/*

 * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.jfr.event.runtime;

import java.util.List;

import jdk.jfr.Recording;

import jdk.jfr.consumer.RecordedEvent;

import jdk.test.lib.Asserts;

import jdk.test.lib.jfr.EventNames;

import jdk.test.lib.jfr.Events;

import jdk.test.lib.jfr.TestClassLoader;

/*

 * @test

 * @key jfr

 * @library /test/lib /test/jdk

 * @build jdk.jfr.event.runtime.TestClasses

 * @run main/othervm jdk.jfr.event.runtime.TestClassLoadingStatisticsEvent

 */

/**

 * This test will load a number of classes. After each load step we verify that

 * the loadedClassCount and unloadedClassCount attributes are correct.

 *

 * System.gc() will trigger class unloading if -XX:+ExplicitGCInvokesConcurrent

 * is NOT set. If this flag is set G1 will never unload classes on System.gc()

 * and CMS will not guarantee that all semantically dead classes will be

 * unloaded. As far as the "jfr" key guarantees no VM flags are set from the

 * outside it should be enough with System.gc().

 */

public class TestClassLoadingStatisticsEvent {

    private final static String EVENT_PATH = EventNames.ClassLoadingStatistics;

    private final static String TESTCLASS_PUBLIC_STATIC =

                "jdk.jfr.event.runtime.TestClasses$TestClassPublicStatic";

    private final static String TESTCLASS_PUBLIC_STATIC_INNER =

                "jdk.jfr.event.runtime.TestClasses$TestClassPublicStatic$TestClassPublicStaticInner";

    // Declare unloadableClassLoader as "public static"

    // to prevent the compiler to optimize away all unread writes

    public static TestClassLoader unloadableClassLoader;

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

        // Load twice to get more stable result.

        RecordedEvent event = getCurrentEvent();

        event = getCurrentEvent();

        // Declare class ClassLoadingStatisticsHelper.

        TestClasses[] helpers = new TestClasses[10];

        event = verifyCountDelta(event, 1, 0);

        // Should load classes TestClassPrivate and TestClassPrivateStatic.

        for (int c = 0; c < helpers.length; c++) {

            helpers[c] = new TestClasses();

        }

        event = verifyCountDelta(event, 2, 0);

        // Load classes TestClassProtected and B2.

        helpers[0].new TestClassProtected();

        helpers[1].new TestClassProtected(); // This class is already loaded.

        new TestClasses.TestClassProtectedStatic();

        event = verifyCountDelta(event, 2, 0);

        // Load classes TestClassProtected1 and TestClassProtectedStatic1.

        for (int c = 0; c < helpers.length; c++) {

            helpers[c].loadClasses();

        }

        event = verifyCountDelta(event, 2, 0);

        // Load the classes with separate class loader. Will be unloaded later.

        unloadableClassLoader = new TestClassLoader();

        unloadableClassLoader.loadClass(TESTCLASS_PUBLIC_STATIC_INNER);

        event = verifyCountDelta(event, 1, 0);

        unloadableClassLoader.loadClass(TESTCLASS_PUBLIC_STATIC);

        event = verifyCountDelta(event, 1, 0);

        // This System.gc() should not unload classes, since the

        // unloadableClassLoader object is still active.

        System.gc();

        event = verifyCountDelta(event, 0, 0);

        // make classes are unloaded.

        unloadableClassLoader = null;

        System.gc();

        event = verifyCountDelta(event, 0, 2);

    }

    private static RecordedEvent getCurrentEvent() throws Throwable {

        Recording recording = new Recording();

        recording.enable(EVENT_PATH);

        recording.start();

        recording.stop();

        List<RecordedEvent> events = Events.fromRecording(recording);

        Asserts.assertFalse(events.isEmpty(), "No events in recording");

        RecordedEvent event = events.get(0);

        return event;

    }

    private static RecordedEvent verifyCountDelta(

        RecordedEvent prevEvent, int loadDelta, int unloadDelta) throws Throwable {

        RecordedEvent currEvent = null;

        try {

            long prevLoad = Events.assertField(prevEvent, "loadedClassCount").getValue();

            long prevUnload = Events.assertField(prevEvent, "unloadedClassCount").getValue();

            currEvent = getCurrentEvent();

            Events.assertField(currEvent, "loadedClassCount").atLeast(prevLoad + loadDelta);

            Events.assertField(currEvent, "unloadedClassCount").atLeast(prevUnload + unloadDelta);

            return currEvent;

        } catch (Throwable t) {

            System.out.println("verifyCountDelta failed. prevEvent=" + prevEvent + ", currEvent=" + currEvent);

            throw t;

        }

    }

}