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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package jdk.jfr.api.consumer.streaming;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;

import jdk.jfr.Event;
import jdk.jfr.Name;
import jdk.jfr.Recording;
import jdk.jfr.consumer.EventStream;
import jdk.jfr.consumer.RecordingStream;

/**
 * @test
 * @summary Verifies that a stream from a repository starts at the latest event
 * @key jfr
 * @requires vm.hasJFR
 * @library /test/lib
 * @run main/othervm jdk.jfr.api.consumer.streaming.TestLatestEvent
 */
public class TestLatestEvent {

    @Name("NotLatest")
    static class NotLatestEvent extends Event {
    }

    @Name("Latest")
    static class LatestEvent extends Event {
    }

    @Name("MakeChunks")
    static class MakeChunks extends Event {
    }

    public static void main(String... args) throws Exception {
        try (RecordingStream r = new RecordingStream()) {
            r.startAsync();
            MakeChunks e = new MakeChunks();
            e.commit();
            CountDownLatch beginChunks = new CountDownLatch(1);
            r.onEvent("MakeChunks", event-> {
                beginChunks.countDown();
            });
            System.out.println("Waitning for first chunk");
            beginChunks.await();
            // Create 5 chunks with events in the repository
            for (int i = 0; i < 5; i++) {
                System.out.println("Creating empty chunk");
                try (Recording r1 = new Recording()) {
                    r1.start();
                    NotLatestEvent notLatest = new NotLatestEvent();
                    notLatest.commit();
                    r1.stop();
                }
            }
            System.out.println("All empty chunks created");
            // Create an event in a segment, typically the first.
            NotLatestEvent notLatest = new NotLatestEvent();
            notLatest.commit();
            try (EventStream s = EventStream.openRepository()) {
                // Wait for next segment
                // to prevent flush to prevent NotLatest to be included
                awaitFlush(r);
                System.out.println("EventStream opened");
                AtomicBoolean foundLatest = new AtomicBoolean();
                s.onEvent(event -> {
                    String name = event.getEventType().getName();
                    System.out.println("Found event " + name);
                    foundLatest.set(name.equals("Latest"));
                    s.close();
                });
                System.out.println("Added onEvent handler");
                s.startAsync();
                // wait for next segment
                awaitFlush(s);
                // Emit the latest event
                LatestEvent latest = new LatestEvent();
                latest.commit();
                System.out.println("Latest event emitted");
                System.out.println("Waiting for termination");
                s.awaitTermination();
                if (!foundLatest.get()) {
                    throw new Exception("Didn't find latest event!");
                }
            }
        }
    }

    private static void awaitFlush(EventStream stream) throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(1);
        System.out.println("Waiting for flush...");
        final Runnable l =  () -> {
            System.out.println("Flush arrived!");
            latch.countDown();
        };
        stream.onFlush(l);
        latch.await();
        stream.remove(l);
    }
}