test/jdk/jdk/jfr/api/flightrecorder/TestRecorderInitializationCallback.java

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package jdk.jfr.api.flightrecorder;

import static jdk.test.lib.Asserts.assertEquals;

import java.util.concurrent.atomic.AtomicInteger;

import jdk.jfr.FlightRecorder;
import jdk.jfr.FlightRecorderListener;

/**
 * @test
 * @summary Test Flight Recorder initialization callback is only called once
 * @key jfr
 * @requires vm.hasJFR
 * @library /test/lib
 * @run main/othervm jdk.jfr.api.flightrecorder.TestRecorderInitializationCallback
 */
public class TestRecorderInitializationCallback {

    private static class TestListener implements FlightRecorderListener {
        private final AtomicInteger count = new AtomicInteger();

        @Override
        public void recorderInitialized(FlightRecorder recorder) {
            count.incrementAndGet();
            System.out.println("recorderInitialized: " + recorder + " count=" + count);
            // Get the recorder again, should not trigger listener
            FlightRecorder.getFlightRecorder();
        }
    }

    public static void main(String[] args) throws Throwable {
        TestListener t = new TestListener();
        FlightRecorder.addListener(t);
        // trigger initialization
        FlightRecorder.getFlightRecorder();
        assertEquals(1, t.count.intValue(), "Expected 1 notification, got " + t.count);
    }
}