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package gc.g1.humongousObjects;

import gc.testlibrary.Helpers;

import jdk.test.lib.Asserts;

import sun.hotspot.WhiteBox;

import java.lang.ref.Reference;

import java.lang.ref.ReferenceQueue;

import java.lang.ref.SoftReference;

import java.lang.ref.WeakReference;

/**

 * @test TestObjectCollected

 * @summary checks that after different type of GCs weak/soft references to humongous object behave correspondingly to

 * actual object behavior

 * @library /testlibrary /test/lib /

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

 * @modules java.management

 * @build sun.hotspot.WhiteBox

 *        gc.testlibrary.Helpers

 *        gc.g1.humongousObjects.TestObjectCollected

 *

 * @run driver ClassFileInstaller sun.hotspot.WhiteBox

 *             sun.hotspot.WhiteBox$WhiteBoxPermission

 *

 * @run main/othervm -XX:+UseG1GC -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions

 *                   -XX:+WhiteBoxAPI -Xbootclasspath/a:. -Xms200m -Xmx200m -Xlog:gc

 *                   -XX:InitiatingHeapOccupancyPercent=100 -XX:G1HeapRegionSize=1M -Xlog:gc=info:file=TestObjectCollected.gc.log

 *                    gc.g1.humongousObjects.TestObjectCollected

 */

/**

 * Test checks that after different type of GCs weak/soft references to humongous object behave correspondingly to

 * actual object behavior.

 * So if object was collected, reference.get() should return null and vice versa

 * Since we check humongous objects after such an object is collected the region where it was allocated becomes free

 * or/and change type to non-humongous. Two WhiteBox method were used - first returns if a region containing certain

 * address is free and second - if a region containing certain address is humongous

 */

public class TestObjectCollected {

    /**

     * Provides methods to initiate GC of requested type

     */

    private enum GC {

        YOUNG_CG {

            @Override

            public void provoke() {

                WHITE_BOX.youngGC();

            }

        },

        FULL_GC {

            @Override

            public void provoke() {

                System.gc();

            }

        },

        CMC {

            @Override

            public void provoke() {

                Helpers.waitTillCMCFinished(WHITE_BOX, 0);

                WHITE_BOX.g1StartConcMarkCycle();

                Helpers.waitTillCMCFinished(WHITE_BOX, 0);

            }

        },

        FULL_GC_MEMORY_PRESSURE {

            @Override

            public void provoke() {

                WHITE_BOX.fullGC();

            }

        };

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

        public abstract void provoke();

    }

    /**

     * Factory for weak and soft references.

     * Allocates byte array of ALLOCATION_SIZE and returns weak/soft reference on it.

     */

    private enum REF_FACTORY {

        WEAK {

            @Override

            public Reference<byte[]> create() {

                return new WeakReference<>(new byte[ALLOCATION_SIZE], referenceQueqe);

            }

        },

        SOFT {

            @Override

            public Reference<byte[]> create() {

                return new SoftReference<>(new byte[ALLOCATION_SIZE], referenceQueqe);

            }

        };

        private static final ReferenceQueue<byte[]> referenceQueqe = new ReferenceQueue<>();

        private static final int ALLOCATION_SIZE = WhiteBox.getWhiteBox().g1RegionSize() * 2 / 3;

        /**

         * Factory method

         *

         * @return weak/soft reference on byte array of ALLOCATION_SIZE

         */

        public abstract Reference<byte[]> create();

    }

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

    /**

     * Does actual testing:

     * Gets a reference

     * Gets address of referenced object using WB method

     * Calls gc of provided type

     * Checks that object was/was not deleted using WB methods.

     */

    public static void doTesting(GC gc, REF_FACTORY ref) {

        System.out.println(String.format("Testing %s reference behavior after %s", ref.name(), gc.name()));

        Reference reference = ref.create();

        Asserts.assertNotNull(reference, "Test Bug: failed to allocate reference");

        long adr = WHITE_BOX.getObjectAddress(reference.get());

        //Sanity checks

        boolean isRefNulled = (reference.get() == null);

        boolean isRegionHumongous = WHITE_BOX.g1BelongsToHumongousRegion(adr);

        boolean isRegionFree = WHITE_BOX.g1BelongsToFreeRegion(adr);

        Asserts.assertEquals(isRefNulled, false,

                "We just allocated an object but reference.get() already returned null");

        Asserts.assertEquals(isRegionFree, false,

                "We just allocated an object but WB returns that allocation region is still considered free");

        Asserts.assertEquals(isRegionHumongous, true,

                "We just allocated a humongous object but WB returns that allocation region is not humongous");

        gc.provoke();

        isRefNulled = (reference.get() == null);

        isRegionHumongous = WHITE_BOX.g1BelongsToHumongousRegion(adr);

        isRegionFree = WHITE_BOX.g1BelongsToFreeRegion(adr);

        boolean isObjCollected = isRegionFree || !isRegionHumongous;

        Asserts.assertEquals(isRefNulled, isObjCollected,

                String.format("There is an inconsistensy between reference and white box "

                                + "method behavior - one considers object referenced with "

                                + "%s type collected and another doesn't!\n"

                                + "\treference.get() returned %snull\n"

                                + "\tWhiteBox methods returned that object was%s collected",

                        reference.getClass().getSimpleName(),

                        (isRefNulled ? "" : "not "),

                        (isObjCollected ? "" : " not")));

        System.out.println("Passed");

    }

    /**

     * Entry point

     *

     * @param args not used

     */

    public static void main(String[] args) {

        // Full gc - System.gc()

        TestObjectCollected.doTesting(GC.FULL_GC, REF_FACTORY.WEAK);

        TestObjectCollected.doTesting(GC.FULL_GC, REF_FACTORY.SOFT);

        // Full gc with memory pressure - WB.fullGC() emulates that no memory left

        TestObjectCollected.doTesting(GC.FULL_GC_MEMORY_PRESSURE, REF_FACTORY.WEAK);

        TestObjectCollected.doTesting(GC.FULL_GC_MEMORY_PRESSURE, REF_FACTORY.SOFT);

        // Young gc

        TestObjectCollected.doTesting(GC.YOUNG_CG, REF_FACTORY.WEAK);

        TestObjectCollected.doTesting(GC.YOUNG_CG, REF_FACTORY.SOFT);

        // Concurrent mark cycle

        TestObjectCollected.doTesting(GC.CMC, REF_FACTORY.WEAK);

        TestObjectCollected.doTesting(GC.CMC, REF_FACTORY.SOFT);

    }

}