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