001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.activemq.broker.region.cursors;
018
019 import java.io.IOException;
020 import java.util.Iterator;
021 import java.util.LinkedList;
022 import java.util.concurrent.atomic.AtomicBoolean;
023 import java.util.concurrent.atomic.AtomicLong;
024 import org.apache.activemq.broker.Broker;
025 import org.apache.activemq.broker.ConnectionContext;
026 import org.apache.activemq.broker.region.Destination;
027 import org.apache.activemq.broker.region.MessageReference;
028 import org.apache.activemq.broker.region.QueueMessageReference;
029 import org.apache.activemq.command.Message;
030 import org.apache.activemq.filter.NonCachedMessageEvaluationContext;
031 import org.apache.activemq.openwire.OpenWireFormat;
032 import org.apache.activemq.store.kahadb.plist.PList;
033 import org.apache.activemq.store.kahadb.plist.PListEntry;
034 import org.apache.activemq.store.kahadb.plist.PListStore;
035 import org.apache.activemq.usage.SystemUsage;
036 import org.apache.activemq.usage.Usage;
037 import org.apache.activemq.usage.UsageListener;
038 import org.apache.activemq.wireformat.WireFormat;
039 import org.slf4j.Logger;
040 import org.slf4j.LoggerFactory;
041 import org.apache.kahadb.util.ByteSequence;
042
043 /**
044 * persist pending messages pending message (messages awaiting dispatch to a
045 * consumer) cursor
046 *
047 *
048 */
049 public class FilePendingMessageCursor extends AbstractPendingMessageCursor implements UsageListener {
050 static final Logger LOG = LoggerFactory.getLogger(FilePendingMessageCursor.class);
051 private static final AtomicLong NAME_COUNT = new AtomicLong();
052 protected Broker broker;
053 private final PListStore store;
054 private final String name;
055 private LinkedList<MessageReference> memoryList = new LinkedList<MessageReference>();
056 private PList diskList;
057 private Iterator<MessageReference> iter;
058 private Destination regionDestination;
059 private boolean iterating;
060 private boolean flushRequired;
061 private final AtomicBoolean started = new AtomicBoolean();
062 private final WireFormat wireFormat = new OpenWireFormat();
063 /**
064 * @param broker
065 * @param name
066 * @param prioritizedMessages
067 */
068 public FilePendingMessageCursor(Broker broker, String name, boolean prioritizedMessages) {
069 super(prioritizedMessages);
070 this.broker = broker;
071 // the store can be null if the BrokerService has persistence
072 // turned off
073 this.store = broker.getTempDataStore();
074 this.name = NAME_COUNT.incrementAndGet() + "_" + name;
075 }
076
077 @Override
078 public void start() throws Exception {
079 if (started.compareAndSet(false, true)) {
080 super.start();
081 if (systemUsage != null) {
082 systemUsage.getMemoryUsage().addUsageListener(this);
083 }
084 }
085 }
086
087 @Override
088 public void stop() throws Exception {
089 if (started.compareAndSet(true, false)) {
090 super.stop();
091 if (systemUsage != null) {
092 systemUsage.getMemoryUsage().removeUsageListener(this);
093 }
094 }
095 }
096
097 /**
098 * @return true if there are no pending messages
099 */
100 @Override
101 public synchronized boolean isEmpty() {
102 if (memoryList.isEmpty() && isDiskListEmpty()) {
103 return true;
104 }
105 for (Iterator<MessageReference> iterator = memoryList.iterator(); iterator.hasNext();) {
106 MessageReference node = iterator.next();
107 if (node == QueueMessageReference.NULL_MESSAGE) {
108 continue;
109 }
110 if (!node.isDropped()) {
111 return false;
112 }
113 // We can remove dropped references.
114 iterator.remove();
115 }
116 return isDiskListEmpty();
117 }
118
119 /**
120 * reset the cursor
121 */
122 @Override
123 public synchronized void reset() {
124 iterating = true;
125 last = null;
126 if (isDiskListEmpty()) {
127 this.iter = this.memoryList.iterator();
128 } else {
129 this.iter = new DiskIterator();
130 }
131 }
132
133 @Override
134 public synchronized void release() {
135 iterating = false;
136 if (flushRequired) {
137 flushRequired = false;
138 flushToDisk();
139 }
140 }
141
142 @Override
143 public synchronized void destroy() throws Exception {
144 stop();
145 for (Iterator<MessageReference> i = memoryList.iterator(); i.hasNext();) {
146 Message node = (Message) i.next();
147 node.decrementReferenceCount();
148 }
149 memoryList.clear();
150 destroyDiskList();
151 }
152
153 private void destroyDiskList() throws Exception {
154 if (!isDiskListEmpty()) {
155 store.removePList(name);
156 }
157 }
158
159 @Override
160 public synchronized LinkedList<MessageReference> pageInList(int maxItems) {
161 LinkedList<MessageReference> result = new LinkedList<MessageReference>();
162 int count = 0;
163 for (Iterator<MessageReference> i = memoryList.iterator(); i.hasNext() && count < maxItems;) {
164 MessageReference ref = i.next();
165 ref.incrementReferenceCount();
166 result.add(ref);
167 count++;
168 }
169 if (count < maxItems && !isDiskListEmpty()) {
170 for (Iterator<MessageReference> i = new DiskIterator(); i.hasNext() && count < maxItems;) {
171 Message message = (Message) i.next();
172 message.setRegionDestination(regionDestination);
173 message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
174 message.incrementReferenceCount();
175 result.add(message);
176 count++;
177 }
178 }
179 return result;
180 }
181
182 /**
183 * add message to await dispatch
184 *
185 * @param node
186 * @throws Exception
187 */
188 @Override
189 public synchronized void addMessageLast(MessageReference node) throws Exception {
190 tryAddMessageLast(node, 0);
191 }
192
193 @Override
194 public synchronized boolean tryAddMessageLast(MessageReference node, long maxWaitTime) throws Exception {
195 if (!node.isExpired()) {
196 try {
197 regionDestination = node.getMessage().getRegionDestination();
198 if (isDiskListEmpty()) {
199 if (hasSpace() || this.store == null) {
200 memoryList.add(node);
201 node.incrementReferenceCount();
202 setCacheEnabled(true);
203 return true;
204 }
205 }
206 if (!hasSpace()) {
207 if (isDiskListEmpty()) {
208 expireOldMessages();
209 if (hasSpace()) {
210 memoryList.add(node);
211 node.incrementReferenceCount();
212 return true;
213 } else {
214 flushToDisk();
215 }
216 }
217 }
218 if (systemUsage.getTempUsage().waitForSpace(maxWaitTime)) {
219 ByteSequence bs = getByteSequence(node.getMessage());
220 getDiskList().addLast(node.getMessageId().toString(), bs);
221 return true;
222 }
223 return false;
224
225 } catch (Exception e) {
226 LOG.error("Caught an Exception adding a message: " + node + " first to FilePendingMessageCursor ", e);
227 throw new RuntimeException(e);
228 }
229 } else {
230 discard(node);
231 }
232 //message expired
233 return true;
234 }
235
236 /**
237 * add message to await dispatch
238 *
239 * @param node
240 */
241 @Override
242 public synchronized void addMessageFirst(MessageReference node) {
243 if (!node.isExpired()) {
244 try {
245 regionDestination = node.getMessage().getRegionDestination();
246 if (isDiskListEmpty()) {
247 if (hasSpace()) {
248 memoryList.addFirst(node);
249 node.incrementReferenceCount();
250 setCacheEnabled(true);
251 return;
252 }
253 }
254 if (!hasSpace()) {
255 if (isDiskListEmpty()) {
256 expireOldMessages();
257 if (hasSpace()) {
258 memoryList.addFirst(node);
259 node.incrementReferenceCount();
260 return;
261 } else {
262 flushToDisk();
263 }
264 }
265 }
266 systemUsage.getTempUsage().waitForSpace();
267 node.decrementReferenceCount();
268 ByteSequence bs = getByteSequence(node.getMessage());
269 getDiskList().addFirst(node.getMessageId().toString(), bs);
270
271 } catch (Exception e) {
272 LOG.error("Caught an Exception adding a message: " + node + " first to FilePendingMessageCursor ", e);
273 throw new RuntimeException(e);
274 }
275 } else {
276 discard(node);
277 }
278 }
279
280 /**
281 * @return true if there pending messages to dispatch
282 */
283 @Override
284 public synchronized boolean hasNext() {
285 return iter.hasNext();
286 }
287
288 /**
289 * @return the next pending message
290 */
291 @Override
292 public synchronized MessageReference next() {
293 Message message = (Message) iter.next();
294 last = message;
295 if (!isDiskListEmpty()) {
296 // got from disk
297 message.setRegionDestination(regionDestination);
298 message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
299 }
300 message.incrementReferenceCount();
301 return message;
302 }
303
304 /**
305 * remove the message at the cursor position
306 */
307 @Override
308 public synchronized void remove() {
309 iter.remove();
310 if (last != null) {
311 last.decrementReferenceCount();
312 }
313 }
314
315 /**
316 * @param node
317 * @see org.apache.activemq.broker.region.cursors.AbstractPendingMessageCursor#remove(org.apache.activemq.broker.region.MessageReference)
318 */
319 @Override
320 public synchronized void remove(MessageReference node) {
321 if (memoryList.remove(node)) {
322 node.decrementReferenceCount();
323 }
324 if (!isDiskListEmpty()) {
325 try {
326 getDiskList().remove(node.getMessageId().toString());
327 } catch (IOException e) {
328 throw new RuntimeException(e);
329 }
330 }
331 }
332
333 /**
334 * @return the number of pending messages
335 */
336 @Override
337 public synchronized int size() {
338 return memoryList.size() + (isDiskListEmpty() ? 0 : getDiskList().size());
339 }
340
341 /**
342 * clear all pending messages
343 */
344 @Override
345 public synchronized void clear() {
346 memoryList.clear();
347 if (!isDiskListEmpty()) {
348 try {
349 getDiskList().destroy();
350 } catch (IOException e) {
351 throw new RuntimeException(e);
352 }
353 }
354 last = null;
355 }
356
357 @Override
358 public synchronized boolean isFull() {
359
360 return super.isFull() || (systemUsage != null && systemUsage.getTempUsage().isFull());
361
362 }
363
364 @Override
365 public boolean hasMessagesBufferedToDeliver() {
366 return !isEmpty();
367 }
368
369 @Override
370 public void setSystemUsage(SystemUsage usageManager) {
371 super.setSystemUsage(usageManager);
372 }
373
374 public void onUsageChanged(Usage usage, int oldPercentUsage, int newPercentUsage) {
375 if (newPercentUsage >= getMemoryUsageHighWaterMark()) {
376 synchronized (this) {
377 flushRequired = true;
378 if (!iterating) {
379 expireOldMessages();
380 if (!hasSpace()) {
381 flushToDisk();
382 flushRequired = false;
383 }
384 }
385 }
386 }
387 }
388
389 @Override
390 public boolean isTransient() {
391 return true;
392 }
393
394 protected boolean isSpaceInMemoryList() {
395 return hasSpace() && isDiskListEmpty();
396 }
397
398 protected synchronized void expireOldMessages() {
399 if (!memoryList.isEmpty()) {
400 LinkedList<MessageReference> tmpList = new LinkedList<MessageReference>(this.memoryList);
401 this.memoryList = new LinkedList<MessageReference>();
402 while (!tmpList.isEmpty()) {
403 MessageReference node = tmpList.removeFirst();
404 if (node.isExpired()) {
405 discard(node);
406 } else {
407 memoryList.add(node);
408 }
409 }
410 }
411
412 }
413
414 protected synchronized void flushToDisk() {
415
416 if (!memoryList.isEmpty()) {
417 while (!memoryList.isEmpty()) {
418 MessageReference node = memoryList.removeFirst();
419 node.decrementReferenceCount();
420 ByteSequence bs;
421 try {
422 bs = getByteSequence(node.getMessage());
423 getDiskList().addLast(node.getMessageId().toString(), bs);
424 } catch (IOException e) {
425 LOG.error("Failed to write to disk list", e);
426 throw new RuntimeException(e);
427 }
428
429 }
430 memoryList.clear();
431 setCacheEnabled(false);
432 }
433 }
434
435 protected boolean isDiskListEmpty() {
436 return diskList == null || diskList.isEmpty();
437 }
438
439 protected PList getDiskList() {
440 if (diskList == null) {
441 try {
442 diskList = store.getPList(name);
443 } catch (Exception e) {
444 LOG.error("Caught an IO Exception getting the DiskList " + name, e);
445 throw new RuntimeException(e);
446 }
447 }
448 return diskList;
449 }
450
451 protected void discard(MessageReference message) {
452 message.decrementReferenceCount();
453 if (LOG.isDebugEnabled()) {
454 LOG.debug("Discarding message " + message);
455 }
456 ConnectionContext ctx = new ConnectionContext(new NonCachedMessageEvaluationContext());
457 ctx.setBroker(broker);
458 broker.getRoot().sendToDeadLetterQueue(ctx, message, null);
459 }
460
461 protected ByteSequence getByteSequence(Message message) throws IOException {
462 org.apache.activemq.util.ByteSequence packet = wireFormat.marshal(message);
463 return new ByteSequence(packet.data, packet.offset, packet.length);
464 }
465
466 protected Message getMessage(ByteSequence bs) throws IOException {
467 org.apache.activemq.util.ByteSequence packet = new org.apache.activemq.util.ByteSequence(bs.getData(), bs
468 .getOffset(), bs.getLength());
469 return (Message) this.wireFormat.unmarshal(packet);
470
471 }
472
473 final class DiskIterator implements Iterator<MessageReference> {
474 private PListEntry next = null;
475 private PListEntry current = null;
476 PList list;
477
478 DiskIterator() {
479 try {
480 this.list = getDiskList();
481 synchronized (this.list) {
482 this.current = this.list.getFirst();
483 this.next = this.current;
484 }
485 } catch (Exception e) {
486 throw new RuntimeException(e);
487 }
488 }
489
490 public boolean hasNext() {
491 return this.next != null;
492 }
493
494 public MessageReference next() {
495 this.current = next;
496 try {
497 ByteSequence bs = this.current.getByteSequence();
498 synchronized (this.list) {
499 this.current = this.list.refresh(this.current);
500 this.next = this.list.getNext(this.current);
501 }
502 return getMessage(bs);
503 } catch (IOException e) {
504 LOG.error("I/O error", e);
505 throw new RuntimeException(e);
506 }
507 }
508
509 public void remove() {
510 try {
511 synchronized (this.list) {
512 this.current = this.list.refresh(this.current);
513 this.list.remove(this.current);
514 }
515
516 } catch (IOException e) {
517 LOG.error("I/O error", e);
518 throw new RuntimeException(e);
519 }
520
521 }
522
523 }
524 }