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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

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 * accompanied this code).

 *

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package jdk.jfr.api.metadata.eventtype;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.nio.file.Path;

import jdk.jfr.Event;

import jdk.jfr.EventType;

import jdk.jfr.FlightRecorder;

import jdk.jfr.Recording;

import jdk.jfr.consumer.RecordingFile;

import jdk.jfr.internal.JVM;

import jdk.test.lib.Utils;

 * @test

 * @key jfr

 * @summary Test that verifies event metadata is removed when an event class is unloaded.

 *

 * @library /test/lib

 * @modules jdk.jfr/jdk.jfr.internal

 *          java.base/jdk.internal.misc

 *

 * @run main/othervm -Xlog:class+unload -Xlog:gc jdk.jfr.api.metadata.eventtype.TestUnloadingEventClass

 */

public class TestUnloadingEventClass {

    private static final String EVENT_NAME = "jdk.jfr.api.metadata.eventtype.TestUnloadingEventClass$ToBeUnloaded";

    public static class ToBeUnloaded extends Event {

    }

    static public class MyClassLoader extends ClassLoader {

        public MyClassLoader() {

            super("MyClassLoader", null);

        }

        public final Class<?> defineClass(String name, byte[] b) {

            return super.defineClass(name, b, 0, b.length);

        }

    }

    private static final JVM jvm = JVM.getJVM();

    public static ClassLoader myClassLoader;

    public static void main(String[] args) throws Throwable {

        assertEventTypeNotAvailable();

        myClassLoader = createClassLoaderWithEventClass();

        try (Recording r0 = new Recording()) {

            r0.start();

            r0.stop();

            if (getEventType(r0, 0, EVENT_NAME) == null) {

                throw new Exception("Expected event class to have corresponding event type");

            }

        }

        try (Recording r1 = new Recording(); Recording r2 = new Recording(); Recording r3 = new Recording()) {

            r1.start();

            r2.start();

            System.out.println("Class loader with name " + myClassLoader.getName() + " is on the heap");

            unLoadEventClass();

            r3.start();

            assertEventTypeNotAvailable();

            r3.stop();

            r2.stop();

            r1.stop();

            if (getEventType(r1, 1, EVENT_NAME) == null) {

                throw new Exception("Expected event class to have corresponding event type in recording with all chunks");

            }

            if (getEventType(r2, 2, EVENT_NAME) == null) {

                throw new Exception("Expected event class to have corresponding event type in recording where event class was unloaded");

            }

            if (getEventType(r3, 3, EVENT_NAME) != null) {

                throw new Exception("Unexpected metadata found for event class tha has been unloaded.");

            }

        }

    }

    private static MyClassLoader createClassLoaderWithEventClass() throws Exception {

        String resourceName = EVENT_NAME.replace('.', '/') + ".class";

        try (InputStream is = TestUnloadingEventClass.class.getClassLoader().getResourceAsStream(resourceName)) {

            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            byte[] buffer = new byte[4096];

            int byteValue = 0;

            while ((byteValue = is.read(buffer, 0, buffer.length)) != -1) {

                baos.write(buffer, 0, byteValue);

            }

            baos.flush();

            MyClassLoader myClassLoader = new MyClassLoader();

            Class<?> eventClass = myClassLoader.defineClass(EVENT_NAME, baos.toByteArray());

            if (eventClass == null) {

                throw new Exception("Could not define test class");

            }

            if (eventClass.getSuperclass() != Event.class) {

                throw new Exception("Superclass should be jdk.jfr.Event");

            }

            if (eventClass.getSuperclass().getClassLoader() != null) {

                throw new Exception("Class loader of jdk.jfr.Event should be null");

            }

            if (eventClass.getClassLoader() != myClassLoader) {

                throw new Exception("Incorrect class loader for event class");

            }

            eventClass.newInstance(); // force <clinit>

            return myClassLoader;

        }

    }

    private static void unLoadEventClass() throws Exception {

        long firstCount = jvm.getUnloadedEventClassCount();

        System.out.println("Initial unloaded count: " + firstCount);

        myClassLoader = null;

        System.out.println("Cleared reference to MyClassLoader");

        long newCount = 0;

        do {

            System.out.println("GC triggered");

            System.gc();

            Thread.sleep(1000);

            newCount = jvm.getUnloadedEventClassCount();

            System.out.println("Unloaded count: " + newCount);

        } while (firstCount + 1 != newCount);

        System.out.println("Event class unloaded!");

        System.out.println("Event classes currently on the heap:");

        for (Class<?> eventClass : JVM.getJVM().getAllEventClasses()) {

            System.out.println(eventClass + " " + (eventClass.getClassLoader() != null ? eventClass.getClassLoader().getName() : null));

        }

    }

    private static void assertEventTypeNotAvailable() throws Exception {

        for (EventType type : FlightRecorder.getFlightRecorder().getEventTypes()) {

            if (type.getName().equals(EVENT_NAME)) {

                throw new Exception("Event type should not be available");

            }

        }

    }

    private static Object getEventType(Recording r, long id, String eventName) throws IOException {

        Path p = Utils.createTempFile("unloading-event-class-recording-" + id + "_", ".jfr");

        r.dump(p);

        try (RecordingFile rf = new RecordingFile(p)) {

            for (EventType et : rf.readEventTypes()) {

                if (et.getName().equals(eventName)) {

                    return et;

                }

            }

        }

        return null;

    }

}