Fix JsonLayout failures under JPMS (#2815)

Fix `JsonLayout` failures under JPMS

To avoid opening the `o.a.l.l.core.layout` package to the Jackson Java 9 module, we:

- register an instance of `LogEvent` serializers explicitly,
- change the access type of the `MapEntry` class to `public`.

Closes #2814 and contains review suggestions (#2815).

Author: ppkarwasz

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/ContextDataAsEntryListDeserializer.java

@@ -17,13 +17,11 @@
 package org.apache.logging.log4j.core.jackson;
 
 import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
 import java.io.IOException;
 import java.util.List;
-import java.util.Map;
 import org.apache.logging.log4j.core.impl.ContextDataFactory;
 import org.apache.logging.log4j.util.StringMap;
 
@@ -37,17 +35,16 @@ public class ContextDataAsEntryListDeserializer extends StdDeserializer<StringMa
     private static final long serialVersionUID = 1L;
 
     ContextDataAsEntryListDeserializer() {
-        super(Map.class);
+        super(StringMap.class);
     }
 
     @Override
-    public StringMap deserialize(final JsonParser jp, final DeserializationContext ctxt)
-            throws IOException, JsonProcessingException {
+    public StringMap deserialize(final JsonParser jp, final DeserializationContext ctxt) throws IOException {
         final List<MapEntry> list = jp.readValueAs(
                 new TypeReference<List<MapEntry>>() {
                     // empty
                 });
-        final StringMap contextData = new ContextDataFactory().createContextData();
+        final StringMap contextData = ContextDataFactory.createContextData();
         for (final MapEntry mapEntry : list) {
             contextData.putValue(mapEntry.getKey(), mapEntry.getValue());
         }

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/ContextDataAsEntryListSerializer.java

@@ -21,7 +21,6 @@
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.ser.std.StdSerializer;
 import java.io.IOException;
-import java.util.Map;
 import org.apache.logging.log4j.util.BiConsumer;
 import org.apache.logging.log4j.util.ReadOnlyStringMap;
 
@@ -35,7 +34,7 @@ public class ContextDataAsEntryListSerializer extends StdSerializer<ReadOnlyStri
     private static final long serialVersionUID = 1L;
 
     protected ContextDataAsEntryListSerializer() {
-        super(Map.class, false);
+        super(ReadOnlyStringMap.class);
     }
 
     @Override

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/ContextDataDeserializer.java

@@ -17,12 +17,10 @@
 package org.apache.logging.log4j.core.jackson;
 
 import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.JsonToken;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
 import java.io.IOException;
-import java.util.Map;
 import org.apache.logging.log4j.core.impl.ContextDataFactory;
 import org.apache.logging.log4j.util.StringMap;
 
@@ -36,12 +34,11 @@ public class ContextDataDeserializer extends StdDeserializer<StringMap> {
     private static final long serialVersionUID = 1L;
 
     ContextDataDeserializer() {
-        super(Map.class);
+        super(StringMap.class);
     }
 
     @Override
-    public StringMap deserialize(final JsonParser jp, final DeserializationContext ctxt)
-            throws IOException, JsonProcessingException {
+    public StringMap deserialize(final JsonParser jp, final DeserializationContext ctxt) throws IOException {
 
         // Sanity check: verify that we got "Json Object":
         //        JsonToken tok = jp.nextToken();
@@ -51,7 +48,7 @@ public StringMap deserialize(final JsonParser jp, final DeserializationContext c
         final StringMap contextData = ContextDataFactory.createContextData();
         // Iterate over object fields:
         while (jp.nextToken() != JsonToken.END_OBJECT) {
-            final String fieldName = jp.getCurrentName();
+            final String fieldName = jp.currentName();
 
             // move to value
             jp.nextToken();

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/ContextDataSerializer.java

@@ -21,7 +21,6 @@
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.ser.std.StdSerializer;
 import java.io.IOException;
-import java.util.Map;
 import org.apache.logging.log4j.util.ReadOnlyStringMap;
 import org.apache.logging.log4j.util.TriConsumer;
 
@@ -35,7 +34,7 @@ public class ContextDataSerializer extends StdSerializer<ReadOnlyStringMap> {
     private static final long serialVersionUID = 1L;
 
     protected ContextDataSerializer() {
-        super(Map.class, false);
+        super(ReadOnlyStringMap.class);
     }
 
     @Override

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/Initializers.java

@@ -16,8 +16,13 @@
  */
 package org.apache.logging.log4j.core.jackson;
 
+import static java.util.Collections.singletonList;
+import static java.util.Collections.singletonMap;
+
 import com.fasterxml.jackson.databind.Module.SetupContext;
+import com.fasterxml.jackson.databind.module.SimpleDeserializers;
 import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.databind.module.SimpleSerializers;
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.Marker;
 import org.apache.logging.log4j.ThreadContext.ContextStack;
@@ -27,6 +32,7 @@
 import org.apache.logging.log4j.core.time.Instant;
 import org.apache.logging.log4j.message.Message;
 import org.apache.logging.log4j.message.ObjectMessage;
+import org.apache.logging.log4j.util.StringMap;
 
 /**
  * Initialization utils.
@@ -36,10 +42,7 @@
  */
 class Initializers {
 
-    /**
-     * Used to set up {@link SetupContext} from different {@link SimpleModule}s.
-     */
-    static class SetupContextInitializer {
+    private abstract static class AbstractInitializer {
 
         void setupModule(
                 final SetupContext context, final boolean includeStacktrace, final boolean stacktraceAsString) {
@@ -50,7 +53,7 @@ void setupModule(
             context.setMixInAnnotations(Marker.class, MarkerMixIn.class);
             context.setMixInAnnotations(Level.class, LevelMixIn.class);
             context.setMixInAnnotations(Instant.class, InstantMixIn.class);
-            context.setMixInAnnotations(LogEvent.class, LogEventWithContextListMixIn.class);
+            context.setMixInAnnotations(LogEvent.class, LogEventMixIn.class);
             // Log4j Core classes: we do not want to bring in Jackson at runtime if we do not have to.
             context.setMixInAnnotations(ExtendedStackTraceElement.class, ExtendedStackTraceElementMixIn.class);
             context.setMixInAnnotations(
@@ -62,33 +65,43 @@ void setupModule(
                             : ThrowableProxyWithoutStacktraceMixIn.class);
         }
     }
+    /**
+     * Used to set up {@link SetupContext} from different {@link SimpleModule}s.
+     * <p>
+     *     Serializes the context map as list of objects.
+     * </p>
+     */
+    static class SetupContextAsEntryListInitializer extends AbstractInitializer {
+
+        @Override
+        void setupModule(
+                final SetupContext context, final boolean includeStacktrace, final boolean stacktraceAsString) {
+            super.setupModule(context, includeStacktrace, stacktraceAsString);
+            // These classes don't have public constructors, so we instantiate them directly.
+            // See https://github.com/apache/logging-log4j2/issues/2814
+            context.addSerializers(new SimpleSerializers(singletonList(new ContextDataAsEntryListSerializer())));
+            context.addDeserializers(
+                    new SimpleDeserializers(singletonMap(StringMap.class, new ContextDataAsEntryListDeserializer())));
+        }
+    }
 
     /**
      * Used to set up {@link SetupContext} from different {@link SimpleModule}s.
-     * Differs from SetupContextInitializer by installing {@code LogEventJsonMixIn} for LogEvents,
-     * not {@code LogEventMixIn}, so it handles ThreadContext serialization differently.
+     * <p>
+     *     Serializes the context map as object.
+     * </p>
      */
-    static class SetupContextJsonInitializer {
+    static class SetupContextInitializer extends AbstractInitializer {
 
+        @Override
         void setupModule(
                 final SetupContext context, final boolean includeStacktrace, final boolean stacktraceAsString) {
-            // JRE classes: we cannot edit those with Jackson annotations
-            context.setMixInAnnotations(StackTraceElement.class, StackTraceElementMixIn.class);
-            // Log4j API classes: we do not want to edit those with Jackson annotations because the API module should
-            // not depend on Jackson.
-            context.setMixInAnnotations(Marker.class, MarkerMixIn.class);
-            context.setMixInAnnotations(Level.class, LevelMixIn.class);
-            context.setMixInAnnotations(Instant.class, InstantMixIn.class);
-            context.setMixInAnnotations(LogEvent.class, LogEventJsonMixIn.class); // different ThreadContext handling
-            // Log4j Core classes: we do not want to bring in Jackson at runtime if we do not have to.
-            context.setMixInAnnotations(ExtendedStackTraceElement.class, ExtendedStackTraceElementMixIn.class);
-            context.setMixInAnnotations(
-                    ThrowableProxy.class,
-                    includeStacktrace
-                            ? (stacktraceAsString
-                                    ? ThrowableProxyWithStacktraceAsStringMixIn.class
-                                    : ThrowableProxyMixIn.class)
-                            : ThrowableProxyWithoutStacktraceMixIn.class);
+            super.setupModule(context, includeStacktrace, stacktraceAsString);
+            // These classes don't have public constructors, so we instantiate them directly.
+            // See https://github.com/apache/logging-log4j2/issues/2814
+            context.addSerializers(new SimpleSerializers(singletonList(new ContextDataSerializer())));
+            context.addDeserializers(
+                    new SimpleDeserializers(singletonMap(StringMap.class, new ContextDataDeserializer())));
         }
     }
 

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/JsonConstants.java

@@ -16,21 +16,31 @@
  */
 package org.apache.logging.log4j.core.jackson;
 
+import aQute.bnd.annotation.baseline.BaselineIgnore;
+
 /**
  * Keeps constants separate from any class that may depend on third party jars.
  */
+@BaselineIgnore("2.24.0")
 public final class JsonConstants {
     public static final String ELT_CAUSE = "cause";
     public static final String ELT_CONTEXT_MAP = "contextMap";
     public static final String ELT_CONTEXT_STACK = "contextStack";
+    public static final String ELT_END_OF_BATCH = "endOfBatch";
+    public static final String ELT_LEVEL = "level";
+    public static final String ELT_LOGGER_FQCN = "loggerFqcn";
+    public static final String ELT_LOGGER_NAME = "loggerName";
     public static final String ELT_MARKER = "marker";
     public static final String ELT_PARENTS = "parents";
     public static final String ELT_SOURCE = "source";
     public static final String ELT_SUPPRESSED = "suppressed";
+    public static final String ELT_THREAD = "thread";
     public static final String ELT_THROWN = "thrown";
     public static final String ELT_MESSAGE = "message";
     public static final String ELT_EXTENDED_STACK_TRACE = "extendedStackTrace";
     public static final String ELT_NANO_TIME = "nanoTime";
     public static final String ELT_INSTANT = "instant";
     public static final String ELT_TIME_MILLIS = "timeMillis";
+
+    private JsonConstants() {}
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/Log4jJsonModule.java

@@ -18,8 +18,8 @@
 
 import com.fasterxml.jackson.core.Version;
 import com.fasterxml.jackson.databind.module.SimpleModule;
+import org.apache.logging.log4j.core.jackson.Initializers.SetupContextAsEntryListInitializer;
 import org.apache.logging.log4j.core.jackson.Initializers.SetupContextInitializer;
-import org.apache.logging.log4j.core.jackson.Initializers.SetupContextJsonInitializer;
 import org.apache.logging.log4j.core.jackson.Initializers.SimpleModuleInitializer;
 
 /**
@@ -33,7 +33,6 @@ class Log4jJsonModule extends SimpleModule {
     private final boolean encodeThreadContextAsList;
     private final boolean includeStacktrace;
     private final boolean stacktraceAsString;
-    private final boolean objectMessageAsJsonObject;
 
     Log4jJsonModule(
             final boolean encodeThreadContextAsList,
@@ -44,7 +43,6 @@ class Log4jJsonModule extends SimpleModule {
         this.encodeThreadContextAsList = encodeThreadContextAsList;
         this.includeStacktrace = includeStacktrace;
         this.stacktraceAsString = stacktraceAsString;
-        this.objectMessageAsJsonObject = objectMessageAsJsonObject;
         // MUST init here.
         // Calling this from setupModule is too late!
         //noinspection ThisEscapedInObjectConstruction
@@ -56,9 +54,9 @@ public void setupModule(final SetupContext context) {
         // Calling super is a MUST!
         super.setupModule(context);
         if (encodeThreadContextAsList) {
-            new SetupContextInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
+            new SetupContextAsEntryListInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
         } else {
-            new SetupContextJsonInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
+            new SetupContextInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
         }
     }
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/Log4jXmlModule.java

@@ -17,7 +17,7 @@
 package org.apache.logging.log4j.core.jackson;
 
 import com.fasterxml.jackson.dataformat.xml.JacksonXmlModule;
-import org.apache.logging.log4j.core.jackson.Initializers.SetupContextInitializer;
+import org.apache.logging.log4j.core.jackson.Initializers.SetupContextAsEntryListInitializer;
 import org.apache.logging.log4j.core.jackson.Initializers.SimpleModuleInitializer;
 
 /**
@@ -43,6 +43,6 @@ final class Log4jXmlModule extends JacksonXmlModule {
     public void setupModule(final SetupContext context) {
         // Calling super is a MUST!
         super.setupModule(context);
-        new SetupContextInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
+        new SetupContextAsEntryListInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
     }
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/jackson/Log4jYamlModule.java

@@ -18,8 +18,8 @@
 
 import com.fasterxml.jackson.core.Version;
 import com.fasterxml.jackson.databind.module.SimpleModule;
+import org.apache.logging.log4j.core.jackson.Initializers.SetupContextAsEntryListInitializer;
 import org.apache.logging.log4j.core.jackson.Initializers.SetupContextInitializer;
-import org.apache.logging.log4j.core.jackson.Initializers.SetupContextJsonInitializer;
 import org.apache.logging.log4j.core.jackson.Initializers.SimpleModuleInitializer;
 
 /**
@@ -53,9 +53,9 @@ public void setupModule(final SetupContext context) {
         // Calling super is a MUST!
         super.setupModule(context);
         if (encodeThreadContextAsList) {
-            new SetupContextInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
+            new SetupContextAsEntryListInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
         } else {
-            new SetupContextJsonInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
+            new SetupContextInitializer().setupModule(context, includeStacktrace, stacktraceAsString);
         }
     }
 }