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.util.Iterator;
020 import org.apache.activemq.broker.region.Destination;
021 import org.apache.activemq.broker.region.MessageReference;
022 import org.apache.activemq.command.Message;
023 import org.apache.activemq.command.MessageId;
024 import org.apache.activemq.store.MessageRecoveryListener;
025 import org.slf4j.Logger;
026 import org.slf4j.LoggerFactory;
027
028 /**
029 * Store based cursor
030 *
031 */
032 public abstract class AbstractStoreCursor extends AbstractPendingMessageCursor implements MessageRecoveryListener {
033 private static final Logger LOG = LoggerFactory.getLogger(AbstractStoreCursor.class);
034 protected final Destination regionDestination;
035 protected final PendingList batchList;
036 private Iterator<MessageReference> iterator = null;
037 protected boolean batchResetNeeded = true;
038 private boolean storeHasMessages = false;
039 protected int size;
040 private MessageId lastCachedId;
041 private boolean hadSpace = false;
042
043 protected AbstractStoreCursor(Destination destination) {
044 super((destination != null ? destination.isPrioritizedMessages():false));
045 this.regionDestination=destination;
046 if (this.prioritizedMessages) {
047 this.batchList= new PrioritizedPendingList();
048 } else {
049 this.batchList = new OrderedPendingList();
050 }
051 }
052
053
054 public final synchronized void start() throws Exception{
055 if (!isStarted()) {
056 clear();
057 super.start();
058 resetBatch();
059 resetSize();
060 setCacheEnabled(!this.storeHasMessages&&useCache);
061 }
062 }
063
064 protected void resetSize() {
065 if (isStarted()) {
066 this.size = getStoreSize();
067 }
068 this.storeHasMessages=this.size > 0;
069 }
070
071 public final synchronized void stop() throws Exception {
072 resetBatch();
073 super.stop();
074 gc();
075 }
076
077
078 public final boolean recoverMessage(Message message) throws Exception {
079 return recoverMessage(message,false);
080 }
081
082 public synchronized boolean recoverMessage(Message message, boolean cached) throws Exception {
083 boolean recovered = false;
084 if (recordUniqueId(message.getMessageId())) {
085 if (!cached) {
086 message.setRegionDestination(regionDestination);
087 if( message.getMemoryUsage()==null ) {
088 message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
089 }
090 }
091 message.incrementReferenceCount();
092 batchList.addMessageLast(message);
093 clearIterator(true);
094 recovered = true;
095 storeHasMessages = true;
096 } else {
097 /*
098 * we should expect to get these - as the message is recorded as it before it goes into
099 * the cache. If subsequently, we pull out that message from the store (before its deleted)
100 * it will be a duplicate - but should be ignored
101 */
102 if (LOG.isTraceEnabled()) {
103 LOG.trace(this + " - cursor got duplicate: " + message.getMessageId() + ", " + message.getPriority());
104 }
105 }
106 return recovered;
107 }
108
109
110 public final synchronized void reset() {
111 if (batchList.isEmpty()) {
112 try {
113 fillBatch();
114 } catch (Exception e) {
115 LOG.error(this + " - Failed to fill batch", e);
116 throw new RuntimeException(e);
117 }
118 }
119 clearIterator(true);
120 size();
121 }
122
123
124 public synchronized void release() {
125 clearIterator(false);
126 }
127
128 private synchronized void clearIterator(boolean ensureIterator) {
129 boolean haveIterator = this.iterator != null;
130 this.iterator=null;
131 if(haveIterator&&ensureIterator) {
132 ensureIterator();
133 }
134 }
135
136 private synchronized void ensureIterator() {
137 if(this.iterator==null) {
138 this.iterator=this.batchList.iterator();
139 }
140 }
141
142
143 public final void finished() {
144 }
145
146
147 public final synchronized boolean hasNext() {
148 if (batchList.isEmpty()) {
149 try {
150 fillBatch();
151 } catch (Exception e) {
152 LOG.error(this + " - Failed to fill batch", e);
153 throw new RuntimeException(e);
154 }
155 }
156 ensureIterator();
157 return this.iterator.hasNext();
158 }
159
160
161 public final synchronized MessageReference next() {
162 MessageReference result = null;
163 if (!this.batchList.isEmpty()&&this.iterator.hasNext()) {
164 result = this.iterator.next();
165 }
166 last = result;
167 if (result != null) {
168 result.incrementReferenceCount();
169 }
170 return result;
171 }
172
173
174 public final synchronized void addMessageLast(MessageReference node) throws Exception {
175 boolean disableCache = false;
176 if (hasSpace()) {
177 if (!isCacheEnabled() && size==0 && isStarted() && useCache) {
178 if (LOG.isTraceEnabled()) {
179 LOG.trace(this + " - enabling cache for empty store " + node.getMessageId());
180 }
181 setCacheEnabled(true);
182 }
183 if (isCacheEnabled()) {
184 if (recoverMessage(node.getMessage(),true)) {
185 lastCachedId = node.getMessageId();
186 } else {
187 // failed to recover, possible duplicate from concurrent dispatchPending,
188 // lets not recover further in case of out of order
189 disableCache = true;
190 }
191 }
192 } else {
193 disableCache = true;
194 }
195
196 if (disableCache && isCacheEnabled()) {
197 setCacheEnabled(false);
198 // sync with store on disabling the cache
199 if (lastCachedId != null) {
200 if (LOG.isTraceEnabled()) {
201 LOG.trace(this + " - disabling cache"
202 + ", lastCachedId: " + lastCachedId
203 + " current node Id: " + node.getMessageId() + " batchList size: " + batchList.size());
204 }
205 setBatch(lastCachedId);
206 lastCachedId = null;
207 }
208 }
209 this.storeHasMessages = true;
210 size++;
211 }
212
213 protected void setBatch(MessageId messageId) throws Exception {
214 }
215
216
217 public final synchronized void addMessageFirst(MessageReference node) throws Exception {
218 setCacheEnabled(false);
219 size++;
220 }
221
222
223 public final synchronized void remove() {
224 size--;
225 if (iterator!=null) {
226 iterator.remove();
227 }
228 if (last != null) {
229 last.decrementReferenceCount();
230 }
231 }
232
233
234 public final synchronized void remove(MessageReference node) {
235 if (batchList.remove(node) != null) {
236 size--;
237 setCacheEnabled(false);
238 }
239 }
240
241
242 public final synchronized void clear() {
243 gc();
244 }
245
246
247 public synchronized void gc() {
248 for (Iterator<MessageReference>i = batchList.iterator();i.hasNext();) {
249 MessageReference msg = i.next();
250 rollback(msg.getMessageId());
251 msg.decrementReferenceCount();
252 }
253 batchList.clear();
254 clearIterator(false);
255 batchResetNeeded = true;
256 // wonder do we need to determine size here, it may change before restart
257 resetSize();
258 setCacheEnabled(false);
259 }
260
261 @Override
262 public boolean hasSpace() {
263 hadSpace = super.hasSpace();
264 return hadSpace;
265 }
266
267 protected final synchronized void fillBatch() {
268 if (LOG.isTraceEnabled()) {
269 LOG.trace(this + " - fillBatch");
270 }
271 if (batchResetNeeded) {
272 resetBatch();
273 this.batchResetNeeded = false;
274 }
275 if (this.batchList.isEmpty() && this.storeHasMessages && this.size >0) {
276 try {
277 doFillBatch();
278 } catch (Exception e) {
279 LOG.error(this + " - Failed to fill batch", e);
280 throw new RuntimeException(e);
281 }
282 this.storeHasMessages = !this.batchList.isEmpty() || !hadSpace;
283 }
284 }
285
286
287 public final synchronized boolean isEmpty() {
288 // negative means more messages added to store through queue.send since last reset
289 return size == 0;
290 }
291
292
293 public final synchronized boolean hasMessagesBufferedToDeliver() {
294 return !batchList.isEmpty();
295 }
296
297
298 public final synchronized int size() {
299 if (size < 0) {
300 this.size = getStoreSize();
301 }
302 return size;
303 }
304
305 @Override
306 public String toString() {
307 return super.toString() + ":" + regionDestination.getActiveMQDestination().getPhysicalName() + ",batchResetNeeded=" + batchResetNeeded
308 + ",storeHasMessages=" + this.storeHasMessages + ",size=" + this.size + ",cacheEnabled=" + isCacheEnabled();
309 }
310
311 protected abstract void doFillBatch() throws Exception;
312
313 protected abstract void resetBatch();
314
315 protected abstract int getStoreSize();
316
317 protected abstract boolean isStoreEmpty();
318 }