CompositeLog respects log level changes at runtime

Closes gh-28477

Author: rstoyanchev

spring-core/src/main/java/org/springframework/core/log/CompositeLog.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -22,6 +22,7 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.impl.NoOpLog;
 
+
 /**
  * Implementation of {@link Log} that wraps a list of loggers and delegates
  * to the first one for which logging is enabled at the given level.
@@ -35,131 +36,119 @@ final class CompositeLog implements Log {
 	private static final Log NO_OP_LOG = new NoOpLog();
 
 
-	private final Log fatalLogger;
-
-	private final Log errorLogger;
-
-	private final Log warnLogger;
-
-	private final Log infoLogger;
-
-	private final Log debugLogger;
-
-	private final Log traceLogger;
+	private final List<Log> loggers;
 
 
 	/**
-	 * Constructor with list of loggers. For optimal performance, the constructor
-	 * checks and remembers which logger is on for each log category.
+	 * Package-private constructor with list of loggers.
 	 * @param loggers the loggers to use
 	 */
-	public CompositeLog(List<Log> loggers) {
-		this.fatalLogger = initLogger(loggers, Log::isFatalEnabled);
-		this.errorLogger = initLogger(loggers, Log::isErrorEnabled);
-		this.warnLogger  = initLogger(loggers, Log::isWarnEnabled);
-		this.infoLogger  = initLogger(loggers, Log::isInfoEnabled);
-		this.debugLogger = initLogger(loggers, Log::isDebugEnabled);
-		this.traceLogger = initLogger(loggers, Log::isTraceEnabled);
-	}
-
-	private static Log initLogger(List<Log> loggers, Predicate<Log> predicate) {
-		for (Log logger : loggers) {
-			if (predicate.test(logger)) {
-				return logger;
-			}
-		}
-		return NO_OP_LOG;
+	CompositeLog(List<Log> loggers) {
+		this.loggers = loggers;
 	}
 
 
 	@Override
 	public boolean isFatalEnabled() {
-		return (this.fatalLogger != NO_OP_LOG);
+		return isEnabled(Log::isFatalEnabled);
 	}
 
 	@Override
 	public boolean isErrorEnabled() {
-		return (this.errorLogger != NO_OP_LOG);
+		return isEnabled(Log::isErrorEnabled);
 	}
 
 	@Override
 	public boolean isWarnEnabled() {
-		return (this.warnLogger != NO_OP_LOG);
+		return isEnabled(Log::isWarnEnabled);
 	}
 
 	@Override
 	public boolean isInfoEnabled() {
-		return (this.infoLogger != NO_OP_LOG);
+		return isEnabled(Log::isInfoEnabled);
 	}
 
 	@Override
 	public boolean isDebugEnabled() {
-		return (this.debugLogger != NO_OP_LOG);
+		return isEnabled(Log::isDebugEnabled);
 	}
 
 	@Override
 	public boolean isTraceEnabled() {
-		return (this.traceLogger != NO_OP_LOG);
+		return isEnabled(Log::isTraceEnabled);
+	}
+
+	private boolean isEnabled(Predicate<Log> predicate) {
+		return (getLogger(predicate) != NO_OP_LOG);
 	}
 
 	@Override
 	public void fatal(Object message) {
-		this.fatalLogger.fatal(message);
+		getLogger(Log::isFatalEnabled).fatal(message);
 	}
 
 	@Override
 	public void fatal(Object message, Throwable ex) {
-		this.fatalLogger.fatal(message, ex);
+		getLogger(Log::isFatalEnabled).fatal(message, ex);
 	}
 
 	@Override
 	public void error(Object message) {
-		this.errorLogger.error(message);
+		getLogger(Log::isErrorEnabled).error(message);
 	}
 
 	@Override
 	public void error(Object message, Throwable ex) {
-		this.errorLogger.error(message, ex);
+		getLogger(Log::isErrorEnabled).error(message, ex);
 	}
 
 	@Override
 	public void warn(Object message) {
-		this.warnLogger.warn(message);
+		getLogger(Log::isWarnEnabled).warn(message);
 	}
 
 	@Override
 	public void warn(Object message, Throwable ex) {
-		this.warnLogger.warn(message, ex);
+		getLogger(Log::isWarnEnabled).warn(message, ex);
 	}
 
 	@Override
 	public void info(Object message) {
-		this.infoLogger.info(message);
+		getLogger(Log::isInfoEnabled).info(message);
 	}
 
 	@Override
 	public void info(Object message, Throwable ex) {
-		this.infoLogger.info(message, ex);
+		getLogger(Log::isInfoEnabled).info(message, ex);
 	}
 
 	@Override
 	public void debug(Object message) {
-		this.debugLogger.debug(message);
+		getLogger(Log::isDebugEnabled).debug(message);
 	}
 
 	@Override
 	public void debug(Object message, Throwable ex) {
-		this.debugLogger.debug(message, ex);
+		getLogger(Log::isDebugEnabled).debug(message, ex);
 	}
 
 	@Override
 	public void trace(Object message) {
-		this.traceLogger.trace(message);
+		getLogger(Log::isTraceEnabled).trace(message);
 	}
 
 	@Override
 	public void trace(Object message, Throwable ex) {
-		this.traceLogger.trace(message, ex);
+		getLogger(Log::isTraceEnabled).trace(message, ex);
+	}
+
+	private Log getLogger(Predicate<Log> predicate) {
+		for (Log logger : this.loggers) {
+			if (predicate.test(logger)) {
+				return logger;
+			}
+		}
+		return NO_OP_LOG;
 	}
 
 }

spring-core/src/test/java/org/springframework/core/log/CompositeLogTests.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2002-2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://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.core.log;
+
+import java.util.Arrays;
+
+import org.apache.commons.logging.Log;
+import org.junit.jupiter.api.Test;
+
+import static org.mockito.BDDMockito.when;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+
+
+/**
+ * Unit tests for {@link CompositeLog}.
+ * @author Rossen Stoyanchev
+ */
+public class CompositeLogTests {
+
+	private final Log logger1 = mock(Log.class);
+
+	private final Log logger2 = mock(Log.class);
+
+	private final CompositeLog compositeLog = new CompositeLog(Arrays.asList(logger1, logger2));
+
+
+	@Test
+	void useFirstLogger() {
+		when(logger1.isInfoEnabled()).thenReturn(true);
+		when(logger2.isInfoEnabled()).thenReturn(true);
+
+		this.compositeLog.info("info message");
+
+		verify(this.logger1).isInfoEnabled();
+		verify(this.logger1).info("info message");
+
+		verifyNoMoreInteractions(this.logger1);
+		verifyNoMoreInteractions(this.logger2);
+	}
+
+	@Test
+	void useSecondLogger() {
+		when(logger1.isInfoEnabled()).thenReturn(false);
+		when(logger2.isInfoEnabled()).thenReturn(true);
+
+		this.compositeLog.info("info message");
+
+		verify(this.logger1).isInfoEnabled();
+		verify(this.logger2).isInfoEnabled();
+		verify(this.logger2).info("info message");
+
+		verifyNoMoreInteractions(this.logger1);
+		verifyNoMoreInteractions(this.logger2);
+	}
+
+	@Test
+	void useNeitherLogger() {
+		when(logger1.isInfoEnabled()).thenReturn(false);
+		when(logger2.isInfoEnabled()).thenReturn(false);
+
+		this.compositeLog.info("info message");
+
+		verify(this.logger1).isInfoEnabled();
+		verify(this.logger2).isInfoEnabled();
+
+		verifyNoMoreInteractions(this.logger1);
+		verifyNoMoreInteractions(this.logger2);
+	}
+
+}