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/* @test

 * @bug 6482247

 * @summary Test that creating MXBeans does not introduce memory leaks.

 * @author Eamonn McManus

 * @run build LeakTest RandomMXBeanTest MerlinMXBean TigerMXBean

 * @run main LeakTest

 */

/* In this test we create a ClassLoader, then use it to load and run another

 * jtreg test.  When the other test has completed, we wait for the ClassLoader

 * to be garbage-collected.  If it has not been gc'd after a reasonable

 * amount of time, then something is keeping a reference to the ClassLoader,

 * which implies a memory leak.

 *

 * This test can be applied to any jtreg test, not just the MXBean tests.

 */

import java.io.File;

import java.lang.ref.Reference;

import java.lang.ref.ReferenceQueue;

import java.lang.ref.WeakReference;

import java.lang.reflect.Method;

import java.net.URL;

import java.net.URLClassLoader;

import java.nio.file.Paths;

public class LeakTest {

    /* Ideally we would include MXBeanTest in the list of tests, since it

     * has fairly complete coverage.  However, the ClassLoader fails to be

     * gc'd when we do that, and I am unable to figure out why.  Examining

     * a heap dump shows only weak references to the ClassLoader.  I suspect

     * something is wrong in the internals of the reflection classes, used

     * quite heavily by MXBeanTest.

     */

//    private static Class<?>[] otherTests = {MXBeanTest.class};

    private static Class<?>[] otherTests = {RandomMXBeanTest.class};

    // This class just makes it easier for us to spot our loader in heap dumps

    private static class ShadowClassLoader extends URLClassLoader {

        ShadowClassLoader(URL[] urls, ClassLoader parent) {

            super(urls, parent);

        }

    }

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

        System.out.println("Testing that no references are held to ClassLoaders " +

                "by caches in the MXBean infrastructure");

        for (Class<?> testClass : otherTests)

            test(testClass);

        if (failure != null)

            throw new Exception("CLASSLOADER LEAK TEST FAILED: " + failure);

        System.out.println("CLASSLOADER LEAK TEST PASSED");

        if (args.length > 0) {

            System.out.println("Waiting for input");

            System.in.read();

        }

    }

    private static void test(Class<?> originalTestClass) throws Exception {

        System.out.println();

        System.out.println("TESTING " + originalTestClass.getName());

        WeakReference<ClassLoader> wr = testShadow(originalTestClass);

        System.out.println("Test passed, waiting for ClassLoader to disappear");

        long deadline = System.currentTimeMillis() + 20*1000;

        Reference<? extends ClassLoader> ref;

        while (wr.get() != null && System.currentTimeMillis() < deadline) {

            System.gc();

            Thread.sleep(100);

        }

        if (wr.get() != null)

            fail(originalTestClass.getName() + " kept ClassLoader reference");

    }

    private static WeakReference<ClassLoader>

            testShadow(Class<?> originalTestClass) throws Exception {

        String[] cpaths = System.getProperty("test.classes", ".")

                                .split(File.pathSeparator);

        URL[] urls = new URL[cpaths.length];

        for (int i=0; i < cpaths.length; i++) {

            urls[i] = Paths.get(cpaths[i]).toUri().toURL();

        }

        URLClassLoader shadowLoader =

                new ShadowClassLoader(urls, originalTestClass.getClassLoader().getParent());

        System.out.println("Shadow loader is " + shadowLoader);

        String className = originalTestClass.getName();

        Class<?> testClass = Class.forName(className, false, shadowLoader);

        if (testClass.getClassLoader() != shadowLoader) {

            throw new IllegalArgumentException("Loader didn't work: " +

                    testClass.getClassLoader() + " != " + shadowLoader);

        }

        Method main = testClass.getMethod("main", String[].class);

        main.invoke(null, (Object) new String[0]);

        return new WeakReference<ClassLoader>(shadowLoader);

    }

    private static void fail(String why) {

        System.out.println("FAILED: " + why);

        failure = why;

    }

    private static String failure;

}