@ -32,7 +36,6 @@ import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.ConfigurationContainer;
 import org.gradle.api.plugins.JavaPlugin;
-import org.gradle.api.plugins.JavaPluginExtension;
 import org.gradle.api.tasks.AbstractCopyTask;
 import org.gradle.api.tasks.SourceSet;
 import org.gradle.api.tasks.compile.JavaCompile;
@@ -114,7 +117,6 @@ public final class CompileConfiguration {
 	}
 
 	public static void configureCompile(Project p) {
-		final JavaPluginExtension javaPluginExtension = p.getExtensions().getByType(JavaPluginExtension.class);
 		LoomGradleExtension extension = LoomGradleExtension.get(p);
 
 		p.getTasks().named(JavaPlugin.JAVADOC_TASK_NAME, Javadoc.class).configure(javadoc -> {
@@ -125,6 +127,13 @@ public final class CompileConfiguration {
 		p.afterEvaluate(project -> {
 			MinecraftSourceSets.get(project).afterEvaluate(project);
 
+			final boolean previousRefreshDeps = extension.refreshDeps();
+
+			if (getAndLock(project)) {
+				project.getLogger().lifecycle("Found existing cache lock file, rebuilding loom cache. This may have been caused by a failed or canceled build.");
+				extension.setRefreshDeps(true);
+			}
+
 			try {
 				setupMinecraft(project);
 			} catch (Exception e) {
@@ -135,6 +144,9 @@ public final class CompileConfiguration {
 			extension.setDependencyManager(dependencyManager);
 			dependencyManager.handleDependencies(project);
 
+			releaseLock(project);
+			extension.setRefreshDeps(previousRefreshDeps);
+
 			MixinExtension mixin = LoomGradleExtension.get(project).getMixin();
 
 			if (mixin.getUseLegacyMixinAp().get()) {
@@ -270,6 +282,38 @@ public final class CompileConfiguration {
 				.apply(project, extension.getNamedMinecraftProvider()).afterEvaluation();
 	}
 
+	private static Path getLockFile(Project project) {
+		final LoomGradleExtension extension = LoomGradleExtension.get(project);
+		final Path cacheDirectory = extension.getFiles().getProjectPersistentCache().toPath();
+		return cacheDirectory.resolve("configuration.lock");
+	}
+
+	private static boolean getAndLock(Project project) {
+		final Path lock = getLockFile(project);
+
+		if (Files.exists(lock)) {
+			return true;
+		}
+
+		try {
+			Files.createFile(lock);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to acquire project configuration lock", e);
+		}
+
+		return false;
+	}
+
+	private static void releaseLock(Project project) {
+		final Path lock = getLockFile(project);
+
+		try {
+			Files.deleteIfExists(lock);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to release project configuration lock", e);
+		}
+	}
+
 	public static void extendsFrom(List<String> parents, String b, Project project) {
 		for (String parent : parents) {
 			extendsFrom(parent, b, project);

src/main/java/net/fabricmc/loom/configuration/mods/ModConfigurationRemapper.java

@@ -49,7 +49,6 @@ import org.gradle.language.base.artifact.SourcesArtifact;
 import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.api.RemapConfigurationSettings;
 import net.fabricmc.loom.configuration.processors.dependency.ModDependencyInfo;
 import net.fabricmc.loom.configuration.processors.dependency.RemapData;
@@ -67,7 +66,6 @@ public class ModConfigurationRemapper {
 
 	public static void supplyModConfigurations(Project project, String mappingsSuffix, LoomGradleExtension extension, SourceRemapper sourceRemapper) {
 		final DependencyHandler dependencies = project.getDependencies();
-		final boolean refreshDeps = LoomGradlePlugin.refreshDeps;
 
 		final File modStore = extension.getFiles().getRemappedModCache();
 		final RemapData remapData = new RemapData(mappingsSuffix, modStore);
@@ -99,7 +97,7 @@ public class ModConfigurationRemapper {
 
 					final ModDependencyInfo info = new ModDependencyInfo(artifact, remappedConfig, clientRemappedConfig, remapData);
 
-					if (refreshDeps) {
+					if (extension.refreshDeps()) {
 						info.forceRemap();
 					}
 
@@ -198,7 +196,7 @@ public class ModConfigurationRemapper {
 			return;
 		}
 
-		if (!output.exists() || input.lastModified() <= 0 || input.lastModified() > output.lastModified() || LoomGradlePlugin.refreshDeps) {
+		if (!output.exists() || input.lastModified() <= 0 || input.lastModified() > output.lastModified() || LoomGradleExtension.get(project).refreshDeps()) {
 			sourceRemapper.scheduleRemapSources(input, output, false, true); // Depenedency sources are used in ide only so don't need to be reproducable
 		} else {
 			project.getLogger().info(output.getName() + " is up to date with " + input.getName());

src/main/java/net/fabricmc/loom/configuration/providers/mappings/GradleMappingContext.java

@@ -89,6 +89,11 @@ public class GradleMappingContext implements MappingContext {
 		return extension.download(url);
 	}
 
+	@Override
+	public boolean refreshDeps() {
+		return extension.refreshDeps();
+	}
+
 	public Project getProject() {
 		return project;
 	}

src/main/java/net/fabricmc/loom/configuration/providers/mappings/IntermediaryMappingsProvider.java

@@ -34,7 +34,6 @@ import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.api.mappings.intermediate.IntermediateMappingsProvider;
 
 public abstract class IntermediaryMappingsProvider extends IntermediateMappingsProvider {
@@ -42,9 +41,11 @@ public abstract class IntermediaryMappingsProvider extends IntermediateMappingsP
 
 	public abstract Property<String> getIntermediaryUrl();
 
+	public abstract Property<Boolean> getRefreshDeps();
+
 	@Override
 	public void provide(Path tinyMappings) throws IOException {
-		if (Files.exists(tinyMappings) && !LoomGradlePlugin.refreshDeps) {
+		if (Files.exists(tinyMappings) && !getRefreshDeps().get()) {
 			return;
 		}
 

src/main/java/net/fabricmc/loom/configuration/providers/mappings/LayeredMappingsDependency.java

@@ -76,7 +76,7 @@ public class LayeredMappingsDependency implements SelfResolvingDependency, FileC
 		Path mappingsDir = mappingContext.minecraftProvider().dir("layered").toPath();
 		Path mappingsFile = mappingsDir.resolve(String.format("%s.%s-%s.tiny", GROUP, MODULE, getVersion()));
 
-		if (!Files.exists(mappingsFile) || LoomGradlePlugin.refreshDeps) {
+		if (!Files.exists(mappingsFile) || mappingContext.refreshDeps()) {
 			try {
 				var processor = new LayeredMappingsProcessor(layeredMappingSpec);
 				List<MappingLayer> layers = processor.resolveLayers(mappingContext);

src/main/java/net/fabricmc/loom/configuration/providers/mappings/MappingsProviderImpl.java

@@ -137,11 +137,11 @@ public class MappingsProviderImpl implements MappingsProvider, SharedService {
 	}
 
 	private void setup(MinecraftProvider minecraftProvider, Path inputJar) throws IOException {
-		if (isRefreshDeps()) {
+		if (minecraftProvider.refreshDeps()) {
 			cleanWorkingDirectory(mappingsWorkingDir);
 		}
 
-		if (Files.notExists(tinyMappings) || isRefreshDeps()) {
+		if (Files.notExists(tinyMappings) || minecraftProvider.refreshDeps()) {
 			storeMappings(minecraftProvider, inputJar);
 		} else {
 			try (FileSystem fileSystem = FileSystems.newFileSystem(inputJar, (ClassLoader) null)) {
@@ -149,7 +149,7 @@ public class MappingsProviderImpl implements MappingsProvider, SharedService {
 			}
 		}
 
-		if (Files.notExists(tinyMappingsJar) || isRefreshDeps()) {
+		if (Files.notExists(tinyMappingsJar) || minecraftProvider.refreshDeps()) {
 			Files.deleteIfExists(tinyMappingsJar);
 			ZipUtils.add(tinyMappingsJar, "mappings/mappings.tiny", Files.readAllBytes(tinyMappings));
 		}
@@ -364,10 +364,6 @@ public class MappingsProviderImpl implements MappingsProvider, SharedService {
 	public record UnpickMetadata(String unpickGroup, String unpickVersion) {
 	}
 
-	protected static boolean isRefreshDeps() {
-		return LoomGradlePlugin.refreshDeps;
-	}
-
 	@Override
 	public void close() throws IOException {
 		mappingTree = null;

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MergedMinecraftProvider.java

@@ -61,7 +61,7 @@ public final class MergedMinecraftProvider extends MinecraftProvider {
 			throw new UnsupportedOperationException("Minecraft versions 1.2.5 and older cannot be merged. Please use `loom { server/clientOnlyMinecraftJar() }`");
 		}
 
-		if (!Files.exists(minecraftMergedJar) || isRefreshDeps()) {
+		if (!Files.exists(minecraftMergedJar) || getExtension().refreshDeps()) {
 			try {
 				mergeJars();
 			} catch (Throwable e) {

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/MinecraftProvider.java

@@ -277,7 +277,7 @@ public abstract class MinecraftProvider {
 		return LoomGradleExtension.get(getProject());
 	}
 
-	protected boolean isRefreshDeps() {
-		return LoomGradlePlugin.refreshDeps;
+	public boolean refreshDeps() {
+		return getExtension().refreshDeps();
 	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/SingleJarMinecraftProvider.java

@@ -69,7 +69,7 @@ public final class SingleJarMinecraftProvider extends MinecraftProvider {
 	public void provide() throws Exception {
 		super.provide();
 
-		boolean requiresRefresh = isRefreshDeps() || Files.notExists(minecraftEnvOnlyJar);
+		boolean requiresRefresh = getExtension().refreshDeps() || Files.notExists(minecraftEnvOnlyJar);
 
 		if (!requiresRefresh) {
 			return;

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/SplitMinecraftProvider.java

@@ -57,7 +57,7 @@ public final class SplitMinecraftProvider extends MinecraftProvider {
 	public void provide() throws Exception {
 		super.provide();
 
-		boolean requiresRefresh = isRefreshDeps() || Files.notExists(minecraftClientOnlyJar) || Files.notExists(minecraftCommonJar);
+		boolean requiresRefresh = getExtension().refreshDeps() || Files.notExists(minecraftClientOnlyJar) || Files.notExists(minecraftCommonJar);
 
 		if (!requiresRefresh) {
 			return;

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/AbstractMappedMinecraftProvider.java

@@ -34,7 +34,6 @@ import java.util.Map;
 import org.gradle.api.Project;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
 import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
@@ -67,7 +66,7 @@ public abstract class AbstractMappedMinecraftProvider<M extends MinecraftProvide
 		final List<RemappedJars> remappedJars = getRemappedJars();
 		assert !remappedJars.isEmpty();
 
-		if (!areOutputsValid(remappedJars) || LoomGradlePlugin.refreshDeps) {
+		if (!areOutputsValid(remappedJars) || extension.refreshDeps()) {
 			try {
 				remapInputs(remappedJars);
 			} catch (Throwable t) {

src/main/java/net/fabricmc/loom/configuration/providers/minecraft/mapped/ProcessedNamedMinecraftProvider.java

@@ -32,7 +32,6 @@ import java.nio.file.StandardCopyOption;
 import java.util.List;
 
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.processors.JarProcessorManager;
 import net.fabricmc.loom.configuration.providers.minecraft.MergedMinecraftProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
@@ -64,7 +63,7 @@ public abstract class ProcessedNamedMinecraftProvider<M extends MinecraftProvide
 		parentMinecraftProvider.provide(false);
 
 		final List<Path> inputJars = parentMinecraftProvider.getMinecraftJars();
-		boolean requiresProcessing = LoomGradlePlugin.refreshDeps || inputJars.stream()
+		boolean requiresProcessing = extension.refreshDeps() || inputJars.stream()
 				.map(this::getProcessedPath)
 				.map(Path::toFile)
 				.anyMatch(jarProcessorManager::isInvalid);

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

@@ -69,6 +69,7 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 	private NamedMinecraftProvider<?> namedMinecraftProvider;
 	private IntermediaryMinecraftProvider<?> intermediaryMinecraftProvider;
 	private InstallerData installerData;
+	private boolean refreshDeps;
 
 	public LoomGradleExtensionImpl(Project project, LoomFiles files) {
 		super(project, files);
@@ -83,7 +84,15 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 			provider.getIntermediaryUrl()
 					.convention(getIntermediaryUrl())
 					.finalizeValueOnRead();
+
+			provider.getRefreshDeps().set(project.provider(() -> LoomGradleExtension.get(project).refreshDeps()));
 		});
+
+		refreshDeps = project.getGradle().getStartParameter().isRefreshDependencies() || Boolean.getBoolean("loom.refresh");
+
+		if (refreshDeps) {
+			project.getLogger().lifecycle("Refresh dependencies is in use, loom will be significantly slower.");
+		}
 	}
 
 	@Override
@@ -227,12 +236,19 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 			builder.forceDownload();
 		}
 
-		// TODO
-		//builder.executor();
-
 		return builder;
 	}
 
+	@Override
+	public boolean refreshDeps() {
+		return refreshDeps;
+	}
+
+	@Override
+	public void setRefreshDeps(boolean refreshDeps) {
+		this.refreshDeps = refreshDeps;
+	}
+
 	@Override
 	protected <T extends IntermediateMappingsProvider> void configureIntermediateMappingsProviderInternal(T provider) {
 		provider.getMinecraftVersion().set(getProject().provider(() -> getMinecraftProvider().minecraftVersion()));