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 }