kafka SnapshotFileReader 源码
kafka SnapshotFileReader 代码
文件路径:/metadata/src/main/java/org/apache/kafka/metadata/util/SnapshotFileReader.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.
*/
package org.apache.kafka.metadata.util;
import org.apache.kafka.common.message.LeaderChangeMessage;
import org.apache.kafka.common.protocol.ByteBufferAccessor;
import org.apache.kafka.common.record.ControlRecordType;
import org.apache.kafka.common.record.FileLogInputStream.FileChannelRecordBatch;
import org.apache.kafka.common.record.FileRecords;
import org.apache.kafka.common.record.Record;
import org.apache.kafka.common.utils.LogContext;
import org.apache.kafka.common.utils.Time;
import org.apache.kafka.metadata.MetadataRecordSerde;
import org.apache.kafka.queue.EventQueue;
import org.apache.kafka.queue.KafkaEventQueue;
import org.apache.kafka.raft.Batch;
import org.apache.kafka.raft.LeaderAndEpoch;
import org.apache.kafka.raft.RaftClient;
import org.apache.kafka.raft.internals.MemoryBatchReader;
import org.apache.kafka.server.common.ApiMessageAndVersion;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.OptionalInt;
import java.util.concurrent.CompletableFuture;
/**
* Reads Kafka metadata snapshots.
*/
public final class SnapshotFileReader implements AutoCloseable {
private static final Logger log = LoggerFactory.getLogger(SnapshotFileReader.class);
private final String snapshotPath;
private final RaftClient.Listener<ApiMessageAndVersion> listener;
private final KafkaEventQueue queue;
private final CompletableFuture<Void> caughtUpFuture;
private FileRecords fileRecords;
private Iterator<FileChannelRecordBatch> batchIterator;
private final MetadataRecordSerde serde = new MetadataRecordSerde();
public SnapshotFileReader(String snapshotPath, RaftClient.Listener<ApiMessageAndVersion> listener) {
this.snapshotPath = snapshotPath;
this.listener = listener;
this.queue = new KafkaEventQueue(Time.SYSTEM,
new LogContext("[snapshotReaderQueue] "), "snapshotReaderQueue_");
this.caughtUpFuture = new CompletableFuture<>();
}
public void startup() throws Exception {
CompletableFuture<Void> future = new CompletableFuture<>();
queue.append(new EventQueue.Event() {
@Override
public void run() throws Exception {
fileRecords = FileRecords.open(new File(snapshotPath), false);
batchIterator = fileRecords.batches().iterator();
scheduleHandleNextBatch();
future.complete(null);
}
@Override
public void handleException(Throwable e) {
future.completeExceptionally(e);
beginShutdown("startup error");
}
});
future.get();
}
private void handleNextBatch() {
if (!batchIterator.hasNext()) {
beginShutdown("done");
return;
}
FileChannelRecordBatch batch = batchIterator.next();
if (batch.isControlBatch()) {
handleControlBatch(batch);
} else {
handleMetadataBatch(batch);
}
scheduleHandleNextBatch();
}
private void scheduleHandleNextBatch() {
queue.append(new EventQueue.Event() {
@Override
public void run() {
handleNextBatch();
}
@Override
public void handleException(Throwable e) {
log.error("Unexpected error while handling a batch of events", e);
beginShutdown("handleBatch error");
}
});
}
private void handleControlBatch(FileChannelRecordBatch batch) {
for (Iterator<Record> iter = batch.iterator(); iter.hasNext(); ) {
Record record = iter.next();
try {
short typeId = ControlRecordType.parseTypeId(record.key());
ControlRecordType type = ControlRecordType.fromTypeId(typeId);
switch (type) {
case LEADER_CHANGE:
LeaderChangeMessage message = new LeaderChangeMessage();
message.read(new ByteBufferAccessor(record.value()), (short) 0);
listener.handleLeaderChange(new LeaderAndEpoch(
OptionalInt.of(message.leaderId()),
batch.partitionLeaderEpoch()
));
break;
default:
log.error("Ignoring control record with type {} at offset {}",
type, record.offset());
}
} catch (Throwable e) {
log.error("unable to read control record at offset {}", record.offset(), e);
}
}
}
private void handleMetadataBatch(FileChannelRecordBatch batch) {
List<ApiMessageAndVersion> messages = new ArrayList<>();
for (Record record : batch) {
ByteBufferAccessor accessor = new ByteBufferAccessor(record.value());
try {
ApiMessageAndVersion messageAndVersion = serde.read(accessor, record.valueSize());
messages.add(messageAndVersion);
} catch (Throwable e) {
log.error("unable to read metadata record at offset {}", record.offset(), e);
}
}
listener.handleCommit(
MemoryBatchReader.of(
Collections.singletonList(
Batch.data(
batch.baseOffset(),
batch.partitionLeaderEpoch(),
batch.maxTimestamp(),
batch.sizeInBytes(),
messages
)
),
reader -> { }
)
);
}
public void beginShutdown(String reason) {
if (reason.equals("done")) {
caughtUpFuture.complete(null);
} else {
caughtUpFuture.completeExceptionally(new RuntimeException(reason));
}
queue.beginShutdown(reason, new EventQueue.Event() {
@Override
public void run() throws Exception {
listener.beginShutdown();
if (fileRecords != null) {
fileRecords.close();
fileRecords = null;
}
batchIterator = null;
}
@Override
public void handleException(Throwable e) {
log.error("shutdown error", e);
}
});
}
@Override
public void close() throws Exception {
beginShutdown("closing");
queue.close();
}
public CompletableFuture<Void> caughtUpFuture() {
return caughtUpFuture;
}
}
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