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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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/**
 * @test TestGarbageCollectorMXBean
 * @requires vm.gc.Z & !vm.graal.enabled
 * @summary Test ZGC garbage collector MXBean
 * @modules java.management
 * @run main/othervm -XX:+UseZGC -Xms256M -Xmx512M -Xlog:gc TestGarbageCollectorMXBean 256 512
 * @run main/othervm -XX:+UseZGC -Xms512M -Xmx512M -Xlog:gc TestGarbageCollectorMXBean 512 512
 */

import java.lang.management.ManagementFactory;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import javax.management.Notification;
import javax.management.NotificationEmitter;
import javax.management.NotificationListener;
import javax.management.openmbean.CompositeData;

import com.sun.management.GarbageCollectionNotificationInfo;

public class TestGarbageCollectorMXBean {
    private static final long startTime = System.nanoTime();

    private static void log(String msg) {
        final String elapsedSeconds = String.format("%.3fs", (System.nanoTime() - startTime) / 1_000_000_000.0);
        System.out.println("[" + elapsedSeconds + "] (" + Thread.currentThread().getName() + ") " + msg);
    }

    public static void main(String[] args) throws Exception {
        final long M = 1024 * 1024;
        final long initialCapacity = Long.parseLong(args[0]) * M;
        final long maxCapacity = Long.parseLong(args[1]) * M;
        final AtomicInteger cycles = new AtomicInteger();
        final AtomicInteger errors = new AtomicInteger();

        final NotificationListener listener = (Notification notification, Object ignored) -> {
            final var type = notification.getType();
            if (!type.equals(GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION)) {
                // Ignore
                return;
            }

            final var data = (CompositeData)notification.getUserData();
            final var info = GarbageCollectionNotificationInfo.from(data);
            final var name = info.getGcName();
            final var id = info.getGcInfo().getId();
            final var action = info.getGcAction();
            final var cause = info.getGcCause();
            final var startTime = info.getGcInfo().getStartTime();
            final var endTime = info.getGcInfo().getEndTime();
            final var duration = info.getGcInfo().getDuration();
            final var memoryUsageBeforeGC = info.getGcInfo().getMemoryUsageBeforeGc().get("ZHeap");
            final var memoryUsageAfterGC = info.getGcInfo().getMemoryUsageAfterGc().get("ZHeap");

            log(name + " (" + type + ")");
            log("                  Id: " + id);
            log("              Action: " + action);
            log("               Cause: " + cause);
            log("           StartTime: " + startTime);
            log("             EndTime: " + endTime);
            log("            Duration: " + duration);
            log(" MemoryUsageBeforeGC: " + memoryUsageBeforeGC);
            log("  MemoryUsageAfterGC: " + memoryUsageAfterGC);
            log("");

            if (name.equals("ZGC")) {
                cycles.incrementAndGet();
            } else {
                log("ERROR: Name");
                errors.incrementAndGet();
            }

            if (!action.equals("end of major GC")) {
                log("ERROR: Action");
                errors.incrementAndGet();
            }

            if (memoryUsageBeforeGC.getInit() != initialCapacity) {
                log("ERROR: MemoryUsageBeforeGC.init");
                errors.incrementAndGet();
            }

            if (memoryUsageBeforeGC.getUsed() > initialCapacity) {
                log("ERROR: MemoryUsageBeforeGC.used");
                errors.incrementAndGet();
            }

            if (memoryUsageBeforeGC.getCommitted() != initialCapacity) {
                log("ERROR: MemoryUsageBeforeGC.committed");
                errors.incrementAndGet();
            }

            if (memoryUsageBeforeGC.getMax() != maxCapacity) {
                log("ERROR: MemoryUsageBeforeGC.max");
                errors.incrementAndGet();
            }

            if (!cause.equals("System.gc()")) {
                log("ERROR: Cause");
                errors.incrementAndGet();
            }

            if (startTime > endTime) {
                log("ERROR: StartTime");
                errors.incrementAndGet();
            }

            if (endTime - startTime != duration) {
                log("ERROR: Duration");
                errors.incrementAndGet();
            }
        };

        // Collect garbage created at startup
        System.gc();

        // Register GC event listener
        for (final var collector : ManagementFactory.getGarbageCollectorMXBeans()) {
            final NotificationEmitter emitter = (NotificationEmitter)collector;
            emitter.addNotificationListener(listener, null, null);
        }

        final int minCycles = 5;

        // Run GCs
        for (int i = 0; i < minCycles; i++) {
            log("Starting GC " + i);
            System.gc();
        }

        // Wait at most 90 seconds
        for (int i = 0; i < 90; i++) {
            log("Waiting...");
            Thread.sleep(1000);

            if (cycles.get() >= minCycles) {
                log("All events received!");
                break;
            }
        }

        final int actualCycles = cycles.get();
        final int actualErrors = errors.get();

        log("   minCycles: " + minCycles);
        log("actualCycles: " + actualCycles);
        log("actualErrors: " + actualErrors);

        // Verify number of cycle events
        if (actualCycles < minCycles) {
            throw new Exception("Unexpected cycles");
        }

        // Verify number of errors
        if (actualErrors != 0) {
            throw new Exception("Unexpected errors");
        }
    }
}