Merged revisions 540107 via svnmerge from

https://svn.apache.org/repos/asf/incubator/qpid/branches/M2

........
  r540107 | rupertlssmith | 2007-05-21 11:57:30 +0100 (Mon, 21 May 2007) | 1 line
  
  Documented all exception.
........


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@540119 13f79535-47bb-0310-9956-ffa450edef68

11 files changed, 218 insertions, 110 deletions

diff --git a/java/broker/src/main/java/org/apache/qpid/server/RequiredDeliveryException.java b/java/broker/src/main/java/org/apache/qpid/server/RequiredDeliveryException.java
index ff933d3c0b..d61bb8916a 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/RequiredDeliveryException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/RequiredDeliveryException.java
@@ -25,9 +25,17 @@ import org.apache.qpid.protocol.AMQConstant;
 import org.apache.qpid.server.queue.AMQMessage;
 
 /**
- * Signals that a required delivery could not be made. This could be bacuse of
- * the immediate flag being set and the queue having no consumers, or the mandatory
- * flag being set and the exchange having no valid bindings.
+ * Signals that a required delivery could not be made. This could be bacuse of the immediate flag being set and the
+ * queue having no consumers, or the mandatory flag being set and the exchange having no valid bindings.
+ *
+ * <p/>The failed message is associated with this error condition, by taking a reference to it. This enables the
+ * correct compensating action to be taken against the message, for example, bouncing it back to the sender.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Represent failure to deliver a message that must be delivered.
+ * <tr><td> Associate the failed message with the error condition. <td> {@link AMQMessage}
+ * </table>
  */
 public abstract class RequiredDeliveryException extends AMQException
 {
@@ -40,10 +48,10 @@ public abstract class RequiredDeliveryException extends AMQException
         // Increment the reference as this message is in the routing phase
         // and so will have the ref decremented as routing fails.
         // we need to keep this message around so we can return it in the
-        // handler. So increment here.  
-	_amqMessage = payload.takeReference();
- 
-        //payload.incrementReference();
+        // handler. So increment here.
+        _amqMessage = payload.takeReference();
+
+        // payload.incrementReference();
     }
 
     public AMQMessage getAMQMessage()
diff --git a/java/broker/src/main/java/org/apache/qpid/server/exchange/ExchangeInUseException.java b/java/broker/src/main/java/org/apache/qpid/server/exchange/ExchangeInUseException.java
index 6b2891c573..c77f114428 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/exchange/ExchangeInUseException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/exchange/ExchangeInUseException.java
@@ -7,9 +7,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -22,6 +22,20 @@ package org.apache.qpid.server.exchange;
 
 import org.apache.qpid.AMQException;
 
+/**
+ * ExchangeInUseRegistry indicates that an exchange cannot be unregistered because it is currently being used.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Represents failure to unregister exchange that is in use.
+ * </table>
+ *
+ * @todo Not an AMQP exception as no status code.
+ *
+ * @todo This exception is not used. However, it is part of the ExchangeRegistry interface, and looks like code is
+ *       going to need to be added to throw/deal with this. Alternatively ExchangeResitries may be able to handle the
+ *       issue internally.
+ */
 public class ExchangeInUseException extends AMQException
 {
     public ExchangeInUseException(String exchangeName)
diff --git a/java/broker/src/main/java/org/apache/qpid/server/exchange/NoRouteException.java b/java/broker/src/main/java/org/apache/qpid/server/exchange/NoRouteException.java
index c972b9d078..1d6ab3842d 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/exchange/NoRouteException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/exchange/NoRouteException.java
@@ -7,9 +7,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -25,8 +25,14 @@ import org.apache.qpid.server.RequiredDeliveryException;
 import org.apache.qpid.server.queue.AMQMessage;
 
 /**
- * Thrown by an exchange if there is no way to route a message with the
- * mandatory flag set.
+ * NoRouteException is a {@link RequiredDeliveryException} that represents the failure case where a manadatory message
+ * cannot be delivered because there is no route for the message. The AMQP status code, 312, is always used to report
+ * this condition.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Represent failure to deliver a message that must be delivered.
+ * </table>
  */
 public class NoRouteException extends RequiredDeliveryException
 {
diff --git a/java/broker/src/main/java/org/apache/qpid/server/protocol/AMQNoMethodHandlerException.java b/java/broker/src/main/java/org/apache/qpid/server/protocol/AMQNoMethodHandlerException.java
index 16d74b6fc0..a7599a3e0d 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/protocol/AMQNoMethodHandlerException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/protocol/AMQNoMethodHandlerException.java
@@ -20,13 +20,25 @@
  */

 package org.apache.qpid.server.protocol;

 

+import org.apache.qpid.AMQException;

 import org.apache.qpid.framing.AMQMethodBody;

 import org.apache.qpid.protocol.AMQMethodEvent;

-import org.apache.qpid.AMQException;

 

+/**

+ * AMQNoMethodHandlerException represents the case where no method handler exists to handle an AQMP method.

+ *

+ * <p/><table id="crc"><caption>CRC Card</caption>

+ * <tr><th> Responsibilities <th> Collaborations

+ * <tr><td> Represents failure to handle an AMQP method.

+ * </table>

+ *

+ * @todo Not an AMQP exception as no status code.

+ *

+ * @todo Missing method handler. Unlikely to ever happen, and if it does its a coding error. Consider replacing with a

+ *       Runtime.

+ */

 public class AMQNoMethodHandlerException extends AMQException

 {

-

     public AMQNoMethodHandlerException(AMQMethodEvent<AMQMethodBody> evt)

     {

         super("AMQMethodEvent " + evt + " was not processed by any listener on Broker.");

diff --git a/java/broker/src/main/java/org/apache/qpid/server/protocol/UnknnownMessageTypeException.java b/java/broker/src/main/java/org/apache/qpid/server/protocol/UnknnownMessageTypeException.java
index 45d09e8f3e..6e72aa062f 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/protocol/UnknnownMessageTypeException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/protocol/UnknnownMessageTypeException.java
@@ -20,14 +20,27 @@
  */

 package org.apache.qpid.server.protocol;

 

-import org.apache.qpid.framing.AMQDataBlock;

 import org.apache.qpid.AMQException;

+import org.apache.qpid.framing.AMQDataBlock;

 

+/**

+ * UnknnownMessageTypeException represents a failure when Mina passes an unexpected frame type.

+ *

+ * <p/><table id="crc"><caption>CRC Card</caption>

+ * <tr><th> Responsibilities <th> Collaborations

+ * <tr><td> Represents failure to cast a frame to its expected type.

+ * </table>

+ *

+ * @todo Not an AMQP exception as no status code.

+ *

+ * @todo Seems like this exception was created to handle an unsafe type cast that will never happen in practice. Would

+ *       be better just to leave that as a ClassCastException. However, check the framing layer catches this error

+ *       first.

+ */

 public class UnknnownMessageTypeException extends AMQException

 {

     public UnknnownMessageTypeException(AMQDataBlock message)

     {

         super("Unknown message type: " + message.getClass().getName() + ": " + message);

-

     }

 }

diff --git a/java/broker/src/main/java/org/apache/qpid/server/queue/AMQQueue.java b/java/broker/src/main/java/org/apache/qpid/server/queue/AMQQueue.java
index fa3b34a634..a17cbb87ff 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/queue/AMQQueue.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/queue/AMQQueue.java
@@ -33,6 +33,7 @@ import java.util.concurrent.atomic.AtomicLong;
 import javax.management.JMException;
 
 import org.apache.log4j.Logger;
+
 import org.apache.qpid.AMQException;
 import org.apache.qpid.configuration.Configured;
 import org.apache.qpid.framing.AMQShortString;
@@ -54,7 +55,19 @@ import org.apache.qpid.server.virtualhost.VirtualHost;
  */
 public class AMQQueue implements Managable, Comparable, StorableQueue
 {
-
+    /**
+     * ExistingExclusiveSubscription signals a failure to create a subscription, because an exclusive subscription
+     * already exists.
+     *
+     * <p/><table id="crc"><caption>CRC Card</caption>
+     * <tr><th> Responsibilities <th> Collaborations
+     * <tr><td> Represent failure to create a subscription, because an exclusive subscription already exists.
+     * </table>
+     *
+     * @todo Not an AMQP exception as no status code.
+     *
+     * @todo Move to top level, used outside this class.
+     */
     public static int s_queueID =0;
     public static final class ExistingExclusiveSubscription extends AMQException
     {
@@ -65,19 +78,27 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         }
     }
 
+    /**
+     * ExistingSubscriptionPreventsExclusive signals a failure to create an exclusize subscription, as a subscription
+     * already exists.
+     *
+     * <p/><table id="crc"><caption>CRC Card</caption>
+     * <tr><th> Responsibilities <th> Collaborations
+     * <tr><td> Represent failure to create an exclusize subscription, as a subscription already exists.
+     * </table>
+     *
+     * @todo Not an AMQP exception as no status code.
+     *
+     * @todo Move to top level, used outside this class.
+     */
     public static final class ExistingSubscriptionPreventsExclusive extends AMQException
     {
-
         public ExistingSubscriptionPreventsExclusive()
         {
             super("");
         }
     }
 
-    private static final ExistingExclusiveSubscription EXISTING_EXCLUSIVE = new ExistingExclusiveSubscription();
-    private static final ExistingSubscriptionPreventsExclusive EXISTING_SUBSCRIPTION = new ExistingSubscriptionPreventsExclusive();
-
-
     private static final Logger _logger = Logger.getLogger(AMQQueue.class);
 
     private final AMQShortString _name;
@@ -134,7 +155,6 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
 
     private final VirtualHost _virtualHost;
 
-
     /**
      * max allowed size(KB) of a single message
      */
@@ -175,40 +195,34 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         return _name.compareTo(((AMQQueue) o).getName());
     }
 
-    public AMQQueue(AMQShortString name, boolean durable, AMQShortString owner,
-                    boolean autoDelete, VirtualHost virtualHost)
-            throws
-            AMQException
+    public AMQQueue(AMQShortString name, boolean durable, AMQShortString owner, boolean autoDelete, VirtualHost virtualHost)
+        throws AMQException
     {
-        this(name, durable, owner, autoDelete, virtualHost,
-                AsyncDeliveryConfig.getAsyncDeliveryExecutor(), new SubscriptionSet(), new SubscriptionImpl.Factory());
+        this(name, durable, owner, autoDelete, virtualHost, AsyncDeliveryConfig.getAsyncDeliveryExecutor(),
+            new SubscriptionSet(), new SubscriptionImpl.Factory());
     }
 
-
-    protected AMQQueue(AMQShortString name, boolean durable, AMQShortString owner,
-                       boolean autoDelete, VirtualHost virtualHost,
-                       SubscriptionSet subscribers)
-            throws
-            AMQException
+    protected AMQQueue(AMQShortString name, boolean durable, AMQShortString owner, boolean autoDelete,
+        VirtualHost virtualHost, SubscriptionSet subscribers) throws AMQException
     {
-        this(name, durable, owner, autoDelete, virtualHost,
-                AsyncDeliveryConfig.getAsyncDeliveryExecutor(), subscribers, new SubscriptionImpl.Factory());
+        this(name, durable, owner, autoDelete, virtualHost, AsyncDeliveryConfig.getAsyncDeliveryExecutor(), subscribers,
+            new SubscriptionImpl.Factory());
     }
 
-    protected AMQQueue(AMQShortString name, boolean durable, AMQShortString owner,
-                       boolean autoDelete, VirtualHost virtualHost,
-                       Executor asyncDelivery, SubscriptionSet subscribers, SubscriptionFactory subscriptionFactory)
-            throws
-            AMQException
+    protected AMQQueue(AMQShortString name, boolean durable, AMQShortString owner, boolean autoDelete,
+        VirtualHost virtualHost, Executor asyncDelivery, SubscriptionSet subscribers,
+        SubscriptionFactory subscriptionFactory) throws AMQException
     {
         if (name == null)
         {
             throw new IllegalArgumentException("Queue name must not be null");
         }
+
         if (virtualHost == null)
         {
             throw new IllegalArgumentException("Virtual Host must not be null");
         }
+
         _name = name;
         _durable = durable;
         _owner = owner;
@@ -304,10 +318,11 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
     public AMQMessage getMessageOnTheQueue(long messageId)
     {
         List<AMQMessage> list = getMessagesOnTheQueue(messageId, messageId);
-        if (list == null || list.size() == 0)
+        if ((list == null) || (list.size() == 0))
         {
             return null;
         }
+
         return list.get(0);
     }
 
@@ -324,7 +339,7 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
      * @param storeContext
      */
     public synchronized void moveMessagesToAnotherQueue(long fromMessageId, long toMessageId, String queueName,
-                                                        StoreContext storeContext)
+        StoreContext storeContext)
     {
         // prepare the delivery manager for moving messages by stopping the async delivery and creating a lock
         AMQQueue anotherQueue = getVirtualHost().getQueueRegistry().getQueue(new AMQShortString(queueName));
@@ -460,6 +475,7 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
                throw new AMQException("Problem binding queue ", e);
             }
         }
+
         _bindings.addBinding(routingKey, arguments, exchange);
     }
 
@@ -478,25 +494,23 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
                 throw new AMQException("problem unbinding queue", e);
             }
         }
+
         _bindings.remove(routingKey, arguments, exchange);
     }
 
-
     public void registerProtocolSession(AMQProtocolSession ps, int channel, AMQShortString consumerTag, boolean acks,
-                                        FieldTable filters, boolean noLocal, boolean exclusive)
-            throws
-            AMQException
+        FieldTable filters, boolean noLocal, boolean exclusive) throws AMQException
     {
         if (incrementSubscriberCount() > 1)
         {
             if (isExclusive())
             {
                 decrementSubscriberCount();
-                throw EXISTING_EXCLUSIVE;
+                throw new ExistingExclusiveSubscription();
             } else if (exclusive)
             {
                 decrementSubscriberCount();
-                throw EXISTING_SUBSCRIPTION;
+                throw new ExistingSubscriptionPreventsExclusive();
             }
 
         } else if (exclusive)
@@ -506,12 +520,13 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
 
         if (_logger.isDebugEnabled())
         {
-            _logger.debug(MessageFormat.format("Registering protocol session {0} with channel {1} and " +
-                    "consumer tag {2} with {3}", ps, channel, consumerTag, this));
+            _logger.debug(MessageFormat.format(
+                    "Registering protocol session {0} with channel {1} and " + "consumer tag {2} with {3}", ps, channel,
+                    consumerTag, this));
         }
 
-        Subscription subscription = _subscriptionFactory.createSubscription(channel, ps, consumerTag, acks,
-                filters, noLocal, this);
+        Subscription subscription =
+            _subscriptionFactory.createSubscription(channel, ps, consumerTag, acks, filters, noLocal, this);
 
         if (subscription.filtersMessages())
         {
@@ -524,7 +539,6 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         _subscribers.addSubscriber(subscription);
     }
 
-
     private boolean isExclusive()
     {
         return _isExclusive.get();
@@ -545,25 +559,25 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         return _subscriberCount.decrementAndGet();
     }
 
-
     public void unregisterProtocolSession(AMQProtocolSession ps, int channel, AMQShortString consumerTag)
             throws
             AMQException
     {
         if (_logger.isDebugEnabled())
         {
-            _logger.debug(MessageFormat.format("Unregistering protocol session {0} with channel {1} and consumer tag {2} from {3}", ps, channel, consumerTag,
-                    this));
+            _logger.debug(MessageFormat.format(
+                    "Unregistering protocol session {0} with channel {1} and consumer tag {2} from {3}", ps, channel,
+                    consumerTag, this));
         }
 
         Subscription removedSubscription;
-        if ((removedSubscription = _subscribers.removeSubscriber(_subscriptionFactory.createSubscription(channel,
-                ps,
-                consumerTag)))
+
+        if ((removedSubscription =
+                        _subscribers.removeSubscriber(_subscriptionFactory.createSubscription(channel, ps, consumerTag)))
                 == null)
         {
-            throw new AMQException("Protocol session with channel " + channel + " and consumer tag " + consumerTag +
-                    " and protocol session key " + ps.getKey() + " not registered with queue " + this);
+            throw new AMQException("Protocol session with channel " + channel + " and consumer tag " + consumerTag
+                + " and protocol session key " + ps.getKey() + " not registered with queue " + this);
         }
 
         removedSubscription.close();
@@ -577,6 +591,7 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
             {
                 _logger.info("Auto-deleteing queue:" + this);
             }
+
             autodelete();
             // we need to manually fire the event to the removed subscription (which was the last one left for this
             // queue. This is because the delete method uses the subscription set which has just been cleared
@@ -594,7 +609,6 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         return !_deliveryMgr.hasQueuedMessages();
     }
 
-
     public int delete(boolean checkUnused, boolean checkEmpty)
             throws
             AMQException
@@ -602,14 +616,17 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         if (checkUnused && !_subscribers.isEmpty())
         {
             _logger.info("Will not delete " + this + " as it is in use.");
+
             return 0;
         } else if (checkEmpty && _deliveryMgr.hasQueuedMessages())
         {
             _logger.info("Will not delete " + this + " as it is not empty.");
+
             return 0;
         } else
         {
             delete();
+
             return _deliveryMgr.getQueueMessageCount();
         }
     }
@@ -628,6 +645,7 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
             {
                 task.doTask(this);
             }
+
             _deleteTaskList.clear();
         }
     }
@@ -640,6 +658,7 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         {
             _logger.debug(MessageFormat.format("autodeleting {0}", this));
         }
+
         delete();
     }
 
@@ -647,7 +666,7 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
             throws
             AMQException
     {
-        //fixme not sure what this is doing. should we be passing deliverFirst through here?
+        // fixme not sure what this is doing. should we be passing deliverFirst through here?
         // This code is not used so when it is perhaps it should
         _deliveryMgr.deliver(storeContext, getName(), msg, deliverFirst);
         try
@@ -663,10 +682,10 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         }
     }
 
-//    public DeliveryManager getDeliveryManager()
-//    {
-//        return _deliveryMgr;
-//    }
+    // public DeliveryManager getDeliveryManager()
+    // {
+    // return _deliveryMgr;
+    // }
 
     public void process(StoreContext storeContext, AMQMessage msg, boolean deliverFirst)
             throws
@@ -696,10 +715,10 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         }
         catch (MessageCleanupException e)
         {
-            //Message was dequeued, but could not then be deleted
-            //though it is no longer referenced. This should be very
-            //rare and can be detected and cleaned up on recovery or
-            //done through some form of manual intervention.
+            // Message was dequeued, but could not then be deleted
+            // though it is no longer referenced. This should be very
+            // rare and can be detected and cleaned up on recovery or
+            // done through some form of manual intervention.
             _logger.error(e, e);
         }
         catch (AMQException e)
@@ -743,7 +762,8 @@ public class AMQQueue implements Managable, Comparable, StorableQueue
         {
             return true;
         }
-        if (o == null || getClass() != o.getClass())
+
+        if ((o == null) || (getClass() != o.getClass()))
         {
             return false;
         }
diff --git a/java/broker/src/main/java/org/apache/qpid/server/queue/FailedDequeueException.java b/java/broker/src/main/java/org/apache/qpid/server/queue/FailedDequeueException.java
index b74c49e6e1..6466e81dd2 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/queue/FailedDequeueException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/queue/FailedDequeueException.java
@@ -7,9 +7,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -23,7 +23,18 @@ package org.apache.qpid.server.queue;
 import org.apache.qpid.AMQException;
 
 /**
- * Signals that the dequeue of a message from a queue failed
+ * Signals that the dequeue of a message from a queue failed.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Indicates the a message could not be dequeued from a queue.
+ * <tr><td>
+ * </table>
+ *
+ * @todo Not an AMQP exception as no status code.
+ *
+ * @todo Happens as a consequence of a message store failure, or reference counting error. Both of which migh become
+ *       runtime exceptions, as unrecoverable conditions? In which case this one might be dropped too.
  */
 public class FailedDequeueException extends AMQException
 {
diff --git a/java/broker/src/main/java/org/apache/qpid/server/queue/MessageCleanupException.java b/java/broker/src/main/java/org/apache/qpid/server/queue/MessageCleanupException.java
index 1e7e6f03d2..090096d3c3 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/queue/MessageCleanupException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/queue/MessageCleanupException.java
@@ -7,9 +7,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -23,8 +23,20 @@ package org.apache.qpid.server.queue;
 import org.apache.qpid.AMQException;
 
 /**
- * Signals that the removal of a message once its refcount reached
- * zero failed.
+ * MessageCleanupException represents the failure to perform reference counting on messages correctly. This should not
+ * happen, but there may be programming errors giving race conditions that cause the reference counting to go wrong.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Signals that the reference count of a message has gone below zero.
+ * <tr><td> Indicates that a message store has lost a message which is still referenced.
+ * </table>
+ *
+ * @todo Not an AMQP exception as no status code.
+ *
+ * @todo The race conditions leading to this error should be cleaned up, and a runtime exception used instead. If the
+ *       message store loses messages, then something is seriously wrong and it would be sensible to terminate the
+ *       broker. This may be disguising out of memory errors.
  */
 public class MessageCleanupException extends AMQException
 {
@@ -32,6 +44,7 @@ public class MessageCleanupException extends AMQException
     {
         super("Failed to cleanup message with id " + messageId, e);
     }
+
     public MessageCleanupException(String message)
     {
         super(message);
diff --git a/java/broker/src/main/java/org/apache/qpid/server/queue/NoConsumersException.java b/java/broker/src/main/java/org/apache/qpid/server/queue/NoConsumersException.java
index c63490f019..d6fd1eec89 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/queue/NoConsumersException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/queue/NoConsumersException.java
@@ -7,9 +7,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -24,9 +24,14 @@ import org.apache.qpid.protocol.AMQConstant;
 import org.apache.qpid.server.RequiredDeliveryException;
 
 /**
- * Signals that no consumers exist for a message at a given point in time.
- * Used if a message has immediate=true and there are no consumers registered
- * with the queue.
+ * NoConsumersException is a {@link RequiredDeliveryException} that represents the failure case where an immediate
+ * message cannot be delivered because there are presently no consumers for the message. The AMQP status code, 313, is
+ * always used to report this condition.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Represent failure to deliver a message that must be delivered.
+ * </table>
  */
 public class NoConsumersException extends RequiredDeliveryException
 {
diff --git a/java/broker/src/main/java/org/apache/qpid/server/state/AMQStateManager.java b/java/broker/src/main/java/org/apache/qpid/server/state/AMQStateManager.java
index 50129ec274..f96900d0a9 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/state/AMQStateManager.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/state/AMQStateManager.java
@@ -26,6 +26,7 @@ import java.util.Map;
 import java.util.concurrent.CopyOnWriteArraySet;
 
 import org.apache.log4j.Logger;
+
 import org.apache.qpid.AMQException;
 import org.apache.qpid.framing.AMQMethodBody;
 import org.apache.qpid.framing.BasicAckBody;
@@ -35,6 +36,7 @@ import org.apache.qpid.framing.BasicGetBody;
 import org.apache.qpid.framing.BasicPublishBody;
 import org.apache.qpid.framing.BasicQosBody;
 import org.apache.qpid.framing.BasicRecoverBody;
+import org.apache.qpid.framing.BasicRejectBody;
 import org.apache.qpid.framing.ChannelCloseBody;
 import org.apache.qpid.framing.ChannelCloseOkBody;
 import org.apache.qpid.framing.ChannelFlowBody;
@@ -55,7 +57,6 @@ import org.apache.qpid.framing.QueuePurgeBody;
 import org.apache.qpid.framing.TxCommitBody;
 import org.apache.qpid.framing.TxRollbackBody;
 import org.apache.qpid.framing.TxSelectBody;
-import org.apache.qpid.framing.BasicRejectBody;
 import org.apache.qpid.protocol.AMQMethodEvent;
 import org.apache.qpid.protocol.AMQMethodListener;
 import org.apache.qpid.server.handler.BasicAckMethodHandler;
@@ -65,6 +66,7 @@ import org.apache.qpid.server.handler.BasicGetMethodHandler;
 import org.apache.qpid.server.handler.BasicPublishMethodHandler;
 import org.apache.qpid.server.handler.BasicQosHandler;
 import org.apache.qpid.server.handler.BasicRecoverMethodHandler;
+import org.apache.qpid.server.handler.BasicRejectMethodHandler;
 import org.apache.qpid.server.handler.ChannelCloseHandler;
 import org.apache.qpid.server.handler.ChannelCloseOkHandler;
 import org.apache.qpid.server.handler.ChannelFlowHandler;
@@ -83,9 +85,8 @@ import org.apache.qpid.server.handler.QueueDeclareHandler;
 import org.apache.qpid.server.handler.QueueDeleteHandler;
 import org.apache.qpid.server.handler.QueuePurgeHandler;
 import org.apache.qpid.server.handler.TxCommitHandler;
-import org.apache.qpid.server.handler.BasicRejectMethodHandler;
-import org.apache.qpid.server.handler.TxSelectHandler;
 import org.apache.qpid.server.handler.TxRollbackHandler;
+import org.apache.qpid.server.handler.TxSelectHandler;
 import org.apache.qpid.server.protocol.AMQProtocolSession;
 import org.apache.qpid.server.virtualhost.VirtualHostRegistry;
 
@@ -107,18 +108,18 @@ public class AMQStateManager implements AMQMethodListener
      * AMQFrame.
      */
     private final EnumMap<AMQState, Map<Class<? extends AMQMethodBody>, StateAwareMethodListener<? extends AMQMethodBody>>> _state2HandlersMap =
-            new EnumMap<AMQState, Map<Class<? extends AMQMethodBody>, StateAwareMethodListener<? extends AMQMethodBody>>>(AMQState.class);
-
+        new EnumMap<AMQState, Map<Class<? extends AMQMethodBody>, StateAwareMethodListener<? extends AMQMethodBody>>>(
+            AMQState.class);
 
     private CopyOnWriteArraySet<StateListener> _stateListeners = new CopyOnWriteArraySet<StateListener>();
 
-
     public AMQStateManager(VirtualHostRegistry virtualHostRegistry, AMQProtocolSession protocolSession)
     {
         this(AMQState.CONNECTION_NOT_STARTED, true, virtualHostRegistry, protocolSession);
     }
 
-    protected AMQStateManager(AMQState initial, boolean register, VirtualHostRegistry virtualHostRegistry, AMQProtocolSession protocolSession)
+    protected AMQStateManager(AMQState initial, boolean register, VirtualHostRegistry virtualHostRegistry,
+        AMQProtocolSession protocolSession)
     {
         _virtualHostRegistry = virtualHostRegistry;
         _protocolSession = protocolSession;
@@ -220,37 +221,38 @@ public class AMQStateManager implements AMQMethodListener
             checkChannel(evt, _protocolSession);
 
             handler.methodReceived(this, evt);
+
             return true;
         }
+
         return false;
     }
 
     private <B extends AMQMethodBody> void checkChannel(AMQMethodEvent<B> evt, AMQProtocolSession protocolSession)
-            throws AMQException
+        throws AMQException
     {
-        if (evt.getChannelId() != 0
-            && !(evt.getMethod() instanceof ChannelOpenBody)
-            && (protocolSession.getChannel(evt.getChannelId()) == null)
-            && !protocolSession.channelAwaitingClosure(evt.getChannelId()))
+        if ((evt.getChannelId() != 0) && !(evt.getMethod() instanceof ChannelOpenBody)
+                && (protocolSession.getChannel(evt.getChannelId()) == null)
+                && !protocolSession.channelAwaitingClosure(evt.getChannelId()))
         {
             throw evt.getMethod().getChannelNotFoundException(evt.getChannelId());
         }
     }
 
     protected <B extends AMQMethodBody> StateAwareMethodListener<B> findStateTransitionHandler(AMQState currentState,
-                                                                                               B frame)
-            throws IllegalStateTransitionException
+        B frame)
+    // throws IllegalStateTransitionException
     {
-        final Map<Class<? extends AMQMethodBody>, StateAwareMethodListener<? extends AMQMethodBody>>
-                classToHandlerMap = _state2HandlersMap.get(currentState);
+        final Map<Class<? extends AMQMethodBody>, StateAwareMethodListener<? extends AMQMethodBody>> classToHandlerMap =
+            _state2HandlersMap.get(currentState);
 
-        final StateAwareMethodListener<B> handler = classToHandlerMap == null
-                                                    ? null
-                                                    : (StateAwareMethodListener<B>) classToHandlerMap.get(frame.getClass());
+        final StateAwareMethodListener<B> handler =
+            (classToHandlerMap == null) ? null : (StateAwareMethodListener<B>) classToHandlerMap.get(frame.getClass());
 
         if (handler == null)
         {
             _logger.debug("No state transition handler defined for receiving frame " + frame);
+
             return null;
         }
         else
diff --git a/java/broker/src/main/java/org/apache/qpid/server/state/IllegalStateTransitionException.java b/java/broker/src/main/java/org/apache/qpid/server/state/IllegalStateTransitionException.java
index 2d7cc27a85..cec67a8a6d 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/state/IllegalStateTransitionException.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/state/IllegalStateTransitionException.java
@@ -7,9 +7,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -22,6 +22,11 @@ package org.apache.qpid.server.state;
 
 import org.apache.qpid.AMQException;
 
+/**
+ * @todo Not an AMQP exception as no status code.
+ *
+ * @todo Not used! Delete.
+ */
 public class IllegalStateTransitionException extends AMQException
 {
     private AMQState _originalState;
@@ -30,8 +35,7 @@ public class IllegalStateTransitionException extends AMQException
 
     public IllegalStateTransitionException(AMQState originalState, Class frame)
     {
-        super("No valid state transition defined for receiving frame " + frame +
-              " from state " + originalState);
+        super("No valid state transition defined for receiving frame " + frame + " from state " + originalState);
         _originalState = originalState;
         _frame = frame;
     }