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 *

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 * version 2 for more details (a copy is included in the LICENSE file that

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 *

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

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/*

 * @test

 * @bug     6396794

 * @summary Check that LastGcInfo contents are reasonable

 * @author  Eamonn McManus

 * @modules jdk.management

 * @run     main/othervm -XX:-ExplicitGCInvokesConcurrent GcInfoCompositeType

 */

// Passing "-XX:-ExplicitGCInvokesConcurrent" to force System.gc()

// run on foreground when CMS is used and prevent situations when "GcInfo"

// is missing even though System.gc() was successfuly processed.

import java.util.*;

import java.lang.management.*;

import java.lang.reflect.*;

import javax.management.*;

import javax.management.openmbean.*;

import com.sun.management.GcInfo;

public class GcInfoCompositeType {

    private static int tested = 0;

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

        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();

        final ObjectName gcMXBeanPattern =

                new ObjectName("java.lang:type=GarbageCollector,*");

        Set<ObjectName> names =

                mbs.queryNames(gcMXBeanPattern, null);

        if (names.isEmpty())

            throw new Exception("Test incorrect: no GC MXBeans");

        System.gc();

        for (ObjectName n : names)

            tested += test(mbs, n);

        if (tested == 0)

            throw new Exception("No MXBeans were tested");

        System.out.println("Test passed");

    }

    private static int test(MBeanServer mbs, ObjectName n) throws Exception {

        System.out.println("Testing " + n);

        MBeanInfo mbi = mbs.getMBeanInfo(n);

        MBeanAttributeInfo lastGcAI = null;

        for (MBeanAttributeInfo mbai : mbi.getAttributes()) {

            if (mbai.getName().equals("LastGcInfo")) {

                lastGcAI = mbai;

                break;

            }

        }

        if (lastGcAI == null)

            throw new Exception("No LastGcInfo attribute");

        CompositeType declaredType =

                (CompositeType) lastGcAI.getDescriptor().getFieldValue("openType");

        checkType(declaredType);

        CompositeData cd =

                (CompositeData) mbs.getAttribute(n, "LastGcInfo");

        if (cd == null) {

            System.out.println("Value of attribute null");

            return 0;

        } else

            return checkType(cd.getCompositeType());

    }

    private static int checkType(CompositeType ct) throws Exception {

        Method[] methods = GcInfo.class.getMethods();

        Set<String> getters = new TreeSet<String>(String.CASE_INSENSITIVE_ORDER);

        for (Method m : methods) {

            if (m.getName().startsWith("get") && m.getParameterTypes().length == 0)

                getters.add(m.getName().substring(3));

        }

        Set<String> items = new HashSet<String>(ct.keySet());

        System.out.println("Items at start: " + items);

        // Now check that all the getters have a corresponding item in the

        // CompositeType, except the following:

        // getClass() inherited from Object should not be an item;

        // getCompositeType() inherited from CompositeData is not useful so

        // our hack removes it too.

        // Also track which items had corresponding getters, to make sure

        // there is at least one item which does not (GcThreadCount or

        // another gc-type-specific item).

        final String[] surplus = {"Class", "CompositeType"};

        for (String key : ct.keySet()) {

            if (getters.remove(key))

                items.remove(key);

        }

        if (!getters.equals(new HashSet<String>(Arrays.asList(surplus)))) {

            throw new Exception("Wrong getters: " + getters);

        }

        if (items.isEmpty()) {

            System.out.println("No type-specific items");

            return 0;

        } else {

            System.out.println("Type-specific items: " + items);

            return 1;

        }

    }

}