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.Exchange;
025 import org.apache.camel.Processor;
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: 563607 $
033 */
034 public abstract class ScheduledPollConsumer<E extends Exchange> extends DefaultConsumer<E> implements
035 Runnable {
036 private static final transient Log LOG = LogFactory.getLog(ScheduledPollConsumer.class);
037
038 private final ScheduledExecutorService executor;
039 private long initialDelay = 1000;
040 private long delay = 500;
041 private TimeUnit timeUnit = TimeUnit.MILLISECONDS;
042 private boolean useFixedDelay;
043 private ScheduledFuture<?> future;
044
045 public ScheduledPollConsumer(DefaultEndpoint<E> endpoint, Processor processor) {
046 this(endpoint, processor, endpoint.getExecutorService());
047 }
048
049 public ScheduledPollConsumer(Endpoint<E> endpoint, Processor processor, ScheduledExecutorService executor) {
050 super(endpoint, processor);
051 this.executor = executor;
052 if (executor == null) {
053 throw new IllegalArgumentException("A non null ScheduledExecutorService must be provided.");
054 }
055 }
056
057 /**
058 * Invoked whenever we should be polled
059 */
060 public void run() {
061 LOG.debug("Starting to poll");
062 try {
063 poll();
064 } catch (Exception e) {
065 LOG.warn("Caught: " + e, e);
066 }
067 }
068
069 // Properties
070 // -------------------------------------------------------------------------
071 public long getInitialDelay() {
072 return initialDelay;
073 }
074
075 public void setInitialDelay(long initialDelay) {
076 this.initialDelay = initialDelay;
077 }
078
079 public long getDelay() {
080 return delay;
081 }
082
083 public void setDelay(long delay) {
084 this.delay = delay;
085 }
086
087 public TimeUnit getTimeUnit() {
088 return timeUnit;
089 }
090
091 public void setTimeUnit(TimeUnit timeUnit) {
092 this.timeUnit = timeUnit;
093 }
094
095 public boolean isUseFixedDelay() {
096 return useFixedDelay;
097 }
098
099 public void setUseFixedDelay(boolean useFixedDelay) {
100 this.useFixedDelay = useFixedDelay;
101 }
102
103 // Implementation methods
104 // -------------------------------------------------------------------------
105
106 /**
107 * The polling method which is invoked periodically to poll this consumer
108 *
109 * @throws Exception
110 */
111 protected abstract void poll() throws Exception;
112
113 @Override
114 protected void doStart() throws Exception {
115 super.doStart();
116 if (isUseFixedDelay()) {
117 future = executor.scheduleWithFixedDelay(this, getInitialDelay(), getDelay(), getTimeUnit());
118 } else {
119 future = executor.scheduleAtFixedRate(this, getInitialDelay(), getDelay(), getTimeUnit());
120 }
121 }
122
123 @Override
124 protected void doStop() throws Exception {
125 if (future != null) {
126 future.cancel(false);
127 }
128 super.doStop();
129 }
130 }