Implement MessageFactory-namespaced logger registry (#2936)

Co-authored-by: Piotr P. Karwasz <piotr.github@karwasz.org>

log4j-api/src/main/java/org/apache/logging/log4j/message/LocalizedMessageFactory.java

@@ -16,7 +16,9 @@
  */
 package org.apache.logging.log4j.message;
 
+import java.util.Objects;
 import java.util.ResourceBundle;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Creates {@link FormattedMessage} instances for {@link MessageFactory2} methods (and {@link MessageFactory} by
@@ -33,8 +35,11 @@
 public class LocalizedMessageFactory extends AbstractMessageFactory {
     private static final long serialVersionUID = -1996295808703146741L;
 
+    @Nullable
     // FIXME: cannot use ResourceBundle name for serialization until Java 8
     private final transient ResourceBundle resourceBundle;
+
+    @Nullable
     private final String baseName;
 
     public LocalizedMessageFactory(final ResourceBundle resourceBundle) {
@@ -92,4 +97,21 @@ public Message newMessage(final String key, final Object... params) {
         }
         return new LocalizedMessage(resourceBundle, key, params);
     }
+
+    @Override
+    public boolean equals(final Object object) {
+        if (this == object) {
+            return true;
+        }
+        if (object == null || getClass() != object.getClass()) {
+            return false;
+        }
+        final LocalizedMessageFactory that = (LocalizedMessageFactory) object;
+        return Objects.equals(resourceBundle, that.resourceBundle) && Objects.equals(baseName, that.baseName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(resourceBundle, baseName);
+    }
 }

log4j-api/src/main/java/org/apache/logging/log4j/message/package-info.java

@@ -19,7 +19,7 @@
  * Public Message Types used for Log4j 2. Users may implement their own Messages.
  */
 @Export
-@Version("2.24.0")
+@Version("2.25.0")
 package org.apache.logging.log4j.message;
 
 import org.osgi.annotation.bundle.Export;

log4j-api/src/main/java/org/apache/logging/log4j/simple/SimpleLoggerContext.java

@@ -20,12 +20,13 @@
 import java.io.PrintStream;
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.message.MessageFactory;
+import org.apache.logging.log4j.message.ParameterizedMessageFactory;
 import org.apache.logging.log4j.simple.internal.SimpleProvider;
-import org.apache.logging.log4j.spi.AbstractLogger;
 import org.apache.logging.log4j.spi.ExtendedLogger;
 import org.apache.logging.log4j.spi.LoggerContext;
 import org.apache.logging.log4j.spi.LoggerRegistry;
 import org.apache.logging.log4j.util.PropertiesUtil;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A simple {@link LoggerContext} implementation.
@@ -41,6 +42,8 @@ public class SimpleLoggerContext implements LoggerContext {
     /** All system properties used by <code>SimpleLog</code> start with this */
     protected static final String SYSTEM_PREFIX = "org.apache.logging.log4j.simplelog.";
 
+    private static final MessageFactory DEFAULT_MESSAGE_FACTORY = ParameterizedMessageFactory.INSTANCE;
+
     private final PropertiesUtil props;
 
     /** Include the instance name in the log message? */
@@ -96,14 +99,14 @@ public ExtendedLogger getLogger(final String name) {
     }
 
     @Override
-    public ExtendedLogger getLogger(final String name, final MessageFactory messageFactory) {
-        // Note: This is the only method where we add entries to the 'loggerRegistry' ivar.
-        final ExtendedLogger extendedLogger = loggerRegistry.getLogger(name, messageFactory);
-        if (extendedLogger != null) {
-            AbstractLogger.checkMessageFactory(extendedLogger, messageFactory);
-            return extendedLogger;
-        }
-        final SimpleLogger simpleLogger = new SimpleLogger(
+    public ExtendedLogger getLogger(final String name, @Nullable final MessageFactory messageFactory) {
+        final MessageFactory effectiveMessageFactory =
+                messageFactory != null ? messageFactory : DEFAULT_MESSAGE_FACTORY;
+        return loggerRegistry.computeIfAbsent(name, effectiveMessageFactory, this::createLogger);
+    }
+
+    private ExtendedLogger createLogger(final String name, @Nullable final MessageFactory messageFactory) {
+        return new SimpleLogger(
                 name,
                 defaultLevel,
                 showLogName,
@@ -114,8 +117,6 @@ public ExtendedLogger getLogger(final String name, final MessageFactory messageF
                 messageFactory,
                 props,
                 stream);
-        loggerRegistry.putIfAbsent(name, messageFactory, simpleLogger);
-        return loggerRegistry.getLogger(name, messageFactory);
     }
 
     /**
@@ -131,16 +132,18 @@ public LoggerRegistry<ExtendedLogger> getLoggerRegistry() {
 
     @Override
     public boolean hasLogger(final String name) {
-        return false;
+        return loggerRegistry.hasLogger(name, DEFAULT_MESSAGE_FACTORY);
     }
 
     @Override
     public boolean hasLogger(final String name, final Class<? extends MessageFactory> messageFactoryClass) {
-        return false;
+        return loggerRegistry.hasLogger(name, messageFactoryClass);
     }
 
     @Override
-    public boolean hasLogger(final String name, final MessageFactory messageFactory) {
-        return false;
+    public boolean hasLogger(final String name, @Nullable final MessageFactory messageFactory) {
+        final MessageFactory effectiveMessageFactory =
+                messageFactory != null ? messageFactory : DEFAULT_MESSAGE_FACTORY;
+        return loggerRegistry.hasLogger(name, effectiveMessageFactory);
     }
 }

log4j-api/src/main/java/org/apache/logging/log4j/simple/package-info.java

@@ -20,7 +20,7 @@
  * Providers are able to be loaded at runtime.
  */
 @Export
-@Version("2.24.0")
+@Version("2.25.0")
 package org.apache.logging.log4j.simple;
 
 import org.osgi.annotation.bundle.Export;

log4j-api/src/main/java/org/apache/logging/log4j/spi/AbstractLogger.java

@@ -166,7 +166,11 @@ private static MessageFactory2 adaptMessageFactory(final MessageFactory result)
      *
      * @param logger The logger to check
      * @param messageFactory The message factory to check.
+     * @deprecated As of version {@code 2.25.0}, planned to be removed!
+     * Instead, in {@link LoggerContext#getLogger(String, MessageFactory)} implementations, namespace loggers with message factories.
+     * If your implementation uses {@link LoggerRegistry}, you are already covered.
      */
+    @Deprecated
     public static void checkMessageFactory(final ExtendedLogger logger, final MessageFactory messageFactory) {
         final String name = logger.getName();
         final MessageFactory loggerMessageFactory = logger.getMessageFactory();

log4j-api/src/main/java/org/apache/logging/log4j/spi/LoggerContext.java

@@ -18,6 +18,7 @@
 
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.MessageFactory;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Anchor point for logging implementations.
@@ -54,7 +55,7 @@ default ExtendedLogger getLogger(Class<?> cls) {
      * @return The logger.
      * @since 2.14.0
      */
-    default ExtendedLogger getLogger(Class<?> cls, MessageFactory messageFactory) {
+    default ExtendedLogger getLogger(Class<?> cls, @Nullable MessageFactory messageFactory) {
         final String canonicalName = cls.getCanonicalName();
         return getLogger(canonicalName != null ? canonicalName : cls.getName(), messageFactory);
     }
@@ -73,7 +74,7 @@ default ExtendedLogger getLogger(Class<?> cls, MessageFactory messageFactory) {
      *                       the logger but will log a warning if mismatched.
      * @return The logger with the specified name.
      */
-    ExtendedLogger getLogger(String name, MessageFactory messageFactory);
+    ExtendedLogger getLogger(String name, @Nullable MessageFactory messageFactory);
 
     /**
      * Gets the LoggerRegistry.
@@ -118,7 +119,7 @@ default Object getObject(String key) {
      * @return true if the Logger exists, false otherwise.
      * @since 2.5
      */
-    boolean hasLogger(String name, MessageFactory messageFactory);
+    boolean hasLogger(String name, @Nullable MessageFactory messageFactory);
 
     /**
      * Associates an object into the LoggerContext by name for later use.