org.apache.camel.impl.ScheduledBatchPollingConsumer Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.camel.impl;
import java.util.concurrent.ScheduledExecutorService;
import org.apache.camel.BatchConsumer;
import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.ShutdownRunningTask;
import org.apache.camel.spi.ShutdownAware;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A useful base class for any consumer which is polling batch based
*/
public abstract class ScheduledBatchPollingConsumer extends ScheduledPollConsumer implements BatchConsumer, ShutdownAware {
private static final transient Logger LOG = LoggerFactory.getLogger(ScheduledBatchPollingConsumer.class);
protected volatile ShutdownRunningTask shutdownRunningTask;
protected volatile int pendingExchanges;
protected int maxMessagesPerPoll;
public ScheduledBatchPollingConsumer(Endpoint endpoint, Processor processor) {
super(endpoint, processor);
}
public ScheduledBatchPollingConsumer(Endpoint endpoint, Processor processor, ScheduledExecutorService executor) {
super(endpoint, processor, executor);
}
@Override
public boolean deferShutdown(ShutdownRunningTask shutdownRunningTask) {
// store a reference what to do in case when shutting down and we have pending messages
this.shutdownRunningTask = shutdownRunningTask;
// do not defer shutdown
return false;
}
@Override
public int getPendingExchangesSize() {
int answer;
// only return the real pending size in case we are configured to complete all tasks
if (ShutdownRunningTask.CompleteAllTasks == shutdownRunningTask) {
answer = pendingExchanges;
} else {
answer = 0;
}
if (answer == 0 && isPolling()) {
// force at least one pending exchange if we are polling as there is a little gap
// in the processBatch method and until an exchange gets enlisted as in-flight
// which happens later, so we need to signal back to the shutdown strategy that
// there is a pending exchange. When we are no longer polling, then we will return 0
LOG.trace("Currently polling so returning 1 as pending exchanges");
answer = 1;
}
return answer;
}
@Override
public void prepareShutdown(boolean forced) {
// reset task as the state of the task is not to be preserved
// which otherwise may cause isBatchAllowed() to return a wrong answer
this.shutdownRunningTask = null;
}
@Override
public void setMaxMessagesPerPoll(int maxMessagesPerPoll) {
this.maxMessagesPerPoll = maxMessagesPerPoll;
}
/**
* Gets the maximum number of messages as a limit to poll at each polling.
*
* Is default unlimited, but use 0 or negative number to disable it as unlimited.
*
* @return max messages to poll
*/
public int getMaxMessagesPerPoll() {
return maxMessagesPerPoll;
}
@Override
public boolean isBatchAllowed() {
// stop if we are not running
boolean answer = isRunAllowed();
if (!answer) {
return false;
}
if (shutdownRunningTask == null) {
// we are not shutting down so continue to run
return true;
}
// we are shutting down so only continue if we are configured to complete all tasks
return ShutdownRunningTask.CompleteAllTasks == shutdownRunningTask;
}
@Override
protected void processEmptyMessage() throws Exception {
Exchange exchange = getEndpoint().createExchange();
// enrich exchange, so we send an empty message with the batch details
exchange.setProperty(Exchange.BATCH_INDEX, 0);
exchange.setProperty(Exchange.BATCH_SIZE, 1);
exchange.setProperty(Exchange.BATCH_COMPLETE, true);
log.debug("Sending empty message as there were no messages from polling: {}", this.getEndpoint());
getProcessor().process(exchange);
}
}