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 }