Improve logging of changes that trigger a DevTools upload or restart

Closes gh-31579

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/LocalDevToolsAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,9 @@ import java.io.File;
 import java.net.URL;
 import java.util.List;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
@@ -44,6 +47,7 @@ import org.springframework.context.annotation.Lazy;
 import org.springframework.context.event.ContextRefreshedEvent;
 import org.springframework.context.event.GenericApplicationListener;
 import org.springframework.core.ResolvableType;
+import org.springframework.core.log.LogMessage;
 import org.springframework.util.StringUtils;
 
 /**
@@ -101,13 +105,9 @@ public class LocalDevToolsAutoConfiguration {
 		}
 
 		@Bean
-		ApplicationListener<ClassPathChangedEvent> restartingClassPathChangedEventListener(
+		RestartingClassPathChangeChangedEventListener restartingClassPathChangedEventListener(
 				FileSystemWatcherFactory fileSystemWatcherFactory) {
-			return (event) -> {
-				if (event.isRestartRequired()) {
-					Restarter.getInstance().restart(new FileWatchingFailureHandler(fileSystemWatcherFactory));
-				}
-			};
+			return new RestartingClassPathChangeChangedEventListener(fileSystemWatcherFactory);
 		}
 
 		@Bean
@@ -194,4 +194,24 @@ public class LocalDevToolsAutoConfiguration {
 
 	}
 
+	static class RestartingClassPathChangeChangedEventListener implements ApplicationListener<ClassPathChangedEvent> {
+
+		private static final Log logger = LogFactory.getLog(RestartingClassPathChangeChangedEventListener.class);
+
+		private final FileSystemWatcherFactory fileSystemWatcherFactory;
+
+		RestartingClassPathChangeChangedEventListener(FileSystemWatcherFactory fileSystemWatcherFactory) {
+			this.fileSystemWatcherFactory = fileSystemWatcherFactory;
+		}
+
+		@Override
+		public void onApplicationEvent(ClassPathChangedEvent event) {
+			if (event.isRestartRequired()) {
+				logger.info(LogMessage.format("Restarting due to %s", event.overview()));
+				Restarter.getInstance().restart(new FileWatchingFailureHandler(this.fileSystemWatcherFactory));
+			}
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/classpath/ClassPathChangedEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.boot.devtools.classpath;
 
 import java.util.Set;
 
+import org.springframework.boot.devtools.filewatch.ChangedFile;
+import org.springframework.boot.devtools.filewatch.ChangedFile.Type;
 import org.springframework.boot.devtools.filewatch.ChangedFiles;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.core.style.ToStringCreator;
@@ -71,4 +73,37 @@ public class ClassPathChangedEvent extends ApplicationEvent {
 				.append("restartRequired", this.restartRequired).toString();
 	}
 
+	/**
+	 * Return an overview of the changes that triggered this event.
+	 * @return an overview of the changes
+	 * @since 2.6.11
+	 */
+	public String overview() {
+		int added = 0;
+		int deleted = 0;
+		int modified = 0;
+		for (ChangedFiles changedFiles : this.changeSet) {
+			for (ChangedFile changedFile : changedFiles) {
+				Type type = changedFile.getType();
+				if (type == Type.ADD) {
+					added++;
+				}
+				else if (type == Type.DELETE) {
+					deleted++;
+				}
+				else if (type == Type.MODIFY) {
+					modified++;
+				}
+			}
+		}
+		int size = added + deleted + modified;
+		return String.format("%s (%s, %s, %s)", quantityOfUnit(size, "class path change"),
+				quantityOfUnit(added, "addition"), quantityOfUnit(deleted, "deletion"),
+				quantityOfUnit(modified, "modification"));
+	}
+
+	private String quantityOfUnit(int quantity, String unit) {
+		return quantity + " " + ((quantity != 1) ? unit + "s" : unit);
+	}
+
 }

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/remote/client/ClassPathChangeUploader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -91,14 +91,15 @@ public class ClassPathChangeUploader implements ApplicationListener<ClassPathCha
 		try {
 			ClassLoaderFiles classLoaderFiles = getClassLoaderFiles(event);
 			byte[] bytes = serialize(classLoaderFiles);
-			performUpload(classLoaderFiles, bytes);
+			performUpload(classLoaderFiles, bytes, event);
 		}
 		catch (IOException ex) {
 			throw new IllegalStateException(ex);
 		}
 	}
 
-	private void performUpload(ClassLoaderFiles classLoaderFiles, byte[] bytes) throws IOException {
+	private void performUpload(ClassLoaderFiles classLoaderFiles, byte[] bytes, ClassPathChangedEvent event)
+			throws IOException {
 		try {
 			while (true) {
 				try {
@@ -107,11 +108,11 @@ public class ClassPathChangeUploader implements ApplicationListener<ClassPathCha
 					headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
 					headers.setContentLength(bytes.length);
 					FileCopyUtils.copy(bytes, request.getBody());
+					logUpload(event);
 					ClientHttpResponse response = request.execute();
 					HttpStatus statusCode = response.getStatusCode();
 					Assert.state(statusCode == HttpStatus.OK,
 							() -> "Unexpected " + statusCode + " response uploading class files");
-					logUpload(classLoaderFiles);
 					return;
 				}
 				catch (SocketException ex) {
@@ -128,9 +129,8 @@ public class ClassPathChangeUploader implements ApplicationListener<ClassPathCha
 		}
 	}
 
-	private void logUpload(ClassLoaderFiles classLoaderFiles) {
-		int size = classLoaderFiles.size();
-		logger.info(LogMessage.format("Uploaded %s class %s", size, (size != 1) ? "resources" : "resource"));
+	private void logUpload(ClassPathChangedEvent event) {
+		logger.info(LogMessage.format("Uploading %s", event.overview()));
 	}
 
 	private byte[] serialize(ClassLoaderFiles classLoaderFiles) throws IOException {