8330734: JFR: Re-engineer mirror class mechanism

Reviewed-by: mgronlun

src/jdk.jfr/share/classes/jdk/jfr/events/DeserializationEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,9 +36,8 @@ import jdk.jfr.internal.RemoveFields;
 @Label("Deserialization")
 @Name("jdk.Deserialization")
 @Description("Results of deserialization and ObjectInputFilter checks")
-@MirrorEvent(className = "jdk.internal.event.DeserializationEvent")
 @RemoveFields("duration")
-public final class DeserializationEvent extends AbstractJDKEvent {
+public final class DeserializationEvent extends MirrorEvent {
 
     @Label("Filter Configured")
     public boolean filterConfigured;

src/jdk.jfr/share/classes/jdk/jfr/events/ErrorThrownEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,9 +36,8 @@ import jdk.jfr.internal.Type;
 @Label("Java Error")
 @Category("Java Application")
 @Description("An object derived from java.lang.Error has been created. OutOfMemoryErrors are ignored")
-@MirrorEvent(className = "jdk.internal.event.ErrorThrownEvent")
 @RemoveFields("duration")
-public final class ErrorThrownEvent extends AbstractJDKEvent {
+public final class ErrorThrownEvent extends MirrorEvent {
 
     @Label("Message")
     public String message;

src/jdk.jfr/share/classes/jdk/jfr/events/ExceptionStatisticsEvent.java

@@ -31,14 +31,15 @@ import jdk.jfr.Label;
 import jdk.jfr.Name;
 import jdk.jfr.StackTrace;
 import jdk.jfr.internal.MirrorEvent;
+import jdk.jfr.internal.RemoveFields;
 import jdk.jfr.internal.Type;
 
 @Name(Type.EVENT_NAME_PREFIX + "ExceptionStatistics")
 @Label("Exception Statistics")
 @Category({ "Java Application", "Statistics" })
 @Description("Number of objects derived from java.lang.Throwable that have been created")
-@MirrorEvent(className = "jdk.internal.event.ExceptionStatisticsEvent")
+@RemoveFields({"duration", "eventThread", "stackTrace"})
-public final class ExceptionStatisticsEvent extends AbstractPeriodicEvent {
+public final class ExceptionStatisticsEvent extends MirrorEvent {
 
     @Label("Exceptions Created")
     public long throwables;

src/jdk.jfr/share/classes/jdk/jfr/events/ExceptionThrownEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,9 +37,8 @@ import jdk.jfr.internal.Type;
 @Label("Java Exception")
 @Category("Java Application")
 @Description("An object derived from java.lang.Exception has been created")
-@MirrorEvent(className = "jdk.internal.event.ExceptionThrownEvent")
 @RemoveFields("duration")
-public final class ExceptionThrownEvent extends AbstractJDKEvent {
+public final class ExceptionThrownEvent extends MirrorEvent {
 
     @Label("Message")
     public String message;

src/jdk.jfr/share/classes/jdk/jfr/events/ProcessStartEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,10 +36,9 @@ import jdk.jfr.internal.RemoveFields;
 @Label("Process Start")
 @Name("jdk.ProcessStart")
 @Description("Operating system process started")
-@MirrorEvent(className = "jdk.internal.event.ProcessStartEvent")
 @RemoveFields("duration")
 @StackFilter({"java.lang.ProcessBuilder", "java.lang.Runtime::exec"})
-public final class ProcessStartEvent extends AbstractJDKEvent {
+public final class ProcessStartEvent extends MirrorEvent {
     @Label("Process Id")
     public long pid;
 

src/jdk.jfr/share/classes/jdk/jfr/events/SecurityPropertyModificationEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,10 +33,9 @@ import jdk.jfr.internal.RemoveFields;
 @Label("Security Property Modification")
 @Name("jdk.SecurityPropertyModification")
 @Description("Modification of Security property")
-@MirrorEvent(className = "jdk.internal.event.SecurityPropertyModificationEvent")
 @RemoveFields("duration")
 @StackFilter({"java.security.Security::setProperty"})
-public final class SecurityPropertyModificationEvent extends AbstractJDKEvent {
+public final class SecurityPropertyModificationEvent extends MirrorEvent {
     @Label("Key")
     public String key;
 

src/jdk.jfr/share/classes/jdk/jfr/events/SecurityProviderServiceEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,10 +36,9 @@ import jdk.jfr.internal.RemoveFields;
 @Label("Security Provider Instance Request")
 @Name("jdk.SecurityProviderService")
 @Description("Details of Provider.getInstance(String type, String algorithm) calls")
-@MirrorEvent(className = "jdk.internal.event.SecurityProviderServiceEvent")
 @RemoveFields("duration")
 @StackFilter({"java.security.Provider::getService"})
-public final class SecurityProviderServiceEvent extends AbstractJDKEvent {
+public final class SecurityProviderServiceEvent extends MirrorEvent {
     @Label("Type of Service")
     public String type;
 

src/jdk.jfr/share/classes/jdk/jfr/events/SerializationMisdeclarationEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,9 +40,8 @@ import jdk.jfr.internal.Type;
         " The checks are usually performed just once per serializable class," +
         " the first time it is used by serialization." +
         " Under high memory pressure, a class might be re-checked again.")
-@MirrorEvent(className = "jdk.internal.event.SerializationMisdeclarationEvent")
 @RemoveFields({"duration", "stackTrace", "eventThread"})
-public final class SerializationMisdeclarationEvent extends AbstractJDKEvent {
+public final class SerializationMisdeclarationEvent extends MirrorEvent {
 
     @Label("Misdeclared Class")
     public Class<?> misdeclaredClass;

src/jdk.jfr/share/classes/jdk/jfr/events/SocketReadEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,8 +38,7 @@ import jdk.jfr.internal.Type;
 @Label("Socket Read")
 @Category("Java Application")
 @Description("Reading data from a socket")
-@MirrorEvent(className = "jdk.internal.event.SocketReadEvent")
+public final class SocketReadEvent extends MirrorEvent {
-public final class SocketReadEvent extends AbstractJDKEvent {
 
     @Label("Remote Host")
     public String host;

src/jdk.jfr/share/classes/jdk/jfr/events/SocketWriteEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,8 +37,7 @@ import jdk.jfr.internal.Type;
 @Label("Socket Write")
 @Category("Java Application")
 @Description("Writing data to a socket")
-@MirrorEvent(className = "jdk.internal.event.SocketWriteEvent")
+public final class SocketWriteEvent extends MirrorEvent {
-public final class SocketWriteEvent extends AbstractJDKEvent {
 
     @Label("Remote Host")
     public String host;

src/jdk.jfr/share/classes/jdk/jfr/events/TLSHandshakeEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,10 +37,9 @@ import jdk.jfr.internal.RemoveFields;
 @Label("TLS Handshake")
 @Name("jdk.TLSHandshake")
 @Description("Parameters used in TLS Handshake")
-@MirrorEvent(className = "jdk.internal.event.TLSHandshakeEvent")
 @RemoveFields("duration")
 @StackFilter("sun.security.ssl.Finished::recordEvent")
-public final class TLSHandshakeEvent extends AbstractJDKEvent {
+public final class TLSHandshakeEvent extends MirrorEvent {
     @Label("Peer Host")
     public String peerHost;
 

src/jdk.jfr/share/classes/jdk/jfr/events/ThreadSleepEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -34,11 +34,10 @@ import jdk.jfr.internal.MirrorEvent;
 @Category("Java Application")
 @Label("Java Thread Sleep")
 @Name("jdk.ThreadSleep")
-@MirrorEvent(className = "jdk.internal.event.ThreadSleepEvent")
 @StackFilter({"java.lang.Thread::afterSleep",
               "java.lang.Thread::sleepNanos",
               "java.lang.Thread::sleep"})
-public final class ThreadSleepEvent extends AbstractJDKEvent {
+public final class ThreadSleepEvent extends MirrorEvent {
     @Label("Sleep Time")
     @Timespan(Timespan.NANOSECONDS)
     public long time;

src/jdk.jfr/share/classes/jdk/jfr/events/VirtualThreadEndEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -34,9 +34,8 @@ import jdk.jfr.internal.RemoveFields;
 @Category("Java Application")
 @Label("Virtual Thread End")
 @Name("jdk.VirtualThreadEnd")
-@MirrorEvent(className = "jdk.internal.event.VirtualThreadEndEvent")
 @RemoveFields({"duration", "stackTrace"})
-public final class VirtualThreadEndEvent extends AbstractJDKEvent {
+public final class VirtualThreadEndEvent extends MirrorEvent {
 
     @Label("Thread Id")
     public long javaThreadId;

src/jdk.jfr/share/classes/jdk/jfr/events/VirtualThreadPinnedEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,5 @@ import jdk.jfr.internal.MirrorEvent;
 @Category("Java Application")
 @Label("Virtual Thread Pinned")
 @Name("jdk.VirtualThreadPinned")
-@MirrorEvent(className = "jdk.internal.event.VirtualThreadPinnedEvent")
+public final class VirtualThreadPinnedEvent extends MirrorEvent {
-public final class VirtualThreadPinnedEvent extends AbstractJDKEvent {
 }

src/jdk.jfr/share/classes/jdk/jfr/events/VirtualThreadStartEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -34,9 +34,8 @@ import jdk.jfr.internal.RemoveFields;
 @Category("Java Application")
 @Label("Virtual Thread Start")
 @Name("jdk.VirtualThreadStart")
-@MirrorEvent(className = "jdk.internal.event.VirtualThreadStartEvent")
 @RemoveFields("duration")
-public final class VirtualThreadStartEvent extends AbstractJDKEvent {
+public final class VirtualThreadStartEvent extends MirrorEvent {
 
     @Label("Thread Id")
     public long javaThreadId;

src/jdk.jfr/share/classes/jdk/jfr/events/VirtualThreadSubmitFailedEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,9 +36,8 @@ import jdk.jfr.internal.RemoveFields;
 @Label("Virtual Thread Submit Failed")
 @Name("jdk.VirtualThreadSubmitFailed")
 @Description("Submit of task for virtual thread failed")
-@MirrorEvent(className = "jdk.internal.event.VirtualThreadSubmitFailedEvent")
 @RemoveFields("duration")
-public final class VirtualThreadSubmitFailedEvent extends AbstractJDKEvent {
+public final class VirtualThreadSubmitFailedEvent extends MirrorEvent {
 
     @Label("Thread Id")
     public long javaThreadId;

src/jdk.jfr/share/classes/jdk/jfr/events/X509CertificateEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,9 +33,8 @@ import jdk.jfr.internal.RemoveFields;
 @Label("X509 Certificate")
 @Name("jdk.X509Certificate")
 @Description("Details of X.509 Certificate parsed by JDK")
-@MirrorEvent(className = "jdk.internal.event.X509CertificateEvent")
 @RemoveFields("duration")
-public final class X509CertificateEvent extends AbstractJDKEvent {
+public final class X509CertificateEvent extends MirrorEvent {
     @Label("Signature Algorithm")
     public String algorithm;
 

src/jdk.jfr/share/classes/jdk/jfr/events/X509ValidationEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,9 +33,8 @@ import jdk.jfr.internal.RemoveFields;
 @Label("X509 Validation")
 @Name("jdk.X509Validation")
 @Description("Serial numbers from X.509 Certificates forming chain of trust")
-@MirrorEvent(className = "jdk.internal.event.X509ValidationEvent")
 @RemoveFields("duration")
-public final class X509ValidationEvent extends AbstractJDKEvent {
+public final class X509ValidationEvent extends MirrorEvent {
     @CertificateId
     @Label("Certificate Id")
     @Unsigned

src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -90,7 +90,6 @@ final class EventInstrumentation {
     private static final ClassDesc TYPE_ISE = Bytecode.classDesc(IllegalStateException.class);
     private static final ClassDesc TYPE_EVENT_WRITER = classDesc(EventWriter.class);
     private static final ClassDesc TYPE_EVENT_WRITER_FACTORY = ClassDesc.of("jdk.jfr.internal.event.EventWriterFactory");
-    private static final ClassDesc TYPE_MIRROR_EVENT = Bytecode.classDesc(MirrorEvent.class);
     private static final ClassDesc TYPE_OBJECT = Bytecode.classDesc(Object.class);
     private static final ClassDesc TYPE_SETTING_DEFINITION = Bytecode.classDesc(SettingDefinition.class);
     private static final MethodDesc METHOD_BEGIN = MethodDesc.of("begin", "()V");
@@ -144,9 +143,7 @@ final class EventInstrumentation {
 
     private ImplicitFields determineImplicitFields() {
         if (isJDK) {
-            // For now, only support mirror events in java.base
+            Class<?> eventClass = MirrorEvents.find(isJDK, className);
-            String fullName = "java.base:" + className;
-            Class<?> eventClass = MirrorEvents.find(fullName);
             if (eventClass != null) {
                 return new ImplicitFields(eventClass);
             }
@@ -221,20 +218,6 @@ final class EventInstrumentation {
         return true;
     }
 
-    boolean isMirrorEvent() {
-        String typeDescriptor = TYPE_MIRROR_EVENT.descriptorString();
-        for (ClassElement ce : classModel.elements()) {
-            if (ce instanceof RuntimeVisibleAnnotationsAttribute rvaa) {
-                for (var annotation : rvaa.annotations()) {
-                    if (annotation.className().equalsString(typeDescriptor)) {
-                        return true;
-                    }
-                }
-            }
-        }
-        return false;
-    }
-
     @SuppressWarnings("unchecked")
     // Only supports String, String[] and Boolean values
     private static <T> T annotationValue(ClassModel classModel, ClassDesc classDesc, Class<T> type) {

src/jdk.jfr/share/classes/jdk/jfr/internal/JVMUpcalls.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -112,9 +112,6 @@ final class JVMUpcalls {
                 Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Skipping instrumentation for " + eventName + " since container support is missing");
                 return oldBytes;
             }
-            if (ei.isMirrorEvent()) {
-                return oldBytes;
-            }
 
             if (!forceInstrumentation) {
                 // Assume we are recording

src/jdk.jfr/share/classes/jdk/jfr/internal/MetadataRepository.java

@@ -144,10 +144,6 @@ public final class MetadataRepository {
         }
         EventConfiguration configuration = getConfiguration(eventClass, true);
         if (configuration == null) {
-            if (eventClass.getAnnotation(MirrorEvent.class) != null) {
-                // Don't register mirror classes.
-                return null;
-            }
             PlatformEventType pe = findMirrorType(eventClass);
             configuration = makeConfiguration(eventClass, pe, dynamicAnnotations, dynamicFields);
         }
@@ -162,8 +158,7 @@ public final class MetadataRepository {
     }
 
     private PlatformEventType findMirrorType(Class<? extends jdk.internal.event.Event> eventClass) throws InternalError {
-        String fullName = eventClass.getModule().getName() + ":" + eventClass.getName();
+        Class<? extends MirrorEvent> mirrorClass = MirrorEvents.find(eventClass);
-        Class<? extends Event> mirrorClass = MirrorEvents.find(fullName);
         if (mirrorClass == null) {
             return null; // not a mirror
         }

src/jdk.jfr/share/classes/jdk/jfr/internal/MirrorEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,32 +22,28 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
-
 package jdk.jfr.internal;
 
-import java.lang.annotation.Retention;
+import jdk.jfr.Enabled;
-import java.lang.annotation.Target;
+import jdk.jfr.Registered;
-import java.lang.annotation.RetentionPolicy;
+import jdk.jfr.StackTrace;
-import java.lang.annotation.ElementType;
-/**
- * Any event class annotated with this annotation must be added
- * to the {@link MirrorEvents) class for it to take effect.
- */
-@Retention(RetentionPolicy.RUNTIME)
-@Target({ ElementType.TYPE })
-public @interface MirrorEvent {
-    /**
-     * Fully qualified name of the class to mirror metadata for (for example,
-     * {@code "jdk.internal.event.Example"})
-     *
-     * @return the fully qualified class name of the event
-     */
-    String className();
 
-    /**
+/**
-     * The module where the event is located, by default {@code "java.base"}.
+ * A mirror event is a fictitious event class that contains metadata about an
-     *
+ * event, but not the implementation to write the event data to buffers.
-     * @return the module name
+ * <p>
+ * A mirror event should be used when an event class is in a module where a
+ * dependency on the jdk.jfr module is not possible, for example, due to a
+ * circular dependency.
+ * <p>
+ * Subclass the MirrorEvent class and add the exact same fields as the actual
+ * event, but with labels, descriptions etc.
+ * <p>
+ * For the mirror mechanism to work, the mirror class must be registered in the
+ * jdk.jfr.internal.MirrorEvents class.
  */
-    String module() default "java.base";
+@Registered(false)
+@Enabled(false)
+@StackTrace(false)
+public abstract class MirrorEvent {
 }

src/jdk.jfr/share/classes/jdk/jfr/internal/MirrorEvents.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,10 +24,9 @@
  */
 package jdk.jfr.internal;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
-import jdk.jfr.Event;
 import jdk.jfr.events.DeserializationEvent;
 import jdk.jfr.events.ErrorThrownEvent;
 import jdk.jfr.events.ExceptionStatisticsEvent;
@@ -47,52 +46,46 @@ import jdk.jfr.events.VirtualThreadSubmitFailedEvent;
 import jdk.jfr.events.X509CertificateEvent;
 import jdk.jfr.events.X509ValidationEvent;
 
-public final class MirrorEvents {
+/**
-    private static final Class<?>[] mirrorEventClasses = {
+ * This class registers all mirror events.
-        DeserializationEvent.class,
+ */
-        ProcessStartEvent.class,
+final class MirrorEvents {
-        SecurityPropertyModificationEvent.class,
+    private static final Map<String, Class<? extends MirrorEvent>> mirrorLookup = new ConcurrentHashMap<>();
-        SecurityProviderServiceEvent.class,
+
-        SerializationMisdeclarationEvent.class,
+    // Add mirror event mapping here. See MirrorEvent class for details.
-        SocketReadEvent.class,
+    static {
-        SocketWriteEvent.class,
+        register("jdk.internal.event.DeserializationEvent", DeserializationEvent.class);
-        ThreadSleepEvent.class,
+        register("jdk.internal.event.ProcessStartEvent", ProcessStartEvent.class);
-        TLSHandshakeEvent.class,
+        register("jdk.internal.event.SecurityPropertyModificationEvent", SecurityPropertyModificationEvent.class);
-        VirtualThreadStartEvent.class,
+        register("jdk.internal.event.SecurityProviderServiceEvent", SecurityProviderServiceEvent.class);
-        VirtualThreadEndEvent.class,
+        register("jdk.internal.event.SerializationMisdeclarationEvent", SerializationMisdeclarationEvent.class);
-        VirtualThreadPinnedEvent.class,
+        register("jdk.internal.event.SocketReadEvent", SocketReadEvent.class);
-        VirtualThreadSubmitFailedEvent.class,
+        register("jdk.internal.event.SocketWriteEvent", SocketWriteEvent.class);
-        X509CertificateEvent.class,
+        register("jdk.internal.event.ThreadSleepEvent", ThreadSleepEvent.class);
-        X509ValidationEvent.class,
+        register("jdk.internal.event.TLSHandshakeEvent", TLSHandshakeEvent.class);
-        ErrorThrownEvent.class,
+        register("jdk.internal.event.VirtualThreadStartEvent", VirtualThreadStartEvent.class);
-        ExceptionStatisticsEvent.class,
+        register("jdk.internal.event.VirtualThreadEndEvent", VirtualThreadEndEvent.class);
-        ExceptionThrownEvent.class,
+        register("jdk.internal.event.VirtualThreadPinnedEvent", VirtualThreadPinnedEvent.class);
+        register("jdk.internal.event.VirtualThreadSubmitFailedEvent", VirtualThreadSubmitFailedEvent.class);
+        register("jdk.internal.event.X509CertificateEvent", X509CertificateEvent.class);
+        register("jdk.internal.event.X509ValidationEvent", X509ValidationEvent.class);
+        register("jdk.internal.event.ErrorThrownEvent", ErrorThrownEvent.class);
+        register("jdk.internal.event.ExceptionStatisticsEvent", ExceptionStatisticsEvent.class);
+        register("jdk.internal.event.ExceptionThrownEvent", ExceptionThrownEvent.class);
     };
 
-    private static final Map<String, Class<? extends Event>> mirrorLookup = createLookup();
+    private static void register(String eventClassName, Class<? extends MirrorEvent> mirrorClass) {
+        mirrorLookup.put(eventClassName, mirrorClass);
+    }
 
-    public static Class<? extends Event> find(String name) {
+    static Class<? extends MirrorEvent> find(Class<? extends jdk.internal.event.Event> eventClass) {
-        // When <clinit> of this class is executed it may lead
+        return find(eventClass.getClassLoader() == null, eventClass.getName());
-        // to a JVM up call and invocation of this method before
+    }
-        // the mirrorLookup field has been set. This is fine,
+
-        // mirrors should not be instrumented.
+    static Class<? extends MirrorEvent> find(boolean bootClassLoader, String name) {
-        if (mirrorLookup != null) {
+        if (bootClassLoader) {
             return mirrorLookup.get(name);
         }
         return null;
     }
-
-    @SuppressWarnings("unchecked")
-    private static Map<String, Class<? extends Event>> createLookup() {
-        Map<String, Class<? extends Event>> mirrors = new HashMap<>();
-        for (Class<?> eventClass : mirrorEventClasses) {
-            MirrorEvent me = eventClass.getAnnotation(MirrorEvent.class);
-            if (me == null) {
-                throw new InternalError("Mirror class must have annotation " + MirrorEvent.class.getName());
-            }
-            String fullName = me.module() + ":" + me.className();
-            mirrors.put(fullName, (Class<? extends Event>) eventClass);
-        }
-        return mirrors;
-    }
 }

src/jdk.jfr/share/classes/jdk/jfr/internal/TypeLibrary.java

@@ -263,7 +263,7 @@ public final class TypeLibrary {
         // STRUCT
         String superType = null;
         boolean eventType = false;
-        if (jdk.internal.event.Event.class.isAssignableFrom(clazz)) {
+        if (isEventClass(clazz)) {
             superType = Type.SUPER_TYPE_EVENT;
             eventType= true;
         }
@@ -291,6 +291,16 @@ public final class TypeLibrary {
         return type;
     }
 
+    private static boolean isEventClass(Class<?> clazz) {
+        if (jdk.internal.event.Event.class.isAssignableFrom(clazz)) {
+            return true;
+        }
+        if (MirrorEvent.class.isAssignableFrom(clazz)) {
+            return true;
+        }
+        return false;
+    }
+
     private static void addAnnotations(Class<?> clazz, Type type, List<AnnotationElement> dynamicAnnotations) {
         ArrayList<AnnotationElement> aes = new ArrayList<>();
         if (dynamicAnnotations.isEmpty()) {

src/jdk.jfr/share/classes/jdk/jfr/internal/util/ImplicitFields.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -41,11 +41,11 @@ public final class ImplicitFields {
     private final List<String> fields = new ArrayList<>(4);
 
     public ImplicitFields(Class<?> eventClass) {
-        fields.add(START_TIME); // for completeness, not really needed
+        fields.add(START_TIME);
         fields.add(DURATION);
         fields.add(STACK_TRACE);
         fields.add(EVENT_THREAD);
-        for (Class<?> c = eventClass; jdk.internal.event.Event.class != c; c = c.getSuperclass()) {
+        for (Class<?> c = eventClass; !Utils.isEventBaseClass(c); c = c.getSuperclass()) {
             RemoveFields rf = c.getAnnotation(RemoveFields.class);
             if (rf != null) {
                 for (String value : rf.value()) {

src/jdk.jfr/share/classes/jdk/jfr/internal/util/Utils.java

@@ -51,6 +51,7 @@ import jdk.jfr.RecordingState;
 import jdk.jfr.internal.LogLevel;
 import jdk.jfr.internal.LogTag;
 import jdk.jfr.internal.Logger;
+import jdk.jfr.internal.MirrorEvent;
 import jdk.jfr.internal.SecuritySupport;
 import jdk.jfr.internal.Type;
 import jdk.jfr.internal.settings.PeriodSetting;
@@ -206,9 +207,8 @@ public final class Utils {
     }
 
     public static List<Field> getVisibleEventFields(Class<?> clazz) {
-        Utils.ensureValidEventSubclass(clazz);
         List<Field> fields = new ArrayList<>();
-        for (Class<?> c = clazz; c != jdk.internal.event.Event.class; c = c.getSuperclass()) {
+        for (Class<?> c = clazz; !Utils.isEventBaseClass(c); c = c.getSuperclass()) {
             for (Field field : c.getDeclaredFields()) {
                 // skip private field in base classes
                 if (c == clazz || !Modifier.isPrivate(field.getModifiers())) {
@@ -219,6 +219,16 @@ public final class Utils {
         return fields;
     }
 
+    public static boolean isEventBaseClass(Class<?> clazz) {
+        if (jdk.internal.event.Event.class == clazz) {
+            return true;
+        }
+        if (jdk.jfr.internal.MirrorEvent.class == clazz) {
+            return true;
+        }
+        return false;
+    }
+
     public static void ensureValidEventSubclass(Class<?> eventClass) {
         if (jdk.internal.event.Event.class.isAssignableFrom(eventClass) && Modifier.isAbstract(eventClass.getModifiers())) {
             throw new IllegalArgumentException("Abstract event classes are not allowed");
@@ -338,7 +348,7 @@ public final class Utils {
         return eventName;
     }
 
-    public static void verifyMirror(Class<?> mirror, Class<?> real) {
+    public static void verifyMirror(Class<? extends MirrorEvent> mirror, Class<?> real) {
         Class<?> cMirror = Objects.requireNonNull(mirror);
         Class<?> cReal = Objects.requireNonNull(real);
 
@@ -353,7 +363,7 @@ public final class Utils {
         }
         while (cReal != null) {
             for (Field realField : cReal.getDeclaredFields()) {
-                if (isSupportedType(realField.getType())) {
+                if (isSupportedType(realField.getType()) && !realField.isSynthetic()) {
                     String fieldName = realField.getName();
                     Field mirrorField = mirrorFields.get(fieldName);
                     if (mirrorField == null) {