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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.internals;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.common.IsolationLevel;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.errors.CorruptRecordException;
import org.apache.kafka.common.errors.RecordDeserializationException;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.header.internals.RecordHeaders;
import org.apache.kafka.common.message.FetchResponseData;
import org.apache.kafka.common.record.ControlRecordType;
import org.apache.kafka.common.record.Record;
import org.apache.kafka.common.record.RecordBatch;
import org.apache.kafka.common.record.TimestampType;
import org.apache.kafka.common.requests.FetchRequest;
import org.apache.kafka.common.requests.FetchResponse;
import org.apache.kafka.common.serialization.Deserializer;
import org.apache.kafka.common.utils.BufferSupplier;
import org.apache.kafka.common.utils.CloseableIterator;
import org.apache.kafka.common.utils.LogContext;
import org.slf4j.Logger;
import java.io.Closeable;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.PriorityQueue;
import java.util.Set;
/**
* {@link CompletedFetch} represents a {@link RecordBatch batch} of {@link Record records} that was returned from the
* broker via a {@link FetchRequest}. It contains logic to maintain state between calls to {@link #fetchRecords(int)}.
*
* @param Record key type
* @param Record value type
*/
class CompletedFetch {
final TopicPartition partition;
final FetchResponseData.PartitionData partitionData;
final short requestVersion;
long nextFetchOffset;
Optional lastEpoch;
boolean isConsumed = false;
boolean initialized = false;
private final Logger log;
private final SubscriptionState subscriptions;
private final FetchConfig fetchConfig;
private final BufferSupplier decompressionBufferSupplier;
private final Iterator batches;
private final Set abortedProducerIds;
private final PriorityQueue abortedTransactions;
private final FetchMetricsAggregator metricAggregator;
private int recordsRead;
private int bytesRead;
private RecordBatch currentBatch;
private Record lastRecord;
private CloseableIterator records;
private Exception cachedRecordException = null;
private boolean corruptLastRecord = false;
CompletedFetch(LogContext logContext,
SubscriptionState subscriptions,
FetchConfig fetchConfig,
BufferSupplier decompressionBufferSupplier,
TopicPartition partition,
FetchResponseData.PartitionData partitionData,
FetchMetricsAggregator metricAggregator,
Long fetchOffset,
short requestVersion) {
this.log = logContext.logger(CompletedFetch.class);
this.subscriptions = subscriptions;
this.fetchConfig = fetchConfig;
this.decompressionBufferSupplier = decompressionBufferSupplier;
this.partition = partition;
this.partitionData = partitionData;
this.metricAggregator = metricAggregator;
this.batches = FetchResponse.recordsOrFail(partitionData).batches().iterator();
this.nextFetchOffset = fetchOffset;
this.requestVersion = requestVersion;
this.lastEpoch = Optional.empty();
this.abortedProducerIds = new HashSet<>();
this.abortedTransactions = abortedTransactions(partitionData);
}
/**
* After each partition is parsed, we update the current metric totals with the total bytes
* and number of records parsed. After all partitions have reported, we write the metric.
*/
void recordAggregatedMetrics(int bytes, int records) {
metricAggregator.record(partition, bytes, records);
}
/**
* Draining a {@link CompletedFetch} will signal that the data has been consumed and the underlying resources
* are closed. This is somewhat analogous to {@link Closeable#close() closing}, though no error will result if a
* caller invokes {@link #fetchRecords(int)}; an empty {@link List list} will be returned instead.
*/
void drain() {
if (!isConsumed) {
maybeCloseRecordStream();
cachedRecordException = null;
this.isConsumed = true;
recordAggregatedMetrics(bytesRead, recordsRead);
// we move the partition to the end if we received some bytes. This way, it's more likely that partitions
// for the same topic can remain together (allowing for more efficient serialization).
if (bytesRead > 0)
subscriptions.movePartitionToEnd(partition);
}
}
private void maybeEnsureValid(RecordBatch batch) {
if (fetchConfig.checkCrcs && batch.magic() >= RecordBatch.MAGIC_VALUE_V2) {
try {
batch.ensureValid();
} catch (CorruptRecordException e) {
throw new KafkaException("Record batch for partition " + partition + " at offset " +
batch.baseOffset() + " is invalid, cause: " + e.getMessage());
}
}
}
private void maybeEnsureValid(Record record) {
if (fetchConfig.checkCrcs) {
try {
record.ensureValid();
} catch (CorruptRecordException e) {
throw new KafkaException("Record for partition " + partition + " at offset " + record.offset()
+ " is invalid, cause: " + e.getMessage());
}
}
}
private void maybeCloseRecordStream() {
if (records != null) {
records.close();
records = null;
}
}
private Record nextFetchedRecord() {
while (true) {
if (records == null || !records.hasNext()) {
maybeCloseRecordStream();
if (!batches.hasNext()) {
// Message format v2 preserves the last offset in a batch even if the last record is removed
// through compaction. By using the next offset computed from the last offset in the batch,
// we ensure that the offset of the next fetch will point to the next batch, which avoids
// unnecessary re-fetching of the same batch (in the worst case, the consumer could get stuck
// fetching the same batch repeatedly).
if (currentBatch != null)
nextFetchOffset = currentBatch.nextOffset();
drain();
return null;
}
currentBatch = batches.next();
lastEpoch = maybeLeaderEpoch(currentBatch.partitionLeaderEpoch());
maybeEnsureValid(currentBatch);
if (fetchConfig.isolationLevel == IsolationLevel.READ_COMMITTED && currentBatch.hasProducerId()) {
// remove from the aborted transaction queue all aborted transactions which have begun
// before the current batch's last offset and add the associated producerIds to the
// aborted producer set
consumeAbortedTransactionsUpTo(currentBatch.lastOffset());
long producerId = currentBatch.producerId();
if (containsAbortMarker(currentBatch)) {
abortedProducerIds.remove(producerId);
} else if (isBatchAborted(currentBatch)) {
log.debug("Skipping aborted record batch from partition {} with producerId {} and " +
"offsets {} to {}",
partition, producerId, currentBatch.baseOffset(), currentBatch.lastOffset());
nextFetchOffset = currentBatch.nextOffset();
continue;
}
}
records = currentBatch.streamingIterator(decompressionBufferSupplier);
} else {
Record record = records.next();
// skip any records out of range
if (record.offset() >= nextFetchOffset) {
// we only do validation when the message should not be skipped.
maybeEnsureValid(record);
// control records are not returned to the user
if (!currentBatch.isControlBatch()) {
return record;
} else {
// Increment the next fetch offset when we skip a control batch.
nextFetchOffset = record.offset() + 1;
}
}
}
}
}
/**
* The {@link RecordBatch batch} of {@link Record records} is converted to a {@link List list} of
* {@link ConsumerRecord consumer records} and returned. {@link BufferSupplier Decompression} and
* {@link Deserializer deserialization} of the {@link Record record's} key and value are performed in
* this step.
*
* @param maxRecords The number of records to return; the number returned may be {@code 0 <= maxRecords}
* @return {@link ConsumerRecord Consumer records}
*/
List> fetchRecords(int maxRecords) {
// Error when fetching the next record before deserialization.
if (corruptLastRecord)
throw new KafkaException("Received exception when fetching the next record from " + partition
+ ". If needed, please seek past the record to "
+ "continue consumption.", cachedRecordException);
if (isConsumed)
return Collections.emptyList();
List> records = new ArrayList<>();
try {
for (int i = 0; i < maxRecords; i++) {
// Only move to next record if there was no exception in the last fetch. Otherwise, we should
// use the last record to do deserialization again.
if (cachedRecordException == null) {
corruptLastRecord = true;
lastRecord = nextFetchedRecord();
corruptLastRecord = false;
}
if (lastRecord == null)
break;
Optional leaderEpoch = maybeLeaderEpoch(currentBatch.partitionLeaderEpoch());
TimestampType timestampType = currentBatch.timestampType();
ConsumerRecord record = parseRecord(partition, leaderEpoch, timestampType, lastRecord);
records.add(record);
recordsRead++;
bytesRead += lastRecord.sizeInBytes();
nextFetchOffset = lastRecord.offset() + 1;
// In some cases, the deserialization may have thrown an exception and the retry may succeed,
// we allow user to move forward in this case.
cachedRecordException = null;
}
} catch (SerializationException se) {
cachedRecordException = se;
if (records.isEmpty())
throw se;
} catch (KafkaException e) {
cachedRecordException = e;
if (records.isEmpty())
throw new KafkaException("Received exception when fetching the next record from " + partition
+ ". If needed, please seek past the record to "
+ "continue consumption.", e);
}
return records;
}
/**
* Parse the record entry, deserializing the key / value fields if necessary
*/
ConsumerRecord parseRecord(TopicPartition partition,
Optional leaderEpoch,
TimestampType timestampType,
Record record) {
try {
long offset = record.offset();
long timestamp = record.timestamp();
Headers headers = new RecordHeaders(record.headers());
ByteBuffer keyBytes = record.key();
K key = keyBytes == null ? null : fetchConfig.keyDeserializer.deserialize(partition.topic(), headers, keyBytes);
ByteBuffer valueBytes = record.value();
V value = valueBytes == null ? null : fetchConfig.valueDeserializer.deserialize(partition.topic(), headers, valueBytes);
return new ConsumerRecord<>(partition.topic(), partition.partition(), offset,
timestamp, timestampType,
keyBytes == null ? ConsumerRecord.NULL_SIZE : keyBytes.remaining(),
valueBytes == null ? ConsumerRecord.NULL_SIZE : valueBytes.remaining(),
key, value, headers, leaderEpoch);
} catch (RuntimeException e) {
throw new RecordDeserializationException(partition, record.offset(),
"Error deserializing key/value for partition " + partition +
" at offset " + record.offset() + ". If needed, please seek past the record to continue consumption.", e);
}
}
private Optional maybeLeaderEpoch(int leaderEpoch) {
return leaderEpoch == RecordBatch.NO_PARTITION_LEADER_EPOCH ? Optional.empty() : Optional.of(leaderEpoch);
}
private void consumeAbortedTransactionsUpTo(long offset) {
if (abortedTransactions == null)
return;
while (!abortedTransactions.isEmpty() && abortedTransactions.peek().firstOffset() <= offset) {
FetchResponseData.AbortedTransaction abortedTransaction = abortedTransactions.poll();
abortedProducerIds.add(abortedTransaction.producerId());
}
}
private boolean isBatchAborted(RecordBatch batch) {
return batch.isTransactional() && abortedProducerIds.contains(batch.producerId());
}
private PriorityQueue abortedTransactions(FetchResponseData.PartitionData partition) {
if (partition.abortedTransactions() == null || partition.abortedTransactions().isEmpty())
return null;
PriorityQueue abortedTransactions = new PriorityQueue<>(
partition.abortedTransactions().size(), Comparator.comparingLong(FetchResponseData.AbortedTransaction::firstOffset)
);
abortedTransactions.addAll(partition.abortedTransactions());
return abortedTransactions;
}
private boolean containsAbortMarker(RecordBatch batch) {
if (!batch.isControlBatch())
return false;
Iterator batchIterator = batch.iterator();
if (!batchIterator.hasNext())
return false;
Record firstRecord = batchIterator.next();
return ControlRecordType.ABORT == ControlRecordType.parse(firstRecord.key());
}
}
