8295375: debug agent class tracking should not piggy back on the cbClassPrepare() callback

Reviewed-by: amenkov, sspitsyn

Author: plummercj

src/jdk.jdwp.agent/share/native/libjdwp/classTrack.c

@@ -46,20 +46,35 @@
  */
 static jvmtiEnv* trackingEnv;
 
+static void addPreparedClass(JNIEnv *env, jclass klass);
+
 /*
  * Invoke the callback when classes are freed.
  */
 void JNICALL
 cbTrackingObjectFree(jvmtiEnv* jvmti_env, jlong tag)
 {
+    JDI_ASSERT(jvmti_env == trackingEnv);
     eventHandler_synthesizeUnloadEvent((char*)jlong_to_ptr(tag), getEnv());
 }
 
-void
-classTrack_addPreparedClass(JNIEnv *env_unused, jclass klass)
+/*
+ * Invoke the callback when classes are prepared.
+ */
+void JNICALL
+cbTrackingClassPrepare(jvmtiEnv* jvmti_env, JNIEnv *env, jthread thread, jclass klass)
+{
+    JDI_ASSERT(jvmti_env == trackingEnv);
+    addPreparedClass(env, klass);
+}
+
+/*
+ * Add a class to the prepared class hash table.
+ */
+static void
+addPreparedClass(JNIEnv *env, jclass klass)
 {
     jvmtiError error;
-    jvmtiEnv* env = trackingEnv;
 
     char* signature;
     error = classSignature(klass, &signature, NULL);
@@ -70,7 +85,7 @@ classTrack_addPreparedClass(JNIEnv *env_unused, jclass klass)
     if (gdata && gdata->assertOn) {
         // Check if already tagged.
         jlong tag;
-        error = JVMTI_FUNC_PTR(trackingEnv, GetTag)(env, klass, &tag);
+        error = JVMTI_FUNC_PTR(trackingEnv, GetTag)(trackingEnv, klass, &tag);
         if (error != JVMTI_ERROR_NONE) {
             EXIT_ERROR(error, "Unable to GetTag with class trackingEnv");
         }
@@ -83,7 +98,7 @@ classTrack_addPreparedClass(JNIEnv *env_unused, jclass klass)
         }
     }
 
-    error = JVMTI_FUNC_PTR(trackingEnv, SetTag)(env, klass, ptr_to_jlong(signature));
+    error = JVMTI_FUNC_PTR(trackingEnv, SetTag)(trackingEnv, klass, ptr_to_jlong(signature));
     if (error != JVMTI_ERROR_NONE) {
         jvmtiDeallocate(signature);
         EXIT_ERROR(error,"SetTag");
@@ -102,15 +117,27 @@ setupEvents()
     }
     jvmtiEventCallbacks cb;
     memset(&cb, 0, sizeof(cb));
+
+    // Setup JVMTI callbacks
     cb.ObjectFree = cbTrackingObjectFree;
+    cb.ClassPrepare = cbTrackingClassPrepare;
     error = JVMTI_FUNC_PTR(trackingEnv, SetEventCallbacks)(trackingEnv, &cb, sizeof(cb));
     if (error != JVMTI_ERROR_NONE) {
         return JNI_FALSE;
     }
+
+    // Enable OBJECT_FREE events
     error = JVMTI_FUNC_PTR(trackingEnv, SetEventNotificationMode)(trackingEnv, JVMTI_ENABLE, JVMTI_EVENT_OBJECT_FREE, NULL);
     if (error != JVMTI_ERROR_NONE) {
         return JNI_FALSE;
     }
+
+    // Enable CLASS_PREPARE events
+    error = JVMTI_FUNC_PTR(trackingEnv, SetEventNotificationMode)(trackingEnv, JVMTI_ENABLE, JVMTI_EVENT_CLASS_PREPARE, NULL);
+    if (error != JVMTI_ERROR_NONE) {
+        return JNI_FALSE;
+    }
+
     return JNI_TRUE;
 }
 
@@ -143,7 +170,7 @@ classTrack_initialize(JNIEnv *env)
             jint wanted = JVMTI_CLASS_STATUS_PREPARED | JVMTI_CLASS_STATUS_ARRAY;
             status = classStatus(klass);
             if ((status & wanted) != 0) {
-                classTrack_addPreparedClass(env, klass);
+                addPreparedClass(env, klass);
             }
         }
         jvmtiDeallocate(classes);

src/jdk.jdwp.agent/share/native/libjdwp/classTrack.h

@@ -33,12 +33,6 @@
 struct bag *
 classTrack_processUnloads(JNIEnv *env);
 
-/*
- * Add a class to the prepared class hash table.
- */
-void
-classTrack_addPreparedClass(JNIEnv *env, jclass klass);
-
 /*
  * Initialize class tracking.
  */

src/jdk.jdwp.agent/share/native/libjdwp/eventFilter.c

@@ -1265,7 +1265,6 @@ enableEvents(HandlerNode *node)
         case EI_THREAD_END:
         case EI_VM_INIT:
         case EI_VM_DEATH:
-        case EI_CLASS_PREPARE:
         case EI_GC_FINISH:
         case EI_VIRTUAL_THREAD_START:
         case EI_VIRTUAL_THREAD_END:
@@ -1326,7 +1325,6 @@ disableEvents(HandlerNode *node)
         case EI_THREAD_END:
         case EI_VM_INIT:
         case EI_VM_DEATH:
-        case EI_CLASS_PREPARE:
         case EI_GC_FINISH:
         case EI_VIRTUAL_THREAD_START:
         case EI_VIRTUAL_THREAD_END:

src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c

@@ -546,11 +546,6 @@ filterAndHandleEvent(JNIEnv *env, EventInfo *evinfo, EventIndex ei,
         HandlerNode *node;
         char        *classname;
 
-        /* We must keep track of all classes prepared to know what's unloaded */
-        if (evinfo->ei == EI_CLASS_PREPARE) {
-            classTrack_addPreparedClass(env, evinfo->clazz);
-        }
-
         node = getHandlerChain(ei)->first;
         classname = getClassname(evinfo->clazz);
 
@@ -1509,11 +1504,6 @@ eventHandler_initialize(jbyte sessionID)
     if (error != JVMTI_ERROR_NONE) {
         EXIT_ERROR(error,"Can't enable thread end events");
     }
-    error = threadControl_setEventMode(JVMTI_ENABLE,
-                                       EI_CLASS_PREPARE, NULL);
-    if (error != JVMTI_ERROR_NONE) {
-        EXIT_ERROR(error,"Can't enable class prepare events");
-    }
     error = threadControl_setEventMode(JVMTI_ENABLE,
                                        EI_GC_FINISH, NULL);
     if (error != JVMTI_ERROR_NONE) {