/*

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 * 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.

 *

 * 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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 */

import sun.hotspot.WhiteBox;

import sun.misc.Unsafe;

import java.io.IOException;

import java.lang.reflect.Method;

import java.net.URL;

import java.net.URLConnection;

/*

 * @test TestAnonymousClassUnloading

 * @bug 8054402

 * @summary "Tests unloading of anonymous classes."

 * @modules java.base/sun.misc

 * @compile TestAnonymousClassUnloading.java

 * @run main ClassFileInstaller TestAnonymousClassUnloading

 *                              sun.hotspot.WhiteBox

 *                              sun.hotspot.WhiteBox$WhiteBoxPermission

 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:-BackgroundCompilation TestAnonymousClassUnloading

 */

public class TestAnonymousClassUnloading {

    private static final WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();

    private static final Unsafe UNSAFE = Unsafe.getUnsafe();

    private static int COMP_LEVEL_SIMPLE = 1;

    private static int COMP_LEVEL_FULL_OPTIMIZATION = 4;

    /**

     * We override hashCode here to be able to access this implementation

     * via an Object reference (we cannot cast to TestAnonymousClassUnloading).

     */

    @Override

    public int hashCode() {

        return 42;

    }

    /**

     * Does some work by using the anonymousClass.

     * @param anonymousClass Class performing some work (will be unloaded)

     */

    static private void doWork(Class<?> anonymousClass) throws InstantiationException, IllegalAccessException {

        // Create a new instance

        Object anon = anonymousClass.newInstance();

        // We would like to call a method of anonymousClass here but we cannot cast because the class

        // was loaded by a different class loader. One solution would be to use reflection but since

        // we want C2 to implement the call as an IC we call Object::hashCode() here which actually

        // calls anonymousClass::hashCode(). C2 will then implement this call as an IC.

        if (anon.hashCode() != 42) {

            new RuntimeException("Work not done");

        }

    }

    /**

     * Makes sure that method is compiled by forcing compilation if not yet compiled.

     * @param m Method to be checked

     */

    static private void makeSureIsCompiled(Method m) {

        // Make sure background compilation is disabled

        if (WHITE_BOX.getBooleanVMFlag("BackgroundCompilation")) {

            throw new RuntimeException("Background compilation enabled");

        }

        // Check if already compiled

        if (!WHITE_BOX.isMethodCompiled(m)) {

            // If not, try to compile it with C2

            if(!WHITE_BOX.enqueueMethodForCompilation(m, COMP_LEVEL_FULL_OPTIMIZATION)) {

                // C2 compiler not available, try to compile with C1

                WHITE_BOX.enqueueMethodForCompilation(m, COMP_LEVEL_SIMPLE);

            }

            // Because background compilation is disabled, method should now be compiled

            if(!WHITE_BOX.isMethodCompiled(m)) {

                throw new RuntimeException(m + " not compiled");

            }

        }

    }

    /**

     * This test creates stale Klass* metadata referenced by a compiled IC.

     *

     * The following steps are performed:

     * (1) An anonymous version of TestAnonymousClassUnloading is loaded by a custom class loader

     * (2) The method doWork that calls a method of the anonymous class is compiled. The call

     *     is implemented as an IC referencing Klass* metadata of the anonymous class.

     * (3) Unloading of the anonymous class is enforced. The IC now references dead metadata.

     */

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

        // (1) Load an anonymous version of this class using the corresponding Unsafe method

        URL classUrl = TestAnonymousClassUnloading.class.getResource("TestAnonymousClassUnloading.class");

        URLConnection connection = classUrl.openConnection();

        int length = connection.getContentLength();

        byte[] classBytes = connection.getInputStream().readAllBytes();

        if (length != -1 && classBytes.length != length) {

            throw new IOException("Expected:" + length + ", actual: " + classBytes.length);

        }

        Class<?> anonymousClass = UNSAFE.defineAnonymousClass(TestAnonymousClassUnloading.class, classBytes, null);

        // (2) Make sure all paths of doWork are profiled and compiled

        for (int i = 0; i < 100000; ++i) {

            doWork(anonymousClass);

        }

        // Make sure doWork is compiled now

        Method doWork = TestAnonymousClassUnloading.class.getDeclaredMethod("doWork", Class.class);

        makeSureIsCompiled(doWork);

        // (3) Throw away reference to anonymousClass to allow unloading

        anonymousClass = null;

        // Force garbage collection to trigger unloading of anonymousClass

        // Dead metadata reference to anonymousClass triggers JDK-8054402

        WHITE_BOX.fullGC();

    }

}