Log condition evaluation delta upon DevTools restart

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/ConditionEvaluationReport.java

@@ -188,6 +188,27 @@ public final class ConditionEvaluationReport {
 		}
 	}
 
+	public ConditionEvaluationReport getDelta(ConditionEvaluationReport previousReport) {
+		ConditionEvaluationReport delta = new ConditionEvaluationReport();
+		for (Entry<String, ConditionAndOutcomes> entry : this.outcomes.entrySet()) {
+			ConditionAndOutcomes previous = previousReport.outcomes.get(entry.getKey());
+			if (previous == null
+					|| previous.isFullMatch() != entry.getValue().isFullMatch()) {
+				entry.getValue()
+						.forEach((conditionAndOutcome) -> delta.recordConditionEvaluation(
+								entry.getKey(), conditionAndOutcome.getCondition(),
+								conditionAndOutcome.getOutcome()));
+			}
+		}
+		List<String> newExclusions = new ArrayList<>(this.exclusions);
+		newExclusions.removeAll(previousReport.getExclusions());
+		delta.recordExclusions(newExclusions);
+		List<String> newUnconditionalClasses = new ArrayList<>(this.unconditionalClasses);
+		newUnconditionalClasses.removeAll(previousReport.unconditionalClasses);
+		delta.unconditionalClasses.addAll(newUnconditionalClasses);
+		return delta;
+	}
+
 	/**
 	 * Provides access to a number of {@link ConditionAndOutcome} items.
 	 */

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/logging/ConditionEvaluationReportMessage.java

@@ -22,6 +22,8 @@ import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
 
 import org.springframework.boot.autoconfigure.condition.ConditionEvaluationReport;
 import org.springframework.boot.autoconfigure.condition.ConditionEvaluationReport.ConditionAndOutcome;
@@ -33,6 +35,7 @@ import org.springframework.util.StringUtils;
  * A condition evaluation report message that can logged or printed.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  * @since 1.4.0
  */
 public class ConditionEvaluationReportMessage {
@@ -40,33 +43,69 @@ public class ConditionEvaluationReportMessage {
 	private StringBuilder message;
 
 	public ConditionEvaluationReportMessage(ConditionEvaluationReport report) {
-		this.message = getLogMessage(report);
+		this(report, "CONDITIONS EVALUATION REPORT");
 	}
 
-	private StringBuilder getLogMessage(ConditionEvaluationReport report) {
+	public ConditionEvaluationReportMessage(ConditionEvaluationReport report,
+			String title) {
+		this.message = getLogMessage(report, title);
+	}
+
+	private StringBuilder getLogMessage(ConditionEvaluationReport report, String title) {
 		StringBuilder message = new StringBuilder();
 		message.append(String.format("%n%n%n"));
-		message.append(String.format("=========================%n"));
-		message.append(String.format("CONDITIONS REPORT%n"));
-		message.append(String.format("=========================%n%n%n"));
-		message.append(String.format("Positive matches:%n"));
-		message.append(String.format("-----------------%n"));
+		StringBuilder separator = new StringBuilder();
+		for (int i = 0; i < title.length(); i++) {
+			separator.append("=");
+		}
+		message.append(String.format("%s%n", separator));
+		message.append(String.format("%s%n", title));
+		message.append(String.format("%s%n%n%n", separator));
 		Map<String, ConditionAndOutcomes> shortOutcomes = orderByName(
 				report.getConditionAndOutcomesBySource());
-		for (Map.Entry<String, ConditionAndOutcomes> entry : shortOutcomes.entrySet()) {
-			if (entry.getValue().isFullMatch()) {
-				addMatchLogMessage(message, entry.getKey(), entry.getValue());
-			}
+		logPositiveMatches(message, shortOutcomes);
+		logNegativeMatches(message, shortOutcomes);
+		logExclusions(report, message);
+		logUnconditionalClasses(report, message);
+		message.append(String.format("%n%n"));
+		return message;
+	}
+
+	private void logPositiveMatches(StringBuilder message,
+			Map<String, ConditionAndOutcomes> shortOutcomes) {
+		message.append(String.format("Positive matches:%n"));
+		message.append(String.format("-----------------%n"));
+		List<Entry<String, ConditionAndOutcomes>> matched = shortOutcomes.entrySet()
+				.stream().filter((entry) -> entry.getValue().isFullMatch())
+				.collect(Collectors.toList());
+		if (matched.isEmpty()) {
+			message.append(String.format("%n    None%n"));
+		}
+		else {
+			matched.forEach((entry) -> addMatchLogMessage(message, entry.getKey(),
+					entry.getValue()));
 		}
 		message.append(String.format("%n%n"));
+	}
+
+	private void logNegativeMatches(StringBuilder message,
+			Map<String, ConditionAndOutcomes> shortOutcomes) {
 		message.append(String.format("Negative matches:%n"));
 		message.append(String.format("-----------------%n"));
-		for (Map.Entry<String, ConditionAndOutcomes> entry : shortOutcomes.entrySet()) {
-			if (!entry.getValue().isFullMatch()) {
-				addNonMatchLogMessage(message, entry.getKey(), entry.getValue());
-			}
+		List<Entry<String, ConditionAndOutcomes>> nonMatched = shortOutcomes.entrySet()
+				.stream().filter((entry) -> !entry.getValue().isFullMatch())
+				.collect(Collectors.toList());
+		if (nonMatched.isEmpty()) {
+			message.append(String.format("%n    None%n"));
+		}
+		else {
+			nonMatched.forEach((entry) -> addNonMatchLogMessage(message, entry.getKey(),
+					entry.getValue()));
 		}
 		message.append(String.format("%n%n"));
+	}
+
+	private void logExclusions(ConditionEvaluationReport report, StringBuilder message) {
 		message.append(String.format("Exclusions:%n"));
 		message.append(String.format("-----------%n"));
 		if (report.getExclusions().isEmpty()) {
@@ -78,6 +117,10 @@ public class ConditionEvaluationReportMessage {
 			}
 		}
 		message.append(String.format("%n%n"));
+	}
+
+	private void logUnconditionalClasses(ConditionEvaluationReport report,
+			StringBuilder message) {
 		message.append(String.format("Unconditional classes:%n"));
 		message.append(String.format("----------------------%n"));
 		if (report.getUnconditionalClasses().isEmpty()) {
@@ -88,8 +131,6 @@ public class ConditionEvaluationReportMessage {
 				message.append(String.format("%n    %s%n", unconditionalClass));
 			}
 		}
-		message.append(String.format("%n%n"));
-		return message;
 	}
 
 	private Map<String, ConditionAndOutcomes> orderByName(

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

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2017 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.
+ * 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 org.springframework.boot.devtools.autoconfigure;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.boot.autoconfigure.condition.ConditionEvaluationReport;
+import org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportMessage;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.ApplicationListener;
+
+/**
+ * An {@link ApplicationListener} that logs the delta of condition evaluation across
+ * restarts.
+ *
+ * @author Andy Wilkinson
+ */
+class ConditionEvaluationDeltaLoggingListener
+		implements ApplicationListener<ApplicationReadyEvent> {
+
+	private final Log logger = LogFactory.getLog(getClass());
+
+	private static ConditionEvaluationReport previousReport;
+
+	@Override
+	public void onApplicationEvent(ApplicationReadyEvent event) {
+		ConditionEvaluationReport report = event.getApplicationContext()
+				.getBean(ConditionEvaluationReport.class);
+		if (previousReport != null) {
+			ConditionEvaluationReport delta = report.getDelta(previousReport);
+			if (!delta.getConditionAndOutcomesBySource().isEmpty()
+					|| !delta.getExclusions().isEmpty()
+					|| !delta.getUnconditionalClasses().isEmpty()) {
+				this.logger.info("Condition evaluation delta:"
+						+ new ConditionEvaluationReportMessage(delta,
+								"CONDITION EVALUATION DELTA"));
+			}
+			else {
+				this.logger.info("Condition evaluation unchanged");
+			}
+		}
+		previousReport = report;
+	}
+
+}

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

@@ -100,6 +100,11 @@ public class DevToolsProperties {
 		 */
 		private List<File> additionalPaths = new ArrayList<>();
 
+		/**
+		 * Whether to log the condition evaluation delta upon restart.
+		 */
+		private boolean logConditionEvaluationDelta = true;
+
 		public boolean isEnabled() {
 			return this.enabled;
 		}
@@ -168,6 +173,14 @@ public class DevToolsProperties {
 			this.additionalPaths = additionalPaths;
 		}
 
+		public boolean isLogConditionEvaluationDelta() {
+			return this.logConditionEvaluationDelta;
+		}
+
+		public void setLogConditionEvaluationDelta(boolean logConditionEvaluationDelta) {
+			this.logConditionEvaluationDelta = logConditionEvaluationDelta;
+		}
+
 	}
 
 	/**

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

@@ -140,6 +140,12 @@ public class LocalDevToolsAutoConfiguration {
 			return this::newFileSystemWatcher;
 		}
 
+		@Bean
+		@ConditionalOnProperty(prefix = "spring.devtools.restart", name = "log-condition-evaluation-delta", matchIfMissing = true)
+		public ConditionEvaluationDeltaLoggingListener conditionEvaluationDeltaLoggingListener() {
+			return new ConditionEvaluationDeltaLoggingListener();
+		}
+
 		private FileSystemWatcher newFileSystemWatcher() {
 			Restart restartProperties = this.properties.getRestart();
 			FileSystemWatcher watcher = new FileSystemWatcher(true,

spring-boot-project/spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc

@@ -813,6 +813,18 @@ http://zeroturnaround.com/software/jrebel/[JRebel] from ZeroTurnaround. These wo
 rewriting classes as they are loaded to make them more amenable to reloading.
 ****
 
+[[using-boot-devtools-restart-logging-condition-delta]]
+==== Logging changes in condition evaluation
+By default, each time your application restarts, a report showing the condition evaluation
+delta is logged. The report shows the changes to your application's auto-configuration as
+you make changes such as adding or removing beans and setting configuration properties.
+
+To disable the logging of the report, set the following property:
+
+[indent=0]
+----
+	spring.devtools.restart.log-condition-evaluation-delta=false
+----
 
 
 [[using-boot-devtools-restart-exclude]]