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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package sun.management.spi;

import java.util.Collections;

import java.util.List;

import java.util.Map;

import java.util.ServiceLoader;

import java.util.Set;

import java.util.stream.Collectors;

/**

 * The PlatformMBeanProvider class defines the abstract service interface

 * that the {@link java.lang.management.ManagementFactory} will invoke to find,

 * load, and register Platform MBeans.

 *

 * ManagementFactory loads the {@linkplain ServiceLoader#loadInstalled(java.lang.Class)

 * installed providers} of this service interface and each provides the

 * {@linkplain PlatformComponent platform components} that defines MXBean

 * or DynamicMBean to be registered in the platform MBeanServer.

 *

 * A {@code PlatformMBeanProvider} will implement the {@code getPlatformComponentList()}

 * method to return the list of {@code PlatformComponents} it provides.

 */

public abstract class PlatformMBeanProvider {

    /**

     * {@code PlatformComponent} models MBeans of a management interface supported

     * by the platform.

     *

     * If a PlatformComponent models a singleton MBean, the {@link #getObjectNamePattern()

     * ObjectName pattern} must be the {@link

     * javax.management.ObjectName#getCanonicalName() canonical name} of that

     * singleton MBean. Otherwise, it must be an ObjectName pattern

     * that can be used to query the MBeans for this

     * PlatformComponent registered in a {@code MBeanServer}.

     * <br>

     * The {@link #getObjectNamePattern() ObjectName pattern} serves as a unique

     * key for identifying the instance of PlatformComponent. It is thus illegal

     * for a given {@link PlatformMBeanProvider} to export several instance of

     * PlatformComponent with the same

     * {@link #getObjectNamePattern() ObjectName pattern} string.

     * <br>

     * If two different provider instances export a PlatformComponent for the

     * same ObjectName pattern, only the PlatformComponent instance of the first

     * provider will be taken into account.

     *

     * @param <T> The higher level interface for which the MBeans modeled by

     * this object should be recognized. For instance, for the {@link

     *        java.lang.management.ManagementFactory#getOperatingSystemMXBean()

     *        Operating System MXBean}, this should be {@link

     *        java.lang.management.OperatingSystemMXBean

     *        java.lang.management.OperatingSystemMXBean}.

     */

    public interface PlatformComponent<T> {

        /**

         * Returns the names of the management interfaces implemented by the

         * MBeans modeled by this {@code PlatformComponent}.

         *

         * @implNote

         * When {@link java.lang.management.ManagementFactory#getPlatformMXBean(java.lang.Class)

         * ManagementFactory.getPlatformMXBean(mxbeanInterface)} or {@link

         * java.lang.management.ManagementFactory#getPlatformMXBeans(java.lang.Class)

         * ManagementFactory.getPlatformMXBeans(mxbeanInterface)} are invoked,

         * this PlatformComponent instance will match only if the name of the

         * given {@code mxbeanInterface} is found in this list.

         *

         * @return the names of the management interfaces exported by the MBeans

         * modeled by this object.

         */

        public Set<String> mbeanInterfaceNames();

        /**

         * A map from ObjectName string to the MBean instance this

         * {@code PlatformComponent} creates.

         *

         * @implNote

         * If {@link #shouldRegister()} is {@code true}, this method

         * will be called when the {@link java.lang.management.ManagementFactory

         * #getPlatformMBeanServer() Platform MBeanServer} is initialized.

         * By default, this method will also be called by {@link

         * #getMBeans(java.lang.Class)}, when {@link

         * java.lang.management.ManagementFactory#getPlatformMXBean(java.lang.Class)

         * ManagementFactory.getPlatformMXBean(mxbeanInterface)} or {@link

         * java.lang.management.ManagementFactory#getPlatformMXBeans(java.lang.Class)

         * ManagementFactory.getPlatformMXBeans(mxbeanInterface)} are invoked,

         * and when the name of the given {@code mxbeanInterface} is contained

         * in the names of management interfaces returned by {@link

         * #mbeanInterfaceNames()}.

         *

         * @return A map with, for each MBean, the ObjectName string as key

         *         and the MBean as value.

         */

        public Map<String, T> nameToMBeanMap();

        /**

         * An ObjectName pattern uniquely identifies the MBeans

         * modeled by this {@code PlatformComponent}.

         * If this instance models a singleton MBean, this must be

         * the {@link

         * javax.management.ObjectName#getCanonicalName() canonical name}

         * of that singleton MBean.

         *

         * @return An ObjectName pattern uniquely identifies the MBeans

         * modeled by this instance.

         */

        public String getObjectNamePattern();

        /**

         * Returns {@code true} if this {@code PlatformComponent} models

         * a singleton MBean. By default, {@code true} is assumed.

         *

         * @return {@code true} if this instance models a singleton MBean.

         */

        public default boolean isSingleton() {

            return true;

        }

        /**

         * Returns {@code true} if the MBeans modeled by this {@code PlatformComponent}

         * should automatically be registered in the {@link

         * java.lang.management.ManagementFactory#getPlatformMBeanServer()

         * Platform MBeanServer}.  By default, {@code true} is assumed.

         *

         * @return {@code true} if the MBeans modeled by this instance should

         * automatically be registered in the Platform MBeanServer.

         */

        public default boolean shouldRegister() {

            return true;

        }

        /**

         * The set of interfaces implemented by the MBeans modeled

         * by this {@code PlatformComponent}.

         *

         * @implNote

         * {@link java.lang.management.ManagementFactory#getPlatformManagementInterfaces()

         * ManagementFactory.getPlatformManagementInterfaces()} calls this

         * method to find the management interfaces supported by the platform.

         *

         * @return The set of interfaces implemented by the MBeans modeled

         *   by this instance

         */

        public Set<Class<? extends T>> mbeanInterfaces();

        /**

         * Return the list of MBeans that implement the given {@code mbeanIntf}

         * modeled by this {@code PlatformComponent}. This method returns an

         * empty list if no MBean implements the given {@code mbeanIntf}.

         *

         * @implNote This method will be called when {@link

         * java.lang.management.ManagementFactory#getPlatformMXBean(java.lang.Class)

         * ManagementFactory.getPlatformMXBean(mbeanIntf)} or {@link

         * java.lang.management.ManagementFactory#getPlatformMXBeans(java.lang.Class)

         * ManagementFactory.getPlatformMXBeans(mbeanIntf)} are invoked.

         * By default it first checks whether the specified {@code mbeanIntf}

         * name is contained in the returned list from the {@link #mbeanInterfaceNames()}

         * method. If yes, it proceeds and calls

         * {@link #mbeans().values()} and filters out all

         * MBeans which are not instances of the given {@code mbeanIntf}.

         * Otherwise, it returns an empty list.

         *

         * @param mbeanIntf A management interface.

         * @return A (possibly empty) list of MBeans implementing the given

         *         {@code mbeanIntf}.

         */

        public default <I> List<? extends I> getMBeans(Class<I> mbeanIntf) {

            List<I> list;

            if (!mbeanInterfaceNames().contains(mbeanIntf.getName())) {

                list = Collections.emptyList();

            } else {

                list = nameToMBeanMap().values().stream()

                        .filter(mbeanIntf::isInstance)

                        .map(mbeanIntf::cast)

                        .collect(Collectors.toList());

            }

            return list;

        }

    }

    /**

     * Instantiates a new PlatformMBeanProvider.

     *

     * @throws SecurityException if the subclass (and calling code) does not

     */

    protected PlatformMBeanProvider () {

        this(checkSubclassPermission());

    }

    private PlatformMBeanProvider(Void unused) {

    }

    /**

     * Returns a list of PlatformComponent instances describing the Platform

     * MBeans provided by this provider.

     *

     * @return a list of PlatformComponent instances describing the Platform

     * MBeans provided by this provider.

     */

    public abstract List<PlatformComponent<?>> getPlatformComponentList();

    private static Void checkSubclassPermission() {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

        }

        return null;

    }

}