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.ScheduledExecutorService;
020 import java.util.concurrent.ScheduledFuture;
021 import java.util.concurrent.TimeUnit;
022
023 import org.apache.camel.Endpoint;
024 import org.apache.camel.Processor;
025 import org.apache.camel.util.ObjectHelper;
026 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028
029 /**
030 * A useful base class for any consumer which is polling based
031 *
032 * @version $Revision: 734684 $
033 */
034 public abstract class ScheduledPollConsumer extends DefaultConsumer implements Runnable {
035 private static final transient Log LOG = LogFactory.getLog(ScheduledPollConsumer.class);
036
037 private final ScheduledExecutorService executor;
038 private ScheduledFuture<?> future;
039 private Exception firstExceptionThrown;
040
041 // if adding more options then align with ScheduledPollEndpoint#configureScheduledPollConsumerProperties
042 private long initialDelay = 1000;
043 private long delay = 500;
044 private TimeUnit timeUnit = TimeUnit.MILLISECONDS;
045 private boolean useFixedDelay;
046
047 public ScheduledPollConsumer(DefaultEndpoint endpoint, Processor processor) {
048 this(endpoint, processor, endpoint.getExecutorService());
049 }
050
051 public ScheduledPollConsumer(Endpoint endpoint, Processor processor, ScheduledExecutorService executor) {
052 super(endpoint, processor);
053 this.executor = executor;
054 ObjectHelper.notNull(executor, "executor");
055 }
056
057 /**
058 * Invoked whenever we should be polled
059 */
060 public void run() {
061 try {
062 if (isRunAllowed()) {
063 if (LOG.isTraceEnabled()) {
064 LOG.trace("Starting to poll: " + this.getEndpoint());
065 }
066 poll();
067 }
068 } catch (Exception e) {
069 LOG.warn("An exception occurred while polling: " + this.getEndpoint() + ": " + e.getMessage(), e);
070 if (firstExceptionThrown == null) {
071 firstExceptionThrown = e;
072 }
073 }
074
075 if (LOG.isTraceEnabled()) {
076 LOG.trace("Finished polling: " + this.getEndpoint());
077 }
078 }
079
080 // Properties
081 // -------------------------------------------------------------------------
082 public long getInitialDelay() {
083 return initialDelay;
084 }
085
086 public void setInitialDelay(long initialDelay) {
087 this.initialDelay = initialDelay;
088 }
089
090 public long getDelay() {
091 return delay;
092 }
093
094 public void setDelay(long delay) {
095 this.delay = delay;
096 }
097
098 public TimeUnit getTimeUnit() {
099 return timeUnit;
100 }
101
102 public void setTimeUnit(TimeUnit timeUnit) {
103 this.timeUnit = timeUnit;
104 }
105
106 public boolean isUseFixedDelay() {
107 return useFixedDelay;
108 }
109
110 public void setUseFixedDelay(boolean useFixedDelay) {
111 this.useFixedDelay = useFixedDelay;
112 }
113
114 // Implementation methods
115 // -------------------------------------------------------------------------
116
117 /**
118 * The polling method which is invoked periodically to poll this consumer
119 *
120 * @throws Exception can be thrown if an exception occurred during polling
121 */
122 protected abstract void poll() throws Exception;
123
124 @Override
125 protected void doStart() throws Exception {
126 firstExceptionThrown = null;
127 super.doStart();
128 if (isUseFixedDelay()) {
129 future = executor.scheduleWithFixedDelay(this, getInitialDelay(), getDelay(), getTimeUnit());
130 } else {
131 future = executor.scheduleAtFixedRate(this, getInitialDelay(), getDelay(), getTimeUnit());
132 }
133 }
134
135 @Override
136 protected void doStop() throws Exception {
137 if (future != null) {
138 future.cancel(false);
139 }
140 super.doStop();
141
142 if (firstExceptionThrown != null) {
143 throw firstExceptionThrown;
144 }
145 }
146 }