org.apache.kafka.clients.consumer.MockConsumer Maven / Gradle / Ivy
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/**
* 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.kafka.clients.consumer;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.apache.kafka.common.Metric;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.MetricName;
/**
* A mock of the {@link Consumer} interface you can use for testing code that uses Kafka.
* This class is not threadsafe
*
* The consumer runs in the user thread and multiplexes I/O over TCP connections to each of the brokers it
* needs to communicate with. Failure to close the consumer after use will leak these resources.
*/
public class MockConsumer implements Consumer {
private final Set subscribedPartitions;
private final Set subscribedTopics;
private final Map committedOffsets;
private final Map consumedOffsets;
public MockConsumer() {
subscribedPartitions = new HashSet();
subscribedTopics = new HashSet();
committedOffsets = new HashMap();
consumedOffsets = new HashMap();
}
@Override
public void subscribe(String... topics) {
if(subscribedPartitions.size() > 0)
throw new IllegalStateException("Subcription to topics and partitions is mutually exclusive");
for(String topic : topics) {
subscribedTopics.add(topic);
}
}
@Override
public void subscribe(TopicPartition... partitions) {
if(subscribedTopics.size() > 0)
throw new IllegalStateException("Subcription to topics and partitions is mutually exclusive");
for(TopicPartition partition : partitions) {
subscribedPartitions.add(partition);
consumedOffsets.put(partition, 0L);
}
}
public void unsubscribe(String... topics) {
// throw an exception if the topic was never subscribed to
for(String topic:topics) {
if(!subscribedTopics.contains(topic))
throw new IllegalStateException("Topic " + topic + " was never subscribed to. subscribe(" + topic + ") should be called prior" +
" to unsubscribe(" + topic + ")");
subscribedTopics.remove(topic);
}
}
public void unsubscribe(TopicPartition... partitions) {
// throw an exception if the partition was never subscribed to
for(TopicPartition partition:partitions) {
if(!subscribedPartitions.contains(partition))
throw new IllegalStateException("Partition " + partition + " was never subscribed to. subscribe(new TopicPartition(" +
partition.topic() + "," + partition.partition() + ") should be called prior" +
" to unsubscribe(new TopicPartition(" + partition.topic() + "," + partition.partition() + ")");
subscribedPartitions.remove(partition);
committedOffsets.remove(partition);
consumedOffsets.remove(partition);
}
}
@Override
public Map> poll(long timeout) {
// hand out one dummy record, 1 per topic
Map> records = new HashMap>();
Map> recordMetadata = new HashMap>();
for(TopicPartition partition : subscribedPartitions) {
// get the last consumed offset
long messageSequence = consumedOffsets.get(partition);
ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
ObjectOutputStream outputStream;
try {
outputStream = new ObjectOutputStream(byteStream);
outputStream.writeLong(messageSequence++);
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
List recordsForTopic = records.get(partition.topic());
if(recordsForTopic == null) {
recordsForTopic = new ArrayList();
records.put(partition.topic(), recordsForTopic);
}
recordsForTopic.add(new ConsumerRecord(partition.topic(), partition.partition(), null, byteStream.toByteArray(), messageSequence));
consumedOffsets.put(partition, messageSequence);
}
for(Entry> recordsPerTopic : records.entrySet()) {
Map> recordsPerPartition = new HashMap>();
for(ConsumerRecord record : recordsPerTopic.getValue()) {
List recordsForThisPartition = recordsPerPartition.get(record.partition());
if(recordsForThisPartition == null) {
recordsForThisPartition = new ArrayList();
recordsPerPartition.put(record.partition(), recordsForThisPartition);
}
recordsForThisPartition.add(record);
}
recordMetadata.put(recordsPerTopic.getKey(), new ConsumerRecords(recordsPerTopic.getKey(), recordsPerPartition));
}
return recordMetadata;
}
@Override
public OffsetMetadata commit(Map offsets, boolean sync) {
if(!sync)
return null;
for(Entry partitionOffset : offsets.entrySet()) {
committedOffsets.put(partitionOffset.getKey(), partitionOffset.getValue());
}
return new OffsetMetadata(committedOffsets, null);
}
@Override
public OffsetMetadata commit(boolean sync) {
if(!sync)
return null;
return commit(consumedOffsets, sync);
}
@Override
public void seek(Map offsets) {
// change the fetch offsets
for(Entry partitionOffset : offsets.entrySet()) {
consumedOffsets.put(partitionOffset.getKey(), partitionOffset.getValue());
}
}
@Override
public Map committed(Collection partitions) {
Map offsets = new HashMap();
for(TopicPartition partition : partitions) {
offsets.put(new TopicPartition(partition.topic(), partition.partition()), committedOffsets.get(partition));
}
return offsets;
}
@Override
public Map position(Collection partitions) {
Map positions = new HashMap();
for(TopicPartition partition : partitions) {
positions.put(partition, consumedOffsets.get(partition));
}
return positions;
}
@Override
public Map offsetsBeforeTime(long timestamp,
Collection partitions) {
throw new UnsupportedOperationException();
}
@Override
public Map metrics() {
return null;
}
@Override
public void close() {
// unsubscribe from all partitions
TopicPartition[] allPartitions = new TopicPartition[subscribedPartitions.size()];
unsubscribe(subscribedPartitions.toArray(allPartitions));
}
}