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 private 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 this.size = getStoreSize();
060 this.storeHasMessages=this.size > 0;
061 setCacheEnabled(!this.storeHasMessages&&useCache);
062 }
063 }
064
065
066 public final synchronized void stop() throws Exception {
067 resetBatch();
068 super.stop();
069 gc();
070 }
071
072
073 public final boolean recoverMessage(Message message) throws Exception {
074 return recoverMessage(message,false);
075 }
076
077 public synchronized boolean recoverMessage(Message message, boolean cached) throws Exception {
078 boolean recovered = false;
079 if (recordUniqueId(message.getMessageId())) {
080 if (!cached) {
081 message.setRegionDestination(regionDestination);
082 if( message.getMemoryUsage()==null ) {
083 message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
084 }
085 }
086 message.incrementReferenceCount();
087 batchList.addMessageLast(message);
088 clearIterator(true);
089 recovered = true;
090 storeHasMessages = true;
091 } else {
092 /*
093 * we should expect to get these - as the message is recorded as it before it goes into
094 * the cache. If subsequently, we pull out that message from the store (before its deleted)
095 * it will be a duplicate - but should be ignored
096 */
097 if (LOG.isTraceEnabled()) {
098 LOG.trace(this + " - cursor got duplicate: " + message.getMessageId() + ", " + message.getPriority());
099 }
100 }
101 return recovered;
102 }
103
104
105 public final void reset() {
106 if (batchList.isEmpty()) {
107 try {
108 fillBatch();
109 } catch (Exception e) {
110 LOG.error(this + " - Failed to fill batch", e);
111 throw new RuntimeException(e);
112 }
113 }
114 clearIterator(true);
115 size();
116 }
117
118
119 public synchronized void release() {
120 clearIterator(false);
121 }
122
123 private synchronized void clearIterator(boolean ensureIterator) {
124 boolean haveIterator = this.iterator != null;
125 this.iterator=null;
126 if(haveIterator&&ensureIterator) {
127 ensureIterator();
128 }
129 }
130
131 private synchronized void ensureIterator() {
132 if(this.iterator==null) {
133 this.iterator=this.batchList.iterator();
134 }
135 }
136
137
138 public final void finished() {
139 }
140
141
142 public final synchronized boolean hasNext() {
143 if (batchList.isEmpty()) {
144 try {
145 fillBatch();
146 } catch (Exception e) {
147 LOG.error(this + " - Failed to fill batch", e);
148 throw new RuntimeException(e);
149 }
150 }
151 ensureIterator();
152 return this.iterator.hasNext();
153 }
154
155
156 public final synchronized MessageReference next() {
157 MessageReference result = null;
158 if (!this.batchList.isEmpty()&&this.iterator.hasNext()) {
159 result = this.iterator.next();
160 }
161 last = result;
162 if (result != null) {
163 result.incrementReferenceCount();
164 }
165 return result;
166 }
167
168
169 public final synchronized void addMessageLast(MessageReference node) throws Exception {
170 if (hasSpace()) {
171 if (!isCacheEnabled() && size==0 && isStarted() && useCache) {
172 if (LOG.isTraceEnabled()) {
173 LOG.trace(this + " - enabling cache for empty store " + node.getMessageId());
174 }
175 setCacheEnabled(true);
176 }
177 if (isCacheEnabled()) {
178 recoverMessage(node.getMessage(),true);
179 lastCachedId = node.getMessageId();
180 }
181 } else if (isCacheEnabled()) {
182 setCacheEnabled(false);
183 // sync with store on disabling the cache
184 if (lastCachedId != null) {
185 if (LOG.isTraceEnabled()) {
186 LOG.trace(this + " - disabling cache"
187 + ", lastCachedId: " + lastCachedId
188 + " current node Id: " + node.getMessageId());
189 }
190 setBatch(lastCachedId);
191 lastCachedId = null;
192 }
193 }
194 this.storeHasMessages = true;
195 size++;
196 }
197
198 protected void setBatch(MessageId messageId) throws Exception {
199 }
200
201
202 public final synchronized void addMessageFirst(MessageReference node) throws Exception {
203 setCacheEnabled(false);
204 size++;
205 }
206
207
208 public final synchronized void remove() {
209 size--;
210 if (iterator!=null) {
211 iterator.remove();
212 }
213 if (last != null) {
214 last.decrementReferenceCount();
215 }
216 }
217
218
219 public final synchronized void remove(MessageReference node) {
220 size--;
221 setCacheEnabled(false);
222 batchList.remove(node);
223 }
224
225
226 public final synchronized void clear() {
227 gc();
228 }
229
230
231 public synchronized void gc() {
232 for (Iterator<MessageReference>i = batchList.iterator();i.hasNext();) {
233 MessageReference msg = i.next();
234 rollback(msg.getMessageId());
235 msg.decrementReferenceCount();
236 }
237 batchList.clear();
238 clearIterator(false);
239 batchResetNeeded = true;
240 setCacheEnabled(false);
241 }
242
243 @Override
244 public boolean hasSpace() {
245 hadSpace = super.hasSpace();
246 return hadSpace;
247 }
248
249 protected final synchronized void fillBatch() {
250 if (LOG.isTraceEnabled()) {
251 LOG.trace(this + " - fillBatch");
252 }
253 if (batchResetNeeded) {
254 resetBatch();
255 this.batchResetNeeded = false;
256 }
257 if (this.batchList.isEmpty() && this.storeHasMessages && this.size >0) {
258 this.storeHasMessages = false;
259 try {
260 doFillBatch();
261 } catch (Exception e) {
262 LOG.error(this + " - Failed to fill batch", e);
263 throw new RuntimeException(e);
264 }
265 if (!this.batchList.isEmpty() || !hadSpace) {
266 this.storeHasMessages=true;
267 }
268 }
269 }
270
271
272 public final synchronized boolean isEmpty() {
273 // negative means more messages added to store through queue.send since last reset
274 return size == 0;
275 }
276
277
278 public final synchronized boolean hasMessagesBufferedToDeliver() {
279 return !batchList.isEmpty();
280 }
281
282
283 public final synchronized int size() {
284 if (size < 0) {
285 this.size = getStoreSize();
286 }
287 return size;
288 }
289
290 public String toString() {
291 return regionDestination.getActiveMQDestination().getPhysicalName() + ",batchResetNeeded=" + batchResetNeeded
292 + ",storeHasMessages=" + this.storeHasMessages + ",size=" + this.size + ",cacheEnabled=" + isCacheEnabled();
293 }
294
295 protected abstract void doFillBatch() throws Exception;
296
297 protected abstract void resetBatch();
298
299 protected abstract int getStoreSize();
300
301 protected abstract boolean isStoreEmpty();
302 }