mvn spotless:apply now prints out statistics (#1507)

lib/src/main/java/com/diffplug/spotless/Formatter.java

@@ -39,13 +39,16 @@
 public final class Formatter implements Serializable, AutoCloseable {
 	private static final long serialVersionUID = 1L;
 
+	// The name is used for logging purpose. It does not convey any applicative purpose
+	private String name;
 	private LineEnding.Policy lineEndingsPolicy;
 	private Charset encoding;
 	private Path rootDir;
 	private List<FormatterStep> steps;
 	private FormatExceptionPolicy exceptionPolicy;
 
-	private Formatter(LineEnding.Policy lineEndingsPolicy, Charset encoding, Path rootDirectory, List<FormatterStep> steps, FormatExceptionPolicy exceptionPolicy) {
+	private Formatter(String name, LineEnding.Policy lineEndingsPolicy, Charset encoding, Path rootDirectory, List<FormatterStep> steps, FormatExceptionPolicy exceptionPolicy) {
+		this.name = name;
 		this.lineEndingsPolicy = Objects.requireNonNull(lineEndingsPolicy, "lineEndingsPolicy");
 		this.encoding = Objects.requireNonNull(encoding, "encoding");
 		this.rootDir = Objects.requireNonNull(rootDirectory, "rootDir");
@@ -55,6 +58,7 @@ private Formatter(LineEnding.Policy lineEndingsPolicy, Charset encoding, Path ro
 
 	// override serialize output
 	private void writeObject(ObjectOutputStream out) throws IOException {
+		out.writeObject(name);
 		out.writeObject(lineEndingsPolicy);
 		out.writeObject(encoding.name());
 		out.writeObject(rootDir.toString());
@@ -65,6 +69,7 @@ private void writeObject(ObjectOutputStream out) throws IOException {
 	// override serialize input
 	@SuppressWarnings("unchecked")
 	private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+		name = (String) in.readObject();
 		lineEndingsPolicy = (LineEnding.Policy) in.readObject();
 		encoding = Charset.forName((String) in.readObject());
 		rootDir = Paths.get((String) in.readObject());
@@ -78,6 +83,10 @@ private void readObjectNoData() throws ObjectStreamException {
 		throw new UnsupportedOperationException();
 	}
 
+	public String getName() {
+		return name;
+	}
+
 	public LineEnding.Policy getLineEndingsPolicy() {
 		return lineEndingsPolicy;
 	}
@@ -103,6 +112,8 @@ public static Formatter.Builder builder() {
 	}
 
 	public static class Builder {
+		// optional parameters
+		private String name = "unnamed";
 		// required parameters
 		private LineEnding.Policy lineEndingsPolicy;
 		private Charset encoding;
@@ -112,6 +123,11 @@ public static class Builder {
 
 		private Builder() {}
 
+		public Builder name(String name) {
+			this.name = name;
+			return this;
+		}
+
 		public Builder lineEndingsPolicy(LineEnding.Policy lineEndingsPolicy) {
 			this.lineEndingsPolicy = lineEndingsPolicy;
 			return this;
@@ -138,7 +154,7 @@ public Builder exceptionPolicy(FormatExceptionPolicy exceptionPolicy) {
 		}
 
 		public Formatter build() {
-			return new Formatter(lineEndingsPolicy, encoding, rootDir, steps,
+			return new Formatter(name, lineEndingsPolicy, encoding, rootDir, steps,
 					exceptionPolicy == null ? FormatExceptionPolicy.failOnlyOnError() : exceptionPolicy);
 		}
 	}
@@ -253,6 +269,7 @@ public String compute(String unix, File file) {
 	public int hashCode() {
 		final int prime = 31;
 		int result = 1;
+		result = prime * result + name.hashCode();
 		result = prime * result + encoding.hashCode();
 		result = prime * result + lineEndingsPolicy.hashCode();
 		result = prime * result + rootDir.hashCode();
@@ -273,7 +290,8 @@ public boolean equals(Object obj) {
 			return false;
 		}
 		Formatter other = (Formatter) obj;
-		return encoding.equals(other.encoding) &&
+		return name.equals(other.name) &&
+				encoding.equals(other.encoding) &&
 				lineEndingsPolicy.equals(other.lineEndingsPolicy) &&
 				rootDir.equals(other.rootDir) &&
 				steps.equals(other.steps) &&

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 DiffPlug
+ * Copyright 2020-2023 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -184,6 +184,7 @@ String formatName() {
 
 	Formatter buildFormatter() {
 		return Formatter.builder()
+				.name(formatName())
 				.lineEndingsPolicy(lineEndingsPolicy.get())
 				.encoding(Charset.forName(encoding))
 				.rootDir(getProjectDir().get().getAsFile().toPath())

plugin-maven/CHANGES.md

@@ -3,6 +3,8 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Added
+* A synthesis log with the number of considered files is added after each formatter execution ([#1507](https://github.com/diffplug/spotless/pull/1507))
 
 ## [2.31.0] - 2023-01-26
 ### Added

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 DiffPlug
+ * Copyright 2016-2023 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -101,7 +101,9 @@ public final Formatter newFormatter(Supplier<Iterable<File>> filesToFormat, Form
 			formatterSteps.add(pair.out());
 		}
 
+		String formatterName = this.getClass().getSimpleName();
 		return Formatter.builder()
+				.name(formatterName)
 				.encoding(formatterEncoding)
 				.lineEndingsPolicy(formatterLineEndingPolicy)
 				.exceptionPolicy(new FormatExceptionPolicyStrict())

plugin-maven/src/main/java/com/diffplug/spotless/maven/ImpactedFilesTracker.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2023 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.spotless.maven;
+
+/**
+ * Tracks the number of processed files, typically by a single Formatter for a whole repository
+ */
+class ImpactedFilesTracker {
+	protected int nbskippedAsCleanCache = 0;
+	protected int nbCheckedButAlreadyClean = 0;
+	protected int nbCleaned = 0;
+
+	/**
+	 * Some cache mechanism may indicate some content is clean, without having to execute the cleaning process
+	 */
+	public void skippedAsCleanCache() {
+		nbskippedAsCleanCache++;
+	}
+
+	public int getSkippedAsCleanCache() {
+		return nbskippedAsCleanCache;
+	}
+
+	public void checkedButAlreadyClean() {
+		nbCheckedButAlreadyClean++;
+	}
+
+	public int getCheckedButAlreadyClean() {
+		return nbCheckedButAlreadyClean;
+	}
+
+	public void cleaned() {
+		nbCleaned++;
+	}
+
+	public int getCleaned() {
+		return nbCleaned;
+	}
+
+	public int getTotal() {
+		return nbskippedAsCleanCache + nbCheckedButAlreadyClean + nbCleaned;
+	}
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/SpotlessApplyMojo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 DiffPlug
+ * Copyright 2016-2023 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,8 +33,11 @@ public class SpotlessApplyMojo extends AbstractSpotlessMojo {
 
 	@Override
 	protected void process(Iterable<File> files, Formatter formatter, UpToDateChecker upToDateChecker) throws MojoExecutionException {
+		ImpactedFilesTracker counter = new ImpactedFilesTracker();
+
 		for (File file : files) {
 			if (upToDateChecker.isUpToDate(file.toPath())) {
+				counter.skippedAsCleanCache();
 				if (getLog().isDebugEnabled()) {
 					getLog().debug("Spotless will not format an up-to-date file: " + file);
 				}
@@ -44,14 +47,26 @@ protected void process(Iterable<File> files, Formatter formatter, UpToDateChecke
 			try {
 				PaddedCell.DirtyState dirtyState = PaddedCell.calculateDirtyState(formatter, file);
 				if (!dirtyState.isClean() && !dirtyState.didNotConverge()) {
+					getLog().info(String.format("Writing clean file: %s", file));
 					dirtyState.writeCanonicalTo(file);
 					buildContext.refresh(file);
+					counter.cleaned();
+				} else {
+					counter.checkedButAlreadyClean();
 				}
 			} catch (IOException e) {
 				throw new MojoExecutionException("Unable to format file " + file, e);
 			}
 
 			upToDateChecker.setUpToDate(file.toPath());
 		}
+
+		// We print the number of considered files which is useful when ratchetFrom is setup
+		if (counter.getTotal() > 0) {
+			getLog().info(String.format("Spotless.%s is keeping %s files clean - %s were changed to be clean, %s were already clean, %s were skipped because caching determined they were already clean",
+					formatter.getName(), counter.getTotal(), counter.getCleaned(), counter.getCheckedButAlreadyClean(), counter.getSkippedAsCleanCache()));
+		} else {
+			getLog().warn(String.format("Spotless.%s has no target files. Examine your `<includes>`: https://github.com/diffplug/spotless/tree/main/plugin-maven#quickstart", formatter.getName()));
+		}
 	}
 }

testlib/src/main/java/com/diffplug/spotless/StepHarnessWithFile.java

@@ -38,6 +38,7 @@ private StepHarnessWithFile(ResourceHarness harness, Formatter formatter) {
 	/** Creates a harness for testing steps which do depend on the file. */
 	public static StepHarnessWithFile forStep(ResourceHarness harness, FormatterStep step) {
 		return new StepHarnessWithFile(harness, Formatter.builder()
+				.name(step.getName())
 				.encoding(StandardCharsets.UTF_8)
 				.lineEndingsPolicy(LineEnding.UNIX.createPolicy())
 				.steps(Collections.singletonList(step))