8288982: JFR: Log event streaming actions

Reviewed-by: mgronlun

Author: egahlin

src/jdk.jfr/share/classes/jdk/jfr/internal/consumer/AbstractEventStream.java

@@ -85,6 +85,9 @@ protected final Dispatcher dispatcher() {
             synchronized (streamConfiguration) {
                 dispatcher = new Dispatcher(streamConfiguration);
                 streamConfiguration.setChanged(false);
+                if (Logger.shouldLog(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG)) {
+                    Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, dispatcher.toString());
+                }
             }
         }
         return dispatcher;

src/jdk.jfr/share/classes/jdk/jfr/internal/consumer/Dispatcher.java

@@ -209,4 +209,15 @@ private void defaultErrorHandler(Throwable e) {
     public boolean hasMetadataHandler() {
         return metadataActions.length > 0;
     }
+
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("Error actions: " + errorActions.length + "\n");
+        sb.append("Meta actions: " + metadataActions.length + "\n");
+        sb.append("Flush actions: " + flushActions.length + "\n");
+        sb.append("Close actions: " + closeActions.length+ "\n");
+        sb.append("Event dispatchers: " + dispatchers.length+ "\n" );
+        sb.append("Dispatch lookup size: " + dispatcherLookup.size());
+        return sb.toString();
+    }
 }

test/jdk/jdk/jfr/api/consumer/recordingstream/TestOnEvent.java

@@ -35,7 +35,7 @@
  * @key jfr
  * @requires vm.hasJFR
  * @library /test/lib /test/jdk
- * @run main/othervm jdk.jfr.api.consumer.recordingstream.TestOnEvent
+ * @run main/othervm -Xlog:jfr+system+streaming=debug jdk.jfr.api.consumer.recordingstream.TestOnEvent
  */
 public class TestOnEvent {
 
@@ -154,12 +154,14 @@ private static void testOnEventAfterStart() {
             EventProducer p = new EventProducer();
             p.start();
             Thread addHandler = new Thread(() ->  {
+                log("About to add handler");
                 r.onEvent(e -> {
                     // Got event, close stream
                     log("Executing onEvent");
                     r.close();
                     log("RecordingStream closed");
                 });
+                log("Handler added");
             });
             r.onFlush(() ->  {
                 // Only add handler once