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 * Copyright (c) 1999, 2017, 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,

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 *

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package javax.management;

import com.sun.jmx.defaults.JmxProperties;

import static com.sun.jmx.defaults.JmxProperties.JMX_INITIAL_BUILDER;

import static com.sun.jmx.defaults.JmxProperties.MBEANSERVER_LOGGER;

import com.sun.jmx.mbeanserver.GetPropertyAction;

import java.security.AccessController;

import java.security.Permission;

import java.util.ArrayList;

import java.lang.System.Logger.Level;

import javax.management.loading.ClassLoaderRepository;

import sun.reflect.misc.ReflectUtil;

/**

 * <p>Provides MBean server references.  There are no instances of

 * this class.</p>

 *

 * <p>Since JMX 1.2 this class makes it possible to replace the default

 * MBeanServer implementation. This is done using the

 * {@link javax.management.MBeanServerBuilder} class.

 * The class of the initial MBeanServerBuilder to be

 * instantiated can be specified through the

 * <b>javax.management.builder.initial</b> system property.

 * The specified class must be a public subclass of

 * {@link javax.management.MBeanServerBuilder}, and must have a public

 * empty constructor.

 * <p>By default, if no value for that property is specified, an instance of

 * {@link

 * javax.management.MBeanServerBuilder javax.management.MBeanServerBuilder}

 * is created. Otherwise, the MBeanServerFactory attempts to load the

 * specified class using

 * {@link java.lang.Thread#getContextClassLoader()

 *   Thread.currentThread().getContextClassLoader()}, or if that is null,

 * {@link java.lang.Class#forName(java.lang.String) Class.forName()}. Then

 * it creates an initial instance of that Class using

 * {@link java.lang.Class#newInstance()}. If any checked exception

 * is raised during this process (e.g.

 * {@link java.lang.ClassNotFoundException},

 * {@link java.lang.InstantiationException}) the MBeanServerFactory

 * will propagate this exception from within a RuntimeException.</p>

 *

 * <p>The <b>javax.management.builder.initial</b> system property is

 * consulted every time a new MBeanServer needs to be created, and the

 * class pointed to by that property is loaded. If that class is different

 * from that of the current MBeanServerBuilder, then a new MBeanServerBuilder

 * is created. Otherwise, the MBeanServerFactory may create a new

 * MBeanServerBuilder or reuse the current one.</p>

 *

 * <p>If the class pointed to by the property cannot be

 * loaded, or does not correspond to a valid subclass of MBeanServerBuilder

 * then an exception is propagated, and no MBeanServer can be created until

 * the <b>javax.management.builder.initial</b> system property is reset to

 * valid value.</p>

 *

 * <p>The MBeanServerBuilder makes it possible to wrap the MBeanServers

 * returned by the default MBeanServerBuilder implementation, for the purpose

 * of e.g. adding an additional security layer.</p>

 *

 * @since 1.5

 */

public class MBeanServerFactory {

    /*

     * There are no instances of this class so don't generate the

     * default public constructor.

     */

    private MBeanServerFactory() {

    }

    /**

     * The builder that will be used to construct MBeanServers.

     *

     **/

    private static MBeanServerBuilder builder = null;

    /**

     * Provide a new {@link javax.management.MBeanServerBuilder}.

     * @param builder The new MBeanServerBuilder that will be used to

     *        create {@link javax.management.MBeanServer}s.

     * @exception IllegalArgumentException if the given builder is null.

     *

     * @exception SecurityException if there is a SecurityManager and

     * the caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("setMBeanServerBuilder")</code>.

     *

     **/

    // public static synchronized void

    //    setMBeanServerBuilder(MBeanServerBuilder builder) {

    //    checkPermission("setMBeanServerBuilder");

    //    MBeanServerFactory.builder = builder;

    // }

    /**

     * Get the current {@link javax.management.MBeanServerBuilder}.

     *

     * @return the current {@link javax.management.MBeanServerBuilder}.

     *

     * @exception SecurityException if there is a SecurityManager and

     * the caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("getMBeanServerBuilder")</code>.

     *

     **/

    // public static synchronized MBeanServerBuilder getMBeanServerBuilder() {

    //     checkPermission("getMBeanServerBuilder");

    //     return builder;

    // }

    /**

     * Remove internal MBeanServerFactory references to a created

     * MBeanServer. This allows the garbage collector to remove the

     * MBeanServer object.

     *

     * @param mbeanServer the MBeanServer object to remove.

     *

     * @exception java.lang.IllegalArgumentException if

     * <code>mbeanServer</code> was not generated by one of the

     * <code>createMBeanServer</code> methods, or if

     * <code>releaseMBeanServer</code> was already called on it.

     *

     * @exception SecurityException if there is a SecurityManager and

     * the caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("releaseMBeanServer")</code>.

     */

    public static void releaseMBeanServer(MBeanServer mbeanServer) {

        checkPermission("releaseMBeanServer");

        removeMBeanServer(mbeanServer);

    }

    /**

     * <p>Return a new object implementing the MBeanServer interface

     * with a standard default domain name.  The default domain name

     * is used as the domain part in the ObjectName of MBeans when the

     * domain is specified by the user is null.</p>

     *

     * <p>The standard default domain name is

     * <code>DefaultDomain</code>.</p>

     *

     * <p>The MBeanServer reference is internally kept. This will

     * allow <CODE>findMBeanServer</CODE> to return a reference to

     * this MBeanServer object.</p>

     *

     * <p>This method is equivalent to <code>createMBeanServer(null)</code>.

     *

     * @return the newly created MBeanServer.

     *

     * @exception SecurityException if there is a SecurityManager and the

     * caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("createMBeanServer")</code>.

     *

     * @exception JMRuntimeException if the property

     * <code>javax.management.builder.initial</code> exists but the

     * class it names cannot be instantiated through a public

     * no-argument constructor; or if the instantiated builder returns

     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate

     * newMBeanServerDelegate} or {@link

     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.

     *

     * @exception ClassCastException if the property

     * <code>javax.management.builder.initial</code> exists and can be

     * instantiated but is not assignment compatible with {@link

     * MBeanServerBuilder}.

     */

    public static MBeanServer createMBeanServer() {

        return createMBeanServer(null);

    }

    /**

     * <p>Return a new object implementing the {@link MBeanServer}

     * interface with the specified default domain name.  The given

     * domain name is used as the domain part in the ObjectName of

     * MBeans when the domain is specified by the user is null.</p>

     *

     * <p>The MBeanServer reference is internally kept. This will

     * allow <CODE>findMBeanServer</CODE> to return a reference to

     * this MBeanServer object.</p>

     *

     * @param domain the default domain name for the created

     * MBeanServer.  This is the value that will be returned by {@link

     * MBeanServer#getDefaultDomain}.

     *

     * @return the newly created MBeanServer.

     *

     * @exception SecurityException if there is a SecurityManager and

     * the caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("createMBeanServer")</code>.

     *

     * @exception JMRuntimeException if the property

     * <code>javax.management.builder.initial</code> exists but the

     * class it names cannot be instantiated through a public

     * no-argument constructor; or if the instantiated builder returns

     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate

     * newMBeanServerDelegate} or {@link

     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.

     *

     * @exception ClassCastException if the property

     * <code>javax.management.builder.initial</code> exists and can be

     * instantiated but is not assignment compatible with {@link

     * MBeanServerBuilder}.

     */

    public static MBeanServer createMBeanServer(String domain)  {

        checkPermission("createMBeanServer");

        final MBeanServer mBeanServer = newMBeanServer(domain);

        addMBeanServer(mBeanServer);

        return mBeanServer;

    }

    /**

     * <p>Return a new object implementing the MBeanServer interface

     * with a standard default domain name, without keeping an

     * internal reference to this new object.  The default domain name

     * is used as the domain part in the ObjectName of MBeans when the

     * domain is specified by the user is null.</p>

     *

     * <p>The standard default domain name is

     * <code>DefaultDomain</code>.</p>

     *

     * <p>No reference is kept. <CODE>findMBeanServer</CODE> will not

     * be able to return a reference to this MBeanServer object, but

     * the garbage collector will be able to remove the MBeanServer

     * object when it is no longer referenced.</p>

     *

     * <p>This method is equivalent to <code>newMBeanServer(null)</code>.</p>

     *

     * @return the newly created MBeanServer.

     *

     * @exception SecurityException if there is a SecurityManager and the

     * caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("newMBeanServer")</code>.

     *

     * @exception JMRuntimeException if the property

     * <code>javax.management.builder.initial</code> exists but the

     * class it names cannot be instantiated through a public

     * no-argument constructor; or if the instantiated builder returns

     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate

     * newMBeanServerDelegate} or {@link

     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.

     *

     * @exception ClassCastException if the property

     * <code>javax.management.builder.initial</code> exists and can be

     * instantiated but is not assignment compatible with {@link

     * MBeanServerBuilder}.

     */

    public static MBeanServer newMBeanServer() {

        return newMBeanServer(null);

    }

    /**

     * <p>Return a new object implementing the MBeanServer interface

     * with the specified default domain name, without keeping an

     * internal reference to this new object.  The given domain name

     * is used as the domain part in the ObjectName of MBeans when the

     * domain is specified by the user is null.</p>

     *

     * <p>No reference is kept. <CODE>findMBeanServer</CODE> will not

     * be able to return a reference to this MBeanServer object, but

     * the garbage collector will be able to remove the MBeanServer

     * object when it is no longer referenced.</p>

     *

     * @param domain the default domain name for the created

     * MBeanServer.  This is the value that will be returned by {@link

     * MBeanServer#getDefaultDomain}.

     *

     * @return the newly created MBeanServer.

     *

     * @exception SecurityException if there is a SecurityManager and the

     * caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("newMBeanServer")</code>.

     *

     * @exception JMRuntimeException if the property

     * <code>javax.management.builder.initial</code> exists but the

     * class it names cannot be instantiated through a public

     * no-argument constructor; or if the instantiated builder returns

     * null from its {@link MBeanServerBuilder#newMBeanServerDelegate

     * newMBeanServerDelegate} or {@link

     * MBeanServerBuilder#newMBeanServer newMBeanServer} methods.

     *

     * @exception ClassCastException if the property

     * <code>javax.management.builder.initial</code> exists and can be

     * instantiated but is not assignment compatible with {@link

     * MBeanServerBuilder}.

     */

    public static MBeanServer newMBeanServer(String domain)  {

        checkPermission("newMBeanServer");

        // Get the builder. Creates a new one if necessary.

        //

        final MBeanServerBuilder mbsBuilder = getNewMBeanServerBuilder();

        // Returned value cannot be null.  NullPointerException if violated.

        synchronized(mbsBuilder) {

            final MBeanServerDelegate delegate  =

                    mbsBuilder.newMBeanServerDelegate();

            if (delegate == null) {

                final String msg =

                        "MBeanServerBuilder.newMBeanServerDelegate() " +

                        "returned null";

                throw new JMRuntimeException(msg);

            }

            final MBeanServer mbeanServer =

                    mbsBuilder.newMBeanServer(domain,null,delegate);

            if (mbeanServer == null) {

                final String msg =

                        "MBeanServerBuilder.newMBeanServer() returned null";

                throw new JMRuntimeException(msg);

            }

            return mbeanServer;

        }

    }

    /**

     * <p>Return a list of registered MBeanServer objects.  A

     * registered MBeanServer object is one that was created by one of

     * the <code>createMBeanServer</code> methods and not subsequently

     * released with <code>releaseMBeanServer</code>.</p>

     *

     * @param agentId The agent identifier of the MBeanServer to

     * retrieve.  If this parameter is null, all registered

     * MBeanServers in this JVM are returned.  Otherwise, only

     * MBeanServers whose id is equal to <code>agentId</code> are

     * returned.  The id of an MBeanServer is the

     * <code>MBeanServerId</code> attribute of its delegate MBean.

     *

     * @return A list of MBeanServer objects.

     *

     * @exception SecurityException if there is a SecurityManager and the

     * caller's permissions do not include or imply <code>{@link

     * MBeanServerPermission}("findMBeanServer")</code>.

     */

    public synchronized static

            ArrayList<MBeanServer> findMBeanServer(String agentId) {

        checkPermission("findMBeanServer");

        if (agentId == null)

            return new ArrayList<MBeanServer>(mBeanServerList);

        ArrayList<MBeanServer> result = new ArrayList<MBeanServer>();

        for (MBeanServer mbs : mBeanServerList) {

            String name = mBeanServerId(mbs);

            if (agentId.equals(name))

                result.add(mbs);

        }

        return result;

    }

    /**

     * Return the ClassLoaderRepository used by the given MBeanServer.

     * This method is equivalent to {@link

     * MBeanServer#getClassLoaderRepository() server.getClassLoaderRepository()}.

     * @param server The MBeanServer under examination. Since JMX 1.2,

     * if <code>server</code> is <code>null</code>, the result is a

     * {@link NullPointerException}.  This behavior differs from what

     * was implemented in JMX 1.1 - where the possibility to use

     * <code>null</code> was deprecated.

     * @return The Class Loader Repository used by the given MBeanServer.

     * @exception SecurityException if there is a SecurityManager and

     * the caller's permissions do not include or imply <code>{@link

     * MBeanPermission}("getClassLoaderRepository")</code>.

     *

     * @exception NullPointerException if <code>server</code> is null.

     *

     **/

    public static ClassLoaderRepository getClassLoaderRepository(

            MBeanServer server) {

        return server.getClassLoaderRepository();

    }

    private static String mBeanServerId(MBeanServer mbs) {

        try {

            return (String) mbs.getAttribute(MBeanServerDelegate.DELEGATE_NAME,

                    "MBeanServerId");

        } catch (JMException e) {

            JmxProperties.MISC_LOGGER.log(Level.TRACE,

                    "Ignoring exception while getting MBeanServerId: "+e);

            return null;

        }

    }

    private static void checkPermission(String action)

    throws SecurityException {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            Permission perm = new MBeanServerPermission(action);

            sm.checkPermission(perm);

        }

    }

    private static synchronized void addMBeanServer(MBeanServer mbs) {

        mBeanServerList.add(mbs);

    }

    private static synchronized void removeMBeanServer(MBeanServer mbs) {

        boolean removed = mBeanServerList.remove(mbs);

        if (!removed) {

            MBEANSERVER_LOGGER.log(Level.TRACE,

                    "MBeanServer was not in list!");

            throw new IllegalArgumentException("MBeanServer was not in list!");

        }

    }

    private static final ArrayList<MBeanServer> mBeanServerList =

            new ArrayList<MBeanServer>();

    /**

     * Load the builder class through the context class loader.

     * @param builderClassName The name of the builder class.

     **/

    private static Class<?> loadBuilderClass(String builderClassName)

    throws ClassNotFoundException {

        final ClassLoader loader =

                Thread.currentThread().getContextClassLoader();

        if (loader != null) {

            // Try with context class loader

            return loader.loadClass(builderClassName);

        }

        // No context class loader? Try with Class.forName()

        return ReflectUtil.forName(builderClassName);

    }

    /**

     * Creates the initial builder according to the

     * javax.management.builder.initial System property - if specified.

     * If any checked exception needs to be thrown, it is embedded in

     * a JMRuntimeException.

     **/

    private static MBeanServerBuilder newBuilder(Class<?> builderClass) {

        try {

            @SuppressWarnings("deprecation")

            final Object abuilder = builderClass.newInstance();

            return (MBeanServerBuilder)abuilder;

        } catch (RuntimeException x) {

            throw x;

        } catch (Exception x) {

            final String msg =

                    "Failed to instantiate a MBeanServerBuilder from " +

                    builderClass + ": " + x;

            throw new JMRuntimeException(msg, x);

        }

    }

    /**

     * Instantiate a new builder according to the

     * javax.management.builder.initial System property - if needed.

     **/

    private static synchronized void checkMBeanServerBuilder() {

        try {

            GetPropertyAction act =

                    new GetPropertyAction(JMX_INITIAL_BUILDER);

            String builderClassName = AccessController.doPrivileged(act);

            try {

                final Class<?> newBuilderClass;

                if (builderClassName == null || builderClassName.length() == 0)

                    newBuilderClass = MBeanServerBuilder.class;

                else

                    newBuilderClass = loadBuilderClass(builderClassName);

                // Check whether a new builder needs to be created

                if (builder != null) {

                    final Class<?> builderClass = builder.getClass();

                    if (newBuilderClass == builderClass)

                        return; // no need to create a new builder...

                }

                // Create a new builder

                builder = newBuilder(newBuilderClass);

            } catch (ClassNotFoundException x) {

                final String msg =

                        "Failed to load MBeanServerBuilder class " +

                        builderClassName + ": " + x;

                throw new JMRuntimeException(msg, x);

            }

        } catch (RuntimeException x) {

            if (MBEANSERVER_LOGGER.isLoggable(Level.DEBUG)) {

                StringBuilder strb = new StringBuilder()

                .append("Failed to instantiate MBeanServerBuilder: ").append(x)

                .append("\n\t\tCheck the value of the ")

                .append(JMX_INITIAL_BUILDER).append(" property.");

                MBEANSERVER_LOGGER.log(Level.DEBUG, strb::toString);

            }

            throw x;

        }

    }

    /**

     * Get the current {@link javax.management.MBeanServerBuilder},

     * as specified by the current value of the

     * javax.management.builder.initial property.

     *