org.apache.kafka.clients.consumer.OffsetAndMetadata 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.kafka.clients.consumer;
import org.apache.kafka.common.requests.OffsetFetchResponse;
import java.io.Serializable;
import java.util.Objects;
import java.util.Optional;
/**
* The Kafka offset commit API allows users to provide additional metadata (in the form of a string)
* when an offset is committed. This can be useful (for example) to store information about which
* node made the commit, what time the commit was made, etc.
*/
public class OffsetAndMetadata implements Serializable {
private static final long serialVersionUID = 2019555404968089681L;
private final long offset;
private final String metadata;
// We use null to represent the absence of a leader epoch to simplify serialization.
// I.e., older serializations of this class which do not have this field will automatically
// initialize its value to null.
private final Integer leaderEpoch;
/**
* Construct a new OffsetAndMetadata object for committing through {@link KafkaConsumer}.
*
* @param offset The offset to be committed
* @param leaderEpoch Optional leader epoch of the last consumed record
* @param metadata Non-null metadata
*/
public OffsetAndMetadata(long offset, Optional leaderEpoch, String metadata) {
if (offset < 0)
throw new IllegalArgumentException("Invalid negative offset");
this.offset = offset;
this.leaderEpoch = leaderEpoch.orElse(null);
// The server converts null metadata to an empty string. So we store it as an empty string as well on the client
// to be consistent.
if (metadata == null)
this.metadata = OffsetFetchResponse.NO_METADATA;
else
this.metadata = metadata;
}
/**
* Construct a new OffsetAndMetadata object for committing through {@link KafkaConsumer}.
* @param offset The offset to be committed
* @param metadata Non-null metadata
*/
public OffsetAndMetadata(long offset, String metadata) {
this(offset, Optional.empty(), metadata);
}
/**
* Construct a new OffsetAndMetadata object for committing through {@link KafkaConsumer}. The metadata
* associated with the commit will be empty.
* @param offset The offset to be committed
*/
public OffsetAndMetadata(long offset) {
this(offset, "");
}
public long offset() {
return offset;
}
public String metadata() {
return metadata;
}
/**
* Get the leader epoch of the previously consumed record (if one is known). Log truncation is detected
* if there exists a leader epoch which is larger than this epoch and begins at an offset earlier than
* the committed offset.
*
* @return the leader epoch or empty if not known
*/
public Optional leaderEpoch() {
return Optional.ofNullable(leaderEpoch);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
OffsetAndMetadata that = (OffsetAndMetadata) o;
return offset == that.offset &&
Objects.equals(metadata, that.metadata) &&
Objects.equals(leaderEpoch, that.leaderEpoch);
}
@Override
public int hashCode() {
return Objects.hash(offset, metadata, leaderEpoch);
}
@Override
public String toString() {
return "OffsetAndMetadata{" +
"offset=" + offset +
", leaderEpoch=" + leaderEpoch +
", metadata='" + metadata + '\'' +
'}';
}
}