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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.common.requests;
import org.apache.kafka.common.IsolationLevel;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.protocol.ApiKeys;
import org.apache.kafka.common.protocol.Errors;
import org.apache.kafka.common.protocol.types.Field;
import org.apache.kafka.common.protocol.types.Schema;
import org.apache.kafka.common.protocol.types.Struct;
import org.apache.kafka.common.protocol.types.Type;
import org.apache.kafka.common.record.MemoryRecords;
import org.apache.kafka.common.utils.Utils;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import static org.apache.kafka.common.protocol.CommonFields.CURRENT_LEADER_EPOCH;
import static org.apache.kafka.common.protocol.CommonFields.PARTITION_ID;
import static org.apache.kafka.common.protocol.CommonFields.TOPIC_NAME;
import static org.apache.kafka.common.requests.FetchMetadata.FINAL_EPOCH;
import static org.apache.kafka.common.requests.FetchMetadata.INVALID_SESSION_ID;
public class FetchRequest extends AbstractRequest {
public static final int CONSUMER_REPLICA_ID = -1;
private static final Field.ComplexArray TOPICS = new Field.ComplexArray("topics",
"Topics to fetch in the order provided.");
private static final Field.ComplexArray FORGOTTEN_TOPICS = new Field.ComplexArray("forgotten_topics_data",
"Topics to remove from the fetch session.");
private static final Field.Int32 MAX_BYTES = new Field.Int32("max_bytes",
"Maximum bytes to accumulate in the response. Note that this is not an absolute maximum, " +
"if the first message in the first non-empty partition of the fetch is larger than this " +
"value, the message will still be returned to ensure that progress can be made.");
private static final Field.Int8 ISOLATION_LEVEL = new Field.Int8("isolation_level",
"This setting controls the visibility of transactional records. Using READ_UNCOMMITTED " +
"(isolation_level = 0) makes all records visible. With READ_COMMITTED (isolation_level = 1), " +
"non-transactional and COMMITTED transactional records are visible. To be more concrete, " +
"READ_COMMITTED returns all data from offsets smaller than the current LSO (last stable offset), " +
"and enables the inclusion of the list of aborted transactions in the result, which allows " +
"consumers to discard ABORTED transactional records");
private static final Field.Int32 SESSION_ID = new Field.Int32("session_id", "The fetch session ID");
private static final Field.Int32 SESSION_EPOCH = new Field.Int32("session_epoch", "The fetch session epoch");
private static final Field.Str RACK_ID = new Field.Str("rack_id", "The consumer's rack id");
// topic level fields
private static final Field.ComplexArray PARTITIONS = new Field.ComplexArray("partitions",
"Partitions to fetch.");
// partition level fields
private static final Field.Int32 REPLICA_ID = new Field.Int32("replica_id",
"Broker id of the follower. For normal consumers, use -1.");
private static final Field.Int64 FETCH_OFFSET = new Field.Int64("fetch_offset", "Message offset.");
private static final Field.Int32 PARTITION_MAX_BYTES = new Field.Int32("partition_max_bytes",
"Maximum bytes to fetch.");
private static final Field.Int32 MAX_WAIT_TIME = new Field.Int32("max_wait_time",
"Maximum time in ms to wait for the response.");
private static final Field.Int32 MIN_BYTES = new Field.Int32("min_bytes",
"Minimum bytes to accumulate in the response.");
private static final Field.Int64 LOG_START_OFFSET = new Field.Int64("log_start_offset",
"Earliest available offset of the follower replica. " +
"The field is only used when request is sent by follower. ");
private static final Field PARTITIONS_V0 = PARTITIONS.withFields(
PARTITION_ID,
FETCH_OFFSET,
PARTITION_MAX_BYTES);
private static final Field TOPICS_V0 = TOPICS.withFields(
TOPIC_NAME,
PARTITIONS_V0);
private static final Schema FETCH_REQUEST_V0 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
TOPICS_V0);
// The V1 Fetch Request body is the same as V0.
// Only the version number is incremented to indicate a newer client
private static final Schema FETCH_REQUEST_V1 = FETCH_REQUEST_V0;
// V2 bumped to indicate the client support message format V1 which uses relative offset and has timestamp.
private static final Schema FETCH_REQUEST_V2 = FETCH_REQUEST_V1;
// V3 added top level max_bytes field - the total size of partition data to accumulate in response.
// The partition ordering is now relevant - partitions will be processed in order they appear in request.
private static final Schema FETCH_REQUEST_V3 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
MAX_BYTES,
TOPICS_V0);
// V4 adds the fetch isolation level and exposes magic v2 (via the response).
private static final Schema FETCH_REQUEST_V4 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
MAX_BYTES,
ISOLATION_LEVEL,
TOPICS_V0);
// V5 added log_start_offset field - the earliest available offset of partition data that can be consumed.
private static final Field PARTITIONS_V5 = PARTITIONS.withFields(
PARTITION_ID,
FETCH_OFFSET,
LOG_START_OFFSET,
PARTITION_MAX_BYTES);
private static final Field TOPICS_V5 = TOPICS.withFields(
TOPIC_NAME,
PARTITIONS_V5);
private static final Schema FETCH_REQUEST_V5 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
MAX_BYTES,
ISOLATION_LEVEL,
TOPICS_V5);
// V6 bumped up to indicate that the client supports KafkaStorageException. The KafkaStorageException will be
// translated to NotLeaderOrFollowerException in the response if version <= 5
private static final Schema FETCH_REQUEST_V6 = FETCH_REQUEST_V5;
// V7 added incremental fetch requests.
private static final Field.Array FORGOTTEN_PARTITIONS = new Field.Array("partitions", Type.INT32,
"Partitions to remove from the fetch session.");
private static final Field FORGOTTEN_TOPIC_DATA_V7 = FORGOTTEN_TOPICS.withFields(
TOPIC_NAME,
FORGOTTEN_PARTITIONS);
private static final Schema FETCH_REQUEST_V7 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
MAX_BYTES,
ISOLATION_LEVEL,
SESSION_ID,
SESSION_EPOCH,
TOPICS_V5,
FORGOTTEN_TOPIC_DATA_V7);
// V8 bump used to indicate that on quota violation brokers send out responses before throttling.
private static final Schema FETCH_REQUEST_V8 = FETCH_REQUEST_V7;
// V9 adds the current leader epoch (see KIP-320)
private static final Field FETCH_REQUEST_PARTITION_V9 = PARTITIONS.withFields(
PARTITION_ID,
CURRENT_LEADER_EPOCH,
FETCH_OFFSET,
LOG_START_OFFSET,
PARTITION_MAX_BYTES);
private static final Field FETCH_REQUEST_TOPIC_V9 = TOPICS.withFields(
TOPIC_NAME,
FETCH_REQUEST_PARTITION_V9);
private static final Schema FETCH_REQUEST_V9 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
MAX_BYTES,
ISOLATION_LEVEL,
SESSION_ID,
SESSION_EPOCH,
FETCH_REQUEST_TOPIC_V9,
FORGOTTEN_TOPIC_DATA_V7);
// V10 bumped up to indicate ZStandard capability. (see KIP-110)
private static final Schema FETCH_REQUEST_V10 = FETCH_REQUEST_V9;
// V11 added rack ID to support read from followers (KIP-392)
private static final Schema FETCH_REQUEST_V11 = new Schema(
REPLICA_ID,
MAX_WAIT_TIME,
MIN_BYTES,
MAX_BYTES,
ISOLATION_LEVEL,
SESSION_ID,
SESSION_EPOCH,
FETCH_REQUEST_TOPIC_V9,
FORGOTTEN_TOPIC_DATA_V7,
RACK_ID);
public static Schema[] schemaVersions() {
return new Schema[]{FETCH_REQUEST_V0, FETCH_REQUEST_V1, FETCH_REQUEST_V2, FETCH_REQUEST_V3, FETCH_REQUEST_V4,
FETCH_REQUEST_V5, FETCH_REQUEST_V6, FETCH_REQUEST_V7, FETCH_REQUEST_V8, FETCH_REQUEST_V9,
FETCH_REQUEST_V10, FETCH_REQUEST_V11};
}
// default values for older versions where a request level limit did not exist
public static final int DEFAULT_RESPONSE_MAX_BYTES = Integer.MAX_VALUE;
public static final long INVALID_LOG_START_OFFSET = -1L;
private final int replicaId;
private final int maxWait;
private final int minBytes;
private final int maxBytes;
private final IsolationLevel isolationLevel;
// Note: the iteration order of this map is significant, since it determines the order
// in which partitions appear in the message. For this reason, this map should have a
// deterministic iteration order, like LinkedHashMap or TreeMap (but unlike HashMap).
private final Map fetchData;
private final List toForget;
private final FetchMetadata metadata;
private final String rackId;
public static final class PartitionData {
public final long fetchOffset;
public final long logStartOffset;
public final int maxBytes;
public final Optional currentLeaderEpoch;
public PartitionData(long fetchOffset, long logStartOffset, int maxBytes, Optional currentLeaderEpoch) {
this.fetchOffset = fetchOffset;
this.logStartOffset = logStartOffset;
this.maxBytes = maxBytes;
this.currentLeaderEpoch = currentLeaderEpoch;
}
@Override
public String toString() {
return "(fetchOffset=" + fetchOffset +
", logStartOffset=" + logStartOffset +
", maxBytes=" + maxBytes +
", currentLeaderEpoch=" + currentLeaderEpoch +
")";
}
@Override
public int hashCode() {
return Objects.hash(fetchOffset, logStartOffset, maxBytes, currentLeaderEpoch);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
PartitionData that = (PartitionData) o;
return fetchOffset == that.fetchOffset &&
logStartOffset == that.logStartOffset &&
maxBytes == that.maxBytes &&
currentLeaderEpoch.equals(that.currentLeaderEpoch);
}
}
static final class TopicAndPartitionData {
public final String topic;
public final LinkedHashMap partitions;
public TopicAndPartitionData(String topic) {
this.topic = topic;
this.partitions = new LinkedHashMap<>();
}
public static List> batchByTopic(Iterator> iter) {
List> topics = new ArrayList<>();
while (iter.hasNext()) {
Map.Entry topicEntry = iter.next();
String topic = topicEntry.getKey().topic();
int partition = topicEntry.getKey().partition();
T partitionData = topicEntry.getValue();
if (topics.isEmpty() || !topics.get(topics.size() - 1).topic.equals(topic))
topics.add(new TopicAndPartitionData(topic));
topics.get(topics.size() - 1).partitions.put(partition, partitionData);
}
return topics;
}
}
public static class Builder extends AbstractRequest.Builder {
private final int maxWait;
private final int minBytes;
private final int replicaId;
private final Map fetchData;
private IsolationLevel isolationLevel = IsolationLevel.READ_UNCOMMITTED;
private int maxBytes = DEFAULT_RESPONSE_MAX_BYTES;
private FetchMetadata metadata = FetchMetadata.LEGACY;
private List toForget = Collections.emptyList();
private String rackId = "";
public static Builder forConsumer(int maxWait, int minBytes, Map fetchData) {
return new Builder(ApiKeys.FETCH.oldestVersion(), ApiKeys.FETCH.latestVersion(),
CONSUMER_REPLICA_ID, maxWait, minBytes, fetchData);
}
public static Builder forReplica(short allowedVersion, int replicaId, int maxWait, int minBytes,
Map fetchData) {
return new Builder(allowedVersion, allowedVersion, replicaId, maxWait, minBytes, fetchData);
}
public Builder(short minVersion, short maxVersion, int replicaId, int maxWait, int minBytes,
Map fetchData) {
super(ApiKeys.FETCH, minVersion, maxVersion);
this.replicaId = replicaId;
this.maxWait = maxWait;
this.minBytes = minBytes;
this.fetchData = fetchData;
}
public Builder isolationLevel(IsolationLevel isolationLevel) {
this.isolationLevel = isolationLevel;
return this;
}
public Builder metadata(FetchMetadata metadata) {
this.metadata = metadata;
return this;
}
public Builder rackId(String rackId) {
this.rackId = rackId;
return this;
}
public Map fetchData() {
return this.fetchData;
}
public Builder setMaxBytes(int maxBytes) {
this.maxBytes = maxBytes;
return this;
}
public List toForget() {
return toForget;
}
public Builder toForget(List toForget) {
this.toForget = toForget;
return this;
}
@Override
public FetchRequest build(short version) {
if (version < 3) {
maxBytes = DEFAULT_RESPONSE_MAX_BYTES;
}
return new FetchRequest(version, replicaId, maxWait, minBytes, maxBytes, fetchData,
isolationLevel, toForget, metadata, rackId);
}
@Override
public String toString() {
StringBuilder bld = new StringBuilder();
bld.append("(type=FetchRequest").
append(", replicaId=").append(replicaId).
append(", maxWait=").append(maxWait).
append(", minBytes=").append(minBytes).
append(", maxBytes=").append(maxBytes).
append(", fetchData=").append(fetchData).
append(", isolationLevel=").append(isolationLevel).
append(", toForget=").append(Utils.join(toForget, ", ")).
append(", metadata=").append(metadata).
append(", rackId=").append(rackId).
append(")");
return bld.toString();
}
}
private FetchRequest(short version, int replicaId, int maxWait, int minBytes, int maxBytes,
Map fetchData, IsolationLevel isolationLevel,
List toForget, FetchMetadata metadata, String rackId) {
super(ApiKeys.FETCH, version);
this.replicaId = replicaId;
this.maxWait = maxWait;
this.minBytes = minBytes;
this.maxBytes = maxBytes;
this.fetchData = fetchData;
this.isolationLevel = isolationLevel;
this.toForget = toForget;
this.metadata = metadata;
this.rackId = rackId;
}
public FetchRequest(Struct struct, short version) {
super(ApiKeys.FETCH, version);
replicaId = struct.get(REPLICA_ID);
maxWait = struct.get(MAX_WAIT_TIME);
minBytes = struct.get(MIN_BYTES);
maxBytes = struct.getOrElse(MAX_BYTES, DEFAULT_RESPONSE_MAX_BYTES);
if (struct.hasField(ISOLATION_LEVEL))
isolationLevel = IsolationLevel.forId(struct.get(ISOLATION_LEVEL));
else
isolationLevel = IsolationLevel.READ_UNCOMMITTED;
toForget = new ArrayList<>(0);
if (struct.hasField(FORGOTTEN_TOPICS)) {
for (Object forgottenTopicObj : struct.get(FORGOTTEN_TOPICS)) {
Struct forgottenTopic = (Struct) forgottenTopicObj;
String topicName = forgottenTopic.get(TOPIC_NAME);
for (Object partObj : forgottenTopic.get(FORGOTTEN_PARTITIONS)) {
Integer part = (Integer) partObj;
toForget.add(new TopicPartition(topicName, part));
}
}
}
metadata = new FetchMetadata(struct.getOrElse(SESSION_ID, INVALID_SESSION_ID),
struct.getOrElse(SESSION_EPOCH, FINAL_EPOCH));
fetchData = new LinkedHashMap<>();
for (Object topicResponseObj : struct.get(TOPICS)) {
Struct topicResponse = (Struct) topicResponseObj;
String topic = topicResponse.get(TOPIC_NAME);
for (Object partitionResponseObj : topicResponse.get(PARTITIONS)) {
Struct partitionResponse = (Struct) partitionResponseObj;
int partition = partitionResponse.get(PARTITION_ID);
long offset = partitionResponse.get(FETCH_OFFSET);
int maxBytes = partitionResponse.get(PARTITION_MAX_BYTES);
long logStartOffset = partitionResponse.getOrElse(LOG_START_OFFSET, INVALID_LOG_START_OFFSET);
// Current leader epoch added in v9
Optional currentLeaderEpoch = RequestUtils.getLeaderEpoch(partitionResponse, CURRENT_LEADER_EPOCH);
PartitionData partitionData = new PartitionData(offset, logStartOffset, maxBytes, currentLeaderEpoch);
fetchData.put(new TopicPartition(topic, partition), partitionData);
}
}
rackId = struct.getOrElse(RACK_ID, "");
}
@Override
public AbstractResponse getErrorResponse(int throttleTimeMs, Throwable e) {
// The error is indicated in two ways: by setting the same error code in all partitions, and by
// setting the top-level error code. The form where we set the same error code in all partitions
// is needed in order to maintain backwards compatibility with older versions of the protocol
// in which there was no top-level error code. Note that for incremental fetch responses, there
// may not be any partitions at all in the response. For this reason, the top-level error code
// is essential for them.
Errors error = Errors.forException(e);
LinkedHashMap> responseData = new LinkedHashMap<>();
for (Map.Entry entry : fetchData.entrySet()) {
FetchResponse.PartitionData partitionResponse = new FetchResponse.PartitionData<>(error,
FetchResponse.INVALID_HIGHWATERMARK, FetchResponse.INVALID_LAST_STABLE_OFFSET,
FetchResponse.INVALID_LOG_START_OFFSET, Optional.empty(), null, MemoryRecords.EMPTY);
responseData.put(entry.getKey(), partitionResponse);
}
return new FetchResponse<>(error, responseData, throttleTimeMs, metadata.sessionId());
}
public int replicaId() {
return replicaId;
}
public int maxWait() {
return maxWait;
}
public int minBytes() {
return minBytes;
}
public int maxBytes() {
return maxBytes;
}
public Map fetchData() {
return fetchData;
}
public List toForget() {
return toForget;
}
public boolean isFromFollower() {
return replicaId >= 0;
}
public IsolationLevel isolationLevel() {
return isolationLevel;
}
public FetchMetadata metadata() {
return metadata;
}
public String rackId() {
return rackId;
}
public static FetchRequest parse(ByteBuffer buffer, short version) {
return new FetchRequest(ApiKeys.FETCH.parseRequest(version, buffer), version);
}
@Override
protected Struct toStruct() {
Struct struct = new Struct(ApiKeys.FETCH.requestSchema(version()));
List> topicsData =
TopicAndPartitionData.batchByTopic(fetchData.entrySet().iterator());
struct.set(REPLICA_ID, replicaId);
struct.set(MAX_WAIT_TIME, maxWait);
struct.set(MIN_BYTES, minBytes);
struct.setIfExists(MAX_BYTES, maxBytes);
struct.setIfExists(ISOLATION_LEVEL, isolationLevel.id());
struct.setIfExists(SESSION_ID, metadata.sessionId());
struct.setIfExists(SESSION_EPOCH, metadata.epoch());
List topicArray = new ArrayList<>();
for (TopicAndPartitionData topicEntry : topicsData) {
Struct topicData = struct.instance(TOPICS);
topicData.set(TOPIC_NAME, topicEntry.topic);
List partitionArray = new ArrayList<>();
for (Map.Entry partitionEntry : topicEntry.partitions.entrySet()) {
PartitionData fetchPartitionData = partitionEntry.getValue();
Struct partitionData = topicData.instance(PARTITIONS);
partitionData.set(PARTITION_ID, partitionEntry.getKey());
partitionData.set(FETCH_OFFSET, fetchPartitionData.fetchOffset);
partitionData.set(PARTITION_MAX_BYTES, fetchPartitionData.maxBytes);
partitionData.setIfExists(LOG_START_OFFSET, fetchPartitionData.logStartOffset);
RequestUtils.setLeaderEpochIfExists(partitionData, CURRENT_LEADER_EPOCH, fetchPartitionData.currentLeaderEpoch);
partitionArray.add(partitionData);
}
topicData.set(PARTITIONS, partitionArray.toArray());
topicArray.add(topicData);
}
struct.set(TOPICS, topicArray.toArray());
if (struct.hasField(FORGOTTEN_TOPICS)) {
Map> topicsToPartitions = new HashMap<>();
for (TopicPartition part : toForget) {
List partitions = topicsToPartitions.computeIfAbsent(part.topic(), topic -> new ArrayList<>());
partitions.add(part.partition());
}
List toForgetStructs = new ArrayList<>();
for (Map.Entry> entry : topicsToPartitions.entrySet()) {
Struct toForgetStruct = struct.instance(FORGOTTEN_TOPICS);
toForgetStruct.set(TOPIC_NAME, entry.getKey());
toForgetStruct.set(FORGOTTEN_PARTITIONS, entry.getValue().toArray());
toForgetStructs.add(toForgetStruct);
}
struct.set(FORGOTTEN_TOPICS, toForgetStructs.toArray());
}
struct.setIfExists(RACK_ID, rackId);
return struct;
}
}
