Revamp AbstractLogger in log4j-sdk

In order for Log4j Core 3.x not to depend on the utility classes in
Log4j API 2.x, we provide a new `AbstractLogger` in `log4j-sdk`.

Author: ppkarwasz

log4j-async-logger/pom.xml

@@ -28,8 +28,21 @@
   <name>Apache Log4j Async Logger</name>
   <description>Alternative implementation of logger that uses LMAX Disruptor.</description>
 
+  <properties>
+    <bnd-extra-package-options>
+      <!-- JSpecify is optional at runtime -->
+      org.jspecify.annotations.*;resolution:=optional
+    </bnd-extra-package-options>
+  </properties>
+
   <dependencies>
 
+    <dependency>
+      <groupId>org.jspecify</groupId>
+      <artifactId>jspecify</artifactId>
+      <scope>provided</scope>
+    </dependency>
+
     <dependency>
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-core</artifactId>

log4j-async-logger/src/main/java/org/apache/logging/log4j/async/logger/AsyncLogger.java

@@ -33,12 +33,16 @@
 import org.apache.logging.log4j.core.impl.ContextDataFactory;
 import org.apache.logging.log4j.core.time.Clock;
 import org.apache.logging.log4j.core.time.NanoClock;
+import org.apache.logging.log4j.message.FlowMessageFactory;
 import org.apache.logging.log4j.message.Message;
 import org.apache.logging.log4j.message.MessageFactory;
-import org.apache.logging.log4j.spi.AbstractLogger;
+import org.apache.logging.log4j.sdk.logger.AbstractLogger;
 import org.apache.logging.log4j.spi.recycler.Recycler;
+import org.apache.logging.log4j.spi.recycler.RecyclerFactory;
 import org.apache.logging.log4j.util.StackLocatorUtil;
 import org.apache.logging.log4j.util.StringMap;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 /**
  * AsyncLogger is a logger designed for high throughput and low latency logging. It does not perform any I/O in the
@@ -59,6 +63,7 @@
  * and they will flush to disk at the end of each batch. This means that even with immediateFlush=false, there will
  * never be any items left in the buffer; all log events will all be written to disk in a very efficient manner.
  */
+@NullMarked
 public class AsyncLogger extends Logger {
     // Implementation note: many methods in this class are tuned for performance. MODIFY WITH CARE!
     // Specifically, try to keep the hot methods to 35 bytecodes or less:
@@ -86,8 +91,10 @@ public class AsyncLogger extends Logger {
             final LoggerContext context,
             final String name,
             final MessageFactory messageFactory,
+            final FlowMessageFactory flowMessageFactory,
+            final RecyclerFactory recyclerFactory,
             final AsyncLoggerDisruptor loggerDisruptor) {
-        super(context, name, messageFactory);
+        super(context, name, messageFactory, flowMessageFactory, recyclerFactory);
         final Configuration configuration = context.getConfiguration();
         this.translatorRecycler = configuration
                 .getRecyclerFactory()
@@ -107,7 +114,7 @@ public class AsyncLogger extends Logger {
     @Override
     protected void updateConfiguration(final Configuration newConfig) {
         nanoClock = newConfig.getNanoClock();
-        includeLocation = newConfig.getLoggerConfig(name).isIncludeLocation();
+        includeLocation = newConfig.getLoggerConfig(getName()).isIncludeLocation();
         super.updateConfiguration(newConfig);
     }
 
@@ -154,21 +161,21 @@ public void logMessage(
      * @param level level at which the caller wants to log the message
      * @param marker message marker
      * @param message the log message
-     * @param thrown a {@code Throwable} or {@code null}
+     * @param throwable a {@code Throwable} or {@code null}
      */
     @Override
-    public void log(
+    protected void doLog(
             final Level level,
-            final Marker marker,
+            final @Nullable Marker marker,
             final String fqcn,
-            final StackTraceElement location,
+            final @Nullable StackTraceElement location,
             final Message message,
-            final Throwable thrown) {
+            final @Nullable Throwable throwable) {
         // Implementation note: this method is tuned for performance. MODIFY WITH CARE!
 
         final RingBufferLogEventTranslator translator = translatorRecycler.acquire();
         try {
-            initTranslator(translator, fqcn, location, level, marker, message, thrown);
+            initTranslator(translator, fqcn, location, level, marker, message, throwable);
             translator.updateThreadValues();
             publish(translator);
         } finally {
@@ -220,7 +227,7 @@ private void initTranslator(
 
         translator.setBasicValues(
                 this,
-                name,
+                getName(),
                 marker,
                 fqcn,
                 level,
@@ -246,7 +253,7 @@ private void initTranslator(
 
         translator.setBasicValues(
                 this,
-                name,
+                getName(),
                 marker,
                 fqcn,
                 level,

log4j-async-logger/src/main/java/org/apache/logging/log4j/async/logger/AsyncLoggerConfig.java

@@ -33,7 +33,7 @@
 import org.apache.logging.log4j.plugins.Configurable;
 import org.apache.logging.log4j.plugins.Plugin;
 import org.apache.logging.log4j.plugins.PluginFactory;
-import org.apache.logging.log4j.spi.AbstractLogger;
+import org.apache.logging.log4j.sdk.logger.AbstractLogger;
 import org.apache.logging.log4j.util.Strings;
 
 /**

log4j-async-logger/src/main/java/org/apache/logging/log4j/async/logger/AsyncLoggerContext.java

@@ -22,8 +22,10 @@
 import org.apache.logging.log4j.core.LoggerContext;
 import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.config.DefaultConfiguration;
+import org.apache.logging.log4j.message.FlowMessageFactory;
 import org.apache.logging.log4j.message.MessageFactory;
 import org.apache.logging.log4j.plugins.di.ConfigurableInstanceFactory;
+import org.apache.logging.log4j.spi.recycler.RecyclerFactory;
 import org.apache.logging.log4j.status.StatusLogger;
 
 /**
@@ -78,8 +80,13 @@ private AsyncWaitStrategyFactory createAsyncWaitStrategyFactory() {
     }
 
     @Override
-    protected Logger newInstance(final LoggerContext ctx, final String name, final MessageFactory messageFactory) {
-        return new AsyncLogger(ctx, name, messageFactory, loggerDisruptor);
+    protected Logger newInstance(
+            final LoggerContext ctx,
+            final String name,
+            final MessageFactory messageFactory,
+            final FlowMessageFactory flowMessageFactory,
+            final RecyclerFactory recyclerFactory) {
+        return new AsyncLogger(ctx, name, messageFactory, flowMessageFactory, recyclerFactory, loggerDisruptor);
     }
 
     @Override

log4j-async-logger/src/test/java/org/apache/logging/log4j/async/logger/AsyncLoggerEventTranslationExceptionTest.java

@@ -30,7 +30,7 @@
 import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
 import org.apache.logging.log4j.message.Message;
 import org.apache.logging.log4j.message.ReusableSimpleMessage;
-import org.apache.logging.log4j.spi.AbstractLogger;
+import org.apache.logging.log4j.sdk.logger.AbstractLogger;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 import org.junitpioneer.jupiter.SetSystemProperty;

log4j-core/pom.xml

@@ -39,6 +39,7 @@
       com.lmax.disruptor.*;resolution:=optional,
       org.apache.commons.compress.*;resolution:=optional,
       org.fusesource.jansi;resolution:=optional,
+      org.jspecify.annotations.*;resolution:=optional,
       <!-- Optional Java modules -->
       <!-- java.management -->
       java.lang.management;resolution:=optional,
@@ -73,6 +74,10 @@
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-plugins</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.apache.logging.log4j</groupId>
+      <artifactId>log4j-sdk</artifactId>
+    </dependency>
     <!-- The dependency on the plugin processor is only required to ensure the processor is built before core. We
        don't want the dependency to be included by consumers -->
     <dependency>

log4j-core/src/main/java/org/apache/logging/log4j/core/Logger.java

@@ -28,12 +28,15 @@
 import org.apache.logging.log4j.core.config.LoggerConfig;
 import org.apache.logging.log4j.core.config.ReliabilityStrategy;
 import org.apache.logging.log4j.core.filter.CompositeFilter;
+import org.apache.logging.log4j.message.FlowMessageFactory;
 import org.apache.logging.log4j.message.Message;
 import org.apache.logging.log4j.message.MessageFactory;
-import org.apache.logging.log4j.message.SimpleMessage;
-import org.apache.logging.log4j.spi.AbstractLogger;
+import org.apache.logging.log4j.sdk.logger.AbstractLogger;
+import org.apache.logging.log4j.spi.recycler.RecyclerFactory;
 import org.apache.logging.log4j.util.Strings;
 import org.apache.logging.log4j.util.Supplier;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 /**
  * The core implementation of the {@link org.apache.logging.log4j.Logger} interface. Besides providing an implementation
@@ -43,40 +46,36 @@
  * unit tests or bridging legacy Log4j 1.x code. Future versions of this class may or may not include the various
  * methods that are noted as not being part of the public API.
  */
+@NullMarked
 public class Logger extends AbstractLogger implements Supplier<LoggerConfig> {
 
     /**
      * Config should be consistent across threads.
      */
     protected volatile PrivateConfig privateConfig;
 
-    // FIXME: ditto to the above
     private final LoggerContext context;
 
     /**
      * The constructor.
      *
      * @param context The LoggerContext this Logger is associated with.
-     * @param messageFactory The message factory.
      * @param name The name of the Logger.
+     * @param messageFactory The message factory to use for logging methods.
+     * @param flowMessageFactory The flow message factory to use for flow logging methods.
+     * @param recyclerFactory The recycler to use for log builder instances.
      */
-    protected Logger(final LoggerContext context, final String name, final MessageFactory messageFactory) {
-        super(name, messageFactory);
+    protected Logger(
+            final LoggerContext context,
+            final String name,
+            final MessageFactory messageFactory,
+            final FlowMessageFactory flowMessageFactory,
+            final RecyclerFactory recyclerFactory) {
+        super(name, messageFactory, flowMessageFactory, recyclerFactory);
         this.context = context;
         privateConfig = new PrivateConfig(context.getConfiguration(), this);
     }
 
-    /**
-     * This is used to construct an InternalLoggerContext, which makes SimpleLoggerContext conmpatible with core.
-     * @param context the InternalLoggerContext.
-     * @param name the Logger name.
-     */
-    protected Logger(final LoggerContext context, final String name) {
-        super(name);
-        this.context = context;
-        privateConfig = null;
-    }
-
     /**
      * This method is only used for 1.x compatibility. Returns the parent of this Logger. If it doesn't already exist
      * return a temporary Logger.
@@ -95,10 +94,7 @@ private Logger getParent(final PrivateConfig config) {
         }
         final String lcName = lc.getName();
         final MessageFactory messageFactory = getMessageFactory();
-        if (context.hasLogger(lcName, messageFactory)) {
-            return context.getLogger(lcName, messageFactory);
-        }
-        return new Logger(context, lcName, messageFactory);
+        return context.getLogger(lcName, messageFactory);
     }
 
     /**
@@ -149,35 +145,32 @@ protected boolean requiresLocation() {
     }
 
     @Override
-    public void logMessage(
-            final String fqcn, final Level level, final Marker marker, final Message message, final Throwable t) {
-        final Message msg = message == null ? new SimpleMessage(Strings.EMPTY) : message;
-        final ReliabilityStrategy strategy = privateConfig.loggerConfig.getReliabilityStrategy();
-        strategy.log(this, getName(), fqcn, marker, level, msg, t);
-    }
-
-    @Override
-    protected void log(
+    protected void doLog(
             final Level level,
-            final Marker marker,
+            final @Nullable Marker marker,
             final String fqcn,
-            final StackTraceElement location,
-            final Message message,
-            final Throwable throwable) {
+            final @Nullable StackTraceElement location,
+            final @Nullable Message message,
+            final @Nullable Throwable throwable) {
         final ReliabilityStrategy strategy = privateConfig.loggerConfig.getReliabilityStrategy();
         strategy.log(this, getName(), fqcn, location, marker, level, message, throwable);
     }
 
     @Override
-    public boolean isEnabled(final Level level, final Marker marker, final String message, final Throwable t) {
-        return privateConfig.filter(level, marker, message, t);
+    public boolean isEnabled(final Level level, final Marker marker) {
+        return privateConfig.filter(level, marker, null);
     }
 
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final String message) {
         return privateConfig.filter(level, marker, message);
     }
 
+    @Override
+    public boolean isEnabled(final Level level, final Marker marker, final String message, final Throwable t) {
+        return privateConfig.filter(level, marker, message, t);
+    }
+
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final String message, final Object... params) {
         return privateConfig.filter(level, marker, message, params);