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/*

 * @test TestOldGenCollectionUsage.java

 * @bug 8195115

 * @summary G1 Old Gen's CollectionUsage.used is zero after mixed GC which is incorrect

 * @key gc

 * @requires vm.gc.G1

 * @library /test/lib

 * @modules java.base/jdk.internal.misc

 * @modules java.management

 * @build sun.hotspot.WhiteBox

 * @run driver ClassFileInstaller sun.hotspot.WhiteBox

 * @run main/othervm -Xbootclasspath/a:. -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -verbose:gc -XX:SurvivorRatio=1 -Xmx14m -Xms14m -XX:MaxTenuringThreshold=1 -XX:InitiatingHeapOccupancyPercent=100 -XX:-G1UseAdaptiveIHOP -XX:G1MixedGCCountTarget=4 -XX:MaxGCPauseMillis=30000 -XX:G1HeapRegionSize=1m -XX:G1HeapWastePercent=0 -XX:G1MixedGCLiveThresholdPercent=100 TestOldGenCollectionUsage

 */

import jdk.test.lib.Asserts;

import sun.hotspot.WhiteBox;

import java.util.ArrayList;

import java.util.List;

import java.util.Collections;

import java.lang.management.*;

// 8195115 says that for the "G1 Old Gen" MemoryPool, CollectionUsage.used

// is zero for G1 after a mixed collection, which is incorrect.

public class TestOldGenCollectionUsage {

    private String poolName = "G1 Old Gen";

    private String collectorName = "G1 Young Generation";

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

        TestOldGenCollectionUsage t = new TestOldGenCollectionUsage();

        t.run();

    }

    public TestOldGenCollectionUsage() {

        System.out.println("Monitor G1 Old Gen pool with G1 Young Generation collector.");

    }

    public void run() {

        // Find memory pool and collector

        List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();

        MemoryPoolMXBean pool = null;

        boolean foundPool = false;

        for (int i = 0; i < pools.size(); i++) {

            pool = pools.get(i);

            String name = pool.getName();

            if (name.contains(poolName)) {

                System.out.println("Found pool: " + name);

                foundPool = true;

                break;

            }

        }

        if (!foundPool) {

            throw new RuntimeException(poolName + " not found, test with -XX:+UseG1GC");

        }

        List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans();

        GarbageCollectorMXBean collector = null;

        boolean foundCollector = false;

        for (int i = 0; i < collectors.size(); i++) {

            collector = collectors.get(i);

            String name = collector.getName();

            if (name.contains(collectorName)) {

                System.out.println("Found collector: " + name);

                foundCollector = true;

                break;

            }

        }

        if (!foundCollector) {

            throw new RuntimeException(collectorName + " not found, test with -XX:+UseG1GC");

        }

        MixedGCProvoker gcProvoker = new MixedGCProvoker();

        gcProvoker.allocateOldObjects();

        // Verify no non-zero result was stored

        long usage = pool.getCollectionUsage().getUsed();

        System.out.println(poolName + ": usage after GC = " + usage);

        if (usage > 0) {

            throw new RuntimeException("Premature mixed collections(s)");

        }

        // Verify that collections were done

        long collectionCount = collector.getCollectionCount();

        System.out.println(collectorName + ": collection count = "

                           + collectionCount);

        long collectionTime = collector.getCollectionTime();

        System.out.println(collectorName + ": collection time  = "

                           + collectionTime);

        if (collectionCount <= 0) {

            throw new RuntimeException("Collection count <= 0");

        }

        if (collectionTime <= 0) {

            throw new RuntimeException("Collector has not run");

        }

        gcProvoker.provokeMixedGC();

        usage = pool.getCollectionUsage().getUsed();

        System.out.println(poolName + ": usage after GC = " + usage);

        if (usage <= 0) {

            throw new RuntimeException(poolName + " found with zero usage");

        }

        long newCollectionCount = collector.getCollectionCount();

        System.out.println(collectorName + ": collection count = "

                           + newCollectionCount);

        long newCollectionTime = collector.getCollectionTime();

        System.out.println(collectorName + ": collection time  = "

                           + newCollectionTime);

        if (newCollectionCount <= collectionCount) {

            throw new RuntimeException("No new collection");

        }

        if (newCollectionTime <= collectionTime) {

            throw new RuntimeException("Collector has not run some more");

        }

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

    }

    /**

     * Utility class to guarantee a mixed GC. The class allocates several arrays and

     * promotes them to the oldgen. After that it tries to provoke mixed GC by

     * allocating new objects.

     *

     * The necessary condition for guaranteed mixed GC is running MixedGCProvoker is

     * running in VM with the following flags: -XX:MaxTenuringThreshold=1 -Xms12M

     * -Xmx12M -XX:G1MixedGCLiveThresholdPercent=100 -XX:G1HeapWastePercent=0

     * -XX:G1HeapRegionSize=1m

     */

    public class MixedGCProvoker {

        private final WhiteBox WB = WhiteBox.getWhiteBox();

        private final List<byte[]> liveOldObjects = new ArrayList<>();

        private final List<byte[]> newObjects = new ArrayList<>();

        public static final int ALLOCATION_SIZE = 20000;

        public static final int ALLOCATION_COUNT = 15;

        public void allocateOldObjects() {

            List<byte[]> deadOldObjects = new ArrayList<>();

            // Allocates buffer and promotes it to the old gen. Mix live and dead old

            // objects

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

                liveOldObjects.add(new byte[ALLOCATION_SIZE * 5]);

                deadOldObjects.add(new byte[ALLOCATION_SIZE * 5]);

            }

            // Do two young collections, MaxTenuringThreshold=1 will force promotion.

            // G1HeapRegionSize=1m guarantees that old gen regions will be filled.

            WB.youngGC();

            WB.youngGC();

            // Check it is promoted & keep alive

            Asserts.assertTrue(WB.isObjectInOldGen(liveOldObjects),

                               "List of the objects is suppose to be in OldGen");

            Asserts.assertTrue(WB.isObjectInOldGen(deadOldObjects),

                               "List of the objects is suppose to be in OldGen");

        }

        /**

         * Waits until Concurent Mark Cycle finishes

         * @param wb  Whitebox instance

         * @param sleepTime sleep time

         */

        private void waitTillCMCFinished(int sleepTime) {

            while (WB.g1InConcurrentMark()) {

                if (sleepTime > -1) {

                    try {

                        Thread.sleep(sleepTime);

                    } catch (InterruptedException e) {

                        System.out.println("Got InterruptedException while waiting for ConcMarkCycle to finish");

                    }

                }

            }

        }

        public void provokeMixedGC() {

            waitTillCMCFinished(0);

            WB.g1StartConcMarkCycle();

            waitTillCMCFinished(0);

            WB.youngGC();

            System.out.println("Allocating new objects to provoke mixed GC");

            // Provoke a mixed collection. G1MixedGCLiveThresholdPercent=100

            // guarantees that full old gen regions will be included.

            for (int i = 0; i < (ALLOCATION_COUNT * 20); i++) {

                try {

                    newObjects.add(new byte[ALLOCATION_SIZE]);

                } catch (OutOfMemoryError e) {

                    newObjects.clear();

                    WB.youngGC();

                    WB.youngGC();

                    System.out.println("OutOfMemoryError is reported, stop allocating new objects");

                    break;

                }

            }

            // check that liveOldObjects still alive

            Asserts.assertTrue(WB.isObjectInOldGen(liveOldObjects),

                               "List of the objects is suppose to be in OldGen");

        }

    }

}