/*
 * Copyright (c) 2013, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.svm.core.jdk.management;

// Checkstyle: allow reflection

import java.lang.management.ClassLoadingMXBean;
import java.lang.management.CompilationMXBean;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.OperatingSystemMXBean;
import java.lang.management.PlatformManagedObject;
import java.lang.management.RuntimeMXBean;
import java.lang.management.ThreadMXBean;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;

import javax.management.MBeanServerBuilder;
import javax.management.openmbean.OpenType;

import org.graalvm.nativeimage.ImageSingletons;
import org.graalvm.nativeimage.hosted.Feature;
import org.graalvm.nativeimage.hosted.RuntimeClassInitialization;
import org.graalvm.nativeimage.hosted.RuntimeReflection;

import com.oracle.svm.core.annotate.AutomaticFeature;
import com.oracle.svm.core.jdk.JNIRegistrationUtil;
import com.oracle.svm.core.jdk.RuntimeFeature;
import com.oracle.svm.util.ReflectionUtil;

See ManagementSupport for documentation. /** See {@link ManagementSupport} for documentation. */
@AutomaticFeature
public final class ManagementFeature extends JNIRegistrationUtil implements Feature {
    private Map<PlatformManagedObject, PlatformManagedObject> platformManagedObjectReplacements;

    @Override
    public List<Class<? extends Feature>> getRequiredFeatures() {
        return Collections.singletonList(RuntimeFeature.class);
    }

    @Override
    public void afterRegistration(AfterRegistrationAccess access) {
        ImageSingletons.add(ManagementSupport.class, new ManagementSupport());
    }

    @Override
    public void duringSetup(DuringSetupAccess access) {
        platformManagedObjectReplacements = new IdentityHashMap<>();
        for (Class<? extends PlatformManagedObject> clazz : Arrays.asList(ClassLoadingMXBean.class, CompilationMXBean.class, RuntimeMXBean.class,
                        ThreadMXBean.class, OperatingSystemMXBean.class, MemoryMXBean.class)) {
            PlatformManagedObject source = ManagementFactory.getPlatformMXBean(clazz);
            PlatformManagedObject target = (PlatformManagedObject) ManagementSupport.getSingleton().platformManagedObjectsMap.get(clazz);
            if (source != null && target != null) {
                platformManagedObjectReplacements.put(source, target);
            }
        }
        access.registerObjectReplacer(this::replaceHostedPlatformManagedObject);

        RuntimeClassInitialization.initializeAtBuildTime("com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory", "Avoids unnecessary reflection in the image");
    }

    
PlatformManagedObject are often caches in static final fields of application classes. Replacing the hosted objects with the proper runtime objects allows these application classes to be initialized at image build time. Note that only singleton beans can be automatically replaced, beans that have a list (like GarbageCollectorMXBean cannot be replaced automatically. /**
     * PlatformManagedObject are often caches in static final fields of application classes.
     * Replacing the hosted objects with the proper runtime objects allows these application classes
     * to be initialized at image build time. Note that only singleton beans can be automatically
     * replaced, beans that have a list (like {@link GarbageCollectorMXBean} cannot be replaced
     * automatically.
     */
    private Object replaceHostedPlatformManagedObject(Object source) {
        if (source instanceof PlatformManagedObject) {
            Object replacement = platformManagedObjectReplacements.get(source);
            if (replacement != null) {
                return replacement;
            }
        }
        return source;
    }

    @Override
    public void beforeAnalysis(BeforeAnalysisAccess access) {
        access.registerReachabilityHandler(ManagementFeature::registerMBeanServerFactoryNewBuilder, method(access, "javax.management.MBeanServerFactory", "newBuilder", Class.class));
        access.registerReachabilityHandler(ManagementFeature::registerMXBeanMappingMakeOpenClass, method(access, "com.sun.jmx.mbeanserver.MXBeanMapping", "makeOpenClass", Type.class, OpenType.class));
    }

    private static void registerMBeanServerFactoryNewBuilder(@SuppressWarnings("unused") DuringAnalysisAccess a) {
        /*
         * MBeanServerBuilder is the default builder used when no class is explicitly specified via
         * a system property.
         */
        RuntimeReflection.register(ReflectionUtil.lookupConstructor(MBeanServerBuilder.class));
    }

    private static void registerMXBeanMappingMakeOpenClass(DuringAnalysisAccess access) {
        /*
         * The allowed "open types" are looked up by class name. According to the specification, all
         * array types of arbitrary depth are allowed, but we cannot register all array classes.
         * Registering the one-dimensional array classes capture the common use cases.
         */
        for (String className : OpenType.ALLOWED_CLASSNAMES_LIST) {
            RuntimeReflection.register(clazz(access, className));
            RuntimeReflection.register(clazz(access, "[L" + className + ";"));
        }
    }
}