Speedup GIT_ATTRIBUTES (#1838)

CHANGES.md

@@ -16,6 +16,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
   the version accordingly. ([#1804](https://github.com/diffplug/spotless/issues/1804)).
 * Support for `google-java-format`'s `skip-javadoc-formatting` option. ([#1793](https://github.com/diffplug/spotless/pull/1793))
 * Support configuration of mirrors for P2 repositories in maven DSL ([#1697](https://github.com/diffplug/spotless/issues/1697)).
+* New line endings mode `GIT_ATTRIBUTES_FAST_ALLSAME`. ([#1838](https://github.com/diffplug/spotless/pull/1838))
 ### Fixed
 * Fix support for plugins when using Prettier version `3.0.0` and newer. ([#1802](https://github.com/diffplug/spotless/pull/1802))
 * Fix configuration cache issue around `external process started '/usr/bin/git --version'`. ([#1806](https://github.com/diffplug/spotless/issues/1806))

lib-extra/src/main/java/com/diffplug/spotless/extra/GitAttributesLineEndings.java

@@ -68,6 +68,42 @@ public final class GitAttributesLineEndings {
 	// prevent direct instantiation
 	private GitAttributesLineEndings() {}
 
+	/**
+	 * Creates a line-endings policy which matches {@link #create(File, Supplier)},
+	 * which is much faster at the cost that every file under the policy
+	 * is assumed to have the same line endings as the first file.
+	 */
+	public static LineEnding.Policy createFastAllSame(File projectDir, Supplier<Iterable<File>> toFormat) {
+		return new LazyAllTheSame(projectDir, toFormat);
+	}
+
+	static class LazyAllTheSame extends LazyForwardingEquality<String> implements LineEnding.Policy {
+		private static final long serialVersionUID = 727912266173243664L;
+		transient File projectDir;
+		transient Supplier<Iterable<File>> toFormat;
+
+		public LazyAllTheSame(File projectDir, Supplier<Iterable<File>> toFormat) {
+			this.projectDir = projectDir;
+			this.toFormat = toFormat;
+		}
+
+		@Override
+		protected String calculateState() throws Exception {
+			var files = toFormat.get().iterator();
+			if (files.hasNext()) {
+				Runtime runtime = new RuntimeInit(projectDir).atRuntime();
+				return runtime.getEndingFor(files.next());
+			} else {
+				return LineEnding.UNIX.str();
+			}
+		}
+
+		@Override
+		public String getEndingFor(File file) {
+			return state();
+		}
+	}
+
 	/**
 	 * Creates a line-endings policy whose serialized state is relativized against projectDir,
 	 * at the cost of eagerly evaluating the line-ending state of every target file when the

lib/src/main/java/com/diffplug/spotless/LineEnding.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.
@@ -19,11 +19,8 @@
 import java.io.Serializable;
 import java.lang.reflect.Method;
 import java.util.Objects;
-import java.util.function.BiFunction;
 import java.util.function.Supplier;
 
-import javax.annotation.Nullable;
-
 /**
  * Represents the line endings which should be written by the tool.
  */
@@ -37,6 +34,14 @@ public Policy createPolicy() {
 			return super.createPolicy();
 		}
 	},
+	/** Uses the same line endings as Git, and assumes that every single file being formatted will have the same line ending. */
+	GIT_ATTRIBUTES_FAST_ALLSAME {
+		/** .gitattributes is path-specific, so you must use {@link LineEnding#createPolicy(File, Supplier)}. */
+		@Override @Deprecated
+		public Policy createPolicy() {
+			return super.createPolicy();
+		}
+	},
 	/** {@code \n} on unix systems, {@code \r\n} on windows systems. */
 	PLATFORM_NATIVE,
 	/** {@code \r\n} */
@@ -51,33 +56,31 @@ public Policy createPolicy() {
 	public Policy createPolicy(File projectDir, Supplier<Iterable<File>> toFormat) {
 		Objects.requireNonNull(projectDir, "projectDir");
 		Objects.requireNonNull(toFormat, "toFormat");
-		if (this != GIT_ATTRIBUTES) {
-			return createPolicy();
+		String gitAttributesMethod;
+		if (this == GIT_ATTRIBUTES) {
+			gitAttributesMethod = "create";
+		} else if (this == GIT_ATTRIBUTES_FAST_ALLSAME) {
+			gitAttributesMethod = "createFastAllSame";
 		} else {
-			if (gitAttributesPolicyCreator == null) {
-				try {
-					Class<?> clazz = Class.forName("com.diffplug.spotless.extra.GitAttributesLineEndings");
-					Method method = clazz.getMethod("create", File.class, Supplier.class);
-					gitAttributesPolicyCreator = (proj, target) -> ThrowingEx.get(() -> (Policy) method.invoke(null, proj, target));
-				} catch (ClassNotFoundException | NoSuchMethodException | SecurityException e) {
-					throw new IllegalStateException("LineEnding.GIT_ATTRIBUTES requires the spotless-lib-extra library, but it is not on the classpath", e);
-				}
-			}
-			// gitAttributesPolicyCreator will always be nonnull at this point
-			return gitAttributesPolicyCreator.apply(projectDir, toFormat);
+			return createPolicy();
+		}
+		try {
+			Class<?> clazz = Class.forName("com.diffplug.spotless.extra.GitAttributesLineEndings");
+			Method method = clazz.getMethod(gitAttributesMethod, File.class, Supplier.class);
+			return ThrowingEx.get(() -> (Policy) method.invoke(null, projectDir, toFormat));
+		} catch (ClassNotFoundException | NoSuchMethodException | SecurityException e) {
+			throw new IllegalStateException("LineEnding.GIT_ATTRIBUTES requires the spotless-lib-extra library, but it is not on the classpath", e);
 		}
 	}
 
-	private static volatile @Nullable BiFunction<File, Supplier<Iterable<File>>, Policy> gitAttributesPolicyCreator;
-
 	// @formatter:off
 	/** Should use {@link #createPolicy(File, Supplier)} instead, but this will work iff its a path-independent LineEnding policy. */
 	public Policy createPolicy() {
 		switch (this) {
 		case PLATFORM_NATIVE:	return _platformNativePolicy;
 		case WINDOWS:			return WINDOWS_POLICY;
 		case UNIX:				return UNIX_POLICY;
-        case MAC_CLASSIC:       return MAC_CLASSIC_POLICY;
+		case MAC_CLASSIC:		return MAC_CLASSIC_POLICY;
 		default:	throw new UnsupportedOperationException(this + " is a path-specific line ending.");
 		}
 	}
@@ -121,7 +124,7 @@ public String str() {
 		case PLATFORM_NATIVE:	return _platformNative;
 		case WINDOWS:			return "\r\n";
 		case UNIX:				return "\n";
-		case MAC_CLASSIC:       return "\r";
+		case MAC_CLASSIC:		return "\r";
 		default:	throw new UnsupportedOperationException(this + " is a path-specific line ending.");
 		}
 	}

plugin-gradle/CHANGES.md

@@ -13,6 +13,9 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * Fixed support for plugins when using Prettier version `3.0.0` and newer. ([#1802](https://github.com/diffplug/spotless/pull/1802))
 ### Changes
 * Bump default `ktlint` version to latest `0.50.0` -> `1.0.0`. ([#1808](https://github.com/diffplug/spotless/pull/1808))
+* **POSSIBLY BREAKING** the default line endings are now `GIT_ATTRIBUTES_FAST_ALLSAME` instead of `GIT_ATTRIBUTES`. ([#1838](https://github.com/diffplug/spotless/pull/1838))
+  * If all the files within a format have the same line endings, then there is no change in behavior.
+  * Fixes large performance regression. ([#1527](https://github.com/diffplug/spotless/issues/1527))
 
 ## [6.21.0] - 2023-08-29
 ### Added

plugin-gradle/README.md

@@ -1425,12 +1425,12 @@ spotless {
     encoding 'Cp1252' // except java, which will be Cp1252
 ```
 
-Line endings can also be set globally or per-format using the `lineEndings` property.  Spotless supports four line ending modes: `UNIX`, `WINDOWS`, `MAC_CLASSIC`, `PLATFORM_NATIVE`, and `GIT_ATTRIBUTES`.  The default value is `GIT_ATTRIBUTES`, and *we highly recommend that you* ***do not change*** *this value*.  Git has opinions about line endings, and if Spotless and git disagree, then you're going to have a bad time.
+Line endings can also be set globally or per-format using the `lineEndings` property.  Spotless supports four line ending modes: `UNIX`, `WINDOWS`, `MAC_CLASSIC`, `PLATFORM_NATIVE`, `GIT_ATTRIBUTES`, and `GIT_ATTRIBUTES_FAST_ALLSAME`.  The default value is `GIT_ATTRIBUTES_FAST_ALLSAME`, and *we highly recommend that you* ***do not change*** *this value*.  Git has opinions about line endings, and if Spotless and git disagree, then you're going to have a bad time. `FAST_ALLSAME` just means that Spotless can assume that every file being formatted has the same line endings ([more info](https://github.com/diffplug/spotless/pull/1838)).
 
 You can easily set the line endings of different files using [a `.gitattributes` file](https://help.github.com/articles/dealing-with-line-endings/).  Here's an example `.gitattributes` which sets all files to unix newlines: `* text eol=lf`.
 
 <a name="custom"></a>
-<a name="custom-rulwa"></a>
+<a name="custom-steps"></a>
 
 ## Custom steps
 

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

@@ -57,7 +57,7 @@ RegisterDependenciesTask getRegisterDependenciesTask() {
 	}
 
 	/** Line endings (if any). */
-	LineEnding lineEndings = LineEnding.GIT_ATTRIBUTES;
+	LineEnding lineEndings = LineEnding.GIT_ATTRIBUTES_FAST_ALLSAME;
 
 	public LineEnding getLineEndings() {
 		return lineEndings;

plugin-maven/CHANGES.md

@@ -28,6 +28,9 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ### Changes
 * Bump default `flexmark` version to latest `0.64.0` -> `0.64.8`. ([#1801](https://github.com/diffplug/spotless/pull/1801))
 * Bump default `ktlint` version to latest `0.50.0` -> `1.0.0`. ([#1808](https://github.com/diffplug/spotless/pull/1808))
+* **POSSIBLY BREAKING** the default line endings are now `GIT_ATTRIBUTES_FAST_ALLSAME` instead of `GIT_ATTRIBUTES`. ([#1838](https://github.com/diffplug/spotless/pull/1838))
+  * If all the files within a format have the same line endings, then there is no change in behavior.
+  * Fixes large performance regression. ([#1527](https://github.com/diffplug/spotless/issues/1527))
 
 ## [2.39.0] - 2023-08-29
 ### Added

plugin-maven/README.md

@@ -1586,7 +1586,7 @@ Spotless uses UTF-8 by default, but you can use [any encoding which Java support
 </configuration>
 ```
 
-Line endings can also be set globally or per-format using the `lineEndings` property.  Spotless supports four line ending modes: `UNIX`, `WINDOWS`, `MAC_CLASSIC`, `PLATFORM_NATIVE`, and `GIT_ATTRIBUTES`.  The default value is `GIT_ATTRIBUTES`, and *we highly recommend that you* ***do not change*** *this value*.  Git has opinions about line endings, and if Spotless and git disagree, then you're going to have a bad time.
+Line endings can also be set globally or per-format using the `lineEndings` property.  Spotless supports four line ending modes: `UNIX`, `WINDOWS`, `MAC_CLASSIC`, `PLATFORM_NATIVE`, `GIT_ATTRIBUTES`, and `GIT_ATTRIBUTES_FAST_ALLSAME`.  The default value is `GIT_ATTRIBUTES_FAST_ALLSAME`, and *we highly recommend that you* ***do not change*** *this value*.  Git has opinions about line endings, and if Spotless and git disagree, then you're going to have a bad time. `FAST_ALLSAME` just means that Spotless can assume that every file being formatted has the same line endings ([more info](https://github.com/diffplug/spotless/pull/1838)).
 
 You can easily set the line endings of different files using [a `.gitattributes` file](https://help.github.com/articles/dealing-with-line-endings/).  Here's an example `.gitattributes` which sets all files to unix newlines: `* text eol=lf`.
 

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

@@ -80,7 +80,7 @@
 public abstract class AbstractSpotlessMojo extends AbstractMojo {
 	private static final String DEFAULT_INDEX_FILE_NAME = "spotless-index";
 	private static final String DEFAULT_ENCODING = "UTF-8";
-	private static final String DEFAULT_LINE_ENDINGS = "GIT_ATTRIBUTES";
+	private static final String DEFAULT_LINE_ENDINGS = "GIT_ATTRIBUTES_FAST_ALLSAME";
 
 	/** Value to allow unsetting the ratchet inherited from parent pom configuration. */
 	static final String RATCHETFROM_NONE = "NONE";