### Eclipse Workspace Patch 1.0
#P JGroups
Index: src/org/jgroups/blocks/mux/Muxer.java
===================================================================
RCS file: /cvsroot/javagroups/JGroups/src/org/jgroups/blocks/mux/Muxer.java,v
retrieving revision 1.1
diff -u -r1.1 Muxer.java
--- src/org/jgroups/blocks/mux/Muxer.java	13 Apr 2010 17:57:07 -0000	1.1
+++ src/org/jgroups/blocks/mux/Muxer.java	6 Jun 2010 15:46:42 -0000
@@ -15,8 +15,31 @@
     void add(short id, T handler);
     
     /**
+     * Gets the handler registered under the specified id
+     * @param id a mux id
+     * @return the handler, or <code>null</code> if no handler is registered under
+     *         <code>id</code>
+     */
+    T get(short id);
+    
+    /**
      * Unregisters the handler associated with the specifed mux identifier
      * @param id a mux id
      */
     void remove(short id);
+    
+    /**
+     * Gets the handler for messages that have no mux header.
+     * 
+     * @return the default handler, or <code>null</code> if no default handler
+     *         has been set
+     */
+    T getDefaultHandler();
+    
+    /**
+     * Sets the handler for messages that have no mux header.
+     * 
+     * @param handler a handler for messages that have no mux header
+     */
+    void setDefaultHandler(T handler);
 }
Index: src/org/jgroups/blocks/mux/MuxUpHandler.java
===================================================================
RCS file: /cvsroot/javagroups/JGroups/src/org/jgroups/blocks/mux/MuxUpHandler.java,v
retrieving revision 1.2
diff -u -r1.2 MuxUpHandler.java
--- src/org/jgroups/blocks/mux/MuxUpHandler.java	15 Apr 2010 20:05:22 -0000	1.2
+++ src/org/jgroups/blocks/mux/MuxUpHandler.java	6 Jun 2010 15:46:42 -0000
@@ -17,7 +17,7 @@
 public class MuxUpHandler implements UpHandler, Muxer<UpHandler> {
 
     private final Map<Short, UpHandler> handlers = new ConcurrentHashMap<Short, UpHandler>();
-    private final UpHandler defaultHandler;
+    private volatile UpHandler defaultHandler;
     
     /**
      * Creates a multiplexing up handler, with no default handler.
@@ -45,6 +45,15 @@
 
     /**
      * {@inheritDoc}
+     * @see org.jgroups.blocks.mux.Muxer#get(short)
+     */
+    @Override
+    public UpHandler get(short id) {
+        return handlers.get(id);
+    }
+    
+    /**
+     * {@inheritDoc}
      * @see org.jgroups.blocks.mux.Muxer#remove(short)
      */
     @Override
@@ -52,7 +61,17 @@
         handlers.remove(id);
     }
 
-    /**
+    @Override
+    public UpHandler getDefaultHandler() {
+        return defaultHandler;
+    }
+
+    @Override
+    public void setDefaultHandler(UpHandler handler) {
+        this.defaultHandler = handler;      
+    }
+
+   /**
      * {@inheritDoc}
      * @see org.jgroups.UpHandler#up(org.jgroups.Event)
      */
Index: src/org/jgroups/blocks/MessageDispatcher.java
===================================================================
RCS file: /cvsroot/javagroups/JGroups/src/org/jgroups/blocks/MessageDispatcher.java,v
retrieving revision 1.105
diff -u -r1.105 MessageDispatcher.java
--- src/org/jgroups/blocks/MessageDispatcher.java	28 Apr 2010 14:54:29 -0000	1.105
+++ src/org/jgroups/blocks/MessageDispatcher.java	6 Jun 2010 15:46:42 -0000
@@ -2,6 +2,7 @@
 package org.jgroups.blocks;
 
 import org.jgroups.*;
+import org.jgroups.blocks.mux.Muxer;
 import org.jgroups.logging.Log;
 import org.jgroups.logging.LogFactory;
 import org.jgroups.protocols.TP;
@@ -64,7 +65,7 @@
         setMessageListener(l);
         setMembershipListener(l2);
         if(channel != null) {
-            channel.setUpHandler(prot_adapter);
+            installUpHandler(prot_adapter, true);
         }
         start();
     }
@@ -79,7 +80,7 @@
         setMessageListener(l);
         setMembershipListener(l2);
         if(channel != null) {
-            channel.setUpHandler(prot_adapter);
+            installUpHandler(prot_adapter, true);
         }
         start();
     }
@@ -95,7 +96,7 @@
         setMessageListener(l);
         setMembershipListener(l2);
         if(channel != null) {
-            channel.setUpHandler(prot_adapter);
+            installUpHandler(prot_adapter, true);
         }
         start();
     }
@@ -352,9 +353,50 @@
         local_addr=channel.getAddress();
         if(prot_adapter == null)
             prot_adapter=new ProtocolAdapter();
-        if (channel.getUpHandler() == null) {
-            channel.setUpHandler(prot_adapter);
-        }
+        // Don't force installing the UpHandler so subclasses can use this
+        // method and still integrate with a MuxUpHandler
+        installUpHandler(prot_adapter, false);
+    }
+    
+    /**
+     * Sets the given UpHandler as the UpHandler for the channel, or, if the
+     * channel already has a Muxer installed as it's UpHandler, sets the given
+     * handler as the Muxer's {@link Muxer#setDefaultHandler(Object) default handler}.
+     * If the relevant handler is already installed, the <code>canReplace</code>
+     * controls whether this method replaces it (after logging a WARN) or simply
+     * leaves <code>handler</code> uninstalled.
+     * <p>
+     * Passing <code>false</code> as the <code>canReplace</code> value allows
+     * callers to use this method to install defaults without concern about
+     * inadvertently overriding
+     * 
+     * @param handler the UpHandler to install
+     * @param canReplace <code>true</code> if an existing Channel upHandler or 
+     *              Muxer default upHandler can be replaced; <code>false</code>
+     *              if this method shouldn't install
+     */
+    protected void installUpHandler(UpHandler handler, boolean canReplace)
+    {
+       UpHandler existing = channel.getUpHandler();
+       if (existing == null) {
+           channel.setUpHandler(handler);
+       }
+       else if (existing instanceof Muxer<?>) {
+           @SuppressWarnings("unchecked")
+           Muxer<UpHandler> mux = (Muxer<UpHandler>) existing;
+           if (mux.getDefaultHandler() == null) {
+               mux.setDefaultHandler(handler);
+           }
+           else if (canReplace) {
+               log.warn("Channel Muxer already has a default up handler installed (" +
+                     mux.getDefaultHandler() + ") but now it is being overridden"); 
+               mux.setDefaultHandler(handler);
+           }
+       }
+       else if (canReplace) {
+           log.warn("Channel already has an up handler installed (" + existing + ") but now it is being overridden");
+           channel.setUpHandler(handler);
+       }
     }
 
     @Deprecated