summaryrefslogtreecommitdiff
path: root/java/broker/src/main/java/org/apache/qpid/server/queue/AMQQueue.java
blob: 7f3d772e4707973031b19174698a6d95779e6025 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * 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
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 */
package org.apache.qpid.server.queue;

import org.apache.log4j.Logger;
import org.apache.qpid.AMQException;
import org.apache.qpid.framing.ContentBody;
import org.apache.qpid.framing.ContentHeaderBody;
import org.apache.qpid.framing.BasicContentHeaderProperties;
import org.apache.qpid.server.exchange.Exchange;
import org.apache.qpid.server.management.*;
import org.apache.qpid.server.protocol.AMQProtocolSession;
import org.apache.mina.common.ByteBuffer;

import javax.management.*;
import javax.management.monitor.MonitorNotification;
import javax.management.openmbean.*;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Executor;

/**
 * This is an AMQ Queue, and should not be confused with a JMS queue or any other abstraction like
 * that. It is described fully in RFC 006.
 */
public class AMQQueue implements Managable, Comparable
{
    private static final Logger _logger = Logger.getLogger(AMQQueue.class);

    private final String _name;

    /**
     * null means shared
     */
    private final String _owner;

    private final boolean _durable;

    /**
     * If true, this queue is deleted when the last subscriber is removed
     */
    private final boolean _autoDelete;

    /**
     * Holds subscribers to the queue.
     */
    private final SubscriptionSet _subscribers;

    private final SubscriptionFactory _subscriptionFactory;

    /**
     * Manages message delivery.
     */
    private final DeliveryManager _deliveryMgr;

    /**
     * The queue registry with which this queue is registered.
     */
    private final QueueRegistry _queueRegistry;

    /**
     * Used to track bindings to exchanges so that on deletion they can easily
     * be cancelled.
     */
    private final ExchangeBindings _bindings = new ExchangeBindings(this);

    /**
     * Executor on which asynchronous delivery will be carriedout where required
     */
    private final Executor _asyncDelivery;

    private final AMQQueueMBean _managedObject;

    /**
     * max allowed size(KB) of a single message
     */
    private long _maxMessageSize = 10000;

    /**
     * max allowed number of messages on a queue.
     */
    private Integer _maxMessageCount = 10000;

    /**
     * max queue depth(KB) for the queue
     */
    private long _maxQueueDepth = 10000000;

    /**
     * total messages received by the queue since startup.
     */
    private long _totalMessagesReceived = 0;

    public int compareTo(Object o)
    {
        return _name.compareTo(((AMQQueue) o).getName());
    }

    /**
     * MBean class for AMQQueue. It implements all the management features exposed
     * for an AMQQueue.
     */
    @MBeanDescription("Management Interface for AMQQueue")
    private final class AMQQueueMBean extends AMQManagedObject implements ManagedQueue
    {
        private String _queueName = null;
        // OpenMBean data types for viewMessages method
        private String[] _msgAttributeNames = {"Message Id", "Header", "Size(bytes)", "Redelivered"};
        private String[] _msgAttributeIndex = {_msgAttributeNames[0]};
        private OpenType[] _msgAttributeTypes = new OpenType[4]; // AMQ message attribute types.
        private CompositeType _messageDataType = null;           // Composite type for representing AMQ Message data.
        private TabularType _messagelistDataType = null;         // Datatype for representing AMQ messages list.

        // OpenMBean data types for viewMessageContent method
        private CompositeType _msgContentType = null;
        private String[]      _msgContentAttributes = {"Message Id", "MimeType", "Encoding", "Content"};
        private OpenType[]    _msgContentAttributeTypes = new OpenType[4];

        @MBeanConstructor("Creates an MBean exposing an AMQQueue")
        public AMQQueueMBean() throws JMException
        {
            super(ManagedQueue.class, ManagedQueue.TYPE);
            init();
        }

        /**
         * initialises the openmbean data types
         */
        private void init() throws OpenDataException
        {
            _queueName = jmxEncode(new StringBuffer(_name), 0).toString();
            _msgContentAttributeTypes[0] = SimpleType.LONG;                    // For message id
            _msgContentAttributeTypes[1] = SimpleType.STRING;                  // For MimeType
            _msgContentAttributeTypes[2] = SimpleType.STRING;                  // For Encoding
            _msgContentAttributeTypes[3] = new ArrayType(1, SimpleType.BYTE);  // For message content
            _msgContentType = new CompositeType("Message Content", "AMQ Message Content", _msgContentAttributes,
                                                 _msgContentAttributes, _msgContentAttributeTypes);

            _msgAttributeTypes[0] = SimpleType.LONG;                      // For message id
            _msgAttributeTypes[1] = new ArrayType(1, SimpleType.STRING);  // For header attributes
            _msgAttributeTypes[2] = SimpleType.LONG;                      // For size
            _msgAttributeTypes[3] = SimpleType.BOOLEAN;                   // For redelivered

            _messageDataType = new CompositeType("Message","AMQ Message", _msgAttributeNames, _msgAttributeNames, _msgAttributeTypes);
            _messagelistDataType = new TabularType("Messages", "List of messages", _messageDataType, _msgAttributeIndex);
        }

        public String getObjectInstanceName()
        {
            return _queueName;
        }

        public String getName()
        {
            return _name;
        }

        public boolean isDurable()
        {
            return _durable;
        }

        public String getOwner()
        {
            return _owner;
        }

        public boolean isAutoDelete()
        {
            return _autoDelete;
        }

        public Integer getMessageCount()
        {
            return _deliveryMgr.getQueueMessageCount();
        }

        public Long getMaximumMessageSize()
        {
            return _maxMessageSize;
        }

        public void setMaximumMessageSize(Long value)
        {
            _maxMessageSize = value;
        }

        public Integer getConsumerCount()
        {
            return _subscribers.size();
        }

        public Integer getActiveConsumerCount()
        {
            return _subscribers.getWeight();
        }

        public Long getReceivedMessageCount()
        {
            return _totalMessagesReceived;
        }

        public Integer getMaximumMessageCount()
        {
            return _maxMessageCount;
        }

        public void setMaximumMessageCount(Integer value)
        {
            _maxMessageCount = value;
        }

        public Long getMaximumQueueDepth()
        {
            return _maxQueueDepth;
        }

        // Sets the queue depth, the max queue size
        public void setMaximumQueueDepth(Long value)
        {
            _maxQueueDepth = value;
        }

        /**
         * returns the size of messages(KB) in the queue.
         */
        public Long getQueueDepth()
        {
            /* TODO: this must return a maintained count not
             * iterate through all messages
             */
            return 0L;
            /*List<AMQMessage> list = _deliveryMgr.getMessages();
            if (list.size() == 0)
            {
                return 0l;
            }

            long queueDepth = 0;
            for (AMQMessage message : list)
            {
                queueDepth = queueDepth + getMessageSize(message);
            }
            return (long)Math.round(queueDepth / 1000);
            */
        }
        // Operations

        /**
         * returns size of message in bytes
         */
        private long getMessageSize(AMQMessage msg) throws AMQException
        {
            if (msg == null)
            {
                return 0L;
            }

            return msg.getContentHeaderBody().bodySize;
        }

        /**
         * Checks if there is any notification to be send to the listeners
         */
        private void checkForNotification(AMQMessage msg) throws AMQException
        {
            // Check for threshold message count
            Integer msgCount = getMessageCount();
            if (msgCount >= getMaximumMessageCount())
            {
                notifyClients("Message count(" + msgCount + ") has reached or exceeded the threshold high value");
            }

            // Check for threshold message size
            long messageSize = getMessageSize(msg);
            if (messageSize >= _maxMessageSize)
            {
                notifyClients("Message size(ID=" + msg.getMessageId() + ", size=" + messageSize + " bytes) is higher than the threshold value");
            }

            // Check for threshold queue depth in bytes
            long queueDepth = getQueueDepth();
            if (queueDepth >= _maxQueueDepth)
            {
                notifyClients("Queue depth(" + queueDepth + "), Queue size has reached the threshold high value");
            }
        }

        /**
         * Sends the notification to the listeners
         */
        private void notifyClients(String notificationMsg)
        {
            Notification n = new Notification(MonitorNotification.THRESHOLD_VALUE_EXCEEDED, this,
                                 ++_notificationSequenceNumber, System.currentTimeMillis(), notificationMsg);

            _broadcaster.sendNotification(n);
        }

        public void deleteMessageFromTop() throws JMException
        {
            try
            {
                _deliveryMgr.removeAMessageFromTop();
            }
            catch (AMQException ex)
            {
                throw new MBeanException(ex, ex.toString());
            }
        }

        public void clearQueue() throws JMException
        {
            try
            {
                _deliveryMgr.clearAllMessages();
            }
            catch (AMQException ex)
            {
                throw new MBeanException(ex, ex.toString());
            }
        }

        /**
         * returns message content as byte array and related attributes for the given message id.
         */
        public CompositeData viewMessageContent(long msgId) throws JMException
        {
            List<AMQMessage> list = _deliveryMgr.getMessages();
            AMQMessage msg = null;
            for (AMQMessage message : list)
            {
                if (message.getMessageId() == msgId)
                {
                    msg = message;
                    break;
                }
            }

            if (msg != null)
            {
                try
                {
                    // get message content
                    Iterator<ContentBody> cBodies = msg.getContentBodyIterator();
                    List<Byte> msgContent = new ArrayList<Byte>();
                    while (cBodies.hasNext())
                    {
                        ContentBody body = cBodies.next();
                        if (body.getSize() != 0)
                        {
                            ByteBuffer slice = body.payload.slice();
                            for (int j = 0; j < slice.limit(); j++)
                            {
                                msgContent.add(slice.get());
                            }
                        }
                    }

                    // Create header attributes list
                    BasicContentHeaderProperties headerProperties = (BasicContentHeaderProperties)msg.getContentHeaderBody().properties;
                    String mimeType = headerProperties.getContentType();
                    String encoding = headerProperties.getEncoding() == null ? "" : headerProperties.getEncoding();
                    Object[] itemValues = {msgId, mimeType, encoding, msgContent.toArray(new Byte[0])};

                    return new CompositeDataSupport(_msgContentType, _msgContentAttributes, itemValues);
                }
                catch (AMQException e)
                {
                    throw new JMException(e.getMessage());
                }
            }
            else
            {
                throw new OperationsException("AMQMessage with message id = " + msgId + " is not in the " + _queueName);
            }
        }

        /**
         * Returns the header contents of the messages stored in this queue in tabular form.
         */
        public TabularData viewMessages(int beginIndex, int endIndex) throws JMException, AMQException
        {
            if ((beginIndex > endIndex) || (beginIndex < 1))
            {
                throw new JMException("From Index = " + beginIndex + ", To Index = " + endIndex +
                                      "\nFrom Index should be greater than 0 and less than To Index");
            }

            List<AMQMessage> list = _deliveryMgr.getMessages();
            TabularDataSupport _messageList = new TabularDataSupport(_messagelistDataType);

            // Create the tabular list of message header contents
            for (int i = beginIndex; i <= endIndex && i <=  list.size(); i++)
            {
                AMQMessage msg = list.get(i - 1);
                ContentHeaderBody headerBody = msg.getContentHeaderBody();
                long size = headerBody.bodySize;
                // Create header attributes list
                BasicContentHeaderProperties headerProperties = (BasicContentHeaderProperties)headerBody.properties;
                List<String> headerAttribsList = new ArrayList<String>();
                headerAttribsList.add("App Id=" + headerProperties.getAppId());
                headerAttribsList.add("MimeType=" + headerProperties.getContentType());
                headerAttribsList.add("Correlation Id=" + headerProperties.getCorrelationId());
                headerAttribsList.add("Encoding=" + headerProperties.getEncoding());
                headerAttribsList.add(headerProperties.toString());

                Object[] itemValues = {msg.getMessageId(), headerAttribsList.toArray(new String[0]),
                                       headerBody.bodySize, msg.isRedelivered()};
                CompositeData messageData = new CompositeDataSupport(_messageDataType, _msgAttributeNames, itemValues);
                _messageList.put(messageData);
            }

            return _messageList;
        }

        /**
         * returns Notifications sent by this MBean.
         */
        @Override
        public MBeanNotificationInfo[] getNotificationInfo()
        {
            String[] notificationTypes = new String[] {MonitorNotification.THRESHOLD_VALUE_EXCEEDED};
            String name = MonitorNotification.class.getName();
            String description = "Either Message count or Queue depth or Message size has reached threshold high value";
            MBeanNotificationInfo info1 = new MBeanNotificationInfo(notificationTypes, name, description);

            return new MBeanNotificationInfo[]{info1};
        }

    } // End of AMQMBean class

    public AMQQueue(String name, boolean durable, String owner,
                    boolean autoDelete, QueueRegistry queueRegistry)
            throws AMQException
    {
        this(name, durable, owner, autoDelete, queueRegistry,
             AsyncDeliveryConfig.getAsyncDeliveryExecutor(), new SubscriptionImpl.Factory());
    }

    public AMQQueue(String name, boolean durable, String owner,
                    boolean autoDelete, QueueRegistry queueRegistry, SubscriptionFactory subscriptionFactory)
            throws AMQException
    {
        this(name, durable, owner, autoDelete, queueRegistry,
             AsyncDeliveryConfig.getAsyncDeliveryExecutor(), subscriptionFactory);
    }

    public AMQQueue(String name, boolean durable, String owner,
                    boolean autoDelete, QueueRegistry queueRegistry, Executor asyncDelivery,
                    SubscriptionFactory subscriptionFactory)
            throws AMQException
    {

        this(name, durable, owner, autoDelete, queueRegistry, asyncDelivery, new SubscriptionSet(), subscriptionFactory);
    }

    public AMQQueue(String name, boolean durable, String owner,
                    boolean autoDelete, QueueRegistry queueRegistry, Executor asyncDelivery)
            throws AMQException
    {

        this(name, durable, owner, autoDelete, queueRegistry, asyncDelivery, new SubscriptionSet(),
             new SubscriptionImpl.Factory());
    }

    protected AMQQueue(String name, boolean durable, String owner,
                       boolean autoDelete, QueueRegistry queueRegistry,
                       SubscriptionSet subscribers, SubscriptionFactory subscriptionFactory)
            throws AMQException
    {
        this(name, durable, owner, autoDelete, queueRegistry,
             AsyncDeliveryConfig.getAsyncDeliveryExecutor(), subscribers, subscriptionFactory);
    }

    protected AMQQueue(String name, boolean durable, String owner,
                       boolean autoDelete, QueueRegistry queueRegistry,
                       SubscriptionSet subscribers)
            throws AMQException
    {
        this(name, durable, owner, autoDelete, queueRegistry,
             AsyncDeliveryConfig.getAsyncDeliveryExecutor(), subscribers, new SubscriptionImpl.Factory());
    }

    protected AMQQueue(String name, boolean durable, String owner,
                       boolean autoDelete, QueueRegistry queueRegistry,
                       Executor asyncDelivery, SubscriptionSet subscribers, SubscriptionFactory subscriptionFactory)
            throws AMQException
    {
        if (name == null)
        {
            throw new IllegalArgumentException("Queue name must not be null");
        }
        if (queueRegistry == null)
        {
            throw new IllegalArgumentException("Queue registry must not be null");
        }
        _name = name;
        _durable = durable;
        _owner = owner;
        _autoDelete = autoDelete;
        _queueRegistry = queueRegistry;
        _asyncDelivery = asyncDelivery;
        _managedObject = createMBean();
        _managedObject.register();
        _subscribers = subscribers;
        _subscriptionFactory = subscriptionFactory;

        //fixme - Pick one.
        if (Boolean.getBoolean("concurrentdeliverymanager"))
        {
            _logger.info("Using ConcurrentDeliveryManager");
            _deliveryMgr = new ConcurrentDeliveryManager(_subscribers, this);
        }
        else
        {
            _logger.info("Using SynchronizedDeliveryManager");
            _deliveryMgr = new SynchronizedDeliveryManager(_subscribers, this);
        }
    }

    private AMQQueueMBean createMBean() throws AMQException
    {
        try
        {
            return new AMQQueueMBean();
        }
        catch (JMException ex)
        {
            throw new AMQException("AMQQueue MBean creation has failed ", ex);
        }
    }

    public String getName()
    {
        return _name;
    }

    public boolean isShared()
    {
        return _owner == null;
    }

    public boolean isDurable()
    {
        return _durable;
    }

    public String getOwner()
    {
        return _owner;
    }

    public boolean isAutoDelete()
    {
        return _autoDelete;
    }

    public int getMessageCount()
    {
        return _deliveryMgr.getQueueMessageCount();
    }

    public ManagedObject getManagedObject()
    {
        return _managedObject;
    }

    public void bind(String routingKey, Exchange exchange)
    {
        _bindings.addBinding(routingKey, exchange);
    }

    public void registerProtocolSession(AMQProtocolSession ps, int channel, String consumerTag, boolean acks)
            throws AMQException
    {
        debug("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);
        _subscribers.addSubscriber(subscription);
    }

    public void unregisterProtocolSession(AMQProtocolSession ps, int channel, String consumerTag) throws AMQException
    {
        debug("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)))
            == null)
        {
            throw new AMQException("Protocol session with channel " + channel + " and consumer tag " + consumerTag +
                                   " and protocol session key " + ps.getKey() + " not registered with queue " + this);
        }

        // if we are eligible for auto deletion, unregister from the queue registry
        if (_autoDelete && _subscribers.isEmpty())
        {
            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
            removedSubscription.queueDeleted(this);
        }
    }

    public int delete(boolean checkUnused, boolean checkEmpty) throws AMQException
    {
        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();
        }
    }

    public void delete() throws AMQException
    {
        _subscribers.queueDeleted(this);
        _bindings.deregister();
        _queueRegistry.unregisterQueue(_name);
        _managedObject.unregister();
    }

    protected void autodelete() throws AMQException
    {
        debug("autodeleting {0}", this);
        delete();
    }

    /*public void deliver(AMQMessage msg) throws AMQException
    {
        TxnBuffer buffer = msg.getTxnBuffer();
        if(buffer == null)
        {
            //non-transactional
            record(msg);
            process(msg);
        }
        else
        {
            buffer.enlist(new Deliver(msg));
        }
    } */

    /*private void record(AMQMessage msg) throws AMQException
    {
        msg.enqueue(this);
        msg.incrementReference();
    } */

    public void process(AMQMessage msg) throws AMQException
    {
        _deliveryMgr.deliver(getName(), msg);
        try
        {
            msg.checkDeliveredToConsumer();
            updateReceivedMessageCount(msg);
        }
        catch (NoConsumersException e)
        {
            // as this message will be returned, it should be removed
            // from the queue:
            dequeue(msg);
        }
    }

    void dequeue(AMQMessage msg) throws FailedDequeueException
    {
        try
        {
            msg.dequeue(this);
            msg.decrementReference();
        }
        catch (MessageCleanupException e)
        {
            //Message was dequeued, but could notthen 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)
        {
            throw new FailedDequeueException(_name, e);
        }
    }

    public void deliverAsync()
    {
        _deliveryMgr.processAsync(_asyncDelivery);
    }

    protected SubscriptionManager getSubscribers()
    {
        return _subscribers;
    }

    protected void updateReceivedMessageCount(AMQMessage msg) throws AMQException
    {
        _totalMessagesReceived++;
        _managedObject.checkForNotification(msg);
    }

    public boolean equals(Object o)
    {
        if (this == o)
        {
            return true;
        }
        if (o == null || getClass() != o.getClass())
        {
            return false;
        }

        final AMQQueue amqQueue = (AMQQueue) o;

        return (_name.equals(amqQueue._name));
    }

    public int hashCode()
    {
        return _name.hashCode();
    }

    public String toString()
    {
        return "Queue(" + _name + ")@" + System.identityHashCode(this);
    }

    private void debug(String msg, Object... args)
    {
        if (_logger.isDebugEnabled())
        {
            _logger.debug(MessageFormat.format(msg, args));
        }
    }
}