/*

 * Copyright (c) 1999, 2013, 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

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package com.sun.jmx.snmp.daemon;

// java import

//

import java.io.ObjectInputStream;

import java.io.IOException;

import java.net.InetAddress;

import java.util.logging.Level;

import java.util.Vector;

import java.util.NoSuchElementException;

// jmx import

//

import javax.management.MBeanServer;

import javax.management.MBeanRegistration;

import javax.management.ObjectName;

import javax.management.NotificationListener;

import javax.management.NotificationFilter;

import javax.management.NotificationBroadcaster;

import javax.management.NotificationBroadcasterSupport;

import javax.management.MBeanNotificationInfo;

import javax.management.AttributeChangeNotification;

import javax.management.ListenerNotFoundException;

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

// JSR 160 import

//

// XXX Revisit:

//   used to import com.sun.jmx.snmp.MBeanServerForwarder

// Now using JSR 160 instead. => this is an additional

// dependency to JSR 160.

//

import javax.management.remote.MBeanServerForwarder;

/**

 * Defines generic behavior for the server part of a connector or an adaptor.

 * Most connectors or adaptors extend <CODE>CommunicatorServer</CODE>

 * and inherit this behavior. Connectors or adaptors that do not fit into

 * this model do not extend <CODE>CommunicatorServer</CODE>.

 * <p>

 * A <CODE>CommunicatorServer</CODE> is an active object, it listens for

 * client requests  and processes them in its own thread. When necessary, a

 * <CODE>CommunicatorServer</CODE> creates other threads to process multiple

 * requests concurrently.

 * <p>

 * A <CODE>CommunicatorServer</CODE> object can be stopped by calling the

 * <CODE>stop</CODE> method. When it is stopped, the

 * <CODE>CommunicatorServer</CODE> no longer listens to client requests and

 * no longer holds any thread or communication resources.

 * It can be started again by calling the <CODE>start</CODE> method.

 * <p>

 * A <CODE>CommunicatorServer</CODE> has a <CODE>State</CODE> attribute

 * which reflects its  activity.

 * <p>

 * <TABLE>

 * <TR><TH>CommunicatorServer</TH>      <TH>State</TH></TR>

 * <TR><TD><CODE>stopped</CODE></TD>    <TD><CODE>OFFLINE</CODE></TD></TR>

 * <TR><TD><CODE>starting</CODE></TD>    <TD><CODE>STARTING</CODE></TD></TR>

 * <TR><TD><CODE>running</CODE></TD>     <TD><CODE>ONLINE</CODE></TD></TR>

 * <TR><TD><CODE>stopping</CODE></TD>     <TD><CODE>STOPPING</CODE></TD></TR>

 * </TABLE>

 * <p>

 * The <CODE>STARTING</CODE> state marks the transition

 * from <CODE>OFFLINE</CODE> to <CODE>ONLINE</CODE>.

 * <p>

 * The <CODE>STOPPING</CODE> state marks the transition from

 * <CODE>ONLINE</CODE> to <CODE>OFFLINE</CODE>. This occurs when the

 * <CODE>CommunicatorServer</CODE> is finishing or interrupting active

 * requests.

 * <p>

 * When a <CODE>CommunicatorServer</CODE> is unregistered from the MBeanServer,

 * it is stopped automatically.

 * <p>

 * When the value of the <CODE>State</CODE> attribute changes the

 * <CODE>CommunicatorServer</CODE> sends a

 * <tt>{@link javax.management.AttributeChangeNotification}</tt> to the

 * registered listeners, if any.

 *

 * <p><b>This API is a Sun Microsystems internal API  and is subject

 * to change without notice.</b></p>

 */

public abstract class CommunicatorServer

    implements Runnable, MBeanRegistration, NotificationBroadcaster,

               CommunicatorServerMBean {

    //

    // States of a CommunicatorServer

    //

    /**

     * Represents an <CODE>ONLINE</CODE> state.

     */

    public static final int ONLINE = 0 ;

    /**

     * Represents an <CODE>OFFLINE</CODE> state.

     */

    public static final int OFFLINE = 1 ;

    /**

     * Represents a <CODE>STOPPING</CODE> state.

     */

    public static final int STOPPING = 2 ;

    /**

     * Represents a <CODE>STARTING</CODE> state.

     */

    public static final int STARTING = 3 ;

    //

    // Types of connectors.

    //

    /**

     * Indicates that it is an RMI connector type.

     */

    //public static final int RMI_TYPE = 1 ;

    /**

     * Indicates that it is an HTTP connector type.

     */

    //public static final int HTTP_TYPE = 2 ;

    /**

     * Indicates that it is an HTML connector type.

     */

    //public static final int HTML_TYPE = 3 ;

    /**

     * Indicates that it is an SNMP connector type.

     */

    public static final int SNMP_TYPE = 4 ;

    /**

     * Indicates that it is an HTTPS connector type.

     */

    //public static final int HTTPS_TYPE = 5 ;

    //

    // Package variables

    //

    /**

     * The state of the connector server.

     */

     transient volatile int state = OFFLINE ;

    /**

     * The object name of the connector server.

     * @serial

     */

    ObjectName objectName ;

    MBeanServer topMBS;

    MBeanServer bottomMBS;

    /**

     */

    transient String dbgTag = null ;

    /**

     * The maximum number of clients that the CommunicatorServer can

     * process concurrently.

     * @serial

     */

    int maxActiveClientCount = 1 ;

    /**

     */

    transient int servedClientCount = 0 ;

    /**

     * The host name used by this CommunicatorServer.

     * @serial

     */

    String host = null ;

    /**

     * The port number used by this CommunicatorServer.

     * @serial

     */

    int port = -1 ;

    //

    // Private fields

    //

    /* This object controls access to the "state" and "interrupted" variables.

       If held at the same time as the lock on "this", the "this" lock must

       be taken first.  */

    private transient Object stateLock = new Object();

    private transient Vector<ClientHandler>

            clientHandlerVector = new Vector<>() ;

    private transient Thread mainThread = null ;

    private volatile boolean stopRequested = false ;

    private boolean interrupted = false;

    private transient Exception startException = null;

    // Notifs count, broadcaster and info

    private transient long notifCount = 0;

    private transient NotificationBroadcasterSupport notifBroadcaster =

        new NotificationBroadcasterSupport();

    private transient MBeanNotificationInfo[] notifInfos = null;

    /**

     * Instantiates a <CODE>CommunicatorServer</CODE>.

     *

     * @param connectorType Indicates the connector type. Possible values are:

     * SNMP_TYPE.

     *

     * @exception <CODE>java.lang.IllegalArgumentException</CODE>

     *            This connector type is not correct.

     */

    public CommunicatorServer(int connectorType)

        throws IllegalArgumentException {

        switch (connectorType) {

        case SNMP_TYPE :

            //No op. int Type deciding debugging removed.

            break;

        default:

            throw new IllegalArgumentException("Invalid connector Type") ;

        }

        dbgTag = makeDebugTag() ;

    }

    protected Thread createMainThread() {

        return new Thread (this, makeThreadName());

    }

    /**

     * Starts this <CODE>CommunicatorServer</CODE>.

     * <p>

     * Has no effect if this <CODE>CommunicatorServer</CODE> is

     * <CODE>ONLINE</CODE> or <CODE>STOPPING</CODE>.

     * @param timeout Time in ms to wait for the connector to start.

     *        If <code>timeout</code> is positive, wait for at most

     *        the specified time. An infinite timeout can be specified

     *        by passing a <code>timeout</code> value equals

     *        <code>Long.MAX_VALUE</code>. In that case the method

     *        will wait until the connector starts or fails to start.

     *        If timeout is negative or zero, returns as soon as possible

     *        without waiting.

     * @exception CommunicationException if the connectors fails to start.

     * @exception InterruptedException if the thread is interrupted or the

     *            timeout expires.

     */

    public void start(long timeout)

        throws CommunicationException, InterruptedException {

        boolean start;

        synchronized (stateLock) {

            if (state == STOPPING) {

                // Fix for bug 4352451:

                //     "java.net.BindException: Address in use".

                waitState(OFFLINE, 60000);

            }

            start = (state == OFFLINE);

            if (start) {

                changeState(STARTING);

                stopRequested = false;

                interrupted = false;

                startException = null;

            }

        }

        if (!start) {

            if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                    "start","Connector is not OFFLINE");

            }

            return;

        }

        if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

            SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                "start","--> Start connector ");

        }

        mainThread = createMainThread();

        mainThread.start() ;

        if (timeout > 0) waitForStart(timeout);

    }

    /**

     * Starts this <CODE>CommunicatorServer</CODE>.

     * <p>

     * Has no effect if this <CODE>CommunicatorServer</CODE> is

     * <CODE>ONLINE</CODE> or <CODE>STOPPING</CODE>.

     */

    @Override

    public void start() {

        try {

            start(0);

        } catch (InterruptedException x) {

            // cannot happen because of `0'

            if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                    "start","interrupted", x);

            }

        }

    }

    /**

     * Stops this <CODE>CommunicatorServer</CODE>.

     * <p>

     * Has no effect if this <CODE>CommunicatorServer</CODE> is

     * <CODE>OFFLINE</CODE> or  <CODE>STOPPING</CODE>.

     */

    @Override

    public void stop() {

        synchronized (stateLock) {

            if (state == OFFLINE || state == STOPPING) {

                if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                    SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                        "stop","Connector is not ONLINE");

                }

                return;

            }

            changeState(STOPPING);

            //

            // Stop the connector thread

            //

            if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                    "stop","Interrupt main thread");

            }

            stopRequested = true ;

            if (!interrupted) {

                interrupted = true;

                mainThread.interrupt();

            }

        }

        //

        // Call terminate on each active client handler

        //

        if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

            SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                "stop","terminateAllClient");

        }

        terminateAllClient() ;

        // ----------------------

        // changeState

        // ----------------------

        synchronized (stateLock) {

            if (state == STARTING)

                changeState(OFFLINE);

        }

    }

    /**

     * Tests whether the <CODE>CommunicatorServer</CODE> is active.

     *

     * @return True if connector is <CODE>ONLINE</CODE>; false otherwise.

     */

    @Override

    public boolean isActive() {

        synchronized (stateLock) {

            return (state == ONLINE);

        }

    }

    /**

     * <p>Waits until either the State attribute of this MBean equals the

     * specified <VAR>wantedState</VAR> parameter,

     * or the specified  <VAR>timeOut</VAR> has elapsed.

     * The method <CODE>waitState</CODE> returns with a boolean value

     * indicating whether the specified <VAR>wantedState</VAR> parameter

     * equals the value of this MBean's State attribute at the time the method

     * terminates.</p>

     *

     * <p>Two special cases for the <VAR>timeOut</VAR> parameter value are:</p>

     * <UL><LI> if <VAR>timeOut</VAR> is negative then <CODE>waitState</CODE>

     *     returns immediately (i.e. does not wait at all),</LI>

     * <LI> if <VAR>timeOut</VAR> equals zero then <CODE>waitState</CODE>

     *     waits untill the value of this MBean's State attribute

     *     is the same as the <VAR>wantedState</VAR> parameter (i.e. will wait

     *     indefinitely if this condition is never met).</LI></UL>

     *

     * @param wantedState The value of this MBean's State attribute to wait

     *        for. <VAR>wantedState</VAR> can be one of:

     * <ul>

     * <li><CODE>CommunicatorServer.OFFLINE</CODE>,</li>

     * <li><CODE>CommunicatorServer.ONLINE</CODE>,</li>

     * <li><CODE>CommunicatorServer.STARTING</CODE>,</li>

     * <li><CODE>CommunicatorServer.STOPPING</CODE>.</li>

     * </ul>

     * @param timeOut The maximum time to wait for, in milliseconds,

     *        if positive.

     * Infinite time out if 0, or no waiting at all if negative.

     *

     * @return true if the value of this MBean's State attribute is the

     *      same as the <VAR>wantedState</VAR> parameter; false otherwise.

     */

    @Override

    public boolean waitState(int wantedState, long timeOut) {

        if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

            SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                "waitState", wantedState + "(0on,1off,2st) TO=" + timeOut +

                  " ; current state = " + getStateString());

        }

        long endTime = 0;

        if (timeOut > 0)

            endTime = System.currentTimeMillis() + timeOut;

        synchronized (stateLock) {

            while (state != wantedState) {

                if (timeOut < 0) {

                    if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                        SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                            "waitState", "timeOut < 0, return without wait");

                    }

                    return false;

                } else {

                    try {

                        if (timeOut > 0) {

                            long toWait = endTime - System.currentTimeMillis();

                            if (toWait <= 0) {

                                if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                                    SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                                        "waitState", "timed out");

                                }

                                return false;

                            }

                            stateLock.wait(toWait);

                        } else {  // timeOut == 0

                            stateLock.wait();

                        }

                    } catch (InterruptedException e) {

                        if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                            SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                                "waitState", "wait interrupted");

                        }

                        return (state == wantedState);

                    }

                }

            }

            if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

                SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                    "waitState","returning in desired state");

            }

            return true;

        }

    }

    /**

     * <p>Waits until the communicator is started or timeout expires.

     *

     * @param timeout Time in ms to wait for the connector to start.

     *        If <code>timeout</code> is positive, wait for at most

     *        the specified time. An infinite timeout can be specified

     *        by passing a <code>timeout</code> value equals

     *        <code>Long.MAX_VALUE</code>. In that case the method

     *        will wait until the connector starts or fails to start.

     *        If timeout is negative or zero, returns as soon as possible

     *        without waiting.

     *

     * @exception CommunicationException if the connectors fails to start.

     * @exception InterruptedException if the thread is interrupted or the

     *            timeout expires.

     *

     */

    private void waitForStart(long timeout)

        throws CommunicationException, InterruptedException {

        if (SNMP_ADAPTOR_LOGGER.isLoggable(Level.FINER)) {

            SNMP_ADAPTOR_LOGGER.logp(Level.FINER, dbgTag,

                "waitForStart", "Timeout=" + timeout +

                 " ; current state = " + getStateString());

        }

        final long startTime = System.currentTimeMillis();

        synchronized (stateLock) {

            while (state == STARTING) {

                // Time elapsed since startTime...

                //

                final long elapsed = System.currentTimeMillis() - startTime;

                // wait for timeout - elapsed.

                // A timeout of Long.MAX_VALUE is equivalent to something

                // like 292271023 years - which is pretty close to

                // forever as far as we are concerned ;-)

                //

                final long remainingTime = timeout-elapsed;

                // If remainingTime is negative, the timeout has elapsed.

                //

                if (remainingTime < 0) {