First pass on "shareCaches".

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

@@ -24,6 +24,7 @@
 
 package net.fabricmc.loom;
 
+import java.io.IOException;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Optional;
@@ -54,6 +55,8 @@ import net.fabricmc.loom.providers.MinecraftProvider;
 import net.fabricmc.loom.providers.MappingsCache;
 import net.fabricmc.loom.task.RemapJarTask;
 import net.fabricmc.loom.task.RemapSourcesJarTask;
+import net.fabricmc.loom.task.shared.RemapAllJarsTask;
+import net.fabricmc.loom.task.shared.RemapAllSourcesTask;
 import net.fabricmc.loom.util.Constants;
 import net.fabricmc.loom.util.GroovyXmlUtil;
 import net.fabricmc.loom.util.LoomDependencyManager;
@@ -64,7 +67,9 @@ import net.fabricmc.loom.util.mixin.JavaApInvoker;
 import net.fabricmc.loom.util.mixin.KaptApInvoker;
 import net.fabricmc.loom.util.mixin.ScalaApInvoker;
 import net.fabricmc.loom.util.FabricApiExtension;
+import net.fabricmc.loom.util.SourceRemapper;
 import net.fabricmc.loom.util.DownloadUtil;
+import net.fabricmc.loom.util.JarRemapper;
 
 public class AbstractPlugin implements Plugin<Project> {
 	protected Project project;
@@ -268,6 +273,48 @@ public class AbstractPlugin implements Plugin<Project> {
 					}
 				}
 
+				SourceRemapper remapper = null;
+				Task parentTask = project1.getTasks().getByName("build");
+
+				if (extension.isShareCaches()) {
+					Project rootProject = project.getRootProject();
+
+					if (extension.isRootProject()) {
+						SourceRemapper sourceRemapper = new SourceRemapper(rootProject, false);
+						JarRemapper jarRemapper = new JarRemapper();
+
+						remapJarTask.jarRemapper = jarRemapper;
+
+						rootProject.getTasks().register("remapAllSources", RemapAllSourcesTask.class, task -> {
+							task.sourceRemapper = sourceRemapper;
+							task.doLast(t -> sourceRemapper.remapAll());
+						});
+
+						parentTask = rootProject.getTasks().getByName("remapAllSources");
+
+						rootProject.getTasks().register("remapAllJars", RemapAllJarsTask.class, task -> {
+							task.doLast(t -> {
+								try {
+									jarRemapper.remap();
+								} catch (IOException e) {
+									throw new RuntimeException("Failed to remap jars", e);
+								}
+							});
+						});
+
+						for (Project subProject : rootProject.getAllprojects()) {
+							subProject.getTasks().getByName("build").dependsOn(parentTask);
+							subProject.getTasks().getByName("build").dependsOn(rootProject.getTasks().getByName("remapAllJars"));
+							rootProject.getTasks().getByName("remapAllJars").dependsOn(subProject.getTasks().getByName("remapJar"));
+						}
+					} else {
+						parentTask = rootProject.getTasks().getByName("remapAllSources");
+						remapper = ((RemapAllSourcesTask) parentTask).sourceRemapper;
+
+						remapJarTask.jarRemapper = ((RemapJarTask) rootProject.getTasks().getByName("remapJar")).jarRemapper;
+					}
+				}
+
 				try {
 					AbstractArchiveTask sourcesTask = (AbstractArchiveTask) project1.getTasks().getByName("sourcesJar");
 
@@ -276,7 +323,12 @@ public class AbstractPlugin implements Plugin<Project> {
 					remapSourcesJarTask.setOutput(sourcesTask.getArchivePath());
 					remapSourcesJarTask.doLast(task -> project1.getArtifacts().add("archives", remapSourcesJarTask.getOutput()));
 					remapSourcesJarTask.dependsOn(project1.getTasks().getByName("sourcesJar"));
-					project1.getTasks().getByName("build").dependsOn(remapSourcesJarTask);
+
+					if (extension.isShareCaches()) {
+						remapSourcesJarTask.setSourceRemapper(remapper);
+					}
+
+					parentTask.dependsOn(remapSourcesJarTask);
 				} catch (UnknownTaskException e) {
 					// pass
 				}

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

@@ -61,6 +61,7 @@ public class LoomGradleExtension {
 	public String customManifest = null;
 	public File accessWidener = null;
 	public Function<String, Object> intermediaryUrl = mcVer -> "https://maven.fabricmc.net/net/fabricmc/intermediary/" + mcVer + "/intermediary-" + mcVer + "-v2.jar";
+	public boolean shareCaches = false;
 
 	private List<Path> unmappedModsBuilt = new ArrayList<>();
 
@@ -338,4 +339,24 @@ public class LoomGradleExtension {
 		//Done like this to work around this possibly not being a java string...
 		return s -> intermediaryUrl.apply(s).toString();
 	}
+
+	public boolean isRootProject() {
+		return project.getRootProject() == project;
+	}
+
+	public LoomGradleExtension getRootGradleExtension() {
+		if (isRootProject()) {
+			return this;
+		}
+
+		return project.getRootProject().getExtensions().getByType(LoomGradleExtension.class);
+	}
+
+	public LoomGradleExtension getSharedGradleExtension() {
+		return isShareCaches() ? getRootGradleExtension() : this;
+	}
+
+	public boolean isShareCaches() {
+		return shareCaches;
+	}
 }

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

@@ -120,6 +120,10 @@ public class MinecraftProvider extends DependencyProvider {
 	private void downloadMcJson(boolean offline) throws IOException {
 		File manifests = new File(getExtension().getUserCache(), "version_manifest.json");
 
+		if (getExtension().isShareCaches() && !getExtension().isRootProject() && manifests.exists() && !isRefreshDeps()) {
+			return;
+		}
+
 		if (offline) {
 			if (manifests.exists()) {
 				//If there is the manifests already we'll presume that's good enough
@@ -171,6 +175,10 @@ public class MinecraftProvider extends DependencyProvider {
 	}
 
 	private void downloadJars(Logger logger) throws IOException {
+		if (getExtension().isShareCaches() && !getExtension().isRootProject() && minecraftClientJar.exists() && minecraftServerJar.exists() && !isRefreshDeps()) {
+			return;
+		}
+
 		DownloadUtil.downloadIfChanged(new URL(versionInfo.downloads.get("client").url), minecraftClientJar, logger);
 		DownloadUtil.downloadIfChanged(new URL(versionInfo.downloads.get("server").url), minecraftServerJar, logger);
 	}

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

@@ -26,6 +26,7 @@ package net.fabricmc.loom.task;
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.LinkedHashSet;
@@ -38,6 +39,7 @@ import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
 import org.gradle.jvm.tasks.Jar;
+import org.zeroturnaround.zip.ZipUtil;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.providers.MappingsProvider;
@@ -46,6 +48,8 @@ import net.fabricmc.loom.util.MixinRefmapHelper;
 import net.fabricmc.loom.util.NestedJars;
 import net.fabricmc.loom.util.TinyRemapperMappingsHelper;
 import net.fabricmc.loom.util.accesswidener.AccessWidenerJarProcessor;
+import net.fabricmc.loom.util.JarRemapper;
+import net.fabricmc.stitch.util.Pair;
 import net.fabricmc.tinyremapper.OutputConsumerPath;
 import net.fabricmc.tinyremapper.TinyRemapper;
 import net.fabricmc.tinyremapper.TinyUtils;
@@ -54,6 +58,7 @@ public class RemapJarTask extends Jar {
 	private RegularFileProperty input;
 	private Property<Boolean> addNestedDependencies;
 	private Property<Boolean> remapAccessWidener;
+	public JarRemapper jarRemapper;
 
 	public RemapJarTask() {
 		super();
@@ -66,6 +71,14 @@ public class RemapJarTask extends Jar {
 
 	@TaskAction
 	public void doTask() throws Throwable {
+		if (jarRemapper == null) {
+			doSingleRemap();
+		} else {
+			scheduleRemap();
+		}
+	}
+
+	public void doSingleRemap() throws Throwable {
 		Project project = getProject();
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 		Path input = this.getInput().getAsFile().get().toPath();
@@ -150,6 +163,81 @@ public class RemapJarTask extends Jar {
 		}*/
 	}
 
+	public void scheduleRemap() throws Throwable {
+		Project project = getProject();
+		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
+		Path input = this.getInput().getAsFile().get().toPath();
+		Path output = this.getArchivePath().toPath();
+
+		if (!Files.exists(input)) {
+			throw new FileNotFoundException(input.toString());
+		}
+
+		MappingsProvider mappingsProvider = extension.getMappingsProvider();
+
+		String fromM = "named";
+		String toM = "intermediary";
+
+		if (extension.isRootProject()) {
+			Set<File> classpathFiles = new LinkedHashSet<>(
+					project.getConfigurations().getByName("compileClasspath").getFiles()
+			);
+
+			Path[] classpath = classpathFiles.stream()
+					.map(File::toPath)
+					.filter(Files::exists)
+					.toArray(Path[]::new);
+
+			jarRemapper.addToClasspath(classpath);
+
+			jarRemapper.addMappings(TinyRemapperMappingsHelper.create(mappingsProvider.getMappings(), fromM, toM, false));
+		}
+
+		File mixinMapFile = mappingsProvider.mappingsMixinExport;
+		Path mixinMapPath = mixinMapFile.toPath();
+
+		if (mixinMapFile.exists()) {
+			jarRemapper.addMappings(TinyUtils.createTinyMappingProvider(mixinMapPath, fromM, toM));
+		}
+
+		jarRemapper.scheduleRemap(input, output)
+				.supplyAccessWidener((remapData, remapper) -> {
+					if (getRemapAccessWidener().getOrElse(false) && extension.accessWidener != null) {
+						AccessWidenerJarProcessor accessWidenerJarProcessor = extension.getJarProcessorManager().getByType(AccessWidenerJarProcessor.class);
+						byte[] data;
+
+						try {
+							data = accessWidenerJarProcessor.getRemappedAccessWidener(remapper);
+						} catch (IOException e) {
+							throw new RuntimeException("Failed to remap access widener");
+						}
+
+						return Pair.of(accessWidenerJarProcessor.getAccessWidenerPath(remapData.output), data);
+					}
+
+					return null;
+				})
+				.complete((data, accessWidener) -> {
+					if (!Files.exists(output)) {
+						throw new RuntimeException("Failed to remap " + input + " to " + output + " - file missing!");
+					}
+
+					if (MixinRefmapHelper.addRefmapName(extension.getRefmapName(), extension.getMixinJsonVersion(), output)) {
+						project.getLogger().debug("Transformed mixin reference maps in output JAR!");
+					}
+
+					if (getAddNestedDependencies().getOrElse(false)) {
+						if (NestedJars.addNestedJars(project, output)) {
+							project.getLogger().debug("Added nested jar paths to mod json");
+						}
+					}
+
+					if (accessWidener != null) {
+						ZipUtil.replaceEntry(data.output.toFile(), accessWidener.getLeft(), accessWidener.getRight());
+					}
+				});
+	}
+
 	@InputFile
 	public RegularFileProperty getInput() {
 		return input;

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

@@ -28,6 +28,7 @@ import java.io.File;
 
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFile;
+import org.gradle.api.tasks.Internal;
 import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
 
@@ -37,10 +38,34 @@ public class RemapSourcesJarTask extends AbstractLoomTask {
 	private Object input;
 	private Object output;
 	private String direction = "intermediary";
+	private SourceRemapper sourceRemapper = null;
 
 	@TaskAction
 	public void remap() throws Exception {
-		SourceRemapper.remapSources(getProject(), getInput(), getOutput(), direction.equals("named"));
+		if (sourceRemapper == null) {
+			SourceRemapper.remapSources(getProject(), getInput(), getOutput(), direction.equals("named"));
+		} else {
+			sourceRemapper.scheduleRemapSources(getInput(), getOutput());
+		}
+	}
+
+	public String getDirection() {
+		return direction;
+	}
+
+	public RemapSourcesJarTask setDirection(String direction) {
+		this.direction = direction;
+		return this;
+	}
+
+	@Internal
+	public SourceRemapper getSourceRemapper() {
+		return sourceRemapper;
+	}
+
+	public RemapSourcesJarTask setSourceRemapper(SourceRemapper sourceRemapper) {
+		this.sourceRemapper = sourceRemapper;
+		return this;
 	}
 
 	@InputFile

src/main/java/net/fabricmc/loom/task/shared/RemapAllJarsTask.java

@@ -0,0 +1,30 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 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.shared;
+
+import net.fabricmc.loom.task.AbstractLoomTask;
+
+public class RemapAllJarsTask extends AbstractLoomTask {
+}

src/main/java/net/fabricmc/loom/task/shared/RemapAllSourcesTask.java

@@ -0,0 +1,32 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 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.shared;
+
+import net.fabricmc.loom.task.AbstractLoomTask;
+import net.fabricmc.loom.util.SourceRemapper;
+
+public class RemapAllSourcesTask extends AbstractLoomTask {
+	public SourceRemapper sourceRemapper;
+}

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

@@ -0,0 +1,141 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 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;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BiFunction;
+
+import org.objectweb.asm.commons.Remapper;
+
+import net.fabricmc.stitch.util.Pair;
+import net.fabricmc.tinyremapper.IMappingProvider;
+import net.fabricmc.tinyremapper.InputTag;
+import net.fabricmc.tinyremapper.OutputConsumerPath;
+import net.fabricmc.tinyremapper.TinyRemapper;
+
+public class JarRemapper {
+	private final List<IMappingProvider> mappingProviders = new ArrayList<>();
+	private final Set<Path> classPath = new HashSet<>();
+	private final List<RemapData> remapData = new ArrayList<>();
+
+	public void addMappings(IMappingProvider mappingProvider) {
+		mappingProviders.add(mappingProvider);
+	}
+
+	public void addToClasspath(Path... paths) {
+		classPath.addAll(Arrays.asList(paths));
+	}
+
+	public RemapData scheduleRemap(Path input, Path output) {
+		RemapData data = new RemapData(input, output);
+		remapData.add(data);
+		return data;
+	}
+
+	public void remap() throws IOException {
+		TinyRemapper.Builder remapperBuilder = TinyRemapper.newRemapper();
+		mappingProviders.forEach(remapperBuilder::withMappings);
+
+		TinyRemapper remapper = remapperBuilder.build();
+
+		Path[] remapClasspath = classPath.stream()
+				.filter(path ->
+						remapData.stream().noneMatch(remapData -> remapData.input.equals(path))
+				)
+				.toArray(Path[]::new);
+
+		remapper.readClassPathAsync(remapClasspath);
+
+		for (RemapData data : remapData) {
+			InputTag tag = remapper.createInputTag();
+			data.tag = tag;
+			remapper.readInputsAsync(tag, data.input);
+		}
+
+		List<OutputConsumerPath> outputConsumers = new ArrayList<>();
+
+		for (RemapData data : remapData) {
+			OutputConsumerPath outputConsumer = new OutputConsumerPath.Builder(data.output).build();
+			outputConsumers.add(outputConsumer);
+
+			outputConsumer.addNonClassFiles(data.input);
+
+			data.processAccessWidener(remapper.getRemapper());
+			remapper.apply(outputConsumer, data.tag);
+		}
+
+		remapper.finish();
+
+		for (OutputConsumerPath outputConsumer : outputConsumers) {
+			outputConsumer.close();
+		}
+
+		remapData.forEach(RemapData::complete);
+	}
+
+	public static class RemapData {
+		public final Path input;
+		public final Path output;
+		BiFunction<RemapData, Remapper, Pair<String, byte[]>> accesWidenerSupplier;
+		BiConsumer<RemapData, Pair<String, byte[]>> onComplete;
+
+		private InputTag tag;
+		private Pair<String, byte[]> accessWidener;
+
+		public RemapData(Path input, Path output) {
+			this.input = input;
+			this.output = output;
+		}
+
+		public RemapData complete(BiConsumer<RemapData, Pair<String, byte[]>> onComplete) {
+			this.onComplete = onComplete;
+			return this;
+		}
+
+		public RemapData supplyAccessWidener(BiFunction<RemapData, Remapper, Pair<String, byte[]>> beforeFinish) {
+			this.accesWidenerSupplier = beforeFinish;
+			return this;
+		}
+
+		private void complete() {
+			if (onComplete != null) {
+				onComplete.accept(this, accessWidener);
+			}
+		}
+
+		private void processAccessWidener(Remapper remapper) {
+			if (accesWidenerSupplier != null) {
+				accessWidener = accesWidenerSupplier.apply(this, remapper);
+			}
+		}
+	}
+}

src/main/java/net/fabricmc/loom/util/accesswidener/AccessWidenerJarProcessor.java

@@ -124,13 +124,7 @@ public class AccessWidenerJarProcessor implements JarProcessor {
 
 	//Called when remapping the mod
 	public void remapAccessWidener(Path modJarPath, Remapper asmRemapper) throws IOException {
-		AccessWidenerRemapper remapper = new AccessWidenerRemapper(accessWidener, asmRemapper, "intermediary");
-		AccessWidener remapped = remapper.remap();
-
-		StringWriter writer = new StringWriter();
-		remapped.write(writer);
-		byte[] bytes = writer.toString().getBytes();
-		writer.close();
+		byte[] bytes = getRemappedAccessWidener(asmRemapper);
 
 		String path = getAccessWidenerPath(modJarPath);
 
@@ -145,7 +139,17 @@ public class AccessWidenerJarProcessor implements JarProcessor {
 		}
 	}
 
-	private String getAccessWidenerPath(Path modJarPath) {
+	public byte[] getRemappedAccessWidener(Remapper asmRemapper) throws IOException {
+		AccessWidenerRemapper remapper = new AccessWidenerRemapper(accessWidener, asmRemapper, "intermediary");
+		AccessWidener remapped = remapper.remap();
+
+		try (StringWriter writer = new StringWriter()) {
+			remapped.write(writer);
+			return writer.toString().getBytes();
+		}
+	}
+
+	public String getAccessWidenerPath(Path modJarPath) {
 		byte[] modJsonBytes = ZipUtil.unpackEntry(modJarPath.toFile(), "fabric.mod.json");
 
 		if (modJsonBytes == null) {