Support configuration cache within a single daemon (JvmLocalCache)

plugin-gradle/CHANGES.md

@@ -3,8 +3,17 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `3.27.0`).
 
 ## [Unreleased]
+### Added
+* Support for Gradle Configuration Cache* ([#982](https://github.com/diffplug/spotless/pull/982), [#986](https://github.com/diffplug/spotless/pull/986))
+  * *Spotless must run on the same daemon that wrote the configuration cache. If it isn't, you'll get this error message:
+  * ```
+    Spotless JVM-local cache is stale. Regenerate the cache with
+      rm -rf .gradle/configuration-cache
+    ```
+  * To make this daemon-restriction obsolete, please see and upvote [#987](https://github.com/diffplug/spotless/issues/987).
 ### Changed
-* **BREAKING** Previously, many projects required `buildscript { repositories { mavenCentral() }}` at the top of their root project, because Spotless resolved its dependencies using the buildscript repositories. Spotless now resolves its dependencies from the normal project repositories of each project with a `spotless {...}` block. This means that you can remove the `buildscript {}` block, but you still need a `repositories { mavenCentral() }` (or similar) in each project which is using Spotless.
+* **BREAKING** Previously, many projects required `buildscript { repositories { mavenCentral() }}` at the top of their root project, because Spotless resolved its dependencies using the buildscript repositories. Spotless now resolves its dependencies from the normal project repositories of each project with a `spotless {...}` block. This means that you can remove the `buildscript {}` block, but you still need a `repositories { mavenCentral() }` (or similar) in each project which is using Spotless. ([#980](https://github.com/diffplug/spotless/pull/980), [#983](https://github.com/diffplug/spotless/pull/983))
+  * If you prefer the old behavior, we are open to adding that back as a new feature, see [#984 predeclared dependencies](https://github.com/diffplug/spotless/issues/984).
 * **BREAKING** `createIndepentApplyTask(String taskName)` now requires that `taskName` does not end with `Apply`
 * Bump minimum required Gradle from `6.1` to `6.1.1`.
 

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/FormatExtension.java

@@ -734,9 +734,7 @@ protected void setupTask(SpotlessTask task) {
 		task.setSteps(steps);
 		task.setLineEndingsPolicy(getLineEndings().createPolicy(getProject().getProjectDir(), () -> totalTarget));
 		spotless.getRegisterDependenciesTask().hookSubprojectTask(task);
-		if (getRatchetFrom() != null) {
-			task.setupRatchet(getRatchetFrom());
-		}
+		task.setupRatchet(getRatchetFrom() != null ? getRatchetFrom() : "");
 	}
 
 	/** Returns the project that this extension is attached to. */

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JvmLocalCache.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2021 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.gradle.spotless;
+
+import java.io.File;
+import java.io.Serializable;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+import org.gradle.api.GradleException;
+import org.gradle.api.Task;
+
+import com.diffplug.spotless.FileSignature;
+
+class JvmLocalCache {
+	private static GradleException cacheIsStale() {
+		return new GradleException("Spotless JVM-local cache is stale. Regenerate the cache with\n" +
+				"  " + (FileSignature.machineIsWin() ? "rmdir /q /s" : "rm -rf") + " .gradle/configuration-cache\n" +
+				"To make this workaround obsolete, please upvote https://github.com/diffplug/spotless/issues/987");
+	}
+
+	interface LiveCache<T> {
+		T get();
+
+		void set(T value);
+	}
+
+	static <T> LiveCache<T> createLive(Task task, String propertyName) {
+		return new LiveCacheKeyImpl<T>(new InternalCacheKey(task.getProject().getProjectDir(), task.getPath(), propertyName));
+	}
+
+	static class LiveCacheKeyImpl<T> implements LiveCache<T>, Serializable {
+		InternalCacheKey internalKey;
+
+		LiveCacheKeyImpl(InternalCacheKey internalKey) {
+			this.internalKey = internalKey;
+		}
+
+		@Override
+		public void set(T value) {
+			daemonState.put(internalKey, value);
+		}
+
+		@Override
+		public T get() {
+			Object value = daemonState.get(internalKey);
+			if (value == null) {
+				// TODO: throw TriggerConfigurationException(); (see https://github.com/diffplug/spotless/issues/987)
+				throw cacheIsStale();
+			} else {
+				return (T) value;
+			}
+		}
+	}
+
+	private static Map<InternalCacheKey, Object> daemonState = Collections.synchronizedMap(new HashMap<>());
+
+	private static class InternalCacheKey implements Serializable {
+		private File projectDir;
+		private String taskPath;
+		private String propertyName;
+
+		InternalCacheKey(File projectDir, String taskPath, String keyName) {
+			this.projectDir = projectDir;
+			this.taskPath = taskPath;
+			this.propertyName = keyName;
+		}
+
+		@Override
+		public boolean equals(Object o) {
+			if (this == o)
+				return true;
+			if (o == null || getClass() != o.getClass())
+				return false;
+			InternalCacheKey that = (InternalCacheKey) o;
+			return projectDir.equals(that.projectDir) && taskPath.equals(that.taskPath) && propertyName.equals(that.propertyName);
+		}
+
+		@Override
+		public int hashCode() {
+			return Objects.hash(projectDir, taskPath, propertyName);
+		}
+	}
+}

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/RegisterDependenciesTask.java

@@ -15,22 +15,16 @@
  */
 package com.diffplug.gradle.spotless;
 
-import java.io.File;
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-
 import javax.inject.Inject;
 
 import org.gradle.api.DefaultTask;
 import org.gradle.api.provider.Property;
 import org.gradle.api.services.BuildServiceRegistry;
 import org.gradle.api.tasks.Internal;
-import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
 import org.gradle.build.event.BuildEventsListenerRegistry;
 
 import com.diffplug.common.base.Preconditions;
-import com.diffplug.common.io.Files;
 
 /**
  * NOT AN END-USER TASK, DO NOT USE FOR ANYTHING!
@@ -46,39 +40,27 @@ public abstract class RegisterDependenciesTask extends DefaultTask {
 	static final String TASK_NAME = "spotlessInternalRegisterDependencies";
 
 	void hookSubprojectTask(SpotlessTask task) {
-		// TODO: in the future, we might use this hook to add an optional perf improvement
-		// spotlessRoot {
+		// TODO: in the future, we might use this hook to implement #984
+		// spotlessSetup {
 		//    java { googleJavaFormat('1.2') }
 		//    ...etc
 		// }
-		// The point would be to reuse configurations from the root project,
-		// with the restriction that you have to declare every formatter in
-		// the root, and you'd get an error if you used a formatter somewhere
-		// which you didn't declare in the root. That's a problem for the future
-		// though, not today!
+		// it's also needed to make sure that jvmLocalCache gets set
+		// in the SpotlessTaskService before any spotless tasks run
 		task.dependsOn(this);
 	}
 
-	File unitOutput;
-
-	@OutputFile
-	public File getUnitOutput() {
-		return unitOutput;
-	}
-
 	void setup() {
 		Preconditions.checkArgument(getProject().getRootProject() == getProject(), "Can only be used on the root project");
-		unitOutput = new File(getProject().getBuildDir(), "tmp/spotless-register-dependencies");
 
 		BuildServiceRegistry buildServices = getProject().getGradle().getSharedServices();
 		getTaskService().set(buildServices.registerIfAbsent("SpotlessTaskService", SpotlessTaskService.class, spec -> {}));
 		getBuildEventsListenerRegistry().onTaskCompletion(getTaskService());
 	}
 
 	@TaskAction
-	public void trivialFunction() throws IOException {
-		Files.createParentDirs(unitOutput);
-		Files.write(Integer.toString(1), unitOutput, StandardCharsets.UTF_8);
+	public void trivialFunction() {
+		// nothing to do :)
 	}
 
 	@Internal

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessTask.java

@@ -38,6 +38,7 @@
 import org.gradle.api.tasks.PathSensitivity;
 import org.gradle.work.Incremental;
 
+import com.diffplug.gradle.spotless.JvmLocalCache.LiveCache;
 import com.diffplug.spotless.FormatExceptionPolicy;
 import com.diffplug.spotless.FormatExceptionPolicyStrict;
 import com.diffplug.spotless.Formatter;
@@ -48,6 +49,10 @@ public abstract class SpotlessTask extends DefaultTask {
 	@Internal
 	abstract Property<SpotlessTaskService> getTaskService();
 
+	protected <T> LiveCache<T> createLive(String keyName) {
+		return JvmLocalCache.createLive(this, keyName);
+	}
+
 	// set by SpotlessExtension, but possibly overridden by FormatExtension
 	protected String encoding = "UTF-8";
 
@@ -60,15 +65,15 @@ public void setEncoding(String encoding) {
 		this.encoding = Objects.requireNonNull(encoding);
 	}
 
-	protected transient LineEnding.Policy lineEndingsPolicy;
+	protected final LiveCache<LineEnding.Policy> lineEndingsPolicy = createLive("lineEndingsPolicy");
 
 	@Input
 	public LineEnding.Policy getLineEndingsPolicy() {
-		return lineEndingsPolicy;
+		return lineEndingsPolicy.get();
 	}
 
 	public void setLineEndingsPolicy(LineEnding.Policy lineEndingsPolicy) {
-		this.lineEndingsPolicy = Objects.requireNonNull(lineEndingsPolicy);
+		this.lineEndingsPolicy.set(lineEndingsPolicy);
 	}
 
 	/*** API which performs git up-to-date tasks. */
@@ -82,12 +87,19 @@ public void setLineEndingsPolicy(LineEnding.Policy lineEndingsPolicy) {
 	 * compared to using the project root.
 	 */
 	private transient ObjectId subtreeSha = ObjectId.zeroId();
+	/** Stored so that the configuration cache can recreate the GitRatchetGradle state. */
+	protected String ratchetFrom;
 
 	public void setupRatchet(String ratchetFrom) {
-		ratchet = getTaskService().get().getRatchet();
-		File projectDir = getProjectDir().get().getAsFile();
-		rootTreeSha = ratchet.rootTreeShaOf(projectDir, ratchetFrom);
-		subtreeSha = ratchet.subtreeShaOf(projectDir, rootTreeSha);
+		this.ratchetFrom = ratchetFrom;
+		if (!ratchetFrom.isEmpty()) {
+			ratchet = getTaskService().get().getRatchet();
+			File projectDir = getProjectDir().get().getAsFile();
+			rootTreeSha = ratchet.rootTreeShaOf(projectDir, ratchetFrom);
+			subtreeSha = ratchet.subtreeShaOf(projectDir, rootTreeSha);
+		} else {
+			subtreeSha = ObjectId.zeroId();
+		}
 	}
 
 	@Internal
@@ -105,6 +117,9 @@ ObjectId getRootTreeSha() {
 
 	@Input
 	public ObjectId getRatchetSha() {
+		if (subtreeSha == null) {
+			setupRatchet(ratchetFrom);
+		}
 		return subtreeSha;
 	}
 
@@ -143,19 +158,22 @@ public File getOutputDirectory() {
 		return outputDirectory;
 	}
 
-	protected transient List<FormatterStep> steps = new ArrayList<>();
+	protected final LiveCache<List<FormatterStep>> steps = createLive("steps");
+	{
+		steps.set(new ArrayList<FormatterStep>());
+	}
 
 	@Input
 	public List<FormatterStep> getSteps() {
-		return Collections.unmodifiableList(steps);
+		return Collections.unmodifiableList(steps.get());
 	}
 
 	public void setSteps(List<FormatterStep> steps) {
-		this.steps = PluginGradlePreconditions.requireElementsNonNull(steps);
+		this.steps.set(PluginGradlePreconditions.requireElementsNonNull(steps));
 	}
 
 	public boolean addStep(FormatterStep step) {
-		return this.steps.add(Objects.requireNonNull(step));
+		return this.steps.get().add(Objects.requireNonNull(step));
 	}
 
 	/** Returns the name of this format. */
@@ -170,10 +188,10 @@ String formatName() {
 
 	Formatter buildFormatter() {
 		return Formatter.builder()
-				.lineEndingsPolicy(lineEndingsPolicy)
+				.lineEndingsPolicy(lineEndingsPolicy.get())
 				.encoding(Charset.forName(encoding))
 				.rootDir(getProjectDir().get().getAsFile().toPath())
-				.steps(steps)
+				.steps(steps.get())
 				.exceptionPolicy(exceptionPolicy)
 				.build();
 	}

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessTaskImpl.java

@@ -64,22 +64,17 @@ public void performAction(InputChanges inputs) throws Exception {
 			Files.createDirectories(outputDirectory.toPath());
 		}
 
-		if (lineEndingsPolicy != null) {
-			try (Formatter formatter = buildFormatter()) {
-				for (FileChange fileChange : inputs.getFileChanges(target)) {
-					File input = fileChange.getFile();
-					if (fileChange.getChangeType() == ChangeType.REMOVED) {
-						deletePreviousResult(input);
-					} else {
-						if (input.isFile()) {
-							processInputFile(formatter, input);
-						}
+		try (Formatter formatter = buildFormatter()) {
+			for (FileChange fileChange : inputs.getFileChanges(target)) {
+				File input = fileChange.getFile();
+				if (fileChange.getChangeType() == ChangeType.REMOVED) {
+					deletePreviousResult(input);
+				} else {
+					if (input.isFile()) {
+						processInputFile(formatter, input);
 					}
 				}
 			}
-		} else {
-			throw new GradleException("Spotless doesn't support configuration cache yet.\n" +
-					"Rerun with --no-configuration-cache");
 		}
 	}