8298175: JFR: Common timestamp for periodic events

Reviewed-by: dholmes, mgronlun

Author: egahlin

make/src/classes/build/tools/jfr/GenerateJfrFiles.java

@@ -573,9 +573,13 @@ private static void printJfrPeriodicHpp(Metadata metadata, File outputFile) thro
             out.write("#include \"jfrfiles/jfrEventIds.hpp\"");
             out.write("#include \"memory/allocation.hpp\"");
             out.write("");
+            out.write("enum PeriodicType {BEGIN_CHUNK, INTERVAL, END_CHUNK};");
+            out.write("");
             out.write("class JfrPeriodicEventSet : public AllStatic {");
             out.write(" public:");
-            out.write("  static void requestEvent(JfrEventId id) {");
+            out.write("  static void requestEvent(JfrEventId id, jlong timestamp, PeriodicType periodicType) {");
+            out.write("    _timestamp = Ticks(timestamp);");
+            out.write("    _type = periodicType;");
             out.write("    switch(id) {");
             out.write("  ");
             for (TypeElement e : metadata.getPeriodicEvents()) {
@@ -595,6 +599,10 @@ private static void printJfrPeriodicHpp(Metadata metadata, File outputFile) thro
                 out.write("  static void request" + e.name + "(void);");
                 out.write("");
             }
+            out.write(" static Ticks timestamp(void);");
+            out.write(" static Ticks _timestamp;");
+            out.write(" static PeriodicType type(void);");
+            out.write(" static PeriodicType _type;");
             out.write("};");
             out.write("");
             out.write("#endif // INCLUDE_JFR");

src/hotspot/share/jfr/jni/jfrJniMethod.cpp

@@ -238,8 +238,8 @@ JVM_ENTRY_NO_ENV(void, jfr_mark_chunk_final(JNIEnv * env, jobject jvm))
   JfrRepository::mark_chunk_final();
 JVM_END
 
-JVM_ENTRY_NO_ENV(jboolean, jfr_emit_event(JNIEnv* env, jobject jvm, jlong eventTypeId, jlong timeStamp, jlong when))
-  JfrPeriodicEventSet::requestEvent((JfrEventId)eventTypeId);
+JVM_ENTRY_NO_ENV(jboolean, jfr_emit_event(JNIEnv* env, jobject jvm, jlong event_type_id, jlong timestamp, jlong periodic_type))
+  JfrPeriodicEventSet::requestEvent((JfrEventId)event_type_id, timestamp, static_cast<PeriodicType>(periodic_type));
   return thread->has_pending_exception() ? JNI_FALSE : JNI_TRUE;
 JVM_END
 

src/hotspot/share/jfr/periodic/jfrPeriodic.cpp

@@ -81,6 +81,18 @@
  */
 #define TRACE_REQUEST_FUNC(id)    void JfrPeriodicEventSet::request##id(void)
 
+// Timestamp to correlate events in the same batch/generation
+Ticks JfrPeriodicEventSet::_timestamp;
+PeriodicType JfrPeriodicEventSet::_type;
+
+Ticks JfrPeriodicEventSet::timestamp(void) {
+  return _timestamp;
+}
+
+PeriodicType JfrPeriodicEventSet::type(void) {
+  return _type;
+}
+
 TRACE_REQUEST_FUNC(JVMInformation) {
   ResourceMark rm;
   EventJVMInformation event;

src/hotspot/share/utilities/ticks.hpp

@@ -231,6 +231,7 @@ class TimeInstant : public Rep<TimeSource> {
   friend class GranularTimer;
   friend class ObjectSample;
   friend class EventEmitter;
+  friend class JfrPeriodicEventSet;
   // GC unit tests
   friend class TimePartitionsTest;
   friend class GCTimerTest;

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

@@ -118,11 +118,11 @@ private JVM() {
      * @param eventTypeId type id
      *
      * @param timestamp commit time for event
-     * @param when when it is being done {@link Periodic.When}
+     * @param periodicType when it is being done {@link PeriodicType.When}
      *
      * @return true if the event was committed
      */
-    public native boolean emitEvent(long eventTypeId, long timestamp, long when);
+    public native boolean emitEvent(long eventTypeId, long timestamp, long periodicType);
 
     /**
      * Return a list of all classes deriving from {@link jdk.internal.event.Event}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2022, 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
@@ -39,6 +39,9 @@
 import jdk.jfr.EventType;
 
 public final class RequestEngine {
+    enum PeriodicType {
+        BEGIN_CHUNK, INTERVAL, END_CHUNK
+    }
 
     private static final JVM jvm = JVM.getJVM();
     private static final ReentrantLock lock = new ReentrantLock();
@@ -62,13 +65,13 @@ private RequestHook(@SuppressWarnings("removal") AccessControlContext acc, Platf
             this(null, eventType, null);
         }
 
-        private void execute() {
+        private void execute(long timestamp, PeriodicType periodicType) {
             try {
                 if (accessControllerContext == null) { // native
                     if (type.isJDK()) {
                         hook.run();
                     } else {
-                        emitJVMEvent(type);
+                        emitJVMEvent(type, timestamp, periodicType);
                     }
                     if (Logger.shouldLog(LogTag.JFR_SYSTEM, LogLevel.DEBUG)) {
                         Logger.log(LogTag.JFR_SYSTEM, LogLevel.DEBUG, "Executed periodic hook for " + type.getLogName());
@@ -82,13 +85,13 @@ private void execute() {
             }
         }
 
-        private void emitJVMEvent(PlatformEventType type) {
+        private void emitJVMEvent(PlatformEventType type, long timestamp, PeriodicType periodicType) {
             try {
                 // There should only be one thread in native at a time.
                 // ReentrantLock is used to avoid JavaMonitorBlocked event
                 // from synchronized block.
                 lock.lock();
-                jvm.emitEvent(type.getId(), JVM.counterTime(), 0);
+                jvm.emitEvent(type.getId(), timestamp, periodicType.ordinal());
             } finally {
                 lock.unlock();
             }
@@ -183,35 +186,33 @@ static void addHooks(List<RequestHook> newEntries) {
     }
 
     static void doChunkEnd() {
-        doChunk(x -> x.isEndChunk());
+        doChunk(x -> x.isEndChunk(), PeriodicType.END_CHUNK);
     }
 
     static void doChunkBegin() {
-        doChunk(x -> x.isBeginChunk());
+        doChunk(x -> x.isBeginChunk(), PeriodicType.BEGIN_CHUNK);
     }
 
-    private static void doChunk(Predicate<PlatformEventType> predicate) {
+    private static void doChunk(Predicate<PlatformEventType> predicate, PeriodicType type) {
+        long timestamp = JVM.counterTime();
         for (RequestHook requestHook : entries) {
             PlatformEventType s = requestHook.type;
             if (s.isEnabled() && predicate.test(s)) {
-                requestHook.execute();
+                requestHook.execute(timestamp, type);
             }
         }
     }
 
     static long doPeriodic() {
-        return run_requests(entries);
+        return run_requests(entries, JVM.counterTime());
     }
 
     // code copied from native impl.
-    private static long run_requests(Collection<RequestHook> entries) {
+    private static long run_requests(Collection<RequestHook> entries, long eventTimestamp) {
         long last = lastTimeMillis;
-        // Bug 9000556 - current time millis has rather lame resolution
-        // The use of os::elapsed_counter() is deliberate here, we don't
-        // want it exchanged for os::ft_elapsed_counter().
-        // Keeping direct call os::elapsed_counter() here for reliable
-        // real time values in order to decide when registered requestable
-        // events are due.
+        // The interval for periodic events is typically at least 1 s, so
+        // System.currentTimeMillis() is sufficient. JVM.counterTime() lacks
+        // unit and has in the past been more unreliable.
         long now = System.currentTimeMillis();
         long min = 0;
         long delta = 0;
@@ -249,7 +250,7 @@ private static long run_requests(Collection<RequestHook> entries) {
                 // Bug 9000556 - don't try to compensate
                 // for wait > period
                 r_delta = 0;
-                he.execute();
+                he.execute(eventTimestamp, PeriodicType.INTERVAL);
             }
 
             // calculate time left