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package gc.z;

/**
 * @test TestZNMT
 * @bug 8310743
 * @requires vm.gc.Z & vm.debug
 * @summary Test NMT and ZGC heap reservation / commits interactions.
 * @library / /test/lib
 * @run driver gc.z.TestZNMT
 */

import static gc.testlibrary.Allocation.blackHole;
import java.util.ArrayList;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;

public class TestZNMT {
    private static final int XmxInM = 2000;
    static class Test {
        private static final int K = 1024;
        private static final int M = K * K;
        public static void main(String[] args) throws Exception {
            final int zForceDiscontiguousHeapReservations = Integer.parseInt(args[0]);
            final int XmsInM = Integer.parseInt(args[1]);
            // 75% of the largest allocation that fits within one reservation
            // (or Xmx / zForceDiscontiguousHeapReservations), whichever is smallest
            final int allocationInM = (int)(Math.min(zForceDiscontiguousHeapReservations == 0
                                                        ? XmxInM
                                                        : XmxInM / zForceDiscontiguousHeapReservations,
                                                     XmsInM) * 0.75);
            ArrayList<byte[]> list = new ArrayList<>(zForceDiscontiguousHeapReservations);
            for (int i = 0; i < zForceDiscontiguousHeapReservations; i++) {
                list.add(new byte[allocationInM * M]);
            }
            blackHole(list);
        }
    }


    private static void testValue(int zForceDiscontiguousHeapReservations) throws Exception  {
        /**
         *  Xmx is picked so that it is divisible by 'ZForceDiscontiguousHeapReservations * ZGranuleSize'
         *  Xms is picked so that it is less than '16 * Xmx / ZForceDiscontiguousHeapReservations' as ZGC
         *   cannot currently handle a discontiguous heap with an initial size larger than the individual
         *   reservations.
         */
        final int XmsInM = Math.min(16 * XmxInM / (zForceDiscontiguousHeapReservations + 1), XmxInM);
        OutputAnalyzer oa = ProcessTools.executeTestJava(
            "-XX:+UseZGC",
            "-Xms" + XmsInM + "M",
            "-Xmx" + XmxInM + "M",
            "-Xlog:gc,gc+init",
            "-XX:ZForceDiscontiguousHeapReservations=" + zForceDiscontiguousHeapReservations,
            "-XX:NativeMemoryTracking=detail",
            "-XX:+PrintNMTStatistics",
            Test.class.getName(),
            Integer.toString(zForceDiscontiguousHeapReservations),
            Integer.toString(XmxInM))
                .outputTo(System.out)
                .errorTo(System.out)
                .shouldHaveExitValue(0);
        if (zForceDiscontiguousHeapReservations > 1) {
            oa.shouldContain("Address Space Type: Discontiguous");
        }
        // We expect to have a report of this type.
        oa.shouldMatch("ZGC heap backing file");
        oa.shouldMatch("allocated \\d+ for Java Heap");
    }

    public static void main(String[] args) throws Exception {
        testValue(100);
    }
}