Fix performance regressions in large multi-project builds. (#571)

* Perf improvements to multi-project builds.

* Fixes.

* More fixes.

* Layered mappings fixes

* Perf improvements. Undo broken fix.

* Fix remap classpath being empty.

* Another gradle bug? Either way this is fine and works.

* Fix broken test

* Final fixes?

* Fix and cleanup mixin ap mappings.

build.gradle

@@ -114,14 +114,8 @@ jar {
 	from configurations.bootstrap.collect { it.isDirectory() ? it : zipTree(it) }
 }
 
-task sourcesJar(type: Jar, dependsOn: classes) {
+java {
-	archiveClassifier = 'sources'
+	withSourcesJar()
-	from sourceSets.main.allSource
-}
-
-task javadocJar(type: Jar, dependsOn: javadoc) {
-	archiveClassifier = 'javadoc'
-	from javadoc.destinationDir
 }
 
 spotless {
@@ -197,10 +191,7 @@ publishing {
 			artifactId project.archivesBaseName
 			version project.version
 
-			from components['java']
+			from components.java
-
-			artifact sourcesJar
-			artifact javadocJar
 
 			pom.withXml {
 				patchPom(asNode())
@@ -213,10 +204,7 @@ publishing {
 			artifactId project.archivesBaseName
 			version baseVersion + '-SNAPSHOT'
 
-			from components['java']
+			from components.java
-
-			artifact sourcesJar
-			artifact javadocJar
 
 			pom.withXml {
 				patchPom(asNode())

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

@@ -24,7 +24,6 @@
 
 package net.fabricmc.loom;
 
-import java.io.File;
 import java.nio.file.Path;
 import java.util.List;
 import java.util.function.Supplier;
@@ -37,7 +36,6 @@ import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.file.FileCollection;
-import org.gradle.api.tasks.SourceSet;
 
 import net.fabricmc.loom.api.LoomGradleExtensionAPI;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
@@ -112,10 +110,6 @@ public interface LoomGradleExtension extends LoomGradleExtensionAPI {
 
 	FileCollection getMinecraftJarsCollection(MappingsNamespace mappingsNamespace);
 
-	File getMixinMappings(SourceSet sourceSet);
-
-	FileCollection getAllMixinMappings();
-
 	boolean isRootProject();
 
 	default String getIntermediaryUrl(String minecraftVersion) {

src/main/java/net/fabricmc/loom/api/decompilers/DecompilerOptions.java

@@ -37,7 +37,7 @@ public abstract class DecompilerOptions implements Named {
 	/**
 	 * Class name for to the {@link LoomDecompiler}.
 	 */
-	public abstract Property<String> getDecompilerClassname();
+	public abstract Property<String> getDecompilerClassName();
 
 	/**
 	 * Additional classpath entries for the decompiler jvm.
@@ -60,7 +60,7 @@ public abstract class DecompilerOptions implements Named {
 	public abstract Property<Integer> getMaxThreads();
 
 	public DecompilerOptions() {
-		getDecompilerClassname().finalizeValueOnRead();
+		getDecompilerClassName().finalizeValueOnRead();
 		getClasspath().finalizeValueOnRead();
 		getOptions().finalizeValueOnRead();
 		getMemory().convention(4096L).finalizeValueOnRead();
@@ -71,9 +71,9 @@ public abstract class DecompilerOptions implements Named {
 	public record Dto(String className, Map<String, String> options, int maxThreads) implements Serializable { }
 
 	public Dto toDto() {
-		Preconditions.checkArgument(getDecompilerClassname().isPresent(), "No decompiler classname specified for decompiler: " + getName());
+		Preconditions.checkArgument(getDecompilerClassName().isPresent(), "No decompiler classname specified for decompiler: " + getName());
 		return new Dto(
-				getDecompilerClassname().get(),
+				getDecompilerClassName().get(),
 				getOptions().get(),
 				getMaxThreads().get()
 		);

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

@@ -25,13 +25,14 @@
 package net.fabricmc.loom.api.mappings.layered;
 
 import java.nio.file.Path;
+import java.util.function.Supplier;
 
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.logging.Logger;
 import org.jetbrains.annotations.ApiStatus;
 
-import net.fabricmc.loom.configuration.providers.mappings.MappingsProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
 
 @ApiStatus.Experimental /* Very Experimental and not cleanly separated from the impl atm */
 public interface MappingContext {
@@ -39,7 +40,7 @@ public interface MappingContext {
 
 	Path resolveMavenDependency(String mavenNotation);
 
-	MappingsProvider mappingsProvider();
+	Supplier<MemoryMappingTree> intermediaryTree();
 
 	MinecraftProvider minecraftProvider();
 

src/main/java/net/fabricmc/loom/build/mixin/AnnotationProcessorInvoker.java

@@ -42,6 +42,7 @@ import org.gradle.api.tasks.SourceSet;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.ide.idea.IdeaUtils;
 import net.fabricmc.loom.extension.MixinExtension;
+import net.fabricmc.loom.task.service.MixinMappingsService;
 import net.fabricmc.loom.util.Constants;
 
 /**
@@ -84,7 +85,7 @@ public abstract class AnnotationProcessorInvoker<T extends Task> {
 			String refmapName = Objects.requireNonNull(MixinExtension.getMixinInformationContainer(sourceSet)).refmapNameProvider().get();
 			Map<String, String> args = new HashMap<>() {{
 					put(Constants.MixinArguments.IN_MAP_FILE_NAMED_INTERMEDIARY, loom.getMappingsProvider().tinyMappings.toFile().getCanonicalPath());
-					put(Constants.MixinArguments.OUT_MAP_FILE_NAMED_INTERMEDIARY, loom.getMixinMappings(sourceSet).getCanonicalPath());
+					put(Constants.MixinArguments.OUT_MAP_FILE_NAMED_INTERMEDIARY, MixinMappingsService.getMixinMappingFile(project, sourceSet).getCanonicalPath());
 					put(Constants.MixinArguments.OUT_REFMAP_FILE, getRefmapDestination(task, refmapName));
 					put(Constants.MixinArguments.DEFAULT_OBFUSCATION_ENV, "named:intermediary");
 				}};

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

@@ -193,15 +193,15 @@ public final class CompileConfiguration {
 
 		boolean split = project.getProperties().get("fabric.loom.experimental.splitMcJars") != null;
 
-		// Provide the vanilla mc jars
+		// Provide the vanilla mc jars -- TODO share across projects.
 		final MinecraftProvider minecraftProvider = split ? new SplitMinecraftProvider(project) : new MergedMinecraftProvider(project);
 		extension.setMinecraftProvider(minecraftProvider);
 		minecraftProvider.provide();
 
-		// Provide the mappings
+		final DependencyInfo mappingsDep = DependencyInfo.create(project, Constants.Configurations.MAPPINGS);
-		final MappingsProviderImpl mappingsProvider = new MappingsProviderImpl(project, minecraftProvider);
+		final MappingsProviderImpl mappingsProvider = MappingsProviderImpl.getInstance(project, mappingsDep, minecraftProvider);
 		extension.setMappingsProvider(mappingsProvider);
-		mappingsProvider.provide();
+		mappingsProvider.applyToProject(project, mappingsDep);
 
 		// Provide the remapped mc jars
 		final IntermediaryMinecraftProvider<?> intermediaryMinecraftProvider;

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

@@ -26,6 +26,7 @@ package net.fabricmc.loom.configuration.providers.mappings;
 
 import java.io.File;
 import java.nio.file.Path;
+import java.util.function.Supplier;
 
 import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
@@ -36,6 +37,7 @@ import org.gradle.api.logging.Logger;
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.mappings.layered.MappingContext;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
 
 public class GradleMappingContext implements MappingContext {
 	private final Project project;
@@ -62,8 +64,8 @@ public class GradleMappingContext implements MappingContext {
 	}
 
 	@Override
-	public MappingsProvider mappingsProvider() {
+	public Supplier<MemoryMappingTree> intermediaryTree() {
-		return extension.getMappingsProvider();
+		return () -> IntermediaryService.getInstance(project, minecraftProvider()).getMemoryMappingTree();
 	}
 
 	@Override

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

@@ -0,0 +1,118 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration.providers.mappings;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collections;
+import java.util.Objects;
+import java.util.function.Supplier;
+
+import com.google.common.base.Suppliers;
+import com.google.common.net.UrlEscapers;
+import org.gradle.api.Project;
+import org.jetbrains.annotations.VisibleForTesting;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.LoomGradlePlugin;
+import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
+import net.fabricmc.loom.util.DownloadUtil;
+import net.fabricmc.loom.util.service.SharedService;
+import net.fabricmc.loom.util.service.SharedServiceManager;
+import net.fabricmc.mappingio.adapter.MappingNsCompleter;
+import net.fabricmc.mappingio.format.Tiny2Reader;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
+
+public final class IntermediaryService implements SharedService {
+	private static final Logger LOGGER = LoggerFactory.getLogger(IntermediaryService.class);
+
+	private final Path intermediaryTiny;
+	private final Supplier<MemoryMappingTree> memoryMappingTree = Suppliers.memoize(this::createMemoryMappingTree);
+
+	private IntermediaryService(Path intermediaryTiny) {
+		this.intermediaryTiny = intermediaryTiny;
+	}
+
+	public static synchronized IntermediaryService getInstance(Project project, MinecraftProvider minecraftProvider) {
+		final LoomGradleExtension extension = LoomGradleExtension.get(project);
+		final String encodedMinecraftVersion = UrlEscapers.urlFragmentEscaper().escape(minecraftProvider.minecraftVersion());
+		final String intermediaryArtifactUrl = extension.getIntermediaryUrl(encodedMinecraftVersion);
+
+		return SharedServiceManager.get(project).getOrCreateService("IntermediaryService:" + intermediaryArtifactUrl,
+				() -> create(intermediaryArtifactUrl, minecraftProvider));
+	}
+
+	@VisibleForTesting
+	public static IntermediaryService create(String intermediaryUrl, MinecraftProvider minecraftProvider) {
+		final Path intermediaryTiny = minecraftProvider.file("intermediary-v2.tiny").toPath();
+
+		if (!Files.exists(intermediaryTiny) || LoomGradlePlugin.refreshDeps) {
+			// Download and extract intermediary
+			File intermediaryJar = minecraftProvider.file("intermediary-v2.jar");
+
+			try {
+				DownloadUtil.downloadIfChanged(new URL(intermediaryUrl), intermediaryJar, LOGGER);
+				MappingsProviderImpl.extractMappings(intermediaryJar.toPath(), intermediaryTiny);
+			} catch (IOException e) {
+				throw new UncheckedIOException("Failed to download and extract intermediary", e);
+			}
+		}
+
+		return new IntermediaryService(intermediaryTiny);
+	}
+
+	private MemoryMappingTree createMemoryMappingTree() {
+		final MemoryMappingTree tree = new MemoryMappingTree();
+
+		try {
+			MappingNsCompleter nsCompleter = new MappingNsCompleter(tree, Collections.singletonMap(MappingsNamespace.NAMED.toString(), MappingsNamespace.INTERMEDIARY.toString()), true);
+
+			try (BufferedReader reader = Files.newBufferedReader(getIntermediaryTiny(), StandardCharsets.UTF_8)) {
+				Tiny2Reader.read(reader, nsCompleter);
+			}
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to read intermediary mappings", e);
+		}
+
+		return tree;
+	}
+
+	public MemoryMappingTree getMemoryMappingTree() {
+		return memoryMappingTree.get();
+	}
+
+	public Path getIntermediaryTiny() {
+		return Objects.requireNonNull(intermediaryTiny, "Intermediary mappings have not been setup");
+	}
+}

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

@@ -28,107 +28,135 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
 import java.io.Reader;
-import java.net.URL;
+import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.Map;
 import java.util.Objects;
-import java.util.regex.Pattern;
+import java.util.function.Supplier;
 
-import com.google.common.base.Stopwatch;
+import com.google.common.base.Suppliers;
-import com.google.common.net.UrlEscapers;
 import com.google.gson.JsonObject;
 import org.apache.tools.ant.util.StringUtils;
 import org.gradle.api.Project;
 import org.jetbrains.annotations.Nullable;
 import org.objectweb.asm.Opcodes;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.LoomGradlePlugin;
-import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
 import net.fabricmc.loom.configuration.DependencyInfo;
+import net.fabricmc.loom.configuration.providers.mappings.tiny.MappingsMerger;
+import net.fabricmc.loom.configuration.providers.mappings.tiny.TinyJarInfo;
 import net.fabricmc.loom.configuration.providers.minecraft.MergedMinecraftProvider;
 import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.DeletingFileVisitor;
-import net.fabricmc.loom.util.DownloadUtil;
 import net.fabricmc.loom.util.ZipUtils;
+import net.fabricmc.loom.util.service.SharedService;
+import net.fabricmc.loom.util.service.SharedServiceManager;
 import net.fabricmc.mappingio.MappingReader;
-import net.fabricmc.mappingio.adapter.MappingNsCompleter;
-import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch;
 import net.fabricmc.mappingio.format.MappingFormat;
-import net.fabricmc.mappingio.format.Tiny2Reader;
-import net.fabricmc.mappingio.format.Tiny2Writer;
-import net.fabricmc.mappingio.tree.MappingTree;
 import net.fabricmc.mappingio.tree.MemoryMappingTree;
 import net.fabricmc.stitch.Command;
 import net.fabricmc.stitch.commands.CommandProposeFieldNames;
 
-public class MappingsProviderImpl implements MappingsProvider {
+public class MappingsProviderImpl implements MappingsProvider, SharedService {
-	public String mappingsIdentifier;
+	private static final Logger LOGGER = LoggerFactory.getLogger(MappingsProviderImpl.class);
 
-	private Path mappingsWorkingDir;
+	private Supplier<MemoryMappingTree> mappingTree;
-	private Path intermediaryTiny;
+	public final String mappingsIdentifier;
-	private boolean hasRefreshed = false;
+
+	private final Path mappingsWorkingDir;
 	// The mappings that gradle gives us
-	private Path baseTinyMappings;
+	private final Path baseTinyMappings;
 	// The mappings we use in practice
-	public Path tinyMappings;
+	public final Path tinyMappings;
-	public Path tinyMappingsJar;
+	public final Path tinyMappingsJar;
-	private Path unpickDefinitions;
+	private final Path unpickDefinitions;
+
 	private boolean hasUnpickDefinitions;
 	private UnpickMetadata unpickMetadata;
-	private MemoryMappingTree mappingTree;
 	private Map<String, String> signatureFixes;
 
-	private final Project project;
+	private final Supplier<IntermediaryService> intermediaryService;
-	private final MinecraftProvider minecraftProvider;
+
-	private final LoomGradleExtension extension;
+	private MappingsProviderImpl(String mappingsIdentifier, Path mappingsWorkingDir, Supplier<IntermediaryService> intermediaryService) {
-	public MappingsProviderImpl(Project project, MinecraftProvider minecraftProvider) {
+		this.mappingsIdentifier = mappingsIdentifier;
-		this.project = project;
+
-		this.minecraftProvider = minecraftProvider;
+		this.mappingsWorkingDir = mappingsWorkingDir;
-		this.extension = LoomGradleExtension.get(project);
+		this.baseTinyMappings = mappingsWorkingDir.resolve("mappings-base.tiny");
+		this.tinyMappings = mappingsWorkingDir.resolve("mappings.tiny");
+		this.tinyMappingsJar = mappingsWorkingDir.resolve("mappings.jar");
+		this.unpickDefinitions = mappingsWorkingDir.resolve("mappings.unpick");
+
+		this.intermediaryService = intermediaryService;
+	}
+
+	public static synchronized MappingsProviderImpl getInstance(Project project, DependencyInfo dependency, MinecraftProvider minecraftProvider) {
+		return SharedServiceManager.get(project).getOrCreateService("MappingsProvider:%s:%s".formatted(dependency.getDepString(), minecraftProvider.minecraftVersion()), () -> {
+			Supplier<IntermediaryService> intermediaryService = Suppliers.memoize(() -> IntermediaryService.getInstance(project, minecraftProvider));
+			return create(dependency, minecraftProvider, intermediaryService);
+		});
 	}
 
 	public MemoryMappingTree getMappings() throws IOException {
-		return Objects.requireNonNull(mappingTree, "Cannot get mappings before they have been read");
+		return Objects.requireNonNull(mappingTree, "Cannot get mappings before they have been read").get();
 	}
 
-	public void provide() throws Exception {
+	private static MappingsProviderImpl create(DependencyInfo dependency, MinecraftProvider minecraftProvider, Supplier<IntermediaryService> intermediaryService) {
-		final DependencyInfo dependency = DependencyInfo.create(project, Constants.Configurations.MAPPINGS);
+		final String version = dependency.getResolvedVersion();
+		final Path inputJar = dependency.resolveFile().orElseThrow(() -> new RuntimeException("Could not resolve mappings: " + dependency)).toPath();
+		final String mappingsName = StringUtils.removeSuffix(dependency.getDependency().getGroup() + "." + dependency.getDependency().getName(), "-unmerged");
 
-		project.getLogger().info(":setting up mappings (" + dependency.getDependency().getName() + " " + dependency.getResolvedVersion() + ")");
+		final TinyJarInfo jarInfo = TinyJarInfo.get(inputJar);
+		jarInfo.minecraftVersionId().ifPresent(id -> {
+			if (!minecraftProvider.minecraftVersion().equals(id)) {
+				LOGGER.warn("The mappings (%s) were not build for minecraft version (%s) produce with caution.".formatted(dependency.getDepString(), minecraftProvider.minecraftVersion()));
+			}
+		});
 
-		String version = dependency.getResolvedVersion();
+		final String mappingsIdentifier = createMappingsIdentifier(mappingsName, version, getMappingsClassifier(dependency, jarInfo.v2()), minecraftProvider.minecraftVersion());
-		File mappingsJar = dependency.resolveFile().orElseThrow(() -> new RuntimeException("Could not find yarn mappings: " + dependency));
+		final Path workingDir = minecraftProvider.dir(mappingsIdentifier).toPath();
 
-		String mappingsName = StringUtils.removeSuffix(dependency.getDependency().getGroup() + "." + dependency.getDependency().getName(), "-unmerged");
+		var mappingProvider = new MappingsProviderImpl(mappingsIdentifier, workingDir, intermediaryService);
-		boolean isV2 = isV2(dependency, mappingsJar);
-		this.mappingsIdentifier = createMappingsIdentifier(mappingsName, version, getMappingsClassifier(dependency, isV2));
 
-		initFiles();
+		try {
+			mappingProvider.setup(minecraftProvider, inputJar);
+		} catch (IOException e) {
+			cleanWorkingDirectory(workingDir);
+			throw new UncheckedIOException("Failed to setup mappings: " + dependency.getDepString(), e);
+		}
+
+		return mappingProvider;
+	}
+
+	private void setup(MinecraftProvider minecraftProvider, Path inputJar) throws IOException {
+		if (isRefreshDeps()) {
+			cleanWorkingDirectory(mappingsWorkingDir);
+		}
 
 		if (Files.notExists(tinyMappings) || isRefreshDeps()) {
-			storeMappings(project, minecraftProvider, mappingsJar.toPath());
+			storeMappings(minecraftProvider, inputJar);
 		} else {
-			try (FileSystem fileSystem = FileSystems.newFileSystem(mappingsJar.toPath(), (ClassLoader) null)) {
+			try (FileSystem fileSystem = FileSystems.newFileSystem(inputJar, (ClassLoader) null)) {
 				extractExtras(fileSystem);
 			}
 		}
 
-		mappingTree = readMappings();
-
 		if (Files.notExists(tinyMappingsJar) || isRefreshDeps()) {
 			Files.deleteIfExists(tinyMappingsJar);
 			ZipUtils.add(tinyMappingsJar, "mappings/mappings.tiny", Files.readAllBytes(tinyMappings));
 		}
 
+		mappingTree = Suppliers.memoize(this::readMappings);
+	}
+
+	public void applyToProject(Project project, DependencyInfo dependency) {
 		if (hasUnpickDefinitions()) {
 			String notation = String.format("%s:%s:%s:constants",
 					dependency.getDependency().getGroup(),
@@ -137,13 +165,13 @@ public class MappingsProviderImpl implements MappingsProvider {
 			);
 
 			project.getDependencies().add(Constants.Configurations.MAPPING_CONSTANTS, notation);
-			populateUnpickClasspath();
+			populateUnpickClasspath(project);
 		}
 
 		project.getDependencies().add(Constants.Configurations.MAPPINGS_FINAL, project.files(tinyMappingsJar.toFile()));
 	}
 
-	private String getMappingsClassifier(DependencyInfo dependency, boolean isV2) {
+	private static String getMappingsClassifier(DependencyInfo dependency, boolean isV2) {
 		String[] depStringSplit = dependency.getDepString().split(":");
 
 		if (depStringSplit.length >= 4) {
@@ -153,42 +181,22 @@ public class MappingsProviderImpl implements MappingsProvider {
 		return isV2 ? "-v2" : "";
 	}
 
-	private boolean isV2(DependencyInfo dependency, File mappingsJar) throws IOException {
+	private void storeMappings(MinecraftProvider minecraftProvider, Path inputJar) throws IOException {
-		String minecraftVersion = minecraftProvider.minecraftVersion();
+		LOGGER.info(":extracting " + inputJar.getFileName());
 
-		// Only do this for official yarn, there isn't really a way we can get the mc version for all mappings
+		try (FileSystem fileSystem = FileSystems.newFileSystem(inputJar, (ClassLoader) null)) {
-		if (dependency.getDependency().getGroup() != null && dependency.getDependency().getGroup().equals("net.fabricmc") && dependency.getDependency().getName().equals("yarn") && dependency.getDependency().getVersion() != null) {
-			String yarnVersion = dependency.getDependency().getVersion();
-			char separator = yarnVersion.contains("+build.") ? '+' : yarnVersion.contains("-") ? '-' : '.';
-			String yarnMinecraftVersion = yarnVersion.substring(0, yarnVersion.lastIndexOf(separator));
-
-			if (!yarnMinecraftVersion.equalsIgnoreCase(minecraftVersion)) {
-				project.getLogger().warn("Minecraft Version ({}) does not match yarn's minecraft version ({})", minecraftVersion, yarnMinecraftVersion);
-			}
-
-			// We can save reading the zip file + header by checking the file name
-			return mappingsJar.getName().endsWith("-v2.jar");
-		} else {
-			return doesJarContainV2Mappings(mappingsJar.toPath());
-		}
-	}
-
-	private void storeMappings(Project project, MinecraftProvider minecraftProvider, Path yarnJar) throws IOException {
-		project.getLogger().info(":extracting " + yarnJar.getFileName());
-
-		try (FileSystem fileSystem = FileSystems.newFileSystem(yarnJar, (ClassLoader) null)) {
 			extractMappings(fileSystem, baseTinyMappings);
 			extractExtras(fileSystem);
 		}
 
 		if (areMappingsV2(baseTinyMappings)) {
 			// These are unmerged v2 mappings
-			mergeAndSaveMappings(project, baseTinyMappings, tinyMappings);
+			MappingsMerger.mergeAndSaveMappings(baseTinyMappings, tinyMappings, intermediaryService.get());
 		} else {
 			if (minecraftProvider instanceof MergedMinecraftProvider mergedMinecraftProvider) {
 				// These are merged v1 mappings
 				Files.deleteIfExists(tinyMappings);
-				project.getLogger().lifecycle(":populating field names");
+				LOGGER.info(":populating field names");
 				suggestFieldNames(mergedMinecraftProvider, baseTinyMappings, tinyMappings);
 			} else {
 				throw new UnsupportedOperationException("V1 mappings only support merged minecraft");
@@ -196,10 +204,14 @@ public class MappingsProviderImpl implements MappingsProvider {
 		}
 	}
 
-	private MemoryMappingTree readMappings() throws IOException {
+	private MemoryMappingTree readMappings() {
+		try {
 			MemoryMappingTree mappingTree = new MemoryMappingTree();
 			MappingReader.read(tinyMappings, mappingTree);
 			return mappingTree;
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to read mappings", e);
+		}
 	}
 
 	private static boolean areMappingsV2(Path path) throws IOException {
@@ -208,15 +220,7 @@ public class MappingsProviderImpl implements MappingsProvider {
 		}
 	}
 
-	private static boolean doesJarContainV2Mappings(Path path) throws IOException {
+	public static void extractMappings(Path jar, Path extractTo) throws IOException {
-		try (FileSystem fs = FileSystems.newFileSystem(path, (ClassLoader) null)) {
-			try (BufferedReader reader = Files.newBufferedReader(fs.getPath("mappings", "mappings.tiny"))) {
-				return MappingReader.detectFormat(reader) == MappingFormat.TINY_2;
-			}
-		}
-	}
-
-	private static void extractMappings(Path jar, Path extractTo) throws IOException {
 		try (FileSystem unmergedIntermediaryFs = FileSystems.newFileSystem(jar, (ClassLoader) null)) {
 			extractMappings(unmergedIntermediaryFs, extractTo);
 		}
@@ -271,7 +275,7 @@ public class MappingsProviderImpl implements MappingsProvider {
 		);
 	}
 
-	private void populateUnpickClasspath() {
+	private void populateUnpickClasspath(Project project) {
 		String unpickCliName = "unpick-cli";
 		project.getDependencies().add(Constants.Configurations.UNPICK_CLASSPATH,
 				String.format("%s:%s:%s", unpickMetadata.unpickGroup, unpickCliName, unpickMetadata.unpickVersion)
@@ -292,76 +296,6 @@ public class MappingsProviderImpl implements MappingsProvider {
 		}
 	}
 
-	private void mergeAndSaveMappings(Project project, Path from, Path out) throws IOException {
-		Stopwatch stopwatch = Stopwatch.createStarted();
-		project.getLogger().info(":merging mappings");
-
-		MemoryMappingTree intermediaryTree = new MemoryMappingTree();
-		readIntermediaryTree().accept(new MappingSourceNsSwitch(intermediaryTree, MappingsNamespace.INTERMEDIARY.toString()));
-
-		try (BufferedReader reader = Files.newBufferedReader(from, StandardCharsets.UTF_8)) {
-			Tiny2Reader.read(reader, intermediaryTree);
-		}
-
-		MemoryMappingTree officialTree = new MemoryMappingTree();
-		MappingNsCompleter nsCompleter = new MappingNsCompleter(officialTree, Map.of(MappingsNamespace.OFFICIAL.toString(), MappingsNamespace.INTERMEDIARY.toString()));
-		MappingSourceNsSwitch nsSwitch = new MappingSourceNsSwitch(nsCompleter, MappingsNamespace.OFFICIAL.toString());
-		intermediaryTree.accept(nsSwitch);
-
-		inheritMappedNamesOfEnclosingClasses(officialTree);
-
-		try (Tiny2Writer writer = new Tiny2Writer(Files.newBufferedWriter(out, StandardCharsets.UTF_8), false)) {
-			officialTree.accept(writer);
-		}
-
-		project.getLogger().info(":merged mappings in " + stopwatch.stop());
-	}
-
-	/**
-	 * Searches the mapping tree for inner classes with no mapped name, whose enclosing classes have mapped names.
-	 * Currently, Yarn does not export mappings for these inner classes.
-	 */
-	private void inheritMappedNamesOfEnclosingClasses(MemoryMappingTree tree) {
-		int intermediaryIdx = tree.getNamespaceId("intermediary");
-		int namedIdx = tree.getNamespaceId("named");
-
-		// The tree does not have an index by intermediary names by default
-		tree.setIndexByDstNames(true);
-
-		for (MappingTree.ClassMapping classEntry : tree.getClasses()) {
-			String intermediaryName = classEntry.getDstName(intermediaryIdx);
-			String namedName = classEntry.getDstName(namedIdx);
-
-			if (intermediaryName.equals(namedName) && intermediaryName.contains("$")) {
-				String[] path = intermediaryName.split(Pattern.quote("$"));
-				int parts = path.length;
-
-				for (int i = parts - 2; i >= 0; i--) {
-					String currentPath = String.join("$", Arrays.copyOfRange(path, 0, i + 1));
-					String namedParentClass = tree.mapClassName(currentPath, intermediaryIdx, namedIdx);
-
-					if (!namedParentClass.equals(currentPath)) {
-						classEntry.setDstName(namedParentClass
-										+ "$" + String.join("$", Arrays.copyOfRange(path, i + 1, path.length)),
-								namedIdx);
-						break;
-					}
-				}
-			}
-		}
-	}
-
-	private MemoryMappingTree readIntermediaryTree() throws IOException {
-		MemoryMappingTree tree = new MemoryMappingTree();
-		MappingNsCompleter nsCompleter = new MappingNsCompleter(tree, Collections.singletonMap(MappingsNamespace.NAMED.toString(), MappingsNamespace.INTERMEDIARY.toString()), true);
-
-		try (BufferedReader reader = Files.newBufferedReader(getIntermediaryTiny(), StandardCharsets.UTF_8)) {
-			Tiny2Reader.read(reader, nsCompleter);
-		}
-
-		return tree;
-	}
-
 	private void suggestFieldNames(MergedMinecraftProvider minecraftProvider, Path oldMappings, Path newMappings) {
 		Command command = new CommandProposeFieldNames();
 		runCommand(command, minecraftProvider.getMergedJar().getAbsolutePath(),
@@ -377,19 +311,7 @@ public class MappingsProviderImpl implements MappingsProvider {
 		}
 	}
 
-	private void initFiles() {
+	private static void cleanWorkingDirectory(Path mappingsWorkingDir) {
-		mappingsWorkingDir = minecraftProvider.dir(mappingsIdentifier).toPath();
-		baseTinyMappings = mappingsWorkingDir.resolve("mappings-base.tiny");
-		tinyMappings = mappingsWorkingDir.resolve("mappings.tiny");
-		tinyMappingsJar = mappingsWorkingDir.resolve("mappings.jar");
-		unpickDefinitions = mappingsWorkingDir.resolve("mappings.unpick");
-
-		if (isRefreshDeps()) {
-			cleanFiles();
-		}
-	}
-
-	public void cleanFiles() {
 		try {
 			if (Files.exists(mappingsWorkingDir)) {
 				Files.walkFileTree(mappingsWorkingDir, new DeletingFileVisitor());
@@ -401,34 +323,20 @@ public class MappingsProviderImpl implements MappingsProvider {
 		}
 	}
 
-	public Path getIntermediaryTiny() throws IOException {
-		if (intermediaryTiny == null) {
-			intermediaryTiny = minecraftProvider.file("intermediary-v2.tiny").toPath();
-
-			if (!Files.exists(intermediaryTiny) || (isRefreshDeps() && !hasRefreshed)) {
-				hasRefreshed = true;
-
-				// Download and extract intermediary
-				String encodedMinecraftVersion = UrlEscapers.urlFragmentEscaper().escape(minecraftProvider.minecraftVersion());
-				String intermediaryArtifactUrl = extension.getIntermediaryUrl(encodedMinecraftVersion);
-				File intermediaryJar = minecraftProvider.file("intermediary-v2.jar");
-				DownloadUtil.downloadIfChanged(new URL(intermediaryArtifactUrl), intermediaryJar, project.getLogger());
-				extractMappings(intermediaryJar.toPath(), intermediaryTiny);
-			}
-		}
-
-		return intermediaryTiny;
-	}
-
 	@Override
 	public Path mappingsWorkingDir() {
 		return mappingsWorkingDir;
 	}
 
-	private String createMappingsIdentifier(String mappingsName, String version, String classifier) {
+	@Override
+	public File intermediaryTinyFile() {
+		return intermediaryService.get().getIntermediaryTiny().toFile();
+	}
+
+	private static String createMappingsIdentifier(String mappingsName, String version, String classifier, String minecraftVersion) {
 		//          mappingsName      . mcVersion . version        classifier
 		// Example: net.fabricmc.yarn . 1_16_5    . 1.16.5+build.5 -v2
-		return mappingsName + "." + minecraftProvider.minecraftVersion().replace(' ', '_').replace('.', '_').replace('-', '_') + "." + version + classifier;
+		return mappingsName + "." + minecraftVersion.replace(' ', '_').replace('.', '_').replace('-', '_') + "." + version + classifier;
 	}
 
 	public String mappingsIdentifier() {
@@ -448,15 +356,6 @@ public class MappingsProviderImpl implements MappingsProvider {
 		return signatureFixes;
 	}
 
-	@Override
-	public File intermediaryTinyFile() {
-		try {
-			return getIntermediaryTiny().toFile();
-		} catch (IOException e) {
-			throw new RuntimeException("Failed to get intermediary", e);
-		}
-	}
-
 	public String getBuildServiceName(String name, String from, String to) {
 		return "%s:%s:%s>%S".formatted(name, mappingsIdentifier(), from, to);
 	}
@@ -464,7 +363,12 @@ public class MappingsProviderImpl implements MappingsProvider {
 	public record UnpickMetadata(String unpickGroup, String unpickVersion) {
 	}
 
-	protected boolean isRefreshDeps() {
+	protected static boolean isRefreshDeps() {
 		return LoomGradlePlugin.refreshDeps;
 	}
+
+	@Override
+	public void close() throws IOException {
+		mappingTree = null;
+	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/mappings/intermediary/IntermediaryMappingLayer.java

@@ -24,20 +24,17 @@
 
 package net.fabricmc.loom.configuration.providers.mappings.intermediary;
 
-import java.io.BufferedReader;
-import java.io.File;
 import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
 import java.util.Collections;
+import java.util.function.Supplier;
 
 import net.fabricmc.loom.api.mappings.layered.MappingLayer;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
 import net.fabricmc.mappingio.MappingVisitor;
 import net.fabricmc.mappingio.adapter.MappingNsCompleter;
-import net.fabricmc.mappingio.format.Tiny2Reader;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
 
-public record IntermediaryMappingLayer(File tinyFile) implements MappingLayer {
+public record IntermediaryMappingLayer(Supplier<MemoryMappingTree> memoryMappingTree) implements MappingLayer {
 	@Override
 	public MappingsNamespace getSourceNamespace() {
 		return MappingsNamespace.OFFICIAL;
@@ -48,8 +45,6 @@ public record IntermediaryMappingLayer(File tinyFile) implements MappingLayer {
 		// Populate named with intermediary and add Add a "named" namespace
 		MappingNsCompleter nsCompleter = new MappingNsCompleter(mappingVisitor, Collections.singletonMap(MappingsNamespace.NAMED.toString(), MappingsNamespace.INTERMEDIARY.toString()), true);
 
-		try (BufferedReader reader = Files.newBufferedReader(tinyFile().toPath(), StandardCharsets.UTF_8)) {
+		memoryMappingTree.get().accept(nsCompleter);
-			Tiny2Reader.read(reader, nsCompleter);
-		}
 	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/mappings/intermediary/IntermediaryMappingsSpec.java

@@ -30,6 +30,6 @@ import net.fabricmc.loom.api.mappings.layered.spec.MappingsSpec;
 public record IntermediaryMappingsSpec() implements MappingsSpec<IntermediaryMappingLayer> {
 	@Override
 	public IntermediaryMappingLayer createLayer(MappingContext context) {
-		return new IntermediaryMappingLayer(context.mappingsProvider().intermediaryTinyFile());
+		return new IntermediaryMappingLayer(context.intermediaryTree());
 	}
 }

src/main/java/net/fabricmc/loom/configuration/providers/mappings/tiny/MappingsMerger.java

@@ -0,0 +1,110 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration.providers.mappings.tiny;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import com.google.common.base.Stopwatch;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
+import net.fabricmc.loom.configuration.providers.mappings.IntermediaryService;
+import net.fabricmc.mappingio.adapter.MappingNsCompleter;
+import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch;
+import net.fabricmc.mappingio.format.Tiny2Reader;
+import net.fabricmc.mappingio.format.Tiny2Writer;
+import net.fabricmc.mappingio.tree.MappingTree;
+import net.fabricmc.mappingio.tree.MemoryMappingTree;
+
+public final class MappingsMerger {
+	private static final Logger LOGGER = LoggerFactory.getLogger(MappingsMerger.class);
+
+	public static void mergeAndSaveMappings(Path from, Path out, IntermediaryService intermediaryService) throws IOException {
+		Stopwatch stopwatch = Stopwatch.createStarted();
+		LOGGER.info(":merging mappings");
+
+		MemoryMappingTree intermediaryTree = new MemoryMappingTree();
+		intermediaryService.getMemoryMappingTree().accept(new MappingSourceNsSwitch(intermediaryTree, MappingsNamespace.INTERMEDIARY.toString()));
+
+		try (BufferedReader reader = Files.newBufferedReader(from, StandardCharsets.UTF_8)) {
+			Tiny2Reader.read(reader, intermediaryTree);
+		}
+
+		MemoryMappingTree officialTree = new MemoryMappingTree();
+		MappingNsCompleter nsCompleter = new MappingNsCompleter(officialTree, Map.of(MappingsNamespace.OFFICIAL.toString(), MappingsNamespace.INTERMEDIARY.toString()));
+		MappingSourceNsSwitch nsSwitch = new MappingSourceNsSwitch(nsCompleter, MappingsNamespace.OFFICIAL.toString());
+		intermediaryTree.accept(nsSwitch);
+
+		inheritMappedNamesOfEnclosingClasses(officialTree);
+
+		try (Tiny2Writer writer = new Tiny2Writer(Files.newBufferedWriter(out, StandardCharsets.UTF_8), false)) {
+			officialTree.accept(writer);
+		}
+
+		LOGGER.info(":merged mappings in " + stopwatch.stop());
+	}
+
+	/**
+	 * Searches the mapping tree for inner classes with no mapped name, whose enclosing classes have mapped names.
+	 * Currently, Yarn does not export mappings for these inner classes.
+	 */
+	private static void inheritMappedNamesOfEnclosingClasses(MemoryMappingTree tree) {
+		int intermediaryIdx = tree.getNamespaceId("intermediary");
+		int namedIdx = tree.getNamespaceId("named");
+
+		// The tree does not have an index by intermediary names by default
+		tree.setIndexByDstNames(true);
+
+		for (MappingTree.ClassMapping classEntry : tree.getClasses()) {
+			String intermediaryName = classEntry.getDstName(intermediaryIdx);
+			String namedName = classEntry.getDstName(namedIdx);
+
+			if (intermediaryName.equals(namedName) && intermediaryName.contains("$")) {
+				String[] path = intermediaryName.split(Pattern.quote("$"));
+				int parts = path.length;
+
+				for (int i = parts - 2; i >= 0; i--) {
+					String currentPath = String.join("$", Arrays.copyOfRange(path, 0, i + 1));
+					String namedParentClass = tree.mapClassName(currentPath, intermediaryIdx, namedIdx);
+
+					if (!namedParentClass.equals(currentPath)) {
+						classEntry.setDstName(namedParentClass
+										+ "$" + String.join("$", Arrays.copyOfRange(path, i + 1, path.length)),
+								namedIdx);
+						break;
+					}
+				}
+			}
+		}
+	}
+}

src/main/java/net/fabricmc/loom/configuration/providers/mappings/tiny/TinyJarInfo.java

@@ -0,0 +1,55 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration.providers.mappings.tiny;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Optional;
+
+import net.fabricmc.mappingio.MappingReader;
+import net.fabricmc.mappingio.format.MappingFormat;
+
+public record TinyJarInfo(boolean v2, Optional<String> minecraftVersionId) {
+	public static TinyJarInfo get(Path jar) {
+		try {
+			return new TinyJarInfo(doesJarContainV2Mappings(jar), Optional.empty());
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to read tiny jar info", e);
+		}
+	}
+
+	private static boolean doesJarContainV2Mappings(Path path) throws IOException {
+		try (FileSystem fs = FileSystems.newFileSystem(path, (ClassLoader) null)) {
+			try (BufferedReader reader = Files.newBufferedReader(fs.getPath("mappings", "mappings.tiny"))) {
+				return MappingReader.detectFormat(reader) == MappingFormat.TINY_2;
+			}
+		}
+	}
+}

src/main/java/net/fabricmc/loom/decompilers/DecompilerConfiguration.java

@@ -41,6 +41,6 @@ public final class DecompilerConfiguration {
 	}
 
 	private static void registerDecompiler(Project project, String name, Class<? extends LoomDecompiler> decompilerClass) {
-		LoomGradleExtension.get(project).getDecompilerOptions().register(name, options -> options.getDecompilerClassname().set(decompilerClass.getName()));
+		LoomGradleExtension.get(project).getDecompilerOptions().register(name, options -> options.getDecompilerClassName().set(decompilerClass.getName()));
 	}
 }

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

@@ -24,7 +24,6 @@
 
 package net.fabricmc.loom.extension;
 
-import java.io.File;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -41,7 +40,6 @@ import org.gradle.api.Project;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.file.FileCollection;
-import org.gradle.api.tasks.SourceSet;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
@@ -60,7 +58,6 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 	private final LoomFiles loomFiles;
 	private final ConfigurableFileCollection unmappedMods;
 
-	private final ConfigurableFileCollection mixinMappings;
 	private final MappingSet[] srcMappingCache = new MappingSet[2];
 	private final Mercury[] srcMercuryCache = new Mercury[2];
 	private final Map<String, NamedDomainObjectProvider<Configuration>> lazyConfigurations = new HashMap<>();
@@ -79,7 +76,6 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 		this.project = project;
 		// Initiate with newInstance to allow gradle to decorate our extension
 		this.mixinApExtension = project.getObjects().newInstance(MixinExtensionImpl.class, project);
-		this.mixinMappings = project.getObjects().fileCollection();
 		this.loomFiles = files;
 		this.unmappedMods = project.files();
 	}
@@ -94,18 +90,6 @@ public class LoomGradleExtensionImpl extends LoomGradleExtensionApiImpl implemen
 		return loomFiles;
 	}
 
-	@Override
-	public synchronized File getMixinMappings(SourceSet sourceSet) {
-		File mixinMapping = new File(getFiles().getProjectBuildCache(), "mixin-map-" + getMappingsProvider().mappingsIdentifier() + "." + sourceSet.getName() + ".tiny");
-		mixinMappings.from(getProject().files(mixinMapping));
-		return mixinMapping;
-	}
-
-	@Override
-	public FileCollection getAllMixinMappings() {
-		return mixinMappings.filter(File::exists);
-	}
-
 	@Override
 	public void setDependencyManager(LoomDependencyManager dependencyManager) {
 		this.dependencyManager = dependencyManager;

src/main/java/net/fabricmc/loom/task/PrepareJarRemapTask.java

@@ -0,0 +1,108 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.task;
+
+import java.nio.file.Path;
+
+import javax.inject.Inject;
+
+import org.gradle.api.file.RegularFileProperty;
+import org.gradle.api.provider.Property;
+import org.gradle.api.tasks.InputFile;
+import org.gradle.api.tasks.TaskAction;
+import org.gradle.workers.WorkAction;
+import org.gradle.workers.WorkParameters;
+import org.gradle.workers.WorkQueue;
+import org.gradle.workers.WorkerExecutor;
+
+import net.fabricmc.loom.task.service.TinyRemapperService;
+import net.fabricmc.loom.util.service.UnsafeWorkQueueHelper;
+import net.fabricmc.tinyremapper.TinyRemapper;
+
+/**
+ * The prepare remap task runs before all other jar remap tasks, should be used to setup tiny remapper.
+ */
+public abstract class PrepareJarRemapTask extends AbstractLoomTask {
+	private final RemapJarTask remapJarTask;
+	@InputFile
+	public abstract RegularFileProperty getInputFile();
+
+	@Inject
+	public PrepareJarRemapTask(RemapJarTask remapJarTask) {
+		this.remapJarTask = remapJarTask;
+
+		getInputFile().set(remapJarTask.getInputFile());
+		// TODO can this be up-to-date when the main task is up-to date?
+		getOutputs().upToDateWhen((o) -> false);
+
+		getProject().getGradle().allprojects(project -> {
+			project.getTasks().configureEach(task -> {
+				if (task instanceof PrepareJarRemapTask otherTask) {
+					if (otherTask == this) return;
+
+					// Ensure that all other prepare tasks inputs have completed
+					dependsOn(otherTask.getInputs());
+					mustRunAfter(otherTask.getInputs());
+				}
+			});
+		});
+	}
+
+	@Inject
+	protected abstract WorkerExecutor getWorkerExecutor();
+
+	@TaskAction
+	public void run() {
+		final WorkQueue workQueue = getWorkerExecutor().noIsolation();
+
+		workQueue.submit(ReadInputsAction.class, params -> {
+			params.getTinyRemapperBuildServiceUuid().set(UnsafeWorkQueueHelper.create(getProject(), remapJarTask.getTinyRemapperService()));
+			params.getInputTagName().set(remapJarTask.getInputTagName());
+			params.getInputFile().set(getInputFile());
+		});
+	}
+
+	public interface ReadInputsParams extends WorkParameters {
+		Property<String> getTinyRemapperBuildServiceUuid();
+		Property<String> getInputTagName();
+		RegularFileProperty getInputFile();
+	}
+
+	public abstract static class ReadInputsAction implements WorkAction<ReadInputsParams> {
+		private final TinyRemapperService tinyRemapperService;
+
+		public ReadInputsAction() {
+			this.tinyRemapperService = UnsafeWorkQueueHelper.get(getParameters().getTinyRemapperBuildServiceUuid(), TinyRemapperService.class);
+		}
+
+		@Override
+		public void execute() {
+			final TinyRemapper tinyRemapper = tinyRemapperService.getTinyRemapperForInputs();
+			final Path inputFile = getParameters().getInputFile().getAsFile().get().toPath();
+
+			tinyRemapper.readInputsAsync(tinyRemapperService.createTag(getParameters().getInputTagName().get()), inputFile);
+		}
+	}
+}

src/main/java/net/fabricmc/loom/task/RemapJarTask.java

@@ -26,7 +26,6 @@ package net.fabricmc.loom.task;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
-import java.io.File;
 import java.io.IOException;
 import java.io.Serializable;
 import java.nio.file.Files;
@@ -34,12 +33,14 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.function.Supplier;
 import java.util.jar.Manifest;
 import java.util.stream.Collectors;
 
 import javax.inject.Inject;
 
 import com.google.common.base.Preconditions;
+import com.google.common.base.Suppliers;
 import com.google.gson.JsonObject;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.ConfigurableFileCollection;
@@ -47,12 +48,11 @@ import org.gradle.api.file.FileCollection;
 import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
-import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFiles;
+import org.gradle.api.tasks.Internal;
 import org.gradle.api.tasks.SourceSet;
 import org.gradle.api.tasks.TaskAction;
-import org.objectweb.asm.commons.Remapper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -60,20 +60,18 @@ import net.fabricmc.accesswidener.AccessWidenerReader;
 import net.fabricmc.accesswidener.AccessWidenerRemapper;
 import net.fabricmc.accesswidener.AccessWidenerWriter;
 import net.fabricmc.loom.LoomGradleExtension;
-import net.fabricmc.loom.api.mappings.layered.MappingsNamespace;
 import net.fabricmc.loom.build.MixinRefmapHelper;
 import net.fabricmc.loom.build.nesting.IncludedJarFactory;
 import net.fabricmc.loom.build.nesting.JarNester;
 import net.fabricmc.loom.configuration.accesswidener.AccessWidenerFile;
 import net.fabricmc.loom.extension.MixinExtension;
 import net.fabricmc.loom.task.service.JarManifestService;
-import net.fabricmc.loom.task.service.MappingsService;
+import net.fabricmc.loom.task.service.TinyRemapperService;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.ZipUtils;
-import net.fabricmc.tinyremapper.InputTag;
+import net.fabricmc.loom.util.service.UnsafeWorkQueueHelper;
 import net.fabricmc.tinyremapper.OutputConsumerPath;
 import net.fabricmc.tinyremapper.TinyRemapper;
-import net.fabricmc.tinyremapper.TinyUtils;
 
 public abstract class RemapJarTask extends AbstractRemapJarTask {
 	private static final String MANIFEST_PATH = "META-INF/MANIFEST.MF";
@@ -84,6 +82,8 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 	@Input
 	public abstract Property<Boolean> getAddNestedDependencies();
 
+	private Supplier<TinyRemapperService> tinyRemapperService = Suppliers.memoize(() -> TinyRemapperService.getOrCreate(this));
+
 	@Inject
 	public RemapJarTask() {
 		super();
@@ -93,6 +93,25 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 
 		Configuration includeConfiguration = getProject().getConfigurations().getByName(Constants.Configurations.INCLUDE);
 		getNestedJars().from(new IncludedJarFactory(getProject()).getNestedJars(includeConfiguration));
+
+		setupPreparationTask();
+	}
+
+	private void setupPreparationTask() {
+		PrepareJarRemapTask prepareJarTask = getProject().getTasks().create("prepare" + getName().substring(0, 1).toUpperCase() + getName().substring(1), PrepareJarRemapTask.class, this);
+
+		dependsOn(prepareJarTask);
+		mustRunAfter(prepareJarTask);
+
+		getProject().getGradle().allprojects(project -> {
+			project.getTasks().configureEach(task -> {
+				if (task instanceof PrepareJarRemapTask otherTask) {
+					// Ensure that all remap jars run after all prepare tasks
+					dependsOn(otherTask);
+					mustRunAfter(otherTask);
+				}
+			});
+		});
 	}
 
 	@TaskAction
@@ -105,14 +124,14 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 			}
 
 			params.getJarManifestService().set(JarManifestService.get(getProject()));
+			params.getTinyRemapperBuildServiceUuid().set(UnsafeWorkQueueHelper.create(getProject(), tinyRemapperService.get()));
 			params.getRemapClasspath().from(getClasspath());
-			params.getMappings().add(MappingsService.createDefault(getProject(), getSourceNamespace().get(), getTargetNamespace().get()));
+			params.getInputTagName().set(getInputTagName());
 
 			final boolean legacyMixin = extension.getMixin().getUseLegacyMixinAp().get();
 			params.getUseMixinExtension().set(!legacyMixin);
 
 			if (legacyMixin) {
-				params.getMixinMappings().from(extension.getAllMixinMappings());
 				setupLegacyMixinRefmapRemapping(params);
 			}
 		});
@@ -174,8 +193,7 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 	public interface RemapParams extends AbstractRemapParams {
 		ConfigurableFileCollection getNestedJars();
 		ConfigurableFileCollection getRemapClasspath();
-		ConfigurableFileCollection getMixinMappings();
+		Property<String> getInputTagName();
-		ListProperty<Provider<MappingsService>> getMappings();
 
 		Property<Boolean> getUseMixinExtension();
 
@@ -183,19 +201,25 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 		ListProperty<RefmapData> getMixinData();
 
 		Property<JarManifestService> getJarManifestService();
+		Property<String> getTinyRemapperBuildServiceUuid();
 	}
 
 	public abstract static class RemapAction extends AbstractRemapAction<RemapParams> {
 		private static final Logger LOGGER = LoggerFactory.getLogger(RemapAction.class);
 
+		private final TinyRemapperService tinyRemapperService;
 		private TinyRemapper tinyRemapper;
 
+		public RemapAction() {
+			this.tinyRemapperService = UnsafeWorkQueueHelper.get(getParameters().getTinyRemapperBuildServiceUuid(), TinyRemapperService.class);
+		}
+
 		@Override
 		public void execute() {
 			try {
 				LOGGER.info("Remapping {} to {}", inputFile, outputFile);
 
-				tinyRemapper = createTinyRemapper();
+				tinyRemapper = tinyRemapperService.getTinyRemapperForRemapping();
 
 				remap();
 				remapAccessWidener();
@@ -204,9 +228,6 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 				modifyJarManifest();
 				rewriteJar();
 
-				tinyRemapper.finish();
-				tinyRemapper = null;
-
 				LOGGER.debug("Finished remapping {}", inputFile);
 			} catch (Exception e) {
 				try {
@@ -220,13 +241,9 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 		}
 
 		private void remap() throws IOException {
-			final InputTag inputTag = tinyRemapper.createInputTag();
-
-			tinyRemapper.readInputsAsync(inputTag, inputFile);
-
 			try (OutputConsumerPath outputConsumer = new OutputConsumerPath.Builder(outputFile).build()) {
 				outputConsumer.addNonClassFiles(inputFile);
-				tinyRemapper.apply(outputConsumer, inputTag);
+				tinyRemapper.apply(outputConsumer, tinyRemapperService.getTag(getParameters().getInputTagName().get()));
 			}
 		}
 
@@ -237,21 +254,21 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 				return;
 			}
 
-			byte[] remapped = remapAccessWidener(accessWidenerFile.content(), tinyRemapper.getEnvironment().getRemapper(), MappingsNamespace.INTERMEDIARY.toString());
+			byte[] remapped = remapAccessWidener(accessWidenerFile.content());
 
 			// Finally, replace the output with the remaped aw
 			ZipUtils.replace(outputFile, accessWidenerFile.path(), remapped);
 		}
 
-		private static byte[] remapAccessWidener(byte[] input, Remapper asmRemapper, String targetNamespace) {
+		private byte[] remapAccessWidener(byte[] input) {
 			int version = AccessWidenerReader.readVersion(input);
 
 			AccessWidenerWriter writer = new AccessWidenerWriter(version);
 			AccessWidenerRemapper remapper = new AccessWidenerRemapper(
 					writer,
-					asmRemapper,
+					tinyRemapper.getEnvironment().getRemapper(),
-					MappingsNamespace.NAMED.toString(),
+					getParameters().getSourceNamespace().get(),
-					targetNamespace
+					getParameters().getTargetNamespace().get()
 			);
 			AccessWidenerReader reader = new AccessWidenerReader(remapper);
 			reader.read(input);
@@ -300,30 +317,15 @@ public abstract class RemapJarTask extends AbstractRemapJarTask {
 				})));
 			}
 		}
-
-		private TinyRemapper createTinyRemapper() {
-			TinyRemapper.Builder builder = TinyRemapper.newRemapper();
-
-			for (Provider<MappingsService> provider : getParameters().getMappings().get()) {
-				builder.withMappings(provider.get().getMappingsProvider());
 	}
 
-			for (File mixinMapping : getParameters().getMixinMappings()) {
+	@Internal
-				builder.withMappings(TinyUtils.createTinyMappingProvider(mixinMapping.toPath(), getParameters().getSourceNamespace().get(), getParameters().getTargetNamespace().get()));
+	public TinyRemapperService getTinyRemapperService() {
+		return tinyRemapperService.get();
 	}
 
-			if (getParameters().getUseMixinExtension().get()) {
+	@Internal
-				builder.extension(new net.fabricmc.tinyremapper.extension.mixin.MixinExtension());
+	String getInputTagName() {
-			}
+		return getProject().getPath() + getName();
-
-			TinyRemapper remapper = builder.build();
-
-			// Apply classpath
-			for (File file : getParameters().getRemapClasspath()) {
-				remapper.readClassPathAsync(file.toPath());
-			}
-
-			return remapper;
-		}
 	}
 }

src/main/java/net/fabricmc/loom/task/RemapSourcesJarTask.java

@@ -35,8 +35,8 @@ import org.gradle.api.tasks.TaskAction;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import net.fabricmc.loom.task.service.MappingsService;
 import net.fabricmc.loom.task.service.SourceRemapperService;
+import net.fabricmc.loom.util.service.UnsafeWorkQueueHelper;
 
 public abstract class RemapSourcesJarTask extends AbstractRemapJarTask {
 	@Inject
@@ -49,12 +49,12 @@ public abstract class RemapSourcesJarTask extends AbstractRemapJarTask {
 	@TaskAction
 	public void run() {
 		submitWork(RemapSourcesAction.class, params -> {
-			params.getSourcesRemapperService().set(SourceRemapperService.create(getProject(), MappingsService.createDefault(getProject(), getSourceNamespace().get(), getTargetNamespace().get()), getClasspath()));
+			params.getSourcesRemapperServiceUuid().set(UnsafeWorkQueueHelper.create(getProject(), SourceRemapperService.create(this)));
 		});
 	}
 
 	public interface RemapSourcesParams extends AbstractRemapParams {
-		Property<SourceRemapperService> getSourcesRemapperService();
+		Property<String> getSourcesRemapperServiceUuid();
 	}
 
 	public abstract static class RemapSourcesAction extends AbstractRemapAction<RemapSourcesParams> {
@@ -65,7 +65,7 @@ public abstract class RemapSourcesJarTask extends AbstractRemapJarTask {
 		public RemapSourcesAction() {
 			super();
 
-			sourceRemapperService = getParameters().getSourcesRemapperService().get();
+			sourceRemapperService = UnsafeWorkQueueHelper.get(getParameters().getSourcesRemapperServiceUuid(), SourceRemapperService.class);
 		}
 
 		@Override

src/main/java/net/fabricmc/loom/task/RemapTaskConfiguration.java

@@ -54,8 +54,8 @@ public class RemapTaskConfiguration {
 			return;
 		}
 
-		// Register the default remap jar task
+		// Register the default remap jar task - must not be lazy to ensure that the prepare tasks get setup for other projects to depend on.
-		TaskProvider<RemapJarTask> remapJarTaskProvider = tasks.register(REMAP_JAR_TASK_NAME, RemapJarTask.class, task -> {
+		RemapJarTask remapJarTask = tasks.create(REMAP_JAR_TASK_NAME, RemapJarTask.class, task -> {
 			final AbstractArchiveTask jarTask = tasks.named(JavaPlugin.JAR_TASK_NAME, AbstractArchiveTask.class).get();
 
 			// Basic task setup
@@ -76,7 +76,7 @@ public class RemapTaskConfiguration {
 			task.getDestinationDirectory().set(new File(project.getBuildDir(), "devlibs"));
 		});
 
-		tasks.named(BasePlugin.ASSEMBLE_TASK_NAME).configure(task -> task.dependsOn(remapJarTaskProvider));
+		tasks.named(BasePlugin.ASSEMBLE_TASK_NAME).configure(task -> task.dependsOn(remapJarTask));
 
 		trySetupSourceRemapping(project);
 

src/main/java/net/fabricmc/loom/task/service/MappingsService.java

@@ -24,49 +24,45 @@
 
 package net.fabricmc.loom.task.service;
 
-import java.io.File;
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.nio.file.Path;
 
 import org.gradle.api.Project;
-import org.gradle.api.file.RegularFileProperty;
-import org.gradle.api.provider.Property;
-import org.gradle.api.provider.Provider;
-import org.gradle.api.services.BuildService;
-import org.gradle.api.services.BuildServiceParameters;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.configuration.providers.mappings.MappingsProviderImpl;
 import net.fabricmc.loom.util.TinyRemapperHelper;
+import net.fabricmc.loom.util.service.SharedService;
+import net.fabricmc.loom.util.service.SharedServiceManager;
 import net.fabricmc.mappingio.MappingReader;
 import net.fabricmc.mappingio.tree.MemoryMappingTree;
 import net.fabricmc.tinyremapper.IMappingProvider;
 
-public abstract class MappingsService implements BuildService<MappingsService.Params>, AutoCloseable {
+public final class MappingsService implements SharedService {
-	interface Params extends BuildServiceParameters {
+	private record Options(Path mappingsFile, String from, String to, boolean remapLocals) { }
-		RegularFileProperty getMappingsFile();
 
-		Property<String> getFromNamespace();
+	public static MappingsService create(Project project, String name, Path mappingsFile, String from, String to, boolean remapLocals) {
-		Property<String> getToNamespace();
+		return create(SharedServiceManager.get(project), name, mappingsFile, from, to, remapLocals);
-
-		Property<Boolean> getRemapLocals();
 	}
 
-	public static synchronized Provider<MappingsService> create(Project project, String name, File mappingsFile, String from, String to, boolean remapLocals) {
+	public static synchronized MappingsService create(SharedServiceManager sharedServiceManager, String name, Path mappingsFile, String from, String to, boolean remapLocals) {
-		return project.getGradle().getSharedServices().registerIfAbsent(name, MappingsService.class, spec -> {
+		final Options options = new Options(mappingsFile, from, to, remapLocals);
-			spec.parameters(params -> {
+		final String id = name + options.hashCode();
-				params.getMappingsFile().set(mappingsFile);
+		return sharedServiceManager.getOrCreateService(id, () -> new MappingsService(options));
-				params.getFromNamespace().set(from);
-				params.getToNamespace().set(to);
-				params.getRemapLocals().set(remapLocals);
-			});
-		});
 	}
 
-	public static Provider<MappingsService> createDefault(Project project, String from, String to) {
+	public static MappingsService createDefault(Project project, String from, String to) {
 		final MappingsProviderImpl mappingsProvider = LoomGradleExtension.get(project).getMappingsProvider();
+
 		final String name = mappingsProvider.getBuildServiceName("mappingsProvider", from, to);
-		return MappingsService.create(project, name, mappingsProvider.tinyMappings.toFile(), from, to, false);
+		return MappingsService.create(project, name, mappingsProvider.tinyMappings, from, to, false);
+	}
+
+	private final Options options;
+
+	public MappingsService(Options options) {
+		this.options = options;
 	}
 
 	private IMappingProvider mappingProvider = null;
@@ -76,13 +72,13 @@ public abstract class MappingsService implements BuildService<MappingsService.Pa
 		if (mappingProvider == null) {
 			try {
 				mappingProvider = TinyRemapperHelper.create(
-						getParameters().getMappingsFile().get().getAsFile().toPath(),
+						options.mappingsFile(),
-						getParameters().getFromNamespace().get(),
+						options.from(),
-						getParameters().getToNamespace().get(),
+						options.to(),
-						getParameters().getRemapLocals().get()
+						options.remapLocals()
 				);
 			} catch (IOException e) {
-				throw new UncheckedIOException("Failed to read mappings from: " + getParameters().getMappingsFile().get().getAsFile().getAbsolutePath(), e);
+				throw new UncheckedIOException("Failed to read mappings from: " + options.mappingsFile(), e);
 			}
 		}
 
@@ -94,9 +90,9 @@ public abstract class MappingsService implements BuildService<MappingsService.Pa
 			memoryMappingTree = new MemoryMappingTree();
 
 			try {
-				MappingReader.read(getParameters().getMappingsFile().get().getAsFile().toPath(), memoryMappingTree);
+				MappingReader.read(options.mappingsFile(), memoryMappingTree);
 			} catch (IOException e) {
-				throw new UncheckedIOException("Failed to read mappings from: " + getParameters().getMappingsFile().get().getAsFile().getAbsolutePath(), e);
+				throw new UncheckedIOException("Failed to read mappings from: " + options.mappingsFile(), e);
 			}
 		}
 
@@ -104,11 +100,11 @@ public abstract class MappingsService implements BuildService<MappingsService.Pa
 	}
 
 	public String getFromNamespace() {
-		return getParameters().getFromNamespace().get();
+		return options.from();
 	}
 
 	public String getToNamespace() {
-		return getParameters().getToNamespace().get();
+		return options.to();
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/task/service/MixinMappingsService.java

@@ -0,0 +1,69 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.task.service;
+
+import java.io.File;
+import java.util.HashSet;
+
+import org.gradle.api.Project;
+import org.gradle.api.tasks.SourceSet;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.util.service.SharedService;
+import net.fabricmc.loom.util.service.SharedServiceManager;
+import net.fabricmc.tinyremapper.IMappingProvider;
+
+public final class MixinMappingsService implements SharedService {
+	private final SharedServiceManager sharedServiceManager;
+	private final HashSet<File> mixinMappings = new HashSet<>();
+
+	private MixinMappingsService(SharedServiceManager sharedServiceManager) {
+		this.sharedServiceManager = sharedServiceManager;
+	}
+
+	public static File getMixinMappingFile(Project project, SourceSet sourceSet) {
+		final LoomGradleExtension extension = LoomGradleExtension.get(project);
+		File mixinMapping = new File(extension.getFiles().getProjectBuildCache(), "mixin-map-" + extension.getMappingsProvider().mappingsIdentifier() + "." + sourceSet.getName() + ".tiny");
+
+		getService(SharedServiceManager.get(project)).mixinMappings.add(mixinMapping);
+
+		return mixinMapping;
+	}
+
+	static MixinMappingsService getService(SharedServiceManager sharedServiceManager) {
+		return sharedServiceManager.getOrCreateService("MixinMappings", () -> new MixinMappingsService(sharedServiceManager));
+	}
+
+	IMappingProvider getMappingProvider(String from, String to) {
+		return out -> {
+			for (File mixinMapping : mixinMappings) {
+				if (!mixinMapping.exists()) continue;
+
+				MappingsService service = MappingsService.create(sharedServiceManager, mixinMapping.getAbsolutePath(), mixinMapping.toPath(), from, to, false);
+				service.getMappingsProvider().load(out);
+			}
+		};
+	}
+}

src/main/java/net/fabricmc/loom/task/service/SourceRemapperService.java

@@ -24,49 +24,57 @@
 
 package net.fabricmc.loom.task.service;
 
+import java.io.File;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.function.Supplier;
 
+import com.google.common.base.Suppliers;
 import org.cadixdev.lorenz.MappingSet;
 import org.cadixdev.mercury.Mercury;
 import org.cadixdev.mercury.remapper.MercuryRemapper;
 import org.gradle.api.Project;
 import org.gradle.api.file.ConfigurableFileCollection;
-import org.gradle.api.file.FileCollection;
-import org.gradle.api.provider.Property;
-import org.gradle.api.provider.Provider;
-import org.gradle.api.services.BuildService;
-import org.gradle.api.services.BuildServiceParameters;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.task.RemapSourcesJarTask;
 import net.fabricmc.loom.util.DeletingFileVisitor;
 import net.fabricmc.loom.util.FileSystemUtil;
 import net.fabricmc.loom.util.SourceRemapper;
 import net.fabricmc.loom.util.ZipUtils;
+import net.fabricmc.loom.util.service.SharedService;
+import net.fabricmc.loom.util.service.SharedServiceManager;
 import net.fabricmc.lorenztiny.TinyMappingsReader;
 
-public abstract class SourceRemapperService implements BuildService<SourceRemapperService.Params>, AutoCloseable {
+public final class SourceRemapperService implements SharedService {
-	public interface Params extends BuildServiceParameters {
+	public static synchronized SourceRemapperService create(RemapSourcesJarTask task) {
-		Property<Provider<MappingsService>> getMappings();
+		final Project project = task.getProject();
+		final String to = task.getTargetNamespace().get();
+		final String from = task.getSourceNamespace().get();
+		final LoomGradleExtension extension = LoomGradleExtension.get(project);
+		final SharedServiceManager sharedServiceManager = SharedServiceManager.get(project);
+		final String id = extension.getMappingsProvider().getBuildServiceName("sourceremapper", from, to);
 
-		ConfigurableFileCollection getClasspath();
+		return sharedServiceManager.getOrCreateService(id, () ->
-	}
+				new SourceRemapperService(MappingsService.createDefault(project, from, to), task.getClasspath()
-
-	public static synchronized Provider<SourceRemapperService> create(Project project, Provider<MappingsService> mappings, FileCollection classpath) {
-		// TODO may need a better name, im not too sure
-		return project.getGradle().getSharedServices().registerIfAbsent("sourceremapper", SourceRemapperService.class, spec ->
-			spec.parameters(params -> {
-				params.getMappings().set(mappings);
-				params.getClasspath().from(classpath);
-			}
 			));
 	}
 
 	private static final Logger LOGGER = LoggerFactory.getLogger(SourceRemapperService.class);
 
-	private Mercury mercury;
+	private final MappingsService mappingsService;
+	private final ConfigurableFileCollection classpath;
+
+	private final Supplier<Mercury> mercury = Suppliers.memoize(this::createMercury);
+
+	private SourceRemapperService(MappingsService mappingsService, ConfigurableFileCollection classpath) {
+		this.mappingsService = mappingsService;
+		this.classpath = classpath;
+	}
 
 	public void remapSourcesJar(Path source, Path destination) throws IOException {
 		if (source.equals(destination)) {
@@ -99,35 +107,34 @@ public abstract class SourceRemapperService implements BuildService<SourceRemapp
 		}
 	}
 
-	private synchronized void doRemap(Path srcPath, Path dstPath, Path source) throws IOException {
+	private synchronized void doRemap(Path srcPath, Path dstPath, Path source) {
-		if (mercury == null) {
-			mercury = new Mercury();
-			mercury.setGracefulClasspathChecks(true);
-			mercury.getProcessors().add(MercuryRemapper.create(getMappings()));
-
-			getParameters().getClasspath().forEach(file -> mercury.getClassPath().add(file.toPath()));
-		}
-
 		try {
-			// Not thread safe!!
+			synchronized (mercury) {
-			mercury.rewrite(srcPath, dstPath);
+				mercury.get().rewrite(srcPath, dstPath);
+			}
 		} catch (Exception e) {
 			LOGGER.warn("Could not remap " + source + " fully!", e);
 		}
 	}
 
 	private MappingSet getMappings() throws IOException {
-		return new TinyMappingsReader(mappingsService().getMemoryMappingTree(), mappingsService().getFromNamespace(), mappingsService().getToNamespace()).read();
+		return new TinyMappingsReader(mappingsService.getMemoryMappingTree(), mappingsService.getFromNamespace(), mappingsService.getToNamespace()).read();
 	}
 
-	private MappingsService mappingsService() {
+	private Mercury createMercury() {
-		return getParameters().getMappings().get().get();
+		var mercury = new Mercury();
+		mercury.setGracefulClasspathChecks(true);
+
+		try {
+			mercury.getProcessors().add(MercuryRemapper.create(getMappings()));
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to read mercury mappings", e);
 		}
 
-	@Override
+		for (File file : classpath.getFiles()) {
-	public void close() throws Exception {
+			mercury.getClassPath().add(file.toPath());
-		mercury = null;
+		}
-		// This is required (:
+
-		System.gc();
+		return mercury;
 	}
 }

src/main/java/net/fabricmc/loom/task/service/TinyRemapperService.java

@@ -0,0 +1,142 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.task.service;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.gradle.api.Project;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.task.AbstractRemapJarTask;
+import net.fabricmc.loom.util.service.SharedService;
+import net.fabricmc.loom.util.service.SharedServiceManager;
+import net.fabricmc.tinyremapper.IMappingProvider;
+import net.fabricmc.tinyremapper.InputTag;
+import net.fabricmc.tinyremapper.TinyRemapper;
+
+public class TinyRemapperService implements SharedService {
+	public static synchronized TinyRemapperService getOrCreate(AbstractRemapJarTask remapJarTask) {
+		final Project project = remapJarTask.getProject();
+		final String to = remapJarTask.getTargetNamespace().get();
+		final String from = remapJarTask.getSourceNamespace().get();
+		final LoomGradleExtension extension = LoomGradleExtension.get(project);
+		final SharedServiceManager sharedServiceManager = SharedServiceManager.get(project);
+		final boolean legacyMixin = extension.getMixin().getUseLegacyMixinAp().get();
+
+		// Generates an id that is used to share the remapper across projects. This tasks in the remap jar task name to handle custom remap jar tasks separately.
+		final String id = extension.getMappingsProvider().getBuildServiceName("remapJarService", from, to) + ":" + remapJarTask.getName();
+
+		TinyRemapperService service = sharedServiceManager.getOrCreateService(id, () -> {
+			List<IMappingProvider> mappings = new ArrayList<>();
+			mappings.add(MappingsService.createDefault(project, from, to).getMappingsProvider());
+
+			if (legacyMixin) {
+				mappings.add(MixinMappingsService.getService(SharedServiceManager.get(project)).getMappingProvider(from, to));
+			}
+
+			return new TinyRemapperService(mappings, !legacyMixin);
+		});
+
+		service.readClasspath(remapJarTask.getClasspath().getFiles().stream().map(File::toPath).toList());
+
+		return service;
+	}
+
+	private TinyRemapper tinyRemapper;
+	private final Map<String, InputTag> inputTagMap = new ConcurrentHashMap<>();
+	private final HashSet<Path> classpath = new HashSet<>();
+	// Set to true once remapping has started, once set no inputs can be read.
+	private boolean isRemapping = false;
+
+	public TinyRemapperService(List<IMappingProvider> mappings, boolean useMixinExtension) {
+		TinyRemapper.Builder builder = TinyRemapper.newRemapper();
+
+		for (IMappingProvider provider : mappings) {
+			builder.withMappings(provider);
+		}
+
+		if (useMixinExtension) {
+			builder.extension(new net.fabricmc.tinyremapper.extension.mixin.MixinExtension());
+		}
+
+		tinyRemapper = builder.build();
+	}
+
+	public InputTag createTag(String key) {
+		if (inputTagMap.containsKey(key)) {
+			throw new IllegalStateException("Input tag already exists for key: " + key);
+		}
+
+		return inputTagMap.put(key, tinyRemapper.createInputTag());
+	}
+
+	public InputTag getTag(String key) {
+		return Objects.requireNonNull(inputTagMap.get(key), "Input tag not found for: " + key);
+	}
+
+	public TinyRemapper getTinyRemapperForRemapping() {
+		synchronized (this) {
+			isRemapping = true;
+			return Objects.requireNonNull(tinyRemapper, "Tiny remapper has not been setup");
+		}
+	}
+
+	public synchronized TinyRemapper getTinyRemapperForInputs() {
+		synchronized (this) {
+			if (isRemapping) {
+				throw new IllegalStateException("Cannot read inputs as remapping has already started");
+			}
+
+			return tinyRemapper;
+		}
+	}
+
+	void readClasspath(List<Path> paths) {
+		List<Path> toRead;
+
+		synchronized (classpath) {
+			toRead = paths.stream().filter(path -> !classpath.contains(path)).toList();
+			classpath.addAll(paths);
+		}
+
+		tinyRemapper.readClassPathAsync(toRead.toArray(Path[]::new));
+	}
+
+	@Override
+	public void close() throws IOException {
+		if (tinyRemapper != null) {
+			tinyRemapper.finish();
+			tinyRemapper = null;
+		}
+	}
+}

src/main/java/net/fabricmc/loom/util/DownloadUtil.java

@@ -35,7 +35,7 @@ import java.util.zip.GZIPInputStream;
 import com.google.common.io.Files;
 import org.apache.commons.io.FileUtils;
 import org.gradle.api.Project;
-import org.gradle.api.logging.Logger;
+import org.slf4j.Logger;
 
 import net.fabricmc.loom.LoomGradlePlugin;
 

src/main/java/net/fabricmc/loom/util/TinyRemapperHelper.java

@@ -110,21 +110,31 @@ public final class TinyRemapperHelper {
 
 	public static IMappingProvider create(MappingTree mappings, String from, String to, boolean remapLocalVariables) {
 		return (acceptor) -> {
+			final int fromId = mappings.getNamespaceId(from);
+			final int toId = mappings.getNamespaceId(to);
+
 			for (MappingTree.ClassMapping classDef : mappings.getClasses()) {
-				String className = classDef.getName(from);
+				String className = classDef.getName(fromId);
-				acceptor.acceptClass(className, classDef.getName(to));
+				String dstName = classDef.getName(toId);
+
+				if (dstName == null) {
+					// Unsure if this is correct, should be better than crashing tho.
+					dstName = className;
+				}
+
+				acceptor.acceptClass(className, dstName);
 
 				for (MappingTree.FieldMapping field : classDef.getFields()) {
-					acceptor.acceptField(memberOf(className, field.getName(from), field.getDesc(from)), field.getName(to));
+					acceptor.acceptField(memberOf(className, field.getName(fromId), field.getDesc(fromId)), field.getName(toId));
 				}
 
 				for (MappingTree.MethodMapping method : classDef.getMethods()) {
-					IMappingProvider.Member methodIdentifier = memberOf(className, method.getName(from), method.getDesc(from));
+					IMappingProvider.Member methodIdentifier = memberOf(className, method.getName(fromId), method.getDesc(fromId));
-					acceptor.acceptMethod(methodIdentifier, method.getName(to));
+					acceptor.acceptMethod(methodIdentifier, method.getName(toId));
 
 					if (remapLocalVariables) {
 						for (MappingTree.MethodArgMapping parameter : method.getArgs()) {
-							String name = parameter.getName(to);
+							String name = parameter.getName(toId);
 
 							if (name == null) {
 								continue;
@@ -136,7 +146,7 @@ public final class TinyRemapperHelper {
 						for (MappingTree.MethodVarMapping localVariable : method.getVars()) {
 							acceptor.acceptMethodVar(methodIdentifier, localVariable.getLvIndex(),
 									localVariable.getStartOpIdx(), localVariable.getLvtRowIndex(),
-									localVariable.getName(to));
+									localVariable.getName(toId));
 						}
 					}
 				}

src/main/java/net/fabricmc/loom/util/service/SharedService.java

@@ -0,0 +1,34 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util.service;
+
+import java.io.Closeable;
+import java.io.IOException;
+
+public interface SharedService extends Closeable {
+	@Override
+	default void close() throws IOException {
+	}
+}

src/main/java/net/fabricmc/loom/util/service/SharedServiceManager.java

@@ -0,0 +1,110 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util.service;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Supplier;
+
+import org.gradle.BuildResult;
+import org.gradle.api.Project;
+import org.gradle.api.invocation.Gradle;
+
+/**
+ * A simple manager for {@link SharedService} to be used across gradle (sub) projects.
+ * This is a basic replacement for gradle's build service api.
+ */
+public final class SharedServiceManager {
+	private static final Map<Gradle, SharedServiceManager> SERVICE_FACTORY_MAP = new ConcurrentHashMap<>();
+	private final Gradle gradle;
+
+	private final Map<String, SharedService> sharedServiceMap = new ConcurrentHashMap<>();
+
+	private boolean shutdown = false;
+
+	private SharedServiceManager(Gradle gradle) {
+		this.gradle = gradle;
+		this.gradle.buildFinished(this::onFinish);
+	}
+
+	public static SharedServiceManager get(Project project) {
+		return get(project.getGradle());
+	}
+
+	public static SharedServiceManager get(Gradle gradle) {
+		return SERVICE_FACTORY_MAP.computeIfAbsent(gradle, SharedServiceManager::new);
+	}
+
+	public <S extends SharedService> S getOrCreateService(String id, Supplier<S> function) {
+		synchronized (sharedServiceMap) {
+			if (shutdown) {
+				throw new UnsupportedOperationException("Cannot get or create service has the manager has been shutdown.");
+			}
+
+			//noinspection unchecked
+			S sharedService = (S) sharedServiceMap.get(id);
+
+			if (sharedService == null) {
+				sharedService = function.get();
+				sharedServiceMap.put(id, sharedService);
+			}
+
+			return sharedService;
+		}
+	}
+
+	private void onFinish(BuildResult buildResult) {
+		synchronized (sharedServiceMap) {
+			shutdown = true;
+		}
+
+		SERVICE_FACTORY_MAP.remove(gradle);
+
+		final List<IOException> exceptionList = new ArrayList<>();
+
+		for (SharedService sharedService : sharedServiceMap.values()) {
+			try {
+				sharedService.close();
+			} catch (IOException e) {
+				exceptionList.add(e);
+			}
+		}
+
+		sharedServiceMap.clear();
+
+		if (!exceptionList.isEmpty()) {
+			// Done to try and close all the services.
+			RuntimeException exception = new RuntimeException("Failed to close all shared services");
+			exceptionList.forEach(exception::addSuppressed);
+			throw exception;
+		}
+
+		// This is required to ensure that mercury releases all of the file handles.
+		System.gc();
+	}
+}

src/main/java/net/fabricmc/loom/util/service/UnsafeWorkQueueHelper.java

@@ -0,0 +1,60 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util.service;
+
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.gradle.api.Project;
+import org.gradle.api.provider.Property;
+
+// Massive hack to work around WorkerExecutor.noIsolation() doing isolation checks.
+public final class UnsafeWorkQueueHelper {
+	private static final Map<String, SharedService> SERVICE_MAP = new ConcurrentHashMap<>();
+
+	private UnsafeWorkQueueHelper() {
+	}
+
+	public static String create(Project project, SharedService service) {
+		final String uuid = UUID.randomUUID().toString();
+		SERVICE_MAP.put(uuid, service);
+
+		// Ensure we don't make a mess if things go wrong.
+		project.getGradle().buildFinished(buildResult -> SERVICE_MAP.remove(uuid));
+		return uuid;
+	}
+
+	public static <S> S get(Property<String> property, Class<S> clazz) {
+		SharedService service = SERVICE_MAP.remove(property.get());
+
+		if (service == null) {
+			throw new NullPointerException("Failed to get service for " + clazz);
+		}
+
+		//noinspection unchecked
+		return (S) service;
+	}
+}

src/test/groovy/net/fabricmc/loom/test/LoomTestConstants.groovy

@@ -28,7 +28,7 @@ import org.gradle.util.GradleVersion
 
 class LoomTestConstants {
     public final static String DEFAULT_GRADLE = GradleVersion.current().getVersion()
-    public final static String PRE_RELEASE_GRADLE = "7.5-20220101231120+0000"
+    public final static String PRE_RELEASE_GRADLE = "7.5-20220110230252+0000"
 
     public final static String[] STANDARD_TEST_VERSIONS = [DEFAULT_GRADLE, PRE_RELEASE_GRADLE]
 }

src/test/groovy/net/fabricmc/loom/test/benchmark/FabricAPIBenchmark.groovy

@@ -0,0 +1,63 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2022 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.benchmark
+
+import groovy.time.TimeCategory
+import groovy.time.TimeDuration
+import net.fabricmc.loom.test.LoomTestConstants
+import net.fabricmc.loom.test.util.GradleProjectTestTrait
+
+/**
+ * Run this class, passing a working dir as the first argument.
+ * Allow for one warm up run before profiling, follow up runs should not be using the network.
+ */
+@Singleton
+class FabricAPIBenchmark implements GradleProjectTestTrait {
+    def run(File dir) {
+        def gradle = gradleProject(
+                version: LoomTestConstants.PRE_RELEASE_GRADLE,
+                projectDir: new File(dir, "project"),
+                gradleHomeDir: new File(dir, "gradlehome"),
+                allowExistingRepo: true,
+
+                repo: "https://github.com/FabricMC/fabric.git",
+                commit: "71b634e5b7845296b11be3fa6545f4fbfacc017f",
+                patch: "fabric_api"
+        )
+
+        def timeStart = new Date()
+
+        def result = gradle.run(tasks: ["clean", "build"], args: ["--parallel", "-x", "check", "-x", "test", "-x", ":fabric-data-generation-api-v1:runDatagen", "-x", "javadoc"])
+
+        def timeStop = new Date()
+        TimeDuration duration = TimeCategory.minus(timeStop, timeStart)
+        println(duration)
+    }
+
+    static void main(String[] args) {
+        getInstance().run(new File(args[0]))
+        System.exit(0)
+    }
+}

src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/IntermediaryMappingLayerTest.groovy

@@ -29,7 +29,7 @@ import net.fabricmc.loom.configuration.providers.mappings.intermediary.Intermedi
 class IntermediaryMappingLayerTest extends LayeredMappingsSpecification {
     def "Read intermediary mappings" () {
         setup:
-            mockMappingsProvider.intermediaryTinyFile() >> extractFileFromZip(downloadFile(INTERMEDIARY_1_17_URL, "intermediary.jar"), "mappings/mappings.tiny")
+            intermediaryUrl = INTERMEDIARY_1_17_URL
         when:
             def mappings = getSingleMapping(new IntermediaryMappingsSpec())
             def tiny = getTiny(mappings)

src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/LayeredMappingsSpecification.groovy

@@ -24,15 +24,14 @@
 
 package net.fabricmc.loom.test.unit.layeredmappings
 
-import groovy.transform.CompileStatic
-import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpec
-import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsProcessor
 import net.fabricmc.loom.api.mappings.layered.MappingContext
 import net.fabricmc.loom.api.mappings.layered.MappingLayer
 import net.fabricmc.loom.api.mappings.layered.MappingsNamespace
-import net.fabricmc.loom.configuration.providers.mappings.MappingsProvider
 import net.fabricmc.loom.api.mappings.layered.spec.MappingsSpec
+import net.fabricmc.loom.configuration.providers.mappings.IntermediaryService
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingSpec
+import net.fabricmc.loom.configuration.providers.mappings.LayeredMappingsProcessor
+import net.fabricmc.loom.configuration.providers.minecraft.MinecraftProvider
 import net.fabricmc.mappingio.adapter.MappingDstNsReorder
 import net.fabricmc.mappingio.adapter.MappingSourceNsSwitch
 import net.fabricmc.mappingio.format.Tiny2Writer
@@ -42,13 +41,13 @@ import org.gradle.api.logging.Logger
 import spock.lang.Specification
 
 import java.nio.file.Path
+import java.util.function.Supplier
 import java.util.zip.ZipFile
 
 abstract class LayeredMappingsSpecification extends Specification implements LayeredMappingsTestConstants {
     Logger mockLogger = Mock(Logger)
-    MappingsProvider mockMappingsProvider = Mock(MappingsProvider)
     MinecraftProvider mockMinecraftProvider = Mock(MinecraftProvider)
-
+    String intermediaryUrl
     MappingContext mappingContext = new TestMappingContext()
 
     File tempDir = File.createTempDir()
@@ -102,7 +101,12 @@ abstract class LayeredMappingsSpecification extends Specification implements Lay
         return reorderedMappings
     }
 
-    @CompileStatic
+    def setup() {
+        mockMinecraftProvider.file(_) >> { args ->
+            return new File(tempDir, args[0])
+        }
+    }
+
     class TestMappingContext implements MappingContext {
         @Override
         Path resolveDependency(Dependency dependency) {
@@ -116,8 +120,10 @@ abstract class LayeredMappingsSpecification extends Specification implements Lay
         }
 
         @Override
-        MappingsProvider mappingsProvider() {
+        Supplier<MemoryMappingTree> intermediaryTree() {
-            return mockMappingsProvider
+            return {
+                IntermediaryService.create(intermediaryUrl, minecraftProvider()).memoryMappingTree
+            }
         }
 
         @Override

src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/MojangMappingLayerTest.groovy

@@ -30,7 +30,7 @@ import net.fabricmc.loom.configuration.providers.mappings.mojmap.MojangMappingsS
 class MojangMappingLayerTest extends LayeredMappingsSpecification {
     def "Read mojang mappings with synthetic field names" () {
         setup:
-            mockMappingsProvider.intermediaryTinyFile() >> extractFileFromZip(downloadFile(INTERMEDIARY_1_17_URL, "intermediary.jar"), "mappings/mappings.tiny")
+            intermediaryUrl = INTERMEDIARY_1_17_URL
             mockMinecraftProvider.getVersionInfo() >> VERSION_META_1_17
         when:
             def mappings = getLayeredMappings(
@@ -50,7 +50,7 @@ class MojangMappingLayerTest extends LayeredMappingsSpecification {
 
     def "Read mojang mappings without synthetic field names" () {
         setup:
-            mockMappingsProvider.intermediaryTinyFile() >> extractFileFromZip(downloadFile(INTERMEDIARY_1_17_URL, "intermediary.jar"), "mappings/mappings.tiny")
+        intermediaryUrl = INTERMEDIARY_1_17_URL
             mockMinecraftProvider.getVersionInfo() >> VERSION_META_1_17
         when:
             def mappings = getLayeredMappings(

src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/ParchmentMappingLayerTest.groovy

@@ -32,7 +32,7 @@ import net.fabricmc.loom.configuration.providers.mappings.parchment.ParchmentMap
 class ParchmentMappingLayerTest extends LayeredMappingsSpecification {
     def "Read parchment mappings" () {
         setup:
-            mockMappingsProvider.intermediaryTinyFile() >> extractFileFromZip(downloadFile(INTERMEDIARY_1_16_5_URL, "intermediary.jar"), "mappings/mappings.tiny")
+            intermediaryUrl = INTERMEDIARY_1_16_5_URL
             mockMinecraftProvider.getVersionInfo() >> VERSION_META_1_16_5
         when:
             withMavenFile(PARCHMENT_NOTATION, downloadFile(PARCHMENT_URL, "parchment.zip"))
@@ -55,7 +55,7 @@ class ParchmentMappingLayerTest extends LayeredMappingsSpecification {
 
     def "Read parchment mappings remove prefix" () {
         setup:
-            mockMappingsProvider.intermediaryTinyFile() >> extractFileFromZip(downloadFile(INTERMEDIARY_1_16_5_URL, "intermediary.jar"), "mappings/mappings.tiny")
+            intermediaryUrl = INTERMEDIARY_1_16_5_URL
             mockMinecraftProvider.getVersionInfo() >> VERSION_META_1_16_5
         when:
             withMavenFile(PARCHMENT_NOTATION, downloadFile(PARCHMENT_URL, "parchment.zip"))

src/test/groovy/net/fabricmc/loom/test/util/GradleProjectTestTrait.groovy

@@ -65,6 +65,10 @@ trait GradleProjectTestTrait {
             String repo  = options.repo
             String commit = options.commit
 
+            if (options.allowExistingRepo && projectDir.listFiles()?.length > 0) {
+                return
+            }
+
             exec(projectDir, "git", "clone", repo, ".")
             exec(projectDir, "git", "checkout", commit)
 
@@ -85,6 +89,7 @@ trait GradleProjectTestTrait {
     }
 
     private void exec(File projectDir, String... args) {
+        projectDir.mkdirs()
         def process = args.execute([], projectDir)
         process.consumeProcessOutput(System.out, System.err)
 

src/test/resources/projects/mixinApAutoRefmap/build.gradle

@@ -90,9 +90,8 @@ shadowJar {
 }
 
 remapJar {
-	dependsOn(shadowJar)
 	archiveClassifier.set("universal")
-	input.fileValue(tasks["shadowJar"].outputs.files.singleFile)
+	inputFile = shadowJar.archiveFile
 }
 
 jar {