Changed name to CHUNK_ROTATION_MONITOR and made some other rearrangements

Author: jaokim

src/hotspot/share/jfr/recorder/repository/jfrChunkRotation.cpp

@@ -38,7 +38,7 @@ static jobject install_chunk_monitor(JavaThread* thread) {
   // read static field
   HandleMark hm(thread);
   static const char klass[] = "jdk/jfr/internal/JVM";
-  static const char field[] = "FILE_DELTA_CHANGE";
+  static const char field[] = "CHUNK_ROTATION_MONITOR";
   static const char signature[] = "Ljava/lang/Object;";
   JavaValue result(T_OBJECT);
   JfrJavaArguments field_args(&result, klass, field, signature, thread);

src/hotspot/share/jfr/support/jfrIntrinsics.hpp

@@ -52,6 +52,7 @@ class JfrIntrinsicSupport : AllStatic {
   template(getEventWriter_signature,                                  "()Ljdk/jfr/internal/event/EventWriter;")      \
   template(eventConfiguration_name,                                   "eventConfiguration")                          \
   template(commit_name,                                               "commit")                                      \
+  template(jfr_chunk_rotation_monitor,                                "jdk/jfr/internal/JVM$ChunkRotationMonitor")   \
 
 #define JFR_INTRINSICS(do_intrinsic, do_class, do_name, do_signature, do_alias)                                      \
   do_intrinsic(_counterTime,        jdk_jfr_internal_JVM, counterTime_name, void_long_signature, F_SN)               \

src/hotspot/share/runtime/objectMonitor.cpp

@@ -1416,31 +1416,32 @@ bool ObjectMonitor::check_owner(TRAPS) {
              "current thread is not owner", false);
 }
 
+static inline bool is_excluded(const Klass* monitor_klass) {
+  assert(monitor_klass != nullptr, "invariant");
+  NOT_JFR_RETURN_(false);
+  JFR_ONLY(return vmSymbols::jfr_chunk_rotation_monitor() == monitor_klass->name());
+}
+
 static void post_monitor_wait_event(EventJavaMonitorWait* event,
                                     ObjectMonitor* monitor,
                                     uint64_t notifier_tid,
                                     jlong timeout,
                                     bool timedout) {
-  bool includeEvent = true;
-  Klass* objectMonitorClass;
   assert(event != NULL, "invariant");
   assert(monitor != NULL, "invariant");
-  objectMonitorClass = monitor->object()->klass();
-  if (objectMonitorClass != NULL &&
-      objectMonitorClass->name()->equals("jdk/jfr/internal/FileDeltaChangeLockObject")) {
-    includeEvent = false;
-  }
-  if (includeEvent) {
-    event->set_monitorClass(objectMonitorClass);
-    event->set_timeout(timeout);
-    // Set an address that is 'unique enough', such that events close in
-    // time and with the same address are likely (but not guaranteed) to
-    // belong to the same object.
-    event->set_address((uintptr_t)monitor);
-    event->set_notifier(notifier_tid);
-    event->set_timedOut(timedout);
-    event->commit();
+  const Klass* monitor_klass = monitor->object()->klass();
+  if (is_excluded(monitor_klass)) {
+    return;
   }
+  event->set_monitorClass(monitor_klass);
+  event->set_timeout(timeout);
+  // Set an address that is 'unique enough', such that events close in
+  // time and with the same address are likely (but not guaranteed) to
+  // belong to the same object.
+  event->set_address((uintptr_t)monitor);
+  event->set_notifier(notifier_tid);
+  event->set_timedOut(timedout);
+  event->commit();
 }
 
 // -----------------------------------------------------------------------------

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

@@ -39,11 +39,17 @@
 public final class JVM {
     private static final JVM jvm = new JVM();
 
-    // JVM signals file changes by doing Object#notify on this object
-    static final Object FILE_DELTA_CHANGE = new FileDeltaChangeLockObject();
-
     static final long RESERVED_CLASS_ID_LIMIT = 500;
 
+    private static class ChunkRotationMonitor {}
+
+    /*
+     * The JVM uses the chunk rotation monitor to notify Java that a rotation is warranted.
+     * The monitor type is used to exclude jdk.JavaMonitorWait events from being generated
+     * when Object.wait() is called on this monitor.
+     */
+    static final Object CHUNK_ROTATION_MONITOR = new ChunkRotationMonitor();
+
     private volatile boolean nativeOK;
 
     private static native void registerNatives();

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

@@ -520,8 +520,8 @@ private boolean isToDisk() {
 
     private void takeNap(long duration) {
         try {
-            synchronized (JVM.FILE_DELTA_CHANGE) {
-                JVM.FILE_DELTA_CHANGE.wait(duration < 10 ? 10 : duration);
+            synchronized (JVM.CHUNK_ROTATION_MONITOR) {
+                JVM.CHUNK_ROTATION_MONITOR.wait(duration < 10 ? 10 : duration);
             }
         } catch (InterruptedException e) {
             // Ignore

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

@@ -302,8 +302,8 @@ static void setFlushInterval(long millis) {
         boolean needNotify = interval < flushInterval;
         flushInterval = interval;
         if (needNotify) {
-            synchronized (JVM.FILE_DELTA_CHANGE) {
-                JVM.FILE_DELTA_CHANGE.notifyAll();
+            synchronized (JVM.CHUNK_ROTATION_MONITOR) {
+                JVM.CHUNK_ROTATION_MONITOR.notifyAll();
             }
         }
     }