JChannel.java - pluralism - Project Hosting on Google Code

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r428

Source path: svn/ trunk/ PluralTestsAndExamples/ src/ edu/ cmu/ cs/ nimby/ test/ oopsla/ JChannel.java

/**
 * This class is part of the JGroups project (www.jgroups.org) and is
 * (c) its creators. It was released under the LGPL v2.1 which allows
 * for its modification and redistribution. This class was modified
 * on 2008/09/15.
 */

/**
 * Copyright (C) 2007, 2008 Carnegie Mellon University and others.
 *
 * This file is part of Plural.
 *
 * Plural is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Plural 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Plural; if not, see <http://www.gnu.org/licenses>.
 *
 * Linking Plural statically or dynamically with other modules is
 * making a combined work based on Plural. Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * In addition, as a special exception, the copyright holders of Plural
 * give you permission to combine Plural with free software programs or
 * libraries that are released under the GNU LGPL and with code
 * included in the standard release of Eclipse under the Eclipse Public
 * License (or modified versions of such code, with unchanged license).
 * You may copy and distribute such a system following the terms of the
 * GNU GPL for Plural and the licenses of the other code concerned.
 *
 * Note that people who make modified versions of Plural are not
 * obligated to grant this special exception for their modified
 * versions; it is their choice whether to do so. The GNU General
 * Public License gives permission to release a modified version
 * without this exception; this exception also makes it possible to
 * release a modified version which carries forward this exception.
 */

package edu.cmu.cs.nimby.test.oopsla;


import java.io.File;
import java.io.Serializable;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Vector;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.Exchanger;

import org.w3c.dom.Element;

import edu.cmu.cs.plural.annot.ClassStates;
import edu.cmu.cs.plural.annot.FalseIndicates;
import edu.cmu.cs.plural.annot.Perm;
import edu.cmu.cs.plural.annot.Pure;
import edu.cmu.cs.plural.annot.Share;
import edu.cmu.cs.plural.annot.State;
import edu.cmu.cs.plural.annot.TrueIndicates;

/**
 * This class is part of JGroups (www.jgroups.org) and is (c) its creators<br>
 * <br>
 * JChannel is a pure Java implementation of Channel.
 * When a JChannel object is instantiated it automatically sets up the
 * protocol stack.
 * <p>
 * <B>Properties</B>
 * <P>
 * Properties are used to configure a channel, and are accepted in
 * several forms; the String form is described here.
 * A property string consists of a number of properties separated by
 * colons.  For example:
 * <p>
 * <pre>"&lt;prop1&gt;(arg1=val1):&lt;prop2&gt;(arg1=val1;arg2=val2):&lt;prop3&gt;:&lt;propn&gt;"</pre>
 * <p>
 * Each property relates directly to a protocol layer, which is
 * implemented as a Java class. When a protocol stack is to be created
 * based on the above property string, the first property becomes the
 * bottom-most layer, the second one will be placed on the first, etc.:
 * the stack is created from the bottom to the top, as the string is
 * parsed from left to right. Each property has to be the name of a
 * Java class that resides in the
 * {@link org.jgroups.protocols} package.
 * <p>
 * Note that only the base name has to be given, not the fully specified
 * class name (e.g., UDP instead of org.jgroups.protocols.UDP).
 * <p>
 * Each layer may have 0 or more arguments, which are specified as a
 * list of name/value pairs in parentheses directly after the property.
 * In the example above, the first protocol layer has 1 argument,
 * the second 2, the third none. When a layer is created, these
 * properties (if there are any) will be set in a layer by invoking
 * the layer's setProperties() method
 * <p>
 * As an example the property string below instructs JGroups to create
 * a JChannel with protocols UDP, PING, FD and GMS:<p>
 * <pre>"UDP(mcast_addr=228.10.9.8;mcast_port=5678):PING:FD:GMS"</pre>
 * <p>
 * The UDP protocol layer is at the bottom of the stack, and it
 * should use mcast address 228.10.9.8. and port 5678 rather than
 * the default IP multicast address and port. The only other argument
 * instructs FD to output debug information while executing.
 * Property UDP refers to a class {@link org.jgroups.protocols.UDP},
 * which is subsequently loaded and an instance of which is created as protocol layer.
 * If any of these classes are not found, an exception will be thrown and
 * the construction of the stack will be aborted.
 *
 * @author Bela Ban
 * @version $Id: JChannel.java,v 1.2 2008/09/17 14:12:28 nbeckman Exp $
 */
@ClassStates({@State(name="unconnected"),
	          @State(name="connected"),
	          @State(name="disconnected")})
public class JChannel extends Channel {

    /**
     * The default protocol stack used by the default constructor.
     */
    public static final String DEFAULT_PROTOCOL_STACK="udp.xml";

    static final String FORCE_PROPS="force.properties";

    /* the protocol stack configuration string */
    private String props=null;

    /*the address of this JChannel instance*/
    private Address local_addr=null;
    /*the channel (also know as group) name*/
    private String cluster_name=null;  // group name
    /*the latest view of the group membership*/
    private View my_view=null;
    /*the queue that is used to receive messages (events) from the protocol stack*/
    private final Queue mq=new Queue();
    /*the protocol stack, used to send and receive messages from the protocol stack*/
    private ProtocolStack prot_stack=null;

    /** Thread responsible for closing a channel and potentially reconnecting to it (e.g., when shunned). */
    protected CloserThread closer=null;

    /** To wait until a local address has been assigned */
    private final Promise<Address> local_addr_promise=new Promise<Address>();

    private final Promise<Boolean> state_promise=new Promise<Boolean>();

    private final Exchanger<StateTransferInfo> applstate_exchanger=new Exchanger<StateTransferInfo>();

    private final Promise<Boolean> flush_unblock_promise=new Promise<Boolean>();

    /** wait until we have a non-null local_addr */
    private long LOCAL_ADDR_TIMEOUT=30000; //=Long.parseLong(System.getProperty("local_addr.timeout", "30000"));
    /*if the states is fetched automatically, this is the default timeout, 5 secs*/
    private static final long GET_STATE_DEFAULT_TIMEOUT=5000;
    /*if FLUSH is used channel waits for UNBLOCK event, this is the default timeout, 5 secs*/
    private static final long FLUSH_UNBLOCK_TIMEOUT=5000;
    /*flag to indicate whether to receive blocks, if this is set to true, receive_views is set to true*/
    private boolean receive_blocks=false;
    /*flag to indicate whether to receive local messages
     *if this is set to false, the JChannel will not receive messages sent by itself*/
    private boolean receive_local_msgs=true;
    /*flag to indicate whether the channel will reconnect (reopen) when the exit message is received*/
    private boolean auto_reconnect=true;
    /*flag t indicate whether the state is supposed to be retrieved after the channel is reconnected
     *setting this to true, automatically forces auto_reconnect to true*/
    private boolean auto_getstate=false;
    /*channel connected flag*/
    protected volatile boolean connected=false;

    /*channel closed flag*/
    protected volatile boolean closed=false;      // close() has been called, channel is unusable

    /** True if a state transfer protocol is available, false otherwise */
    private boolean state_transfer_supported=false; // set by CONFIG event from STATE_TRANSFER protocol

    /** True if a flush protocol is available, false otherwise */
    private volatile boolean flush_supported=false; // set by CONFIG event from FLUSH protocol

    /** Provides storage for arbitrary objects. Protocols can send up CONFIG events, and all key-value pairs of
     * a CONFIG event will be added to additional_data. On reconnect, a CONFIG event will be sent down by the channel,
     * containing all key-value pairs of additional_data
     */
    protected final Map<String,Object> additional_data=new HashMap<String,Object>();
    
    protected final ConcurrentMap<String,Object> info=new ConcurrentHashMap<String,Object>();

    protected final Log log=LogFactory.getLog(getClass()); 

    /** Collect statistics */
    protected boolean stats=true;

    protected long sent_msgs=0, received_msgs=0, sent_bytes=0, received_bytes=0;





    /** Used by subclass to create a JChannel without a protocol stack, don't use as application programmer */
    protected JChannel(boolean no_op) {
        ;
    }

    /**
     * Constructs a <code>JChannel</code> instance with the protocol stack
     * specified by the <code>DEFAULT_PROTOCOL_STACK</code> member.
     *
     * @throws ChannelException if problems occur during the initialization of
     *                          the protocol stack.
     */
    public JChannel() throws ChannelException {
        this(DEFAULT_PROTOCOL_STACK);
    }

    /**
     * Constructs a <code>JChannel</code> instance with the protocol stack
     * configuration contained by the specified file.
     *
     * @param properties a file containing a JGroups XML protocol stack
     *                   configuration.
     *
     * @throws ChannelException if problems occur during the configuration or
     *                          initialization of the protocol stack.
     */
    public JChannel(File properties) throws ChannelException {
        this(ConfiguratorFactory.getStackConfigurator(properties));
    }

    /**
     * Constructs a <code>JChannel</code> instance with the protocol stack
     * configuration contained by the specified XML element.
     *
     * @param properties a XML element containing a JGroups XML protocol stack
     *                   configuration.
     *
     * @throws ChannelException if problems occur during the configuration or
     *                          initialization of the protocol stack.
     */
    public JChannel(Element properties) throws ChannelException {
        this(ConfiguratorFactory.getStackConfigurator(properties));
    }

    /**
     * Constructs a <code>JChannel</code> instance with the protocol stack
     * configuration indicated by the specified URL.
     *
     * @param properties a URL pointing to a JGroups XML protocol stack
     *                   configuration.
     *
     * @throws ChannelException if problems occur during the configuration or
     *                          initialization of the protocol stack.
     */
    public JChannel(URL properties) throws ChannelException {
        this(ConfiguratorFactory.getStackConfigurator(properties));
    }

    /**
     * Constructs a <code>JChannel</code> instance with the protocol stack
     * configuration based upon the specified properties parameter.
     *
     * @param properties an old style property string, a string representing a
     *                   system resource containing a JGroups XML configuration,
     *                   a string representing a URL pointing to a JGroups XML
     *                   XML configuration, or a string representing a file name
     *                   that contains a JGroups XML configuration.
     *
     * @throws ChannelException if problems occur during the configuration and
     *                          initialization of the protocol stack.
     */
    @Perm(ensures="unique(this!fr) in unconnected")
    public JChannel(String properties) throws ChannelException {
        this(ConfiguratorFactory.getStackConfigurator(properties));
    }

    /**
     * Constructs a <code>JChannel</code> instance with the protocol stack
     * configuration contained by the protocol stack configurator parameter.
     * <p>
     * All of the public constructors of this class eventually delegate to this
     * method.
     *
     * @param configurator a protocol stack configurator containing a JGroups
     *                     protocol stack configuration.
     *
     * @throws ChannelException if problems occur during the initialization of
     *                          the protocol stack.
     */
    public JChannel(ProtocolStackConfigurator configurator) throws ChannelException {
        init(configurator);
    }




    /**
     * Creates a new JChannel with the protocol stack as defined in the properties
     * parameter. an example of this parameter is<BR>
     * "UDP:PING:FD:STABLE:NAKACK:UNICAST:FRAG:FLUSH:GMS:VIEW_ENFORCER:STATE_TRANSFER:QUEUE"<BR>
     * Other examples can be found in the ./conf directory<BR>
     * @param properties the protocol stack setup; if null, the default protocol stack will be used.
     * 					 The properties can also be a java.net.URL object or a string that is a URL spec.
     *                   The JChannel will validate any URL object and String object to see if they are a URL.
     *                   In case of the parameter being a url, the JChannel will try to load the xml from there.
     *                   In case properties is a org.w3c.dom.Element, the ConfiguratorFactory will parse the
     *                   DOM tree with the element as its root element.
     * @deprecated Use the constructors with specific parameter types instead.
     */
//    public JChannel(Object properties) throws ChannelException {
//        if (properties == null)
//            properties = DEFAULT_PROTOCOL_STACK;
//
//        ProtocolStackConfigurator c=null;
//
//        try {
//            c=ConfiguratorFactory.getStackConfigurator(properties);
//        }
//        catch(Exception x) {
//            throw new ChannelException("unable to load protocol stack", x);
//        }
//        init(c);
//    }
//
//
//    /**
//     * Returns the protocol stack.
//     * Currently used by Debugger.
//     * Specific to JChannel, therefore
//     * not visible in Channel
//     */
//    public ProtocolStack getProtocolStack() {
//        return prot_stack;
//    }
//
//    protected Log getLog() {
//        return log;
//    }
//
//    /**
//     * returns the protocol stack configuration in string format.
//     * an example of this property is<BR>
//     * "UDP:PING:FD:STABLE:NAKACK:UNICAST:FRAG:FLUSH:GMS:VIEW_ENFORCER:STATE_TRANSFER:QUEUE"
//     */
//    public String getProperties() {
//        return props;
//    }
//
//    public boolean statsEnabled() {
//        return stats;
//    }
//
//    public void enableStats(boolean stats) {
//        this.stats=stats;
//    }
//
//    public void resetStats() {
//        sent_msgs=received_msgs=sent_bytes=received_bytes=0;
//    }
//
//    public long getSentMessages() {return sent_msgs;}
//    public long getSentBytes() {return sent_bytes;}
//    public long getReceivedMessages() {return received_msgs;}
//    public long getReceivedBytes() {return received_bytes;}
//    public int getNumberOfTasksInTimer() {
//        ProtocolStack ps=getProtocolStack();
//        return ps != null? ps.timer.size() : -1;
//    }
//
//    public int getTimerThreads() {
//        ProtocolStack ps=getProtocolStack();
//        return ps != null? ps.getTimerThreads() : -1;
//    }
//
//    public String dumpTimerQueue() {
//        ProtocolStack ps=getProtocolStack();
//        return ps != null? ps.dumpTimerQueue() : "<n/a";
//    }

    /**
     * Returns a pretty-printed form of all the protocols. If include_properties
     * is set, the properties for each protocol will also be printed.
     */
//    public String printProtocolSpec(boolean include_properties) {
//        ProtocolStack ps=getProtocolStack();
//        return ps != null? ps.printProtocolSpec(include_properties) : null;
//    }


    /**
     * Connects the channel to a group.
     * If the channel is already connected, an error message will be printed to the error log.
     * If the channel is closed a ChannelClosed exception will be thrown.
     * This method starts the protocol stack by calling ProtocolStack.start,
     * then it sends an Event.CONNECT event down the stack and waits for the return value.
     * Once the call returns, the channel listeners are notified and the channel is considered connected.
     *
     * @param cluster_name A <code>String</code> denoting the group name. Cannot be null.
     * @exception ChannelException The protocol stack cannot be started
     * @exception ChannelClosedException The channel is closed and therefore cannot be used any longer.
     *                                   A new channel has to be created first.
     */
    @Share(requires="unconnected", ensures="connected")
    public synchronized void connect(String cluster_name) throws ChannelException {
        startStack(cluster_name);


        // only connect if we are not a unicast channel
        if(cluster_name != null) {            
            
            Event connect_event=new Event(Event.CONNECT, cluster_name);
            Object res=downcall(connect_event);  // waits forever until connected (or channel is closed)
            if(res != null && res instanceof Exception) { // the JOIN was rejected by the coordinator
                stopStack(true, false);
                init();
                throw new ChannelException("connect() failed", (Throwable)res);
            }

            //if FLUSH is used do not return from connect() until UNBLOCK event is received                       
            if(flushSupported()) {
               try {
                  flush_unblock_promise.getResultWithTimeout(FLUSH_UNBLOCK_TIMEOUT);
               }
               catch (TimeoutException timeout) {
                  if(log.isWarnEnabled())
                     log.warn(local_addr + " waiting on UNBLOCK after connect() timed out");
               }
            }
        }
        connected=true;
        notifyChannelConnected(this);
    }


    /**
     * Connects this channel to a group and gets a state from a specified state
     * provider.
     * <p>
     * 
     * This method essentially invokes
     * <code>connect<code> and <code>getState<code> methods successively. 
     * If FLUSH protocol is in channel's stack definition only one flush is executed for both connecting and 
     * fetching state rather than two flushes if we invoke <code>connect<code> and <code>getState<code> in succesion. 
     *   
     * If the channel is already connected, an error message will be printed to the error log.
     * If the channel is closed a ChannelClosed exception will be thrown.
     * 
     *                                       
     * @param cluster_name  the cluster name to connect to. Cannot be null.
     * @param target the state provider. If null state will be fetched from coordinator, unless this channel is coordinator.
     * @param state_id the substate id for partial state transfer. If null entire state will be transferred. 
     * @param timeout the timeout for state transfer.      
     * 
     * @exception ChannelException The protocol stack cannot be started
     * @exception ChannelException Connecting to cluster was not successful 
     * @exception ChannelClosedException The channel is closed and therefore cannot be used any longer.
     *                                   A new channel has to be created first.
     * @exception StateTransferException State transfer was not successful
     *
     */
    @Share(requires="unconnected", ensures="connected")
    public synchronized void connect(String cluster_name,
                                     Address target,
                                     String state_id,
                                     long timeout) throws ChannelException {

        startStack(cluster_name);

        boolean stateTransferOk=false;
        boolean joinSuccessful=false;
        boolean canFetchState=false;
        // only connect if we are not a unicast channel
        if(cluster_name != null) {

            try {
                Event connect_event=new Event(Event.CONNECT_WITH_STATE_TRANSFER, cluster_name);
                Object res=downcall(connect_event); // waits forever until
                // connected (or channel is
                // closed)
                joinSuccessful=!(res != null && res instanceof Exception);
                if(!joinSuccessful) {
                    stopStack(true, false);
                    init();
                    throw new ChannelException("connect() failed", (Throwable)res);
                }

                connected=true;
                notifyChannelConnected(this);
                canFetchState=getView() != null && getView().size() > 1;

                // if I am not the only member in cluster then
                if(canFetchState) {
                    try {
                        // fetch state from target
                        stateTransferOk=getState(target, state_id, timeout, false);
                        if(!stateTransferOk) {
                            throw new StateTransferException(getLocalAddress() + " could not fetch state "
                                    + state_id
                                    + " from "
                                    + target);
                        }
                    }
                    catch(Exception e) {
                        throw new StateTransferException(getLocalAddress() + " could not fetch state "
                                + state_id
                                + " from "
                                + target, e);
                    }
                }

            }
            finally {
                if(flushSupported() && canFetchState)
                    stopFlush();
            }
        }
    }


    /**
     * Disconnects the channel if it is connected. If the channel is closed,
     * this operation is ignored<BR>
     * Otherwise the following actions happen in the listed order<BR>
     * <ol>
     * <li> The JChannel sends a DISCONNECT event down the protocol stack<BR>
     * <li> Blocks until the event has returned<BR>
     * <li> Sends a STOP_QUEING event down the stack<BR>
     * <li> Stops the protocol stack by calling ProtocolStack.stop()<BR>
     * <li> Notifies the listener, if the listener is available<BR>
     * </ol>
     */
    @Share(ensures="closed")
    public synchronized void disconnect() {
        if(closed) return;

        if(connected) {

            if(cluster_name != null) {
                // Send down a DISCONNECT event, which travels down to the GMS, where a response is returned
                Event disconnect_event=new Event(Event.DISCONNECT, local_addr);
                down(disconnect_event);   // DISCONNECT is handled by each layer
            }
            connected=false;
            stopStack(true, false);            
            notifyChannelDisconnected(this);
            init(); // sets local_addr=null; changed March 18 2003 (bela) -- prevented successful rejoining
        }
    }


    /**
     * Destroys the channel.
     * After this method has been called, the channel us unusable.<BR>
     * This operation will disconnect the channel and close the channel receive queue immediately<BR>
     */
    @Share(ensures="closed")
    public synchronized void close() {
        _close(true, true); // by default disconnect before closing channel and close mq
    }


    /** Shuts down the channel without disconnecting */
    @Share(ensures="closed")
    public synchronized void shutdown() {
        down(new Event(Event.SHUTDOWN));
        _close(false, true); // by default disconnect before closing channel and close mq
    }

    /**
     * Opens the channel. Note that the channel is only open, but <em>not connected</em>.
     * This does the following actions:
     * <ol>
     * <li> Resets the receiver queue by calling Queue.reset
     * <li> Sets up the protocol stack by calling ProtocolStack.setup
     * <li> Sets the closed flag to false
     * </ol>
     */
    @Share(requires="closed", ensures="unconnected")
    public synchronized void open() throws ChannelException {
        if(!closed)
            throw new ChannelException("channel is already open");

        try {
            mq.reset();

            // new stack is created on open() - bela June 12 2003
            prot_stack=new ProtocolStack(this, props);
            prot_stack.setup();
            closed=false;
        }
        catch(Exception e) {
            throw new ChannelException("failed to open channel" , e);
        }
    }

    /**
     * returns true if the Open operation has been called successfully
     */
    @Pure
    @FalseIndicates("closed")
    public boolean isOpen() {
        return !closed;
    }


    /**
     * returns true if the Connect operation has been called successfully
     */
    @Pure
    @TrueIndicates("connected")
    public boolean isConnected() {
        return connected;
    }


    public int getNumMessages() {
        return mq != null? mq.size() : -1;
    }


    public String dumpQueue() {
        return Util.dumpQueue(mq);
    }

    /**
     * Returns a map of statistics of the various protocols and of the channel itself.
     * @return Map<String,Map>. A map where the keys are the protocols ("channel" pseudo key is
     * used for the channel itself") and the values are property maps.
     */
    public Map<String,Object> dumpStats() {
        Map<String,Object> retval=prot_stack.dumpStats();
        if(retval != null) {
            Map<String,Long> tmp=dumpChannelStats();
            if(tmp != null)
                retval.put("channel", tmp);
        }
        return retval;
    }

    protected Map<String,Long> dumpChannelStats() {
        Map<String,Long> retval=new HashMap<String,Long>();
        retval.put("sent_msgs", new Long(sent_msgs));
        retval.put("sent_bytes", new Long(sent_bytes));
        retval.put("received_msgs", new Long(received_msgs));
        retval.put("received_bytes", new Long(received_bytes));
        return retval;
    }


    /**
     * Sends a message through the protocol stack.
     * Implements the Transport interface.
     *
     * @param msg the message to be sent through the protocol stack,
     *        the destination of the message is specified inside the message itself
     * @exception ChannelNotConnectedException
     * @exception ChannelClosedException
     */
    @Share(requires="connected", ensures="connected")
    public void send(Message msg) throws ChannelNotConnectedException, ChannelClosedException {
        checkClosedOrNotConnected();
        if(msg == null)
            throw new NullPointerException("msg is null");
        if(stats) {
            sent_msgs++;
            sent_bytes+=msg.getLength();
        }

        down(new Event(Event.MSG, msg));
    }


    /**
     * creates a new message with the destination address, and the source address
     * and the object as the message value
     * @param dst - the destination address of the message, null for all members
     * @param src - the source address of the message
     * @param obj - the value of the message
     * @exception ChannelNotConnectedException
     * @exception ChannelClosedException
     * @see JChannel#send
     */
    @Share(requires="connected", ensures="connected")
    public void send(Address dst, Address src, Serializable obj) throws ChannelNotConnectedException, ChannelClosedException {
        send(new Message(dst, src, obj));
    }


    /**
     * Blocking receive method.
     * This method returns the object that was first received by this JChannel and that has not been
     * received before. After the object is received, it is removed from the receive queue.<BR>
     * If you only want to inspect the object received without removing it from the queue call
     * JChannel.peek<BR>
     * If no messages are in the receive queue, this method blocks until a message is added or the operation times out<BR>
     * By specifying a timeout of 0, the operation blocks forever, or until a message has been received.
     * @param timeout the number of milliseconds to wait if the receive queue is empty. 0 means wait forever
     * @exception TimeoutException if a timeout occured prior to a new message was received
     * @exception ChannelNotConnectedException
     * @exception ChannelClosedException
     * @see JChannel#peek
     * @deprecated Use a {@link Receiver} instead
     */
    @Share(requires="connected", ensures="connected")
    public Object receive(long timeout) throws ChannelNotConnectedException, ChannelClosedException, TimeoutException {

        checkClosedOrNotConnected();

        try {
            Event evt=(timeout <= 0)? (Event)mq.remove() : (Event)mq.remove(timeout);
            Object retval=getEvent(evt);
            evt=null;
            return retval;
        }
        catch(QueueClosedException queue_closed) {
            throw new ChannelClosedException();
        }
        catch(TimeoutException t) {
            throw t;
        }
        catch(Exception e) {
            if(log.isErrorEnabled()) log.error("exception: " + e);  
            return null;
        }
    }


    /**
     * Just peeks at the next message, view or block. Does <em>not</em> install
     * new view if view is received<BR>
     * Does the same thing as JChannel.receive but doesn't remove the object from the
     * receiver queue
     */
    public Object peek(long timeout) throws ChannelNotConnectedException, ChannelClosedException, TimeoutException {

        checkClosedOrNotConnected();

        try {
            Event evt=(timeout <= 0)? (Event)mq.peek() : (Event)mq.peek(timeout);
            Object retval=getEvent(evt);
            evt=null;
            return retval;
        }
        catch(QueueClosedException queue_closed) {
            if(log.isErrorEnabled()) log.error("exception: " + queue_closed);
            return null;
        }
        catch(TimeoutException t) {
            return null;
        }
        catch(Exception e) {
            if(log.isErrorEnabled()) log.error("exception: " + e);
            return null;
        }
    }




    /**
     * Returns the current view.
     * <BR>
     * If the channel is not connected or if it is closed it will return null.
     * <BR>
     * @return returns the current group view, or null if the channel is closed or disconnected
     */
    @Share(requires="connected", ensures="connected")
    public View getView() {
        return closed || !connected ? null : my_view;
    }


    /**
     * returns the local address of the channel
     * returns null if the channel is closed
     */
    @Share(requires="connected", ensures="connected")
    public Address getLocalAddress() {
        return closed ? null : local_addr;
    }


    /**
     * returns the name of the channel
     * if the channel is not connected or if it is closed it will return null
     * @deprecated Use {@link #getClusterName()} instead
     */
    public String getChannelName() {
        return closed ? null : !connected ? null : cluster_name;
    }

    public String getClusterName() {
        return closed ? null : !connected ? null : cluster_name;
    }


    /**
     * Sets a channel option.  The options can be one of the following:
     * <UL>
     * <LI>    Channel.BLOCK
     * <LI>    Channel.LOCAL
     * <LI>    Channel.AUTO_RECONNECT
     * <LI>    Channel.AUTO_GETSTATE
     * </UL>
     * <P>
     * There are certain dependencies between the options that you can set,
     * I will try to describe them here.
     * <P>
     * Option: Channel.BLOCK<BR>
     * Value:  java.lang.Boolean<BR>
     * Result: set to true will set setOpt(VIEW, true) and the JChannel will receive BLOCKS and VIEW events<BR>
     *<BR>
     * Option: LOCAL<BR>
     * Value:  java.lang.Boolean<BR>
     * Result: set to true the JChannel will receive messages that it self sent out.<BR>
     *<BR>
     * Option: AUTO_RECONNECT<BR>
     * Value:  java.lang.Boolean<BR>
     * Result: set to true and the JChannel will try to reconnect when it is being closed<BR>
     *<BR>
     * Option: AUTO_GETSTATE<BR>
     * Value:  java.lang.Boolean<BR>
     * Result: set to true, the AUTO_RECONNECT will be set to true and the JChannel will try to get the state after a close and reconnect happens<BR>
     * <BR>
     *
     * @param option the parameter option Channel.VIEW, Channel.SUSPECT, etc
     * @param value the value to set for this option
     *
     */
//    public void setOpt(int option, Object value) {
//        if(closed) {
//            if(log.isWarnEnabled()) log.warn("channel is closed; option not set !");
//            return;
//        }
//
//        switch(option) {
//            case VIEW:
//                if(log.isWarnEnabled())
//                    log.warn("option VIEW has been deprecated (it is always true now); this option is ignored");
//                break;
//            case SUSPECT:
//                if(log.isWarnEnabled())
//                    log.warn("option SUSPECT has been deprecated (it is always true now); this option is ignored");
//                break;
//            case BLOCK:
//                if(value instanceof Boolean)
//                    receive_blocks=((Boolean)value).booleanValue();
//                else
//                    if(log.isErrorEnabled()) log.error("option " + Channel.option2String(option) +
//                                                     " (" + value + "): value has to be Boolean");
//                break;
//
//            case GET_STATE_EVENTS:
//                if(log.isWarnEnabled())
//                    log.warn("option GET_STATE_EVENTS has been deprecated (it is always true now); this option is ignored");
//                break;
//
//            case LOCAL:
//                if(value instanceof Boolean)
//                    receive_local_msgs=((Boolean)value).booleanValue();
//                else
//                    if(log.isErrorEnabled()) log.error("option " + Channel.option2String(option) +
//                                                     " (" + value + "): value has to be Boolean");
//                break;
//
//            case AUTO_RECONNECT:
//                if(value instanceof Boolean)
//                    auto_reconnect=((Boolean)value).booleanValue();
//                else
//                    if(log.isErrorEnabled()) log.error("option " + Channel.option2String(option) +
//                                                     " (" + value + "): value has to be Boolean");
//                break;
//
//            case AUTO_GETSTATE:
//                if(value instanceof Boolean) {
//                    auto_getstate=((Boolean)value).booleanValue();
//                    if(auto_getstate)
//                        auto_reconnect=true;
//                }
//                else
//                    if(log.isErrorEnabled()) log.error("option " + Channel.option2String(option) +
//                                                     " (" + value + "): value has to be Boolean");
//                break;
//
//            default:
//                if(log.isErrorEnabled()) log.error("option " + Channel.option2String(option) + " not known");
//                break;
//        }
//    }



    /**
     * returns the value of an option.
     * @param option the option you want to see the value for
     * @return the object value, in most cases java.lang.Boolean
     * @see JChannel#setOpt
     */
//    public Object getOpt(int option) {
//        switch(option) {
//            case VIEW:
//            	return Boolean.TRUE;
//            case BLOCK:
//            	return receive_blocks ? Boolean.TRUE : Boolean.FALSE;
//            case SUSPECT:
//            	return Boolean.TRUE;
//            case AUTO_RECONNECT:
//                return auto_reconnect ? Boolean.TRUE : Boolean.FALSE;
//            case AUTO_GETSTATE:
//                return auto_getstate ? Boolean.TRUE : Boolean.FALSE;
//            case GET_STATE_EVENTS:
//                return Boolean.TRUE;
//            case LOCAL:
//            	return receive_local_msgs ? Boolean.TRUE : Boolean.FALSE;
//            default:
//                if(log.isErrorEnabled()) log.error("option " + Channel.option2String(option) + " not known");
//                return null;
//        }
//    }


    /**
     * Called to acknowledge a block() (callback in <code>MembershipListener</code> or
     * <code>BlockEvent</code> received from call to <code>receive()</code>).
     * After sending blockOk(), no messages should be sent until a new view has been received.
     * Calling this method on a closed channel has no effect.
     */
    public void blockOk() {
        
    }


    /**
     * Retrieves the current group state. Sends GET_STATE event down to STATE_TRANSFER layer.
     * Blocks until STATE_TRANSFER sends up a GET_STATE_OK event or until <code>timeout</code>
     * milliseconds have elapsed. The argument of GET_STATE_OK should be a single object.
     * @param target the target member to receive the state from. if null, state is retrieved from coordinator
     * @param timeout the number of milliseconds to wait for the operation to complete successfully. 0 waits until
     * the state has been received
     * @return true of the state was received, false if the operation timed out
     */
    public boolean getState(Address target, long timeout) throws ChannelNotConnectedException, ChannelClosedException {
        return getState(target,null,timeout);
    }

    /**
     * Retrieves a substate (or partial state) from the target.
     * @param target State provider. If null, coordinator is used
     * @param state_id The ID of the substate. If null, the entire state will be transferred
     * @param timeout the number of milliseconds to wait for the operation to complete successfully. 0 waits until
     * the state has been received
     * @return
     * @throws ChannelNotConnectedException
     * @throws ChannelClosedException
     */
    public boolean getState(Address target, String state_id, long timeout) throws ChannelNotConnectedException, ChannelClosedException {
        return getState(target, state_id, timeout, true);
    }
    
    /**
     * Retrieves a substate (or partial state) from the target.
     * @param target State provider. If null, coordinator is used
     * @param state_id The ID of the substate. If null, the entire state will be transferred
     * @param timeout the number of milliseconds to wait for the operation to complete successfully. 0 waits until
     * the state has been received
     * @return
     * @throws ChannelNotConnectedException
     * @throws ChannelClosedException
     */
    public boolean getState(Address target, String state_id, long timeout,boolean useFlushIfPresent) throws ChannelNotConnectedException, ChannelClosedException {
        checkClosedOrNotConnected();
        if(!state_transfer_supported) {
            throw new IllegalStateException("fetching state will fail as state transfer is not supported. "
                    + "Add one of the STATE_TRANSFER protocols to your protocol configuration");
        }
        
        if(target == null)
            target=determineCoordinator();
        if(target != null && local_addr != null && target.equals(local_addr)) {
            if(log.isTraceEnabled())
                log.trace("cannot get state from myself (" + target + "): probably the first member");
            return false;
        }

        
        StateTransferInfo state_info=new StateTransferInfo(target, state_id, timeout);
        boolean initiateFlush = flushSupported() && useFlushIfPresent;
        
        if(initiateFlush)
            startFlush(false);

        state_promise.reset();
        down(new Event(Event.GET_STATE, state_info));
        Boolean b=state_promise.getResult(state_info.timeout);
        
        if(initiateFlush)
            stopFlush();
        
        boolean state_transfer_successfull = b != null && b.booleanValue();
        if(!state_transfer_successfull)
            down(new Event(Event.RESUME_STABLE));
        return state_transfer_successfull;
    }


    /**
     * Retrieves the current group state. Sends GET_STATE event down to STATE_TRANSFER layer.
     * Blocks until STATE_TRANSFER sends up a GET_STATE_OK event or until <code>timeout</code>
     * milliseconds have elapsed. The argument of GET_STATE_OK should be a vector of objects.
     * @param targets - the target members to receive the state from ( an Address list )
     * @param timeout - the number of milliseconds to wait for the operation to complete successfully
     * @return true of the state was received, false if the operation timed out
     * @deprecated Not really needed - we always want to get the state from a single member,
     * use {@link #getState(org.jgroups.Address, long)} instead
     */
    public boolean getAllStates(Vector targets, long timeout) throws ChannelNotConnectedException, ChannelClosedException {
        throw new UnsupportedOperationException("use getState() instead");
    }


    /**
     * Called by the application is response to receiving a <code>getState()</code> object when
     * calling <code>receive()</code>.
     * When the application receives a getState() message on the receive() method,
     * it should call returnState() to reply with the state of the application
     * @param state The state of the application as a byte buffer
     *              (to send over the network).
     */
    public void returnState(byte[] state) {
        try {
            StateTransferInfo state_info=new StateTransferInfo(null, null, 0L, state);
            applstate_exchanger.exchange(state_info);
        }
        catch(InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }

    /**
     * Returns a substate as indicated by state_id
     * @param state
     * @param state_id
     */
    public void returnState(byte[] state, String state_id) {
        try {
            StateTransferInfo state_info=new StateTransferInfo(null, state_id, 0L, state);
            applstate_exchanger.exchange(state_info);
        }
        catch(InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }





    /**
     * Callback method <BR>
     * Called by the ProtocolStack when a message is received.
     * It will be added to the message queue from which subsequent
     * <code>Receive</code>s will dequeue it.
     * @param evt the event carrying the message from the protocol stack
     */
//    public Object up(Event evt) {
//        int     type=evt.getType();
//        Message msg;
//
//
//        switch(type) {
//
//        case Event.MSG:
//            msg=(Message)evt.getArg();
//            if(stats) {
//                received_msgs++;
//                received_bytes+=msg.getLength();
//            }
//
//            if(!receive_local_msgs) {  // discard local messages (sent by myself to me)
//                if(local_addr != null && msg.getSrc() != null)
//                    if(local_addr.equals(msg.getSrc()))
//                        return null;
//            }
//            break;
//
//        case Event.VIEW_CHANGE:
//            View tmp=(View)evt.getArg();
//            if(tmp instanceof MergeView)
//                my_view=new View(tmp.getVid(), tmp.getMembers());
//            else
//                my_view=tmp;
//
//            /*
//             * Bela&Vladimir Oct 27th,2006 (JGroups 2.4)- we need to switch to
//             * connected=true because client can invoke channel.getView() in
//             * viewAccepted() callback invoked on this thread
//             * (see Event.VIEW_CHANGE handling below)
//             */
//
//            // not good: we are only connected when we returned from connect() - bela June 22 2007
//            //            if(connected == false) {
//            //                connected=true;
//            //            }
//            break;
//
//        case Event.CONFIG:
//            Map<String,Object> config=(Map<String,Object>)evt.getArg();
//            if(config != null) {
//                if(config.containsKey("state_transfer")) {
//                    state_transfer_supported=((Boolean)config.get("state_transfer")).booleanValue();
//                }
//                if(config.containsKey("flush_supported")) {
//                    flush_supported=((Boolean)config.get("flush_supported")).booleanValue();
//                }
//            }
//            break;
//            
//        case Event.INFO:
//           Map<String, Object> m = (Map<String, Object>) evt.getArg();
//           info.putAll(m);            
//           break;    
//
//        case Event.GET_STATE_OK:
//            StateTransferInfo state_info = (StateTransferInfo) evt.getArg();
//            byte[] state = state_info.state;
//
//            try{
//                if(up_handler != null){
//                    return up_handler.up(evt);
//                }
//
//                if(state != null){
//                    String state_id = state_info.state_id;
//                    if(receiver != null){
//                        try{
//                            if(receiver instanceof ExtendedReceiver && state_id != null)
//                                ((ExtendedReceiver) receiver).setState(state_id, state);
//                            else
//                                receiver.setState(state);
//                        }catch(Throwable t){
//                            if(log.isWarnEnabled())
//                                log.warn("failed calling setState() in receiver", t);
//                        }
//                    }else{
//                        try{
//                            mq.add(new Event(Event.STATE_RECEIVED, state_info));
//                        }catch(Exception e){
//                        }
//                    }
//                }
//            }finally{
//                state_promise.setResult(state != null ? Boolean.TRUE : Boolean.FALSE);
//            }
//            break;
//        case Event.STATE_TRANSFER_INPUTSTREAM_CLOSED:
//            state_promise.setResult(Boolean.TRUE);
//            break;     
//
//        case Event.STATE_TRANSFER_INPUTSTREAM:
//            StateTransferInfo sti=(StateTransferInfo)evt.getArg();
//            InputStream is=sti.inputStream;
//            //Oct 13,2006 moved to down() when Event.STATE_TRANSFER_INPUTSTREAM_CLOSED is received
//            //state_promise.setResult(is != null? Boolean.TRUE : Boolean.FALSE);
//
//            if(up_handler != null) {
//                return up_handler.up(evt);
//            }
//
//            if(is != null) {
//                if(receiver instanceof ExtendedReceiver) {
//                    try {
//                        if(sti.state_id == null)
//                            ((ExtendedReceiver)receiver).setState(is);
//                        else
//                            ((ExtendedReceiver)receiver).setState(sti.state_id, is);
//                    }
//                    catch(Throwable t) {
//                        if(log.isWarnEnabled())
//                            log.warn("failed calling setState() in receiver", t);
//                    }
//                }
//                else if(receiver instanceof Receiver){
//                    if(log.isWarnEnabled()){
//                        log.warn("Channel has STREAMING_STATE_TRANSFER, however," +
//                                " application does not implement ExtendedMessageListener. State is not transfered");
//                        Util.close(is);
//                    }
//                }
//                else {
//                    try {
//                        mq.add(new Event(Event.STATE_TRANSFER_INPUTSTREAM, sti));
//                    }
//                    catch(Exception e) {
//                    }
//                }
//            }
//            break;
//
//        case Event.SET_LOCAL_ADDRESS:
//            local_addr_promise.setResult((Address)evt.getArg());
//            break;
//
//        case Event.EXIT:
//            handleExit(evt);
//            return null;  // no need to pass event up; already done in handleExit()
//
//        default:
//            break;
//        }
//
//
//        // If UpHandler is installed, pass all events to it and return (UpHandler is e.g. a building block)
//        if(up_handler != null) {
//            Object ret=up_handler.up(evt);
//
//            if(type == Event.UNBLOCK){
//               flush_unblock_promise.setResult(Boolean.TRUE);
//            }
//            return ret;
//        }
//
//        switch(type) {
//            case Event.MSG:
//                if(receiver != null) {
//                    try {
//                        receiver.receive((Message)evt.getArg());
//                    }
//                    catch(Throwable t) {
//                        if(log.isWarnEnabled())
//                            log.warn("failed calling receive() in receiver", t);
//                    }
//                    return null;
//                }
//                break;
//            case Event.VIEW_CHANGE:
//                if(receiver != null) {
//                    try {
//                        receiver.viewAccepted((View)evt.getArg());
//                    }
//                    catch(Throwable t) {
//                        if(log.isWarnEnabled())
//                            log.warn("failed calling viewAccepted() in receiver", t);
//                    }
//                    return null;
//                }
//                break;
//            case Event.SUSPECT:
//                if(receiver != null) {
//                    try {
//                        receiver.suspect((Address)evt.getArg());
//                    }
//                    catch(Throwable t) {
//                        if(log.isWarnEnabled())
//                            log.warn("failed calling suspect() in receiver", t); 
//                    }
//                    return null;
//                }
//                break;
//            case Event.GET_APPLSTATE:
//                if(receiver != null) {
//                    StateTransferInfo state_info=(StateTransferInfo)evt.getArg();
//                    byte[] tmp_state=null;
//                    String state_id=state_info.state_id;
//                    try {
//                        if(receiver instanceof ExtendedReceiver && state_id!=null) {
//                            tmp_state=((ExtendedReceiver)receiver).getState(state_id);
//                        }
//                        else {
//                            tmp_state=receiver.getState();
//                        }
//                    }
//                    catch(Throwable t) {
//                        if(log.isWarnEnabled())
//                            log.warn("failed calling getState() in receiver", t);
//                    }
//                    return new StateTransferInfo(null, state_id, 0L, tmp_state);
//                }
//                break;
//            case Event.STATE_TRANSFER_OUTPUTSTREAM:
//        	StateTransferInfo sti=(StateTransferInfo)evt.getArg();
//                OutputStream os=sti.outputStream;
//                if(receiver instanceof ExtendedReceiver) {                    
//                    if(os != null) {
//                        try {
//                            if(sti.state_id == null)
//                                ((ExtendedReceiver)receiver).getState(os);
//                            else
//                                ((ExtendedReceiver)receiver).getState(sti.state_id, os);
//                        }
//                        catch(Throwable t) {

//                            if(log.isWarnEnabled())
//                                log.warn("failed calling getState() in receiver", t);
//                        }                       
//                    }                    
//                }
//                else if(receiver instanceof Receiver){
//                    if(log.isWarnEnabled()){
//                        log.warn("Channel has STREAMING_STATE_TRANSFER, however," +
//                                " application does not implement ExtendedMessageListener. State is not transfered");
//                        Util.close(os);
//                    }
//                }
//                break;
//
//            case Event.BLOCK:
//                if(!receive_blocks) {  // discard if client has not set 'receiving blocks' to 'on'
//                    return Boolean.TRUE;
//                }
//
//                if(receiver != null) {
//                    try {
//                        receiver.block();
//                    }
//                    catch(Throwable t) {
//                        if(log.isErrorEnabled())
//                            log.error("failed calling block() in receiver", t);
//                    }                     
//                    return Boolean.TRUE;
//                }
//                break;
//            case Event.UNBLOCK:
//                //invoke receiver if block receiving is on
//                if(receive_blocks && receiver instanceof ExtendedReceiver) {                                                     
//                    try {
//                        ((ExtendedReceiver)receiver).unblock();
//                    }
//                    catch(Throwable t) {
//                        if(log.isErrorEnabled())
//                            log.error("failed calling unblock() in receiver", t);
//                    }                                                            
//                }
//                //flip promise
//                flush_unblock_promise.setResult(Boolean.TRUE);              
//                return null;                
//            default:
//                break;
//        }
//
//        if(type == Event.MSG || type == Event.VIEW_CHANGE || type == Event.SUSPECT ||
//                type == Event.GET_APPLSTATE || type== Event.STATE_TRANSFER_OUTPUTSTREAM
//                || type == Event.BLOCK || type == Event.UNBLOCK) {
//            try {
//                mq.add(evt);
//            }
//            catch(QueueClosedException queue_closed) {
//                ; // ignore
//            }
//            catch(Exception e) {
//                if(log.isWarnEnabled()) log.warn("exception adding event " + evt + " to message queue", e);
//            }
//        }
//
//        if(type == Event.GET_APPLSTATE) {
//            try {
//                return applstate_exchanger.exchange(null);
//            }
//            catch(InterruptedException e) {
//                Thread.currentThread().interrupt();
//                return null;
//            }
//        }
//        return null;
//    }


    /**
     * Sends a message through the protocol stack if the stack is available
     * @param evt the message to send down, encapsulated in an event
     */
    public void down(Event evt) {
        if(evt == null) return;

        switch(evt.getType()) {
            case Event.CONFIG:
                try {
                    Map<String,Object> m=(Map<String,Object>)evt.getArg();
                    if(m != null) {
                        additional_data.putAll(m);
                        if(m.containsKey("additional_data")) {
                            byte[] tmp=(byte[])m.get("additional_data");
                            if(local_addr instanceof IpAddress)
                                ((IpAddress)local_addr).setAdditionalData(tmp);
                        }
                    }
                }
                catch(Throwable t) {
                    if(log.isErrorEnabled()) log.error("CONFIG event did not contain a hashmap: " + t);
                }
                break;            
        }

        prot_stack.down(evt);
    }


    public Object downcall(Event evt) {
        if(evt == null) return null;

        switch(evt.getType()) {
            case Event.CONFIG:
                try {
                    Map<String,Object> m=(Map<String,Object>)evt.getArg();
                    if(m != null) {
                        additional_data.putAll(m);
                        if(m.containsKey("additional_data")) {
                            byte[] tmp=(byte[])m.get("additional_data");
                            if(local_addr instanceof IpAddress)
                                ((IpAddress)local_addr).setAdditionalData(tmp);
                        }
                    }
                }
                catch(Throwable t) {
                    if(log.isErrorEnabled()) log.error("CONFIG event did not contain a hashmap: " + t);
                }
                break;           
        }

        return prot_stack.down(evt);
    }



    public String toString(boolean details) {
        StringBuilder sb=new StringBuilder();
        sb.append("local_addr=").append(local_addr).append('\n');
        sb.append("cluster_name=").append(cluster_name).append('\n');
        sb.append("my_view=").append(my_view).append('\n');
        sb.append("connected=").append(connected).append('\n');
        sb.append("closed=").append(closed).append('\n');
        if(mq != null)
            sb.append("incoming queue size=").append(mq.size()).append('\n');
        if(details) {
            sb.append("receive_blocks=").append(receive_blocks).append('\n');
            sb.append("receive_local_msgs=").append(receive_local_msgs).append('\n');
            sb.append("auto_reconnect=").append(auto_reconnect).append('\n');
            sb.append("auto_getstate=").append(auto_getstate).append('\n');
            sb.append("state_transfer_supported=").append(state_transfer_supported).append('\n');
            sb.append("props=").append(props).append('\n');
        }

        return sb.toString();
    }


    /* ----------------------------------- Private Methods ------------------------------------- */


    protected final void init(ProtocolStackConfigurator configurator) throws ChannelException {
        if(log.isInfoEnabled()) 
            log.info("JGroups version: " + Version.description);
        ConfiguratorFactory.substituteVariables(configurator); // replace vars with system props
        props=configurator.getProtocolStackString();
        prot_stack=new ProtocolStack(this, props);
        try {
            prot_stack.setup(); // Setup protocol stack (creates protocol, calls init() on them)
        }
        catch(Throwable e) {
            throw new ChannelException("unable to setup the protocol stack: " + e.getMessage(), e);
        }
    }


    /**
     * Initializes all variables. Used after <tt>close()</tt> or <tt>disconnect()</tt>,
     * to be ready for new <tt>connect()</tt>
     */
    private void init() {
        local_addr=null;
        cluster_name=null;
        my_view=null;

        // changed by Bela Sept 25 2003
        //if(mq != null && mq.closed())
          //  mq.reset();
        connected=false;
    }


    private void startStack(String cluster_name) throws ChannelException {
        /*make sure the channel is not closed*/
        checkClosed();

        /*if we already are connected, then ignore this*/
        if(connected) {
            if(log.isTraceEnabled()) log.trace("already connected to " + cluster_name);
            return;
        }

        /*make sure we have a valid channel name*/
        if(cluster_name == null) { 
            if(log.isDebugEnabled()) log.debug("cluster_name is null, assuming unicast channel");
        }
        else
            this.cluster_name=cluster_name;


        try {
            prot_stack.startStack(cluster_name); // calls start() in all protocols, from top to bottom
        }
        catch(Throwable e) {
            throw new ChannelException("failed to start protocol stack", e);
        }

        String tmp=Util.getProperty(new String[]{Global.CHANNEL_LOCAL_ADDR_TIMEOUT, "local_addr.timeout"},
                                    null, null, false, "30000");
        LOCAL_ADDR_TIMEOUT=Long.parseLong(tmp);

        /* Wait LOCAL_ADDR_TIMEOUT milliseconds for local_addr to have a non-null value (set by SET_LOCAL_ADDRESS) */
        local_addr=local_addr_promise.getResult(LOCAL_ADDR_TIMEOUT);
        if(local_addr == null) {
            log.fatal("local_addr is null; cannot connect");
            throw new ChannelException("local_addr is null");
        }

        /*create a temporary view, assume this channel is the only member and is the coordinator*/
        Vector<Address> t=new Vector<Address>(1);
        t.addElement(local_addr);
        my_view=new View(local_addr, 0, t);  // create a dummy view
    }



    /**
     * health check<BR>
     * throws a ChannelClosed exception if the channel is closed
     */
    protected void checkClosed() throws ChannelClosedException {
        if(closed)
            throw new ChannelClosedException();
    }


    protected void checkClosedOrNotConnected() throws ChannelNotConnectedException, ChannelClosedException {
        if(closed)
            throw new ChannelClosedException();
        if(!connected)
            throw new ChannelNotConnectedException();
    }


    /**
     * returns the value of the event<BR>
     * These objects will be returned<BR>
     * <PRE>
     * <B>Event Type    - Return Type</B>
     * Event.MSG           - returns a Message object
     * Event.VIEW_CHANGE   - returns a View object
     * Event.SUSPECT       - returns a SuspectEvent object
     * Event.BLOCK         - returns a new BlockEvent object
     * Event.GET_APPLSTATE - returns a GetStateEvent object
     * Event.STATE_RECEIVED- returns a SetStateEvent object
     * Event.Exit          - returns an ExitEvent object
     * All other           - return the actual Event object
     * </PRE>
     * @param   evt - the event of which you want to extract the value
     * @return the event value if it matches the select list,
     *         returns null if the event is null
     *         returns the event itself if a match (See above) can not be made of the event type
     */
    static Object getEvent(Event evt) {
        if(evt == null)
            return null; // correct ?

        switch(evt.getType()) {
            case Event.MSG:
                return evt.getArg();
            case Event.VIEW_CHANGE:
                return evt.getArg();
            case Event.SUSPECT:
                return new SuspectEvent(evt.getArg());
            case Event.BLOCK:
                return new BlockEvent();
            case Event.UNBLOCK:
                return new UnblockEvent();
            case Event.GET_APPLSTATE:
                StateTransferInfo info=(StateTransferInfo)evt.getArg();
                return new GetStateEvent(info.target, info.state_id);
            case Event.STATE_RECEIVED:
                info=(StateTransferInfo)evt.getArg();
                return new SetStateEvent(info.state, info.state_id);
            case Event.STATE_TRANSFER_OUTPUTSTREAM:
            	info = (StateTransferInfo)evt.getArg();
                return new StreamingGetStateEvent(info.outputStream,info.state_id);
            case Event.STATE_TRANSFER_INPUTSTREAM:
            	info = (StateTransferInfo)evt.getArg();
                return new StreamingSetStateEvent(info.inputStream,info.state_id);
            case Event.EXIT:
                return new ExitEvent();
            default:
                return evt;
        }
    }

    /**
     * Disconnects and closes the channel.
     * This method does the following things
     * <ol>
     * <li>Calls <code>this.disconnect</code> if the disconnect parameter is true
     * <li>Calls <code>Queue.close</code> on mq if the close_mq parameter is true
     * <li>Calls <code>ProtocolStack.stop</code> on the protocol stack
     * <li>Calls <code>ProtocolStack.destroy</code> on the protocol stack
     * <li>Sets the channel closed and channel connected flags to true and false
     * <li>Notifies any channel listener of the channel close operation
     * </ol>
     */
    protected void _close(boolean disconnect, boolean close_mq) {
        if(closed)
            return;

        if(disconnect)
            disconnect();                     // leave group if connected

        if(close_mq) 
            closeMessageQueue(false);       

        stopStack(true, true);
        closed=true;
        connected=false;
        notifyChannelClosed(this);
        init(); // sets local_addr=null; changed March 18 2003 (bela) -- prevented successful rejoining
    }

    protected void stopStack(boolean disconnect, boolean destroy) {
        if(prot_stack != null) {
            try {
                if(disconnect)
                    prot_stack.stopStack(cluster_name);

                if(destroy)
                    prot_stack.destroy();
            }
            catch(Exception e) {
                if(log.isErrorEnabled())
                    log.error("failed destroying the protocol stack", e);
            }
        }
    }


    public final void closeMessageQueue(boolean flush_entries) {
        if(mq != null)
            mq.close(flush_entries);
    }


    /**
     * Creates a separate thread to close the protocol stack.
     * This is needed because the thread that called JChannel.up() with the EXIT event would
     * hang waiting for up() to return, while up() actually tries to kill that very thread.
     * This way, we return immediately and allow the thread to terminate.
     */
    private void handleExit(Event evt) {
        notifyChannelShunned();
        if(closer != null && !closer.isAlive())
            closer=null;
        if(closer == null) {
            if(log.isDebugEnabled())
                log.debug("received an EXIT event, will leave the channel");
            closer=new CloserThread(evt);
            closer.start();
        }
    }

    public boolean flushSupported() {
        return flush_supported;
    }

    /**
     * Will perform a flush of the system, ie. all pending messages are flushed out of the 
     * system and all members ack their reception. After this call returns, no member will
     * be sending any messages until {@link #stopFlush()} is called.
     * <p>
     * In case of flush collisions, random sleep time backoff algorithm is employed and
     * flush is reattempted for numberOfAttempts. Therefore this method is guaranteed 
     * to return after timeout x numberOfAttempts miliseconds.
     * 
     * @param automatic_resume Call {@link #stopFlush()} after the flush
     * @return true if FLUSH completed within the timeout
     */
    public boolean startFlush(boolean automatic_resume) {
        if(!flushSupported()) {
            throw new IllegalStateException("Flush is not supported, add pbcast.FLUSH protocol to your configuration");
        }           	  
        boolean successfulFlush = (Boolean) downcall(new Event(Event.SUSPEND));
        
        if(automatic_resume)
            stopFlush();

        return successfulFlush;              
    }
    
    /**
     * Performs a partial flush in a cluster for flush participants. 
     * <p>
     * All pending messages are flushed out only for flush participants.
     * Remaining members in a cluster are not included in flush.
     * Flush participants should be a proper subset of a current view. 
     * 
     * <p>
     * In case of flush collisions, random sleep time backoff algorithm is employed and
     * flush is reattempted for numberOfAttempts. Therefore this method is guaranteed 
     * to return after timeout x numberOfAttempts miliseconds.
     * 
     * @param automatic_resume Call {@link #stopFlush()} after the flush
     * @return true if FLUSH completed within the timeout
     */
    public boolean startFlush(List<Address> flushParticipants,boolean automatic_resume) {
        boolean successfulFlush = false;
        if(!flushSupported()){
            throw new IllegalStateException("Flush is not supported, add pbcast.FLUSH protocol to your configuration");
        }
        View v = getView();
        if(v != null && v.getMembers().containsAll(flushParticipants)){
            successfulFlush = (Boolean) downcall(new Event(Event.SUSPEND, flushParticipants));
        }else{
            throw new IllegalArgumentException("Current view " + v
                                               + " does not contain all flush participants "
                                               + flushParticipants);
        }
        
        if(automatic_resume)
            stopFlush(flushParticipants);


        return successfulFlush;              
    }
    
    /**
     * Will perform a flush of the system, ie. all pending messages are flushed out of the 
     * system and all members ack their reception. After this call returns, no member will
     * be sending any messages until {@link #stopFlush()} is called.
     * <p>
     * In case of flush collisions, random sleep time backoff algorithm is employed and
     * flush is reattempted for numberOfAttempts. Therefore this method is guaranteed 
     * to return after timeout x numberOfAttempts miliseconds.
     * @param timeout
     * @param automatic_resume Call {@link #stopFlush()} after the flush
     * @return true if FLUSH completed within the timeout
     */
    public boolean startFlush(long timeout, boolean automatic_resume) {        
        return startFlush(automatic_resume);       
    }

    public void stopFlush() {
        if(!flushSupported()) {
            throw new IllegalStateException("Flush is not supported, add pbcast.FLUSH protocol to your configuration");
        }
       
        down(new Event(Event.RESUME));

        //do not return until UNBLOCK event is received            
        try {
            flush_unblock_promise.getResultWithTimeout(FLUSH_UNBLOCK_TIMEOUT);
        }
        catch(TimeoutException te) {
            log.warn("Timeout waiting for UNBLOCK event at " + getLocalAddress());
        }
    }

    public void stopFlush(List<Address> flushParticipants) {
        if(!flushSupported()) {
            throw new IllegalStateException("Flush is not supported, add pbcast.FLUSH protocol to your configuration");
        }
        
        down(new Event(Event.RESUME, flushParticipants));

        // do not return until UNBLOCK event is received
        try {
            flush_unblock_promise.getResultWithTimeout(FLUSH_UNBLOCK_TIMEOUT);
        }
        catch(TimeoutException te) {
            log.warn("Timeout waiting for UNBLOCK event at " + getLocalAddress());
        }
    }
    
    @Override
    public Map<String, Object> getInfo(){
       return new HashMap<String, Object>(info);
    }

    public void setInfo(String key, Object value) {
        if(key != null)
            info.put(key, value);
    }

    Address determineCoordinator() {
        Vector<Address> mbrs=my_view != null? my_view.getMembers() : null;
        if(mbrs == null)
            return null;
        if(!mbrs.isEmpty())
            return (Address)mbrs.firstElement();
        return null;
    }

    /* ------------------------------- End of Private Methods ---------------------------------- */


    class CloserThread extends Thread2 {
        final Event evt;
        final Thread2 t=null;


        CloserThread(Event evt) {
            super(Util.getGlobalThreadGroup(), "CloserThread");
            this.evt=evt;
            setDaemon(true);
        }


        public void run() {
            try {
                String old_cluster_name=cluster_name; // remember because close() will null it
                if(log.isDebugEnabled())
                    log.debug("closing the channel");
                _close(false, false); // do not disconnect before closing channel, do not close mq (yet !)

                if(up_handler != null)
                    up_handler.up(this.evt);
                else {
                    try {
                        if(receiver == null)
                            mq.add(this.evt);
                    }
                    catch(Exception ex) {
                        if(log.isErrorEnabled()) log.error("exception: " + ex);
                    }
                }

                if(mq != null) {
                    Util.sleep(500); // give the mq thread a bit of time to deliver EXIT to the application
                    try {
                        mq.close(false);
                    }
                    catch(Exception ex) {
                    }
                }

                if(auto_reconnect) {
                    try {
                        if(log.isDebugEnabled()) log.debug("reconnecting to group " + old_cluster_name);
                        open();
                        if(additional_data != null) {
                            // send previously set additional_data down the stack - other protocols (e.g. TP) use it
                            Map<String,Object> m=new HashMap<String,Object>(additional_data);
                            down(new Event(Event.CONFIG, m));
                        }
                    }
                    catch(Exception ex) {
                        if(log.isErrorEnabled()) log.error("failure reopening channel: " + ex);
                        return;
                    }

                    while(!connected) {
                        try {
                            connect(old_cluster_name);
                            notifyChannelReconnected(local_addr);
                        }
                        catch(Exception ex) {
                            if(log.isErrorEnabled()) log.error("failure reconnecting to channel, retrying", ex);
                            Util.sleep(1000); // sleep 1 sec between reconnect attempts
                        }
                    }
                }

                if(auto_getstate) {
                    if(log.isDebugEnabled())
                        log.debug("fetching the state (auto_getstate=true)");
                    boolean rc=JChannel.this.getState(null, GET_STATE_DEFAULT_TIMEOUT);
                    if(log.isDebugEnabled()) {
                        if(rc)
                            log.debug("state was retrieved successfully");
                        else
                            log.debug("state transfer failed");
                    }
                }

            }
            catch(Exception ex) {
                if(log.isErrorEnabled()) log.error("exception: " + ex);
            }
            finally {
                closer=null;
            }
        }
    }

}

/******************************************************************************
 * 
 * 
 * Classes that we have defined ourselves so that we don't have to include the
 * entire JGroups project. They do not preserve the original functionality of the
 * JChannel class.
 * 
 * ****************************************************************************
 */

class ChannelException extends Exception {

	public ChannelException(String string, Throwable res) {
		// TODO Auto-generated constructor stub
	}

	public ChannelException(String string) {
		// TODO Auto-generated constructor stub
	}
	
}

class View {

	public View(Address local_addr, int i, Vector<Address> t) {
		// TODO Auto-generated constructor stub
	}

	public Vector getMembers() {
		// TODO Auto-generated method stub
		return null;
	}

	public int size() {
		// TODO Auto-generated method stub
		return 0;
	}
	
}


class Util {

	public static String dumpQueue(Queue mq) {
		// TODO Auto-generated method stub
		return null;
	}

	public static void sleep(int i) {
		// TODO Auto-generated method stub
		
	}

	public static ThreadGroup getGlobalThreadGroup() {
		// TODO Auto-generated method stub
		return null;
	}

	public static String getProperty(String[] strings, Object object,
			Object object2, boolean b, String string) {
		// TODO Auto-generated method stub
		return null;
	}
	
}

class Queue {

	public void reset() {
		// TODO Auto-generated method stub
		
	}

	public void add(Event evt) {
		// TODO Auto-generated method stub
		
	}

	public void close(boolean flush_entries) {
		// TODO Auto-generated method stub
		
	}

	public Event peek() throws QueueClosedException {
		// TODO Auto-generated method stub
		return null;
	}

	public Event peek(long timeout) throws TimeoutException {
		// TODO Auto-generated method stub
		return null;
	}

	public Event remove() throws QueueClosedException {
		// TODO Auto-generated method stub
		return null;
	}

	public Event remove(long timeout) throws TimeoutException {
		// TODO Auto-generated method stub
		return null;
	}

	public int size() {
		// TODO Auto-generated method stub
		return 0;
	}
	
}

class ProtocolStack {

	public ProtocolStack(JChannel channel, String props) {
		// TODO Auto-generated constructor stub
	}

	public void destroy() {
		// TODO Auto-generated method stub
		
	}

	public void stopStack(String cluster_name) {
		// TODO Auto-generated method stub
		
	}

	public void startStack(String cluster_name) {
		// TODO Auto-generated method stub
		
	}

	public Object down(Event evt) {
		// TODO Auto-generated method stub
		return null;
	}

	public Map<String, Object> dumpStats() {
		// TODO Auto-generated method stub
		return null;
	}

	public void setup() {
		// TODO Auto-generated method stub
		
	}
	
}

class Promise<T> {

	public void getResultWithTimeout(long flushUnblockTimeout) throws TimeoutException {
		// TODO Auto-generated method stub
		
	}

	public T getResult(long timeout) {
		// TODO Auto-generated method stub
		return null;
	}

	public void reset() {
		// TODO Auto-generated method stub
		
	}
	
}

class StateTransferInfo {

	public Object inputStream;
	public Object outputStream;
	public Object state;
	public Object state_id;
	public Object target;
	public long timeout;

	public StateTransferInfo(Address target, String state_id, long timeout) {
		// TODO Auto-generated constructor stub
	}

	public StateTransferInfo(Object object, Object object2, long l, byte[] state) {
		// TODO Auto-generated constructor stub
	}
	
}

class ProtocolStackConfigurator {

	public String getProtocolStackString() {
		// TODO Auto-generated method stub
		return null;
	}
	
}

class TimeoutException extends Exception {

}

class ChannelClosedException extends ChannelException {

	public ChannelClosedException(String string) {
		super(string);
	}

	public ChannelClosedException() {
		this(null);
	}
	
}

abstract class Channel {
	JChannel up_handler;
	Object receiver;
	
	void up(Event e) {
		
	}
	
	void notifyChannelConnected(Channel c) {
		
	}
	
	void notifyChannelDisconnected(Channel c) {
		
	}
	
	void notifyChannelClosed(Channel c) {
		
	}
	
	void notifyChannelShunned() {
		
	}
	
	void notifyChannelReconnected(Object o) {
		
	}
	
    public abstract Map<String, Object> getInfo();
}


class StateTransferException extends ChannelException {

	public StateTransferException(String string) {
		super(string, null);
	}

	public StateTransferException(String string, Exception e) {
		super(string, e);
	}
	
}

class Log {

	public boolean isInfoEnabled() {
		// TODO Auto-generated method stub
		return false;
	}
	public void error(String string, Exception e) {
		// TODO Auto-generated method stub
		
	}
	public void fatal(String string) {
		// TODO Auto-generated method stub

	}
	public void debug(String string) {
		// TODO Auto-generated method stub

	}
	public boolean isDebugEnabled() {
		// TODO Auto-generated method stub
		return false;
	}
	public void info(String string) {
		// TODO Auto-generated method stub

	}
	public void error(Exception e) {
	}

	public void trace(String string) {
		// TODO Auto-generated method stub

	}

	public boolean isTraceEnabled() {
		// TODO Auto-generated method stub
		return false;
	}

	public void error(String string) {
		// TODO Auto-generated method stub

	}

	public boolean isErrorEnabled() {
		// TODO Auto-generated method stub
		return false;
	}

	public boolean isWarnEnabled() {
		// TODO Auto-generated method stub
		return false;
	}

	public void warn(String string) {
		// TODO Auto-generated method stub

	}

}

class GetStateEvent {

	public GetStateEvent(Object target, Object state_id) {
		// TODO Auto-generated constructor stub
	}
	
}

class SetStateEvent {

	public SetStateEvent(Object state, Object state_id) {
		// TODO Auto-generated constructor stub
	}
	
}

class Event {


	public static final String RESUME = null;
	public static final String SUSPEND = null;
	public static final int STATE_RECEIVED = 0;
	public static final int GET_APPLSTATE = 1;
	public static final int UNBLOCK = 2;
	public static final int BLOCK = 3;
	public static final int SUSPECT = 4;
	public static final int VIEW_CHANGE = 5;
	public static final int CONFIG = 6;
	public static final String RESUME_STABLE = null;
	public static final String GET_STATE = null;
	public static final int MSG = 7;
	public static final int EXIT = 8;
	public static final int STATE_TRANSFER_INPUTSTREAM = 9;
	public static final int STATE_TRANSFER_OUTPUTSTREAM = 10;
	public static final String SHUTDOWN = null;
	public static final String DISCONNECT = null;
	public static final String CONNECT_WITH_STATE_TRANSFER = null;

	public Event(String connect2, String cluster_name) {
		// TODO Auto-generated constructor stub
	}

	public Map<String, Object> getArg() {
		// TODO Auto-generated method stub
		return null;
	}

	public int getType() {
		// TODO Auto-generated method stub
		return 0;
	}

	public Event(String disconnect2, Address local_addr) {
		// TODO Auto-generated constructor stub
	}

	public Event(String shutdown2) {
		// TODO Auto-generated constructor stub
	}

	public Event(String msg2, Message msg3) {
		// TODO Auto-generated constructor stub
	}

	public Event(String getState, StateTransferInfo state_info) {
		// TODO Auto-generated constructor stub
	}

	public Event(int msg2, Message msg3) {
		// TODO Auto-generated constructor stub
	}

	public Event(String suspend2, List<Address> flushParticipants) {
		// TODO Auto-generated constructor stub
	}

	public Event(int config2, Map<String, Object> m) {
		// TODO Auto-generated constructor stub
	}

	public static final String CONNECT = null;
	
}

class Message {

	public Message(Address dst, Address src, Serializable obj) {
		// TODO Auto-generated constructor stub
	}

	public CausalMessage getObject() {
		// TODO Auto-generated method stub
		return null;
	}

	public long getLength() {
		// TODO Auto-generated method stub
		return 0;
	}
	
}

class LogFactory {

	public static edu.cmu.cs.nimby.test.oopsla.Log getLog(Class<?> class1) {
		return null;
	}
	
}

class ChannelNotConnectedException extends Exception {
	
}

class Address {
	
}

class CausalMessage implements Serializable
{
	public final String message;
	public final Address member;

	public CausalMessage(String message, Address member)
	{
		this.message = message;
		this.member = member;
	}


	public String toString()
	{
		return "CausalMessage[" + message + '=' + message + "member=" + member + ']';
	}

}

class IpAddress extends Address {

	public void setAdditionalData(byte[] tmp) {
		// TODO Auto-generated method stub
		
	}
	
}

class Global {

	public static final String CHANNEL_LOCAL_ADDR_TIMEOUT = null;
	
}

class Version {

	public static String description;
	
}

class QueueClosedException extends Exception {
	
}

class SuspectEvent {

	public SuspectEvent(Map<String, Object> arg) {
		// TODO Auto-generated constructor stub
	}
	
}

class BlockEvent {
	
}

class UnblockEvent {
	
}

class StreamingGetStateEvent {

	public StreamingGetStateEvent(Object outputStream, Object state_id) {
		// TODO Auto-generated constructor stub
	}
	
}

class StreamingSetStateEvent {

	public StreamingSetStateEvent(Object inputStream, Object state_id) {
		// TODO Auto-generated constructor stub
	}
	
}

class ExitEvent {
	
}

class ConfiguratorFactory {

	public static ProtocolStackConfigurator getStackConfigurator(File properties) {
		// TODO Auto-generated method stub
		return null;
	}

	public static void substituteVariables(
			ProtocolStackConfigurator configurator) {
		// TODO Auto-generated method stub
		
	}

	public static ProtocolStackConfigurator getStackConfigurator(String properties) {
		// TODO Auto-generated method stub
		return null;
	}

	public static ProtocolStackConfigurator getStackConfigurator(URL properties) {
		// TODO Auto-generated method stub
		return null;
	}

	public static ProtocolStackConfigurator getStackConfigurator(Element properties) {
		// TODO Auto-generated method stub
		return null;
	}
	
}

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Change log

r264 by kevin.bierhoff on Mar 26, 2009 Diff

Port to new "use" attribute, replacing
fieldAccess flag

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Older revisions

r50 by nels.beckman on Sep 17, 2008 Diff

[license] Updated the copyright notice
for the two JGroups programs.

r49 by nels.beckman on Sep 17, 2008 Diff

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