kafka ConsumerTask 源码
kafka ConsumerTask 代码
文件路径：/storage/src/main/java/org/apache/kafka/server/log/remote/metadata/storage/ConsumerTask.java
/*
* 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.
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package org.apache.kafka.server.log.remote.metadata.storage;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.TopicIdPartition;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.utils.Time;
import org.apache.kafka.server.log.remote.metadata.storage.serialization.RemoteLogMetadataSerde;
import org.apache.kafka.server.log.remote.storage.RemoteLogMetadata;
import org.apache.kafka.server.log.remote.storage.RemoteLogSegmentMetadata;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.Closeable;
import java.io.IOException;
import java.nio.file.Path;
import java.time.Duration;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;
import static org.apache.kafka.server.log.remote.metadata.storage.TopicBasedRemoteLogMetadataManagerConfig.REMOTE_LOG_METADATA_TOPIC_NAME;
/**
* This class is responsible for consuming messages from remote log metadata topic ({@link TopicBasedRemoteLogMetadataManagerConfig#REMOTE_LOG_METADATA_TOPIC_NAME})
* partitions and maintain the state of the remote log segment metadata. It gives an API to add or remove
* for what topic partition's metadata should be consumed by this instance using
* {{@link #addAssignmentsForPartitions(Set)}} and {@link #removeAssignmentsForPartitions(Set)} respectively.
* <p>
* When a broker is started, controller sends topic partitions that this broker is leader or follower for and the
* partitions to be deleted. This class receives those notifications with
* {@link #addAssignmentsForPartitions(Set)} and {@link #removeAssignmentsForPartitions(Set)} assigns consumer for the
* respective remote log metadata partitions by using {@link RemoteLogMetadataTopicPartitioner#metadataPartition(TopicIdPartition)}.
* Any leadership changes later are called through the same API. We will remove the partitions that are deleted from
* this broker which are received through {@link #removeAssignmentsForPartitions(Set)}.
* <p>
* After receiving these events it invokes {@link RemotePartitionMetadataEventHandler#handleRemoteLogSegmentMetadata(RemoteLogSegmentMetadata)},
* which maintains in-memory representation of the state of {@link RemoteLogSegmentMetadata}.
*/
class ConsumerTask implements Runnable, Closeable {
private static final Logger log = LoggerFactory.getLogger(ConsumerTask.class);
private static final long POLL_INTERVAL_MS = 100L;
private final RemoteLogMetadataSerde serde = new RemoteLogMetadataSerde();
private final KafkaConsumer<byte[], byte[]> consumer;
private final RemotePartitionMetadataEventHandler remotePartitionMetadataEventHandler;
private final RemoteLogMetadataTopicPartitioner topicPartitioner;
private final Time time;
// It indicates whether the closing process has been started or not. If it is set as true,
// consumer will stop consuming messages and it will not allow partition assignments to be updated.
private volatile boolean closing = false;
// It indicates whether the consumer needs to assign the partitions or not. This is set when it is
// determined that the consumer needs to be assigned with the updated partitions.
private volatile boolean assignPartitions = false;
// It represents a lock for any operations related to the assignedTopicPartitions.
private final Object assignPartitionsLock = new Object();
// Remote log metadata topic partitions that consumer is assigned to.
private volatile Set<Integer> assignedMetaPartitions = Collections.emptySet();
// User topic partitions that this broker is a leader/follower for.
private Set<TopicIdPartition> assignedTopicPartitions = Collections.emptySet();
// Map of remote log metadata topic partition to consumed offsets. Received consumer records
// may or may not have been processed based on the assigned topic partitions.
private final Map<Integer, Long> partitionToConsumedOffsets = new ConcurrentHashMap<>();
// Map of remote log metadata topic partition to processed offsets that were synced in committedOffsetsFile.
private Map<Integer, Long> lastSyncedPartitionToConsumedOffsets = Collections.emptyMap();
private final long committedOffsetSyncIntervalMs;
private CommittedOffsetsFile committedOffsetsFile;
private long lastSyncedTimeMs;
public ConsumerTask(KafkaConsumer<byte[], byte[]> consumer,
RemotePartitionMetadataEventHandler remotePartitionMetadataEventHandler,
RemoteLogMetadataTopicPartitioner topicPartitioner,
Path committedOffsetsPath,
Time time,
long committedOffsetSyncIntervalMs) {
this.consumer = Objects.requireNonNull(consumer);
this.remotePartitionMetadataEventHandler = Objects.requireNonNull(remotePartitionMetadataEventHandler);
this.topicPartitioner = Objects.requireNonNull(topicPartitioner);
this.time = Objects.requireNonNull(time);
this.committedOffsetSyncIntervalMs = committedOffsetSyncIntervalMs;
initializeConsumerAssignment(committedOffsetsPath);
}
private void initializeConsumerAssignment(Path committedOffsetsPath) {
try {
committedOffsetsFile = new CommittedOffsetsFile(committedOffsetsPath.toFile());
} catch (IOException e) {
throw new KafkaException(e);
}
Map<Integer, Long> committedOffsets = Collections.emptyMap();
try {
// Load committed offset and assign them in the consumer.
committedOffsets = committedOffsetsFile.readEntries();
} catch (IOException e) {
// Ignore the error and consumer consumes from the earliest offset.
log.error("Encountered error while building committed offsets from the file. " +
"Consumer will consume from the earliest offset for the assigned partitions.", e);
}
if (!committedOffsets.isEmpty()) {
// Assign topic partitions from the earlier committed offsets file.
Set<Integer> earlierAssignedPartitions = committedOffsets.keySet();
assignedMetaPartitions = Collections.unmodifiableSet(earlierAssignedPartitions);
Set<TopicPartition> metadataTopicPartitions = earlierAssignedPartitions.stream()
.map(x -> new TopicPartition(REMOTE_LOG_METADATA_TOPIC_NAME, x))
.collect(Collectors.toSet());
consumer.assign(metadataTopicPartitions);
// Seek to the committed offsets
for (Map.Entry<Integer, Long> entry : committedOffsets.entrySet()) {
partitionToConsumedOffsets.put(entry.getKey(), entry.getValue());
consumer.seek(new TopicPartition(REMOTE_LOG_METADATA_TOPIC_NAME, entry.getKey()), entry.getValue());
}
lastSyncedPartitionToConsumedOffsets = Collections.unmodifiableMap(committedOffsets);
}
}
@Override
public void run() {
log.info("Started Consumer task thread.");
lastSyncedTimeMs = time.milliseconds();
try {
while (!closing) {
maybeWaitForPartitionsAssignment();
log.info("Polling consumer to receive remote log metadata topic records");
ConsumerRecords<byte[], byte[]> consumerRecords = consumer.poll(Duration.ofMillis(POLL_INTERVAL_MS));
for (ConsumerRecord<byte[], byte[]> record : consumerRecords) {
processConsumerRecord(record);
}
maybeSyncCommittedDataAndOffsets(false);
}
} catch (Exception e) {
log.error("Error occurred in consumer task, close:[{}]", closing, e);
} finally {
maybeSyncCommittedDataAndOffsets(true);
closeConsumer();
log.info("Exiting from consumer task thread");
}
}
private void processConsumerRecord(ConsumerRecord<byte[], byte[]> record) {
// Taking assignPartitionsLock here as updateAssignmentsForPartitions changes assignedTopicPartitions
// and also calls remotePartitionMetadataEventHandler.clearTopicPartition(removedPartition) for the removed
// partitions.
RemoteLogMetadata remoteLogMetadata = serde.deserialize(record.value());
synchronized (assignPartitionsLock) {
if (assignedTopicPartitions.contains(remoteLogMetadata.topicIdPartition())) {
remotePartitionMetadataEventHandler.handleRemoteLogMetadata(remoteLogMetadata);
} else {
log.debug("This event {} is skipped as the topic partition is not assigned for this instance.", remoteLogMetadata);
}
partitionToConsumedOffsets.put(record.partition(), record.offset());
}
}
private void maybeSyncCommittedDataAndOffsets(boolean forceSync) {
// Return immediately if there is no consumption from last time.
boolean noConsumedOffsetUpdates = partitionToConsumedOffsets.equals(lastSyncedPartitionToConsumedOffsets);
if (noConsumedOffsetUpdates || !forceSync && time.milliseconds() - lastSyncedTimeMs < committedOffsetSyncIntervalMs) {
log.debug("Skip syncing committed offsets, noConsumedOffsetUpdates: {}, forceSync: {}", noConsumedOffsetUpdates, forceSync);
return;
}
try {
// Need to take lock on assignPartitionsLock as assignedTopicPartitions might
// get updated by other threads.
synchronized (assignPartitionsLock) {
for (TopicIdPartition topicIdPartition : assignedTopicPartitions) {
int metadataPartition = topicPartitioner.metadataPartition(topicIdPartition);
Long offset = partitionToConsumedOffsets.get(metadataPartition);
if (offset != null) {
remotePartitionMetadataEventHandler.syncLogMetadataSnapshot(topicIdPartition, metadataPartition, offset);
} else {
log.debug("Skipping syncup of the remote-log-metadata-file for partition:{} , with remote log metadata partition{}, and no offset",
topicIdPartition, metadataPartition);
}
}
// Write partitionToConsumedOffsets into committed offsets file as we do not want to process them again
// in case of restarts.
committedOffsetsFile.writeEntries(partitionToConsumedOffsets);
lastSyncedPartitionToConsumedOffsets = new HashMap<>(partitionToConsumedOffsets);
}
lastSyncedTimeMs = time.milliseconds();
} catch (IOException e) {
throw new KafkaException("Error encountered while writing committed offsets to a local file", e);
}
}
private void closeConsumer() {
log.info("Closing the consumer instance");
try {
consumer.close(Duration.ofSeconds(30));
} catch (Exception e) {
log.error("Error encountered while closing the consumer", e);
}
}
private void maybeWaitForPartitionsAssignment() {
Set<Integer> assignedMetaPartitionsSnapshot = Collections.emptySet();
synchronized (assignPartitionsLock) {
// If it is closing, return immediately. This should be inside the assignPartitionsLock as the closing is updated
// in close() method with in the same lock to avoid any race conditions.
if (closing) {
return;
}
while (assignedMetaPartitions.isEmpty()) {
// If no partitions are assigned, wait until they are assigned.
log.debug("Waiting for assigned remote log metadata partitions..");
try {
// No timeout is set here, as it is always notified. Even when it is closed, the race can happen
// between the thread calling this method and the thread calling close(). We should have a check
// for closing as that might have been set and notified with assignPartitionsLock by `close`
// method.
assignPartitionsLock.wait();
if (closing) {
return;
}
} catch (InterruptedException e) {
throw new KafkaException(e);
}
}
if (assignPartitions) {
assignedMetaPartitionsSnapshot = new HashSet<>(assignedMetaPartitions);
// Removing unassigned meta partitions from partitionToConsumedOffsets and partitionToCommittedOffsets
partitionToConsumedOffsets.entrySet().removeIf(entry -> !assignedMetaPartitions.contains(entry.getKey()));
assignPartitions = false;
}
}
if (!assignedMetaPartitionsSnapshot.isEmpty()) {
executeReassignment(assignedMetaPartitionsSnapshot);
}
}
private void executeReassignment(Set<Integer> assignedMetaPartitionsSnapshot) {
Set<TopicPartition> assignedMetaTopicPartitions =
assignedMetaPartitionsSnapshot.stream()
.map(partitionNum -> new TopicPartition(REMOTE_LOG_METADATA_TOPIC_NAME, partitionNum))
.collect(Collectors.toSet());
log.info("Reassigning partitions to consumer task [{}]", assignedMetaTopicPartitions);
consumer.assign(assignedMetaTopicPartitions);
}
public void addAssignmentsForPartitions(Set<TopicIdPartition> partitions) {
updateAssignmentsForPartitions(partitions, Collections.emptySet());
}
public void removeAssignmentsForPartitions(Set<TopicIdPartition> partitions) {
updateAssignmentsForPartitions(Collections.emptySet(), partitions);
}
private void updateAssignmentsForPartitions(Set<TopicIdPartition> addedPartitions,
Set<TopicIdPartition> removedPartitions) {
log.info("Updating assignments for addedPartitions: {} and removedPartition: {}", addedPartitions, removedPartitions);
Objects.requireNonNull(addedPartitions, "addedPartitions must not be null");
Objects.requireNonNull(removedPartitions, "removedPartitions must not be null");
if (addedPartitions.isEmpty() && removedPartitions.isEmpty()) {
return;
}
synchronized (assignPartitionsLock) {
Set<TopicIdPartition> updatedReassignedPartitions = new HashSet<>(assignedTopicPartitions);
updatedReassignedPartitions.addAll(addedPartitions);
updatedReassignedPartitions.removeAll(removedPartitions);
Set<Integer> updatedAssignedMetaPartitions = new HashSet<>();
for (TopicIdPartition tp : updatedReassignedPartitions) {
updatedAssignedMetaPartitions.add(topicPartitioner.metadataPartition(tp));
}
// Clear removed topic partitions from inmemory cache.
for (TopicIdPartition removedPartition : removedPartitions) {
remotePartitionMetadataEventHandler.clearTopicPartition(removedPartition);
}
assignedTopicPartitions = Collections.unmodifiableSet(updatedReassignedPartitions);
log.debug("Assigned topic partitions: {}", assignedTopicPartitions);
if (!updatedAssignedMetaPartitions.equals(assignedMetaPartitions)) {
assignedMetaPartitions = Collections.unmodifiableSet(updatedAssignedMetaPartitions);
log.debug("Assigned metadata topic partitions: {}", assignedMetaPartitions);
assignPartitions = true;
assignPartitionsLock.notifyAll();
} else {
log.debug("No change in assigned metadata topic partitions: {}", assignedMetaPartitions);
}
}
}
public Optional<Long> receivedOffsetForPartition(int partition) {
return Optional.ofNullable(partitionToConsumedOffsets.get(partition));
}
public boolean isPartitionAssigned(int partition) {
return assignedMetaPartitions.contains(partition);
}
public void close() {
if (!closing) {
synchronized (assignPartitionsLock) {
// Closing should be updated only after acquiring the lock to avoid race in
// maybeWaitForPartitionsAssignment() where it waits on assignPartitionsLock. It should not wait
// if the closing is already set.
closing = true;
consumer.wakeup();
assignPartitionsLock.notifyAll();
}
}
}
}
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