test/jdk/jdk/jfr/api/consumer/TestReadTwice.java

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package jdk.jfr.api.consumer;

import java.nio.file.Path;
import java.util.LinkedList;
import java.util.List;

import jdk.jfr.Event;
import jdk.jfr.Recording;
import jdk.jfr.consumer.RecordedEvent;
import jdk.jfr.consumer.RecordingFile;
import jdk.test.lib.Asserts;
import jdk.test.lib.Utils;


/**
 * @test
 * @summary Reads the recorded file two times and verifies that both reads are the same
 * @key jfr
 * @requires vm.hasJFR
 * @library /test/lib
 * @run main/othervm jdk.jfr.api.consumer.TestReadTwice
 */
public class TestReadTwice {

    private static class MyEvent extends Event {
    }

    public static void main(String[] args) throws Throwable {
        Recording r = new Recording();
        r.enable(MyEvent.class).withoutStackTrace();
        r.start();

        // Commit a single event to the recording
        MyEvent event = new MyEvent();
        event.commit();

        r.stop();

        // Dump the recording to a file
        Path path = Utils.createTempFile("read-twice", ".jfr");
        System.out.println("Dumping to " + path);
        r.dump(path);
        r.close();

        // Read all events from the file in one go
        List<RecordedEvent> events = RecordingFile.readAllEvents(path);

        // Read again the same events one by one
        RecordingFile rfile = new RecordingFile(path);
        List<RecordedEvent> events2 = new LinkedList<>();
        while (rfile.hasMoreEvents()) {
            events2.add(rfile.readEvent());
        }

        // Compare sizes
        Asserts.assertEquals(events.size(), events2.size());
        rfile.close();
    }
}