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.camel.component.ibatis;
018
019 import java.util.LinkedList;
020 import java.util.List;
021 import java.util.Queue;
022
023 import org.apache.camel.BatchConsumer;
024 import org.apache.camel.Exchange;
025 import org.apache.camel.ExchangePattern;
026 import org.apache.camel.Message;
027 import org.apache.camel.Processor;
028 import org.apache.camel.ShutdownRunningTask;
029 import org.apache.camel.impl.ScheduledPollConsumer;
030 import org.apache.camel.spi.ShutdownAware;
031 import org.apache.camel.util.CastUtils;
032 import org.apache.camel.util.ObjectHelper;
033 import org.apache.commons.logging.Log;
034 import org.apache.commons.logging.LogFactory;
035
036 /**
037 * <pre>
038 * Ibatis Camel Component used to read data from a database.
039 *
040 * Example Configuration :
041 * <route>
042 * <from uri="ibatis:selectRecords" />
043 * <to uri="jms:destinationQueue" />
044 * </route>
045 *
046 *
047 * This also can be configured to treat a table as a logical queue by defining
048 * an "onConsume" statement.
049 *
050 * Example Configuration :
051 * <route>
052 * <from uri="ibatis:selectRecords?consumer.onConsume=updateRecord" />
053 * <to uri="jms:destinationQueue" />
054 * </route>
055 *
056 * By default, if the select statement contains multiple rows, it will
057 * iterate over the set and deliver each row to the route. If this is not the
058 * desired behavior then set "useIterator=false". This will deliver the entire
059 * set to the route as a list.
060 * </pre>
061 *
062 * <b>URI Options</b>
063 * <table border="1">
064 * <thead>
065 * <th>Name</th>
066 * <th>Default Value</th>
067 * <th>description</th>
068 * </thead>
069 * <tbody>
070 * <tr>
071 * <td>initialDelay</td>
072 * <td>1000 ms</td>
073 * <td>time before polling starts</td>
074 * </tr>
075 * <tr>
076 * <td>delay</td>
077 * <td>500 ms</td>
078 * <td>time before the next poll</td>
079 * </tr>
080 * <tr>
081 * <td>timeUnit</td>
082 * <td>MILLISECONDS</td>
083 * <td>Time unit to use for delay properties (NANOSECONDS, MICROSECONDS,
084 * MILLISECONDS, SECONDS)</td>
085 * </tr>
086 * <tr>
087 * <td>useIterator</td>
088 * <td>true</td>
089 * <td>If true, processes one exchange per row. If false processes one exchange
090 * for all rows</td>
091 * </tr>
092 * <tr>
093 * <td>onConsume</td>
094 * <td>null</td>
095 * <td>statement to run after data has been processed</td>
096 * </tr>
097 * <tbody> </table>
098 *
099 * @see org.apache.camel.component.ibatis.strategy.IBatisProcessingStrategy
100 */
101 public class IBatisPollingConsumer extends ScheduledPollConsumer implements BatchConsumer, ShutdownAware {
102
103 private static final Log LOG = LogFactory.getLog(IBatisPollingConsumer.class);
104
105 private final class DataHolder {
106 private Exchange exchange;
107 private Object data;
108 private DataHolder() {
109 }
110 }
111
112 protected volatile ShutdownRunningTask shutdownRunningTask;
113 protected volatile int pendingExchanges;
114
115 /**
116 * Statement to run after data has been processed in the route
117 */
118 private String onConsume;
119
120 /**
121 * Process resultset individually or as a list
122 */
123 private boolean useIterator = true;
124
125 /**
126 * Whether allow empty resultset to be routed to the next hop
127 */
128 private boolean routeEmptyResultSet;
129
130 private int maxMessagesPerPoll;
131
132
133 public IBatisPollingConsumer(IBatisEndpoint endpoint, Processor processor) throws Exception {
134 super(endpoint, processor);
135 }
136
137 public IBatisEndpoint getEndpoint() {
138 return (IBatisEndpoint) super.getEndpoint();
139 }
140
141 /**
142 * Polls the database
143 */
144 @Override
145 protected void poll() throws Exception {
146
147 // must reset for each poll
148 shutdownRunningTask = null;
149 pendingExchanges = 0;
150
151 // poll data from the database
152 IBatisEndpoint endpoint = getEndpoint();
153 if (LOG.isTraceEnabled()) {
154 LOG.trace("Polling: " + endpoint);
155 }
156 List<Object> data = CastUtils.cast(endpoint.getProcessingStrategy().poll(this, getEndpoint()));
157
158 // create a list of exchange objects with the data
159 Queue<DataHolder> answer = new LinkedList<DataHolder>();
160 if (useIterator) {
161 for (Object item : data) {
162 Exchange exchange = createExchange(item);
163 DataHolder holder = new DataHolder();
164 holder.exchange = exchange;
165 holder.data = item;
166 answer.add(holder);
167 }
168 } else {
169 if (!data.isEmpty() || routeEmptyResultSet) {
170 Exchange exchange = createExchange(data);
171 DataHolder holder = new DataHolder();
172 holder.exchange = exchange;
173 holder.data = data;
174 answer.add(holder);
175 }
176 }
177
178 // process all the exchanges in this batch
179 processBatch(CastUtils.cast(answer));
180 }
181
182 public void setMaxMessagesPerPoll(int maxMessagesPerPoll) {
183 this.maxMessagesPerPoll = maxMessagesPerPoll;
184 }
185
186 public void processBatch(Queue<Object> exchanges) throws Exception {
187 final IBatisEndpoint endpoint = getEndpoint();
188
189 int total = exchanges.size();
190
191 // limit if needed
192 if (maxMessagesPerPoll > 0 && total > maxMessagesPerPoll) {
193 LOG.debug("Limiting to maximum messages to poll " + maxMessagesPerPoll + " as there was " + total + " messages in this poll.");
194 total = maxMessagesPerPoll;
195 }
196
197 for (int index = 0; index < total && isBatchAllowed(); index++) {
198 // only loop if we are started (allowed to run)
199 DataHolder holder = ObjectHelper.cast(DataHolder.class, exchanges.poll());
200 Exchange exchange = holder.exchange;
201 Object data = holder.data;
202
203 // add current index and total as properties
204 exchange.setProperty(Exchange.BATCH_INDEX, index);
205 exchange.setProperty(Exchange.BATCH_SIZE, total);
206 exchange.setProperty(Exchange.BATCH_COMPLETE, index == total - 1);
207
208 // update pending number of exchanges
209 pendingExchanges = total - index - 1;
210
211 // process the current exchange
212 if (LOG.isDebugEnabled()) {
213 LOG.debug("Processing exchange: " + exchange);
214 }
215 getProcessor().process(exchange);
216
217 try {
218 if (onConsume != null) {
219 endpoint.getProcessingStrategy().commit(endpoint, exchange, data, onConsume);
220 }
221 } catch (Exception e) {
222 handleException(e);
223 }
224 }
225 }
226
227 public boolean deferShutdown(ShutdownRunningTask shutdownRunningTask) {
228 // store a reference what to do in case when shutting down and we have pending messages
229 this.shutdownRunningTask = shutdownRunningTask;
230 // do not defer shutdown
231 return false;
232 }
233
234 public int getPendingExchangesSize() {
235 // only return the real pending size in case we are configured to complete all tasks
236 if (ShutdownRunningTask.CompleteAllTasks == shutdownRunningTask) {
237 return pendingExchanges;
238 } else {
239 return 0;
240 }
241 }
242
243 public boolean isBatchAllowed() {
244 // stop if we are not running
245 boolean answer = isRunAllowed();
246 if (!answer) {
247 return false;
248 }
249
250 if (shutdownRunningTask == null) {
251 // we are not shutting down so continue to run
252 return true;
253 }
254
255 // we are shutting down so only continue if we are configured to complete all tasks
256 return ShutdownRunningTask.CompleteAllTasks == shutdownRunningTask;
257 }
258
259 private Exchange createExchange(Object data) {
260 final IBatisEndpoint endpoint = getEndpoint();
261 final Exchange exchange = endpoint.createExchange(ExchangePattern.InOnly);
262
263 Message msg = exchange.getIn();
264 msg.setBody(data);
265 msg.setHeader(IBatisConstants.IBATIS_STATEMENT_NAME, endpoint.getStatement());
266
267 return exchange;
268 }
269
270 /**
271 * Gets the statement(s) to run after successful processing.
272 * Use comma to separate multiple statements.
273 */
274 public String getOnConsume() {
275 return onConsume;
276 }
277
278 /**
279 * Sets the statement to run after successful processing.
280 * Use comma to separate multiple statements.
281 */
282 public void setOnConsume(String onConsume) {
283 this.onConsume = onConsume;
284 }
285
286 /**
287 * Indicates how resultset should be delivered to the route
288 */
289 public boolean isUseIterator() {
290 return useIterator;
291 }
292
293 /**
294 * Sets how resultset should be delivered to route.
295 * Indicates delivery as either a list or individual object.
296 * defaults to true.
297 */
298 public void setUseIterator(boolean useIterator) {
299 this.useIterator = useIterator;
300 }
301
302 /**
303 * Indicates whether empty resultset should be allowed to be sent to the next hop or not
304 */
305 public boolean isRouteEmptyResultSet() {
306 return routeEmptyResultSet;
307 }
308
309 /**
310 * Sets whether empty resultset should be allowed to be sent to the next hop.
311 * defaults to false. So the empty resultset will be filtered out.
312 */
313 public void setRouteEmptyResultSet(boolean routeEmptyResultSet) {
314 this.routeEmptyResultSet = routeEmptyResultSet;
315 }
316 }