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.impl;
018
019 import java.util.concurrent.ExecutorService;
020 import java.util.concurrent.ScheduledExecutorService;
021 import java.util.concurrent.ScheduledFuture;
022 import java.util.concurrent.TimeUnit;
023
024 import org.apache.camel.Endpoint;
025 import org.apache.camel.PollingConsumerPollStrategy;
026 import org.apache.camel.Processor;
027 import org.apache.camel.util.ObjectHelper;
028 import org.apache.camel.util.concurrent.ExecutorServiceHelper;
029 import org.apache.commons.logging.Log;
030 import org.apache.commons.logging.LogFactory;
031
032 /**
033 * A useful base class for any consumer which is polling based
034 *
035 * @version $Revision: 789216 $
036 */
037 public abstract class ScheduledPollConsumer extends DefaultConsumer implements Runnable {
038 private static final transient Log LOG = LogFactory.getLog(ScheduledPollConsumer.class);
039
040 private final ScheduledExecutorService executor;
041 private ScheduledFuture<?> future;
042
043 // if adding more options then align with ScheduledPollEndpoint#configureScheduledPollConsumerProperties
044 private long initialDelay = 1000;
045 private long delay = 500;
046 private TimeUnit timeUnit = TimeUnit.MILLISECONDS;
047 private boolean useFixedDelay;
048 private PollingConsumerPollStrategy pollStrategy = new DefaultPollingConsumerPollStrategy();
049
050 public ScheduledPollConsumer(DefaultEndpoint endpoint, Processor processor) {
051 super(endpoint, processor);
052
053 ScheduledExecutorService scheduled;
054 ExecutorService service = endpoint.getExecutorService();
055 if (service instanceof ScheduledExecutorService) {
056 scheduled = (ScheduledExecutorService) service;
057 } else {
058 scheduled = ExecutorServiceHelper.newScheduledThreadPool(5, getEndpoint().getEndpointUri(), true);
059 }
060
061 this.executor = scheduled;
062 ObjectHelper.notNull(executor, "executor");
063 }
064
065 public ScheduledPollConsumer(Endpoint endpoint, Processor processor, ScheduledExecutorService executor) {
066 super(endpoint, processor);
067 this.executor = executor;
068 ObjectHelper.notNull(executor, "executor");
069 }
070
071 /**
072 * Invoked whenever we should be polled
073 */
074 public void run() {
075 int retryCounter = -1;
076 boolean done = false;
077
078 while (!done) {
079 try {
080 // eager assume we are done
081 done = true;
082 if (isRunAllowed()) {
083
084 if (retryCounter == -1) {
085 if (LOG.isTraceEnabled()) {
086 LOG.trace("Starting to poll: " + this.getEndpoint());
087 }
088 } else {
089 if (LOG.isDebugEnabled()) {
090 if (LOG.isDebugEnabled()) {
091 LOG.debug("Retrying attempt " + retryCounter + " to poll: " + this.getEndpoint());
092 }
093 }
094 }
095
096 pollStrategy.begin(this, getEndpoint());
097 retryCounter++;
098 poll();
099 pollStrategy.commit(this, getEndpoint());
100 }
101 } catch (Exception e) {
102 try {
103 boolean retry = pollStrategy.rollback(this, getEndpoint(), retryCounter, e);
104 if (retry) {
105 done = false;
106 }
107 } catch (Exception re) {
108 throw ObjectHelper.wrapRuntimeCamelException(re);
109 }
110 }
111 }
112
113 if (LOG.isTraceEnabled()) {
114 LOG.trace("Finished polling: " + this.getEndpoint());
115 }
116 }
117
118 // Properties
119 // -------------------------------------------------------------------------
120 public long getInitialDelay() {
121 return initialDelay;
122 }
123
124 public void setInitialDelay(long initialDelay) {
125 this.initialDelay = initialDelay;
126 }
127
128 public long getDelay() {
129 return delay;
130 }
131
132 public void setDelay(long delay) {
133 this.delay = delay;
134 }
135
136 public TimeUnit getTimeUnit() {
137 return timeUnit;
138 }
139
140 public void setTimeUnit(TimeUnit timeUnit) {
141 this.timeUnit = timeUnit;
142 }
143
144 public boolean isUseFixedDelay() {
145 return useFixedDelay;
146 }
147
148 public void setUseFixedDelay(boolean useFixedDelay) {
149 this.useFixedDelay = useFixedDelay;
150 }
151
152 public PollingConsumerPollStrategy getPollStrategy() {
153 return pollStrategy;
154 }
155
156 public void setPollStrategy(PollingConsumerPollStrategy pollStrategy) {
157 this.pollStrategy = pollStrategy;
158 }
159
160 // Implementation methods
161 // -------------------------------------------------------------------------
162
163 /**
164 * The polling method which is invoked periodically to poll this consumer
165 *
166 * @throws Exception can be thrown if an exception occurred during polling
167 */
168 protected abstract void poll() throws Exception;
169
170 @Override
171 protected void doStart() throws Exception {
172 super.doStart();
173 if (isUseFixedDelay()) {
174 future = executor.scheduleWithFixedDelay(this, getInitialDelay(), getDelay(), getTimeUnit());
175 } else {
176 future = executor.scheduleAtFixedRate(this, getInitialDelay(), getDelay(), getTimeUnit());
177 }
178 }
179
180 @Override
181 protected void doStop() throws Exception {
182 if (future != null) {
183 future.cancel(false);
184 }
185 super.doStop();
186 }
187 }