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/*
* Copyright 2019-2020 the original author or authors.
*
* Licensed 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
*
* https://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.springframework.kafka.requestreply;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.BiPredicate;
import java.util.stream.Collectors;
import org.apache.kafka.clients.consumer.Consumer;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.OffsetAndMetadata;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.header.Header;
import org.apache.kafka.common.header.internals.RecordHeader;
import org.springframework.kafka.core.ProducerFactory;
import org.springframework.kafka.listener.BatchConsumerAwareMessageListener;
import org.springframework.kafka.listener.ContainerProperties.AckMode;
import org.springframework.kafka.listener.GenericMessageListenerContainer;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.util.Assert;
/**
* A replying template that aggregates multiple replies with the same correlation id.
*
* @param the key type.
* @param the outbound data type.
* @param the reply data type.
*
* @author Gary Russell
* @since 2.3
*
*/
public class AggregatingReplyingKafkaTemplate
extends ReplyingKafkaTemplate>>
implements BatchConsumerAwareMessageListener>> {
/**
* Pseudo topic name for the "outer" {@link ConsumerRecord} that has the aggregated
* results in its value after a normal release by the release strategy.
*/
public static final String AGGREGATED_RESULTS_TOPIC = "aggregatedResults";
/**
* Pseudo topic name for the "outer" {@link ConsumerRecord} that has the aggregated
* results in its value after a timeout.
*/
public static final String PARTIAL_RESULTS_AFTER_TIMEOUT_TOPIC = "partialResultsAfterTimeout";
private static final int DEFAULT_COMMIT_TIMEOUT = 30;
private final Map>> pending = new HashMap<>();
private final Map offsets = new HashMap<>();
private final BiPredicate>, Boolean> releaseStrategy;
private Duration commitTimeout = Duration.ofSeconds(DEFAULT_COMMIT_TIMEOUT);
private boolean returnPartialOnTimeout;
/**
* Construct an instance using the provided parameter arguments. The releaseStrategy
* is consulted to determine when a collection is "complete".
* @param producerFactory the producer factory.
* @param replyContainer the reply container.
* @param releaseStrategy the release strategy which is a {@link BiPredicate} which is
* passed the current list and a boolean to indicate if this is for a normal delivery
* or a timeout (when {@link #setReturnPartialOnTimeout(boolean)} is true. The
* predicate may modify the list of records.
* @since 2.3.5
*/
public AggregatingReplyingKafkaTemplate(ProducerFactory producerFactory,
GenericMessageListenerContainer>> replyContainer,
BiPredicate>, Boolean> releaseStrategy) {
super(producerFactory, replyContainer);
Assert.notNull(releaseStrategy, "'releaseStrategy' cannot be null");
AckMode ackMode = replyContainer.getContainerProperties().getAckMode();
Assert.isTrue(ackMode.equals(AckMode.MANUAL) || ackMode.equals(AckMode.MANUAL_IMMEDIATE),
"The reply container must have a MANUAL or MANUAL_IMMEDIATE AckMode");
this.releaseStrategy = releaseStrategy;
}
/**
* Set the timeout to use when committing offsets.
* @param commitTimeout the timeout.
*/
public void setCommitTimeout(Duration commitTimeout) {
Assert.notNull(commitTimeout, "'commitTimeout' cannot be null");
this.commitTimeout = commitTimeout;
}
/**
* Set to true to return a partial result when a request times out.
* @param returnPartialOnTimeout true to return a partial result.
*/
public synchronized void setReturnPartialOnTimeout(boolean returnPartialOnTimeout) {
this.returnPartialOnTimeout = returnPartialOnTimeout;
}
@Override
public void onMessage(List>>> data, Consumer consumer) {
List>>> completed = new ArrayList<>();
data.forEach(record -> {
Header correlation = record.headers().lastHeader(KafkaHeaders.CORRELATION_ID);
if (correlation == null) {
this.logger.error(() -> "No correlationId found in reply: " + record
+ " - to use request/reply semantics, the responding server must return the correlation id "
+ " in the '" + KafkaHeaders.CORRELATION_ID + "' header");
}
else {
CorrelationKey correlationId = new CorrelationKey(correlation.value());
synchronized (this) {
if (isPending(correlationId)) {
List> list = addToCollection(record, correlationId).stream()
.map(RecordHolder::getRecord)
.collect(Collectors.toList());
if (this.releaseStrategy.test(list, false)) {
ConsumerRecord>> done =
new ConsumerRecord<>(AGGREGATED_RESULTS_TOPIC, 0, 0L, null, list);
done.headers()
.add(new RecordHeader(KafkaHeaders.CORRELATION_ID, correlationId
.getCorrelationId()));
this.pending.remove(correlationId);
checkOffsetsAndCommitIfNecessary(list, consumer);
completed.add(done);
}
}
else {
logLateArrival(record, correlationId);
}
}
}
});
if (completed.size() > 0) {
super.onMessage(completed);
}
}
@Override
protected synchronized boolean handleTimeout(CorrelationKey correlationId,
RequestReplyFuture>> future) {
Set> removed = this.pending.remove(correlationId);
if (removed != null && this.returnPartialOnTimeout) {
List> list = removed.stream()
.map(RecordHolder::getRecord)
.collect(Collectors.toList());
if (this.releaseStrategy.test(list, true)) {
future.set(new ConsumerRecord<>(PARTIAL_RESULTS_AFTER_TIMEOUT_TOPIC, 0, 0L, null, list));
return true;
}
}
return false;
}
private void checkOffsetsAndCommitIfNecessary(List> list, Consumer consumer) {
list.forEach(record -> this.offsets.compute(
new TopicPartition(record.topic(), record.partition()),
(k, v) -> v == null ? record.offset() + 1 : Math.max(v, record.offset() + 1)));
if (this.pending.isEmpty() && !this.offsets.isEmpty()) {
consumer.commitSync(this.offsets.entrySet().stream()
.collect(Collectors.toMap(Map.Entry::getKey,
entry -> new OffsetAndMetadata(entry.getValue()))),
this.commitTimeout);
this.offsets.clear();
}
}
@SuppressWarnings({ "rawtypes", "unchecked" })
private Set> addToCollection(ConsumerRecord record, CorrelationKey correlationId) {
Set> set = this.pending.computeIfAbsent(correlationId, id -> new LinkedHashSet<>());
set.add(new RecordHolder<>(record));
return set;
}
private static final class RecordHolder {
private final ConsumerRecord record;
RecordHolder(ConsumerRecord record) {
this.record = record;
}
ConsumerRecord getRecord() {
return this.record;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ this.record.topic().hashCode()
+ this.record.partition()
+ (int) this.record.offset();
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
@SuppressWarnings("rawtypes")
RecordHolder other = (RecordHolder) obj;
if (this.record == null) {
if (other.record != null) {
return false;
}
}
else {
return this.record.topic().equals(other.record.topic())
&& this.record.partition() == other.record.partition()
&& this.record.offset() == other.record.offset();
}
return false;
}
}
}
