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/*

 * @test

 * @bug     4530538

 * @summary Basic unit test of MemoryMXBean.getMemoryPools() and

 *          MemoryMXBean.getMemoryManager().

 * @author  Mandy Chung

 *

 * @run main MemoryTest 2

 */

/*

 * NOTE: This expected result is hardcoded in this test and this test

 *       will be affected if the heap memory layout is changed in

 *       the future implementation.

 */

import java.lang.management.*;

import java.util.*;

public class MemoryTest {

    private static boolean testFailed = false;

    private static MemoryMXBean mm = ManagementFactory.getMemoryMXBean();

    private static final int HEAP = 0;

    private static final int NONHEAP = 1;

    private static final int NUM_TYPES = 2;

    // WARNING: if the number of pools changes in the future,

    // this test needs to be modified to handle different version of VMs.

    // Hotspot VM 1.5 expected to have

    //   heap memory pools     = 3 (Eden, Survivor spaces, Old gen)

    //   non-heap memory pools = 2 (Perm gen, Code cache)

    //                           or 4 if Class Sharing is enabled.

    // Number of memory managers = 3

    // They are: Copy/Scavenger + MSC + CodeCache manager

    // (or equivalent for other collectors)

    // Number of GC memory managers = 2

    // Hotspot VM 1.8+ after perm gen removal is expected to have between two

    // or five non-heap memory pools:

    // - Code cache (between one and three depending on the -XX:SegmentedCodeCache option)

    // - Metaspace

    // - Compressed Class Space (if compressed class pointers are used)

    private static int[] expectedMinNumPools = {3, 2};

    private static int[] expectedMaxNumPools = {3, 5};

    private static int expectedNumGCMgrs = 2;

    private static int expectedNumMgrs = expectedNumGCMgrs + 2;

    private static String[] types = { "heap", "non-heap" };

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

        Integer value = new Integer(args[0]);

        expectedNumGCMgrs = value.intValue();

        expectedNumMgrs = expectedNumGCMgrs + 2;

        checkMemoryPools();

        checkMemoryManagers();

        if (testFailed)

            throw new RuntimeException("TEST FAILED.");

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

    }

    private static void checkMemoryPools() throws Exception {

        List pools = ManagementFactory.getMemoryPoolMXBeans();

        boolean hasPerm = false;

        int[] numPools = new int[NUM_TYPES];

        for (ListIterator iter = pools.listIterator(); iter.hasNext();) {

            MemoryPoolMXBean pool = (MemoryPoolMXBean) iter.next();

            if (pool.getType() == MemoryType.HEAP) {

                numPools[HEAP]++;

            }

            if (pool.getType() == MemoryType.NON_HEAP) {

                numPools[NONHEAP]++;

            }

            if (pool.getName().toLowerCase().contains("perm")) {

                hasPerm = true;

            }

        }

        if (hasPerm) {

            // If the VM has perm gen there will be between 2 and 4 non heap

            // pools (4 if class data sharing is used)

            expectedMinNumPools[NONHEAP] = 2;

            expectedMaxNumPools[NONHEAP] = 4;

        }

        // Check the number of Memory pools

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

            if (numPools[i] < expectedMinNumPools[i] ||

                    numPools[i] > expectedMaxNumPools[i]) {

                throw new RuntimeException("TEST FAILED: " +

                    "Number of " + types[i] + " pools = " + numPools[i] +

                    " but expected <= " + expectedMaxNumPools[i] +

                    " and >= " + expectedMinNumPools[i]);

            }

        }

    }

    private static void checkMemoryManagers() throws Exception {

        List mgrs = ManagementFactory.getMemoryManagerMXBeans();

        int numGCMgr = 0;

        // Check the number of Memory Managers

        for (ListIterator iter = mgrs.listIterator(); iter.hasNext();) {

            MemoryManagerMXBean mgr = (MemoryManagerMXBean) iter.next();

            String[] poolNames = mgr.getMemoryPoolNames();

            if (poolNames == null || poolNames.length == 0) {

                throw new RuntimeException("TEST FAILED: " +

                    "Expected to have one or more pools for " +

                    mgr.getName() + "manager.");

            }

            if (mgr instanceof GarbageCollectorMXBean) {

                numGCMgr++;

            } else {

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

                    checkPoolType(poolNames[i], MemoryType.NON_HEAP);

                }

            }

        }

        if (mgrs.size() != expectedNumMgrs) {

            throw new RuntimeException("TEST FAILED: " +

                "Number of memory managers = " + mgrs.size() +

                " but expected = " + expectedNumMgrs);

        }

        if (numGCMgr != expectedNumGCMgrs) {

            throw new RuntimeException("TEST FAILED: " +

                "Number of GC managers = " + numGCMgr + " but expected = " +

                expectedNumGCMgrs);

        }

    }

    private static List pools = ManagementFactory.getMemoryPoolMXBeans();

    private static void checkPoolType(String name, MemoryType type)

        throws Exception {

        for (ListIterator iter = pools.listIterator(); iter.hasNext(); ) {

            MemoryPoolMXBean pool = (MemoryPoolMXBean) iter.next();

            if (pool.getName().equals(name)) {

                if (pool.getType() != type) {

                    throw new RuntimeException("TEST FAILED: " +

                        "Pool " + pool.getName() + " is of type " +

                        pool.getType() + " but expected to be " + type);

                } else {

                    return;

                }

            }

        }

        throw new RuntimeException("TEST FAILED: " +

            "Pool " + name + " is of type " + type +

            " not found");

    }

}