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
021 import org.apache.camel.BatchConsumer;
022 import org.apache.camel.Endpoint;
023 import org.apache.camel.Exchange;
024 import org.apache.camel.Processor;
025 import org.apache.camel.ShutdownRunningTask;
026 import org.apache.camel.spi.ShutdownAware;
027 import org.apache.camel.spi.UriParam;
028 import org.slf4j.Logger;
029 import org.slf4j.LoggerFactory;
030
031 /**
032 * A useful base class for any consumer which is polling batch based
033 */
034 public abstract class ScheduledBatchPollingConsumer extends ScheduledPollConsumer implements BatchConsumer, ShutdownAware {
035 private static final Logger LOG = LoggerFactory.getLogger(ScheduledBatchPollingConsumer.class);
036 protected volatile ShutdownRunningTask shutdownRunningTask;
037 protected volatile int pendingExchanges;
038 @UriParam
039 protected int maxMessagesPerPoll;
040
041 public ScheduledBatchPollingConsumer(Endpoint endpoint, Processor processor) {
042 super(endpoint, processor);
043 }
044
045 public ScheduledBatchPollingConsumer(Endpoint endpoint, Processor processor, ScheduledExecutorService executor) {
046 super(endpoint, processor, executor);
047 }
048
049 @Override
050 public boolean deferShutdown(ShutdownRunningTask shutdownRunningTask) {
051 // store a reference what to do in case when shutting down and we have pending messages
052 this.shutdownRunningTask = shutdownRunningTask;
053 // do not defer shutdown
054 return false;
055 }
056
057 @Override
058 public int getPendingExchangesSize() {
059 int answer;
060 // only return the real pending size in case we are configured to complete all tasks
061 if (ShutdownRunningTask.CompleteAllTasks == shutdownRunningTask) {
062 answer = pendingExchanges;
063 } else {
064 answer = 0;
065 }
066
067 if (answer == 0 && isPolling()) {
068 // force at least one pending exchange if we are polling as there is a little gap
069 // in the processBatch method and until an exchange gets enlisted as in-flight
070 // which happens later, so we need to signal back to the shutdown strategy that
071 // there is a pending exchange. When we are no longer polling, then we will return 0
072 LOG.trace("Currently polling so returning 1 as pending exchanges");
073 answer = 1;
074 }
075
076 return answer;
077 }
078
079 @Override
080 public void prepareShutdown(boolean forced) {
081 // reset task as the state of the task is not to be preserved
082 // which otherwise may cause isBatchAllowed() to return a wrong answer
083 this.shutdownRunningTask = null;
084 }
085
086 @Override
087 public void setMaxMessagesPerPoll(int maxMessagesPerPoll) {
088 this.maxMessagesPerPoll = maxMessagesPerPoll;
089 }
090
091 /**
092 * Gets the maximum number of messages as a limit to poll at each polling.
093 * <p/>
094 * Is default unlimited, but use 0 or negative number to disable it as unlimited.
095 *
096 * @return max messages to poll
097 */
098 public int getMaxMessagesPerPoll() {
099 return maxMessagesPerPoll;
100 }
101
102 @Override
103 public boolean isBatchAllowed() {
104 // stop if we are not running
105 boolean answer = isRunAllowed();
106 if (!answer) {
107 return false;
108 }
109
110 if (shutdownRunningTask == null) {
111 // we are not shutting down so continue to run
112 return true;
113 }
114
115 // we are shutting down so only continue if we are configured to complete all tasks
116 return ShutdownRunningTask.CompleteAllTasks == shutdownRunningTask;
117 }
118
119 @Override
120 protected void processEmptyMessage() throws Exception {
121 Exchange exchange = getEndpoint().createExchange();
122 // enrich exchange, so we send an empty message with the batch details
123 exchange.setProperty(Exchange.BATCH_INDEX, 0);
124 exchange.setProperty(Exchange.BATCH_SIZE, 1);
125 exchange.setProperty(Exchange.BATCH_COMPLETE, true);
126 log.debug("Sending empty message as there were no messages from polling: {}", this.getEndpoint());
127 getProcessor().process(exchange);
128 }
129 }