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 */ 017package org.apache.camel.impl; 018 019import java.util.concurrent.ScheduledExecutorService; 020 021import org.apache.camel.BatchConsumer; 022import org.apache.camel.Endpoint; 023import org.apache.camel.Exchange; 024import org.apache.camel.Processor; 025import org.apache.camel.ShutdownRunningTask; 026import org.apache.camel.spi.ShutdownAware; 027import org.slf4j.Logger; 028import org.slf4j.LoggerFactory; 029 030/** 031 * A useful base class for any consumer which is polling batch based 032 */ 033public abstract class ScheduledBatchPollingConsumer extends ScheduledPollConsumer implements BatchConsumer, ShutdownAware { 034 private static final 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 suspendOnly, 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}