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.Processor;
026 import org.apache.camel.util.ObjectHelper;
027 import org.apache.camel.util.concurrent.ExecutorServiceHelper;
028 import org.apache.commons.logging.Log;
029 import org.apache.commons.logging.LogFactory;
030
031 /**
032 * A useful base class for any consumer which is polling based
033 *
034 * @version $Revision: 772598 $
035 */
036 public abstract class ScheduledPollConsumer extends DefaultConsumer implements Runnable {
037 private static final transient Log LOG = LogFactory.getLog(ScheduledPollConsumer.class);
038
039 private final ScheduledExecutorService executor;
040 private ScheduledFuture<?> future;
041 private Exception firstExceptionThrown;
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
049 public ScheduledPollConsumer(DefaultEndpoint endpoint, Processor processor) {
050 super(endpoint, processor);
051
052 ScheduledExecutorService scheduled;
053 ExecutorService service = endpoint.getExecutorService();
054 if (service instanceof ScheduledExecutorService) {
055 scheduled = (ScheduledExecutorService) service;
056 } else {
057 scheduled = ExecutorServiceHelper.newScheduledThreadPool(5, getEndpoint().getEndpointUri(), true);
058 }
059
060 this.executor = scheduled;
061 ObjectHelper.notNull(executor, "executor");
062 }
063
064 public ScheduledPollConsumer(Endpoint endpoint, Processor processor, ScheduledExecutorService executor) {
065 super(endpoint, processor);
066 this.executor = executor;
067 ObjectHelper.notNull(executor, "executor");
068 }
069
070 /**
071 * Invoked whenever we should be polled
072 */
073 public void run() {
074 try {
075 if (isRunAllowed()) {
076 if (LOG.isTraceEnabled()) {
077 LOG.trace("Starting to poll: " + this.getEndpoint());
078 }
079 poll();
080 }
081 } catch (Exception e) {
082 LOG.warn("An exception occurred while polling: " + this.getEndpoint() + ": " + e.getMessage(), e);
083 if (firstExceptionThrown == null) {
084 firstExceptionThrown = e;
085 }
086 }
087
088 if (LOG.isTraceEnabled()) {
089 LOG.trace("Finished polling: " + this.getEndpoint());
090 }
091 }
092
093 // Properties
094 // -------------------------------------------------------------------------
095 public long getInitialDelay() {
096 return initialDelay;
097 }
098
099 public void setInitialDelay(long initialDelay) {
100 this.initialDelay = initialDelay;
101 }
102
103 public long getDelay() {
104 return delay;
105 }
106
107 public void setDelay(long delay) {
108 this.delay = delay;
109 }
110
111 public TimeUnit getTimeUnit() {
112 return timeUnit;
113 }
114
115 public void setTimeUnit(TimeUnit timeUnit) {
116 this.timeUnit = timeUnit;
117 }
118
119 public boolean isUseFixedDelay() {
120 return useFixedDelay;
121 }
122
123 public void setUseFixedDelay(boolean useFixedDelay) {
124 this.useFixedDelay = useFixedDelay;
125 }
126
127 // Implementation methods
128 // -------------------------------------------------------------------------
129
130 /**
131 * The polling method which is invoked periodically to poll this consumer
132 *
133 * @throws Exception can be thrown if an exception occurred during polling
134 */
135 protected abstract void poll() throws Exception;
136
137 @Override
138 protected void doStart() throws Exception {
139 firstExceptionThrown = null;
140 super.doStart();
141 if (isUseFixedDelay()) {
142 future = executor.scheduleWithFixedDelay(this, getInitialDelay(), getDelay(), getTimeUnit());
143 } else {
144 future = executor.scheduleAtFixedRate(this, getInitialDelay(), getDelay(), getTimeUnit());
145 }
146 }
147
148 @Override
149 protected void doStop() throws Exception {
150 if (future != null) {
151 future.cancel(false);
152 }
153 super.doStop();
154
155 if (firstExceptionThrown != null) {
156 throw firstExceptionThrown;
157 }
158 }
159 }