kafka LogLoader 源码
kafka LogLoader 代码
文件路径：/core/src/main/scala/kafka/log/LogLoader.scala
/**
* 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 kafka.log
import java.io.{File, IOException}
import java.nio.file.{Files, NoSuchFileException}
import kafka.common.LogSegmentOffsetOverflowException
import kafka.log.UnifiedLog.{CleanedFileSuffix, DeletedFileSuffix, SwapFileSuffix, isIndexFile, isLogFile, offsetFromFile}
import kafka.server.{LogDirFailureChannel, LogOffsetMetadata}
import kafka.server.epoch.LeaderEpochFileCache
import kafka.utils.{CoreUtils, Logging, Scheduler}
import org.apache.kafka.common.TopicPartition
import org.apache.kafka.common.errors.InvalidOffsetException
import org.apache.kafka.common.utils.Time
import org.apache.kafka.snapshot.Snapshots
import java.util.concurrent.{ConcurrentHashMap, ConcurrentMap}
import scala.collection.{Set, mutable}
case class LoadedLogOffsets(logStartOffset: Long,
recoveryPoint: Long,
nextOffsetMetadata: LogOffsetMetadata)
object LogLoader extends Logging {
/**
* Clean shutdown file that indicates the broker was cleanly shutdown in 0.8 and higher.
* This is used to avoid unnecessary recovery after a clean shutdown. In theory this could be
* avoided by passing in the recovery point, however finding the correct position to do this
* requires accessing the offset index which may not be safe in an unclean shutdown.
* For more information see the discussion in PR#2104
*/
val CleanShutdownFile = ".kafka_cleanshutdown"
}
/**
* @param dir The directory from which log segments need to be loaded
* @param topicPartition The topic partition associated with the log being loaded
* @param config The configuration settings for the log being loaded
* @param scheduler The thread pool scheduler used for background actions
* @param time The time instance used for checking the clock
* @param logDirFailureChannel The LogDirFailureChannel instance to asynchronously handle log
* directory failure
* @param hadCleanShutdown Boolean flag to indicate whether the associated log previously had a
* clean shutdown
* @param segments The LogSegments instance into which segments recovered from disk will be
* populated
* @param logStartOffsetCheckpoint The checkpoint of the log start offset
* @param recoveryPointCheckpoint The checkpoint of the offset at which to begin the recovery
* @param leaderEpochCache An optional LeaderEpochFileCache instance to be updated during recovery
* @param producerStateManager The ProducerStateManager instance to be updated during recovery
* @param numRemainingSegments The remaining segments to be recovered in this log keyed by recovery thread name
*/
class LogLoader(
dir: File,
topicPartition: TopicPartition,
config: LogConfig,
scheduler: Scheduler,
time: Time,
logDirFailureChannel: LogDirFailureChannel,
hadCleanShutdown: Boolean,
segments: LogSegments,
logStartOffsetCheckpoint: Long,
recoveryPointCheckpoint: Long,
leaderEpochCache: Option[LeaderEpochFileCache],
producerStateManager: ProducerStateManager,
numRemainingSegments: ConcurrentMap[String, Int] = new ConcurrentHashMap[String, Int]
) extends Logging {
logIdent = s"[LogLoader partition=$topicPartition, dir=${dir.getParent}] "
/**
* Load the log segments from the log files on disk, and returns the components of the loaded log.
* Additionally, it also suitably updates the provided LeaderEpochFileCache and ProducerStateManager
* to reflect the contents of the loaded log.
*
* In the context of the calling thread, this function does not need to convert IOException to
* KafkaStorageException because it is only called before all logs are loaded.
*
* @return the offsets of the Log successfully loaded from disk
*
* @throws LogSegmentOffsetOverflowException if we encounter a .swap file with messages that
* overflow index offset
*/
def load(): LoadedLogOffsets = {
// First pass: through the files in the log directory and remove any temporary files
// and find any interrupted swap operations
val swapFiles = removeTempFilesAndCollectSwapFiles()
// The remaining valid swap files must come from compaction or segment split operation. We can
// simply rename them to regular segment files. But, before renaming, we should figure out which
// segments are compacted/split and delete these segment files: this is done by calculating
// min/maxSwapFileOffset.
// We store segments that require renaming in this code block, and do the actual renaming later.
var minSwapFileOffset = Long.MaxValue
var maxSwapFileOffset = Long.MinValue
swapFiles.filter(f => UnifiedLog.isLogFile(new File(CoreUtils.replaceSuffix(f.getPath, SwapFileSuffix, "")))).foreach { f =>
val baseOffset = offsetFromFile(f)
val segment = LogSegment.open(f.getParentFile,
baseOffset = baseOffset,
config,
time = time,
fileSuffix = UnifiedLog.SwapFileSuffix)
info(s"Found log file ${f.getPath} from interrupted swap operation, which is recoverable from ${UnifiedLog.SwapFileSuffix} files by renaming.")
minSwapFileOffset = Math.min(segment.baseOffset, minSwapFileOffset)
maxSwapFileOffset = Math.max(segment.readNextOffset, maxSwapFileOffset)
}
// Second pass: delete segments that are between minSwapFileOffset and maxSwapFileOffset. As
// discussed above, these segments were compacted or split but haven't been renamed to .delete
// before shutting down the broker.
for (file <- dir.listFiles if file.isFile) {
try {
if (!file.getName.endsWith(SwapFileSuffix)) {
val offset = offsetFromFile(file)
if (offset >= minSwapFileOffset && offset < maxSwapFileOffset) {
info(s"Deleting segment files ${file.getName} that is compacted but has not been deleted yet.")
file.delete()
}
}
} catch {
// offsetFromFile with files that do not include an offset in the file name
case _: StringIndexOutOfBoundsException =>
case _: NumberFormatException =>
}
}
// Third pass: rename all swap files.
for (file <- dir.listFiles if file.isFile) {
if (file.getName.endsWith(SwapFileSuffix)) {
info(s"Recovering file ${file.getName} by renaming from ${UnifiedLog.SwapFileSuffix} files.")
file.renameTo(new File(CoreUtils.replaceSuffix(file.getPath, UnifiedLog.SwapFileSuffix, "")))
}
}
// Fourth pass: load all the log and index files.
// We might encounter legacy log segments with offset overflow (KAFKA-6264). We need to split such segments. When
// this happens, restart loading segment files from scratch.
retryOnOffsetOverflow(() => {
// In case we encounter a segment with offset overflow, the retry logic will split it after which we need to retry
// loading of segments. In that case, we also need to close all segments that could have been left open in previous
// call to loadSegmentFiles().
segments.close()
segments.clear()
loadSegmentFiles()
})
val (newRecoveryPoint: Long, nextOffset: Long) = {
if (!dir.getAbsolutePath.endsWith(UnifiedLog.DeleteDirSuffix)) {
val (newRecoveryPoint, nextOffset) = retryOnOffsetOverflow(recoverLog)
// reset the index size of the currently active log segment to allow more entries
segments.lastSegment.get.resizeIndexes(config.maxIndexSize)
(newRecoveryPoint, nextOffset)
} else {
if (segments.isEmpty) {
segments.add(
LogSegment.open(
dir = dir,
baseOffset = 0,
config,
time = time,
initFileSize = config.initFileSize))
}
(0L, 0L)
}
}
leaderEpochCache.foreach(_.truncateFromEnd(nextOffset))
val newLogStartOffset = math.max(logStartOffsetCheckpoint, segments.firstSegment.get.baseOffset)
// The earliest leader epoch may not be flushed during a hard failure. Recover it here.
leaderEpochCache.foreach(_.truncateFromStart(logStartOffsetCheckpoint))
// Any segment loading or recovery code must not use producerStateManager, so that we can build the full state here
// from scratch.
if (!producerStateManager.isEmpty)
throw new IllegalStateException("Producer state must be empty during log initialization")
// Reload all snapshots into the ProducerStateManager cache, the intermediate ProducerStateManager used
// during log recovery may have deleted some files without the LogLoader.producerStateManager instance witnessing the
// deletion.
producerStateManager.removeStraySnapshots(segments.baseOffsets.toSeq)
UnifiedLog.rebuildProducerState(
producerStateManager,
segments,
newLogStartOffset,
nextOffset,
config.recordVersion,
time,
reloadFromCleanShutdown = hadCleanShutdown,
logIdent)
val activeSegment = segments.lastSegment.get
LoadedLogOffsets(
newLogStartOffset,
newRecoveryPoint,
LogOffsetMetadata(nextOffset, activeSegment.baseOffset, activeSegment.size))
}
/**
* Removes any temporary files found in log directory, and creates a list of all .swap files which could be swapped
* in place of existing segment(s). For log splitting, we know that any .swap file whose base offset is higher than
* the smallest offset .clean file could be part of an incomplete split operation. Such .swap files are also deleted
* by this method.
*
* @return Set of .swap files that are valid to be swapped in as segment files and index files
*/
private def removeTempFilesAndCollectSwapFiles(): Set[File] = {
val swapFiles = mutable.Set[File]()
val cleanedFiles = mutable.Set[File]()
var minCleanedFileOffset = Long.MaxValue
for (file <- dir.listFiles if file.isFile) {
if (!file.canRead)
throw new IOException(s"Could not read file $file")
val filename = file.getName
// Delete stray files marked for deletion, but skip KRaft snapshots.
// These are handled in the recovery logic in `KafkaMetadataLog`.
if (filename.endsWith(DeletedFileSuffix) && !filename.endsWith(Snapshots.DELETE_SUFFIX)) {
debug(s"Deleting stray temporary file ${file.getAbsolutePath}")
Files.deleteIfExists(file.toPath)
} else if (filename.endsWith(CleanedFileSuffix)) {
minCleanedFileOffset = Math.min(offsetFromFile(file), minCleanedFileOffset)
cleanedFiles += file
} else if (filename.endsWith(SwapFileSuffix)) {
swapFiles += file
}
}
// KAFKA-6264: Delete all .swap files whose base offset is greater than the minimum .cleaned segment offset. Such .swap
// files could be part of an incomplete split operation that could not complete. See Log#splitOverflowedSegment
// for more details about the split operation.
val (invalidSwapFiles, validSwapFiles) = swapFiles.partition(file => offsetFromFile(file) >= minCleanedFileOffset)
invalidSwapFiles.foreach { file =>
debug(s"Deleting invalid swap file ${file.getAbsoluteFile} minCleanedFileOffset: $minCleanedFileOffset")
Files.deleteIfExists(file.toPath)
}
// Now that we have deleted all .swap files that constitute an incomplete split operation, let's delete all .clean files
cleanedFiles.foreach { file =>
debug(s"Deleting stray .clean file ${file.getAbsolutePath}")
Files.deleteIfExists(file.toPath)
}
validSwapFiles
}
/**
* Retries the provided function only whenever an LogSegmentOffsetOverflowException is raised by
* it during execution. Before every retry, the overflowed segment is split into one or more segments
* such that there is no offset overflow in any of them.
*
* @param fn The function to be executed
* @return The value returned by the function, if successful
* @throws Exception whenever the executed function throws any exception other than
* LogSegmentOffsetOverflowException, the same exception is raised to the caller
*/
private def retryOnOffsetOverflow[T](fn: () => T): T = {
while (true) {
try {
return fn()
} catch {
case e: LogSegmentOffsetOverflowException =>
info(s"Caught segment overflow error: ${e.getMessage}. Split segment and retry.")
val result = UnifiedLog.splitOverflowedSegment(
e.segment,
segments,
dir,
topicPartition,
config,
scheduler,
logDirFailureChannel,
logIdent)
deleteProducerSnapshotsAsync(result.deletedSegments)
}
}
throw new IllegalStateException()
}
/**
* Loads segments from disk into the provided params.segments.
*
* This method does not need to convert IOException to KafkaStorageException because it is only called before all logs are loaded.
* It is possible that we encounter a segment with index offset overflow in which case the LogSegmentOffsetOverflowException
* will be thrown. Note that any segments that were opened before we encountered the exception will remain open and the
* caller is responsible for closing them appropriately, if needed.
*
* @throws LogSegmentOffsetOverflowException if the log directory contains a segment with messages that overflow the index offset
*/
private def loadSegmentFiles(): Unit = {
// load segments in ascending order because transactional data from one segment may depend on the
// segments that come before it
for (file <- dir.listFiles.sortBy(_.getName) if file.isFile) {
if (isIndexFile(file)) {
// if it is an index file, make sure it has a corresponding .log file
val offset = offsetFromFile(file)
val logFile = UnifiedLog.logFile(dir, offset)
if (!logFile.exists) {
warn(s"Found an orphaned index file ${file.getAbsolutePath}, with no corresponding log file.")
Files.deleteIfExists(file.toPath)
}
} else if (isLogFile(file)) {
// if it's a log file, load the corresponding log segment
val baseOffset = offsetFromFile(file)
val timeIndexFileNewlyCreated = !UnifiedLog.timeIndexFile(dir, baseOffset).exists()
val segment = LogSegment.open(
dir = dir,
baseOffset = baseOffset,
config,
time = time,
fileAlreadyExists = true)
try segment.sanityCheck(timeIndexFileNewlyCreated)
catch {
case _: NoSuchFileException =>
if (hadCleanShutdown || segment.baseOffset < recoveryPointCheckpoint)
error(s"Could not find offset index file corresponding to log file" +
s" ${segment.log.file.getAbsolutePath}, recovering segment and rebuilding index files...")
recoverSegment(segment)
case e: CorruptIndexException =>
warn(s"Found a corrupted index file corresponding to log file" +
s" ${segment.log.file.getAbsolutePath} due to ${e.getMessage}}, recovering segment and" +
" rebuilding index files...")
recoverSegment(segment)
}
segments.add(segment)
}
}
}
/**
* Just recovers the given segment, without adding it to the provided params.segments.
*
* @param segment Segment to recover
*
* @return The number of bytes truncated from the segment
*
* @throws LogSegmentOffsetOverflowException if the segment contains messages that cause index offset overflow
*/
private def recoverSegment(segment: LogSegment): Int = {
val producerStateManager = new ProducerStateManager(
topicPartition,
dir,
this.producerStateManager.maxTransactionTimeoutMs,
this.producerStateManager.producerStateManagerConfig,
time)
UnifiedLog.rebuildProducerState(
producerStateManager,
segments,
logStartOffsetCheckpoint,
segment.baseOffset,
config.recordVersion,
time,
reloadFromCleanShutdown = false,
logIdent)
val bytesTruncated = segment.recover(producerStateManager, leaderEpochCache)
// once we have recovered the segment's data, take a snapshot to ensure that we won't
// need to reload the same segment again while recovering another segment.
producerStateManager.takeSnapshot()
bytesTruncated
}
/**
* Recover the log segments (if there was an unclean shutdown). Ensures there is at least one
* active segment, and returns the updated recovery point and next offset after recovery. Along
* the way, the method suitably updates the LeaderEpochFileCache or ProducerStateManager inside
* the provided LogComponents.
*
* This method does not need to convert IOException to KafkaStorageException because it is only
* called before all logs are loaded.
*
* @return a tuple containing (newRecoveryPoint, nextOffset).
*
* @throws LogSegmentOffsetOverflowException if we encountered a legacy segment with offset overflow
*/
private[log] def recoverLog(): (Long, Long) = {
/** return the log end offset if valid */
def deleteSegmentsIfLogStartGreaterThanLogEnd(): Option[Long] = {
if (segments.nonEmpty) {
val logEndOffset = segments.lastSegment.get.readNextOffset
if (logEndOffset >= logStartOffsetCheckpoint)
Some(logEndOffset)
else {
warn(s"Deleting all segments because logEndOffset ($logEndOffset) " +
s"is smaller than logStartOffset $logStartOffsetCheckpoint. " +
"This could happen if segment files were deleted from the file system.")
removeAndDeleteSegmentsAsync(segments.values)
leaderEpochCache.foreach(_.clearAndFlush())
producerStateManager.truncateFullyAndStartAt(logStartOffsetCheckpoint)
None
}
} else None
}
// If we have the clean shutdown marker, skip recovery.
if (!hadCleanShutdown) {
val unflushed = segments.values(recoveryPointCheckpoint, Long.MaxValue)
val numUnflushed = unflushed.size
val unflushedIter = unflushed.iterator
var truncated = false
var numFlushed = 0
val threadName = Thread.currentThread().getName
numRemainingSegments.put(threadName, numUnflushed)
while (unflushedIter.hasNext && !truncated) {
val segment = unflushedIter.next()
info(s"Recovering unflushed segment ${segment.baseOffset}. $numFlushed/$numUnflushed recovered for $topicPartition.")
val truncatedBytes =
try {
recoverSegment(segment)
} catch {
case _: InvalidOffsetException =>
val startOffset = segment.baseOffset
warn(s"Found invalid offset during recovery. Deleting the" +
s" corrupt segment and creating an empty one with starting offset $startOffset")
segment.truncateTo(startOffset)
}
if (truncatedBytes > 0) {
// we had an invalid message, delete all remaining log
warn(s"Corruption found in segment ${segment.baseOffset}," +
s" truncating to offset ${segment.readNextOffset}")
removeAndDeleteSegmentsAsync(unflushedIter.toList)
truncated = true
// segment is truncated, so set remaining segments to 0
numRemainingSegments.put(threadName, 0)
} else {
numFlushed += 1
numRemainingSegments.put(threadName, numUnflushed - numFlushed)
}
}
}
val logEndOffsetOption = deleteSegmentsIfLogStartGreaterThanLogEnd()
if (segments.isEmpty) {
// no existing segments, create a new mutable segment beginning at logStartOffset
segments.add(
LogSegment.open(
dir = dir,
baseOffset = logStartOffsetCheckpoint,
config,
time = time,
initFileSize = config.initFileSize,
preallocate = config.preallocate))
}
// Update the recovery point if there was a clean shutdown and did not perform any changes to
// the segment. Otherwise, we just ensure that the recovery point is not ahead of the log end
// offset. To ensure correctness and to make it easier to reason about, it's best to only advance
// the recovery point when the log is flushed. If we advanced the recovery point here, we could
// skip recovery for unflushed segments if the broker crashed after we checkpoint the recovery
// point and before we flush the segment.
(hadCleanShutdown, logEndOffsetOption) match {
case (true, Some(logEndOffset)) =>
(logEndOffset, logEndOffset)
case _ =>
val logEndOffset = logEndOffsetOption.getOrElse(segments.lastSegment.get.readNextOffset)
(Math.min(recoveryPointCheckpoint, logEndOffset), logEndOffset)
}
}
/**
* This method deletes the given log segments and the associated producer snapshots, by doing the
* following for each of them:
* - It removes the segment from the segment map so that it will no longer be used for reads.
* - It schedules asynchronous deletion of the segments that allows reads to happen concurrently without
* synchronization and without the possibility of physically deleting a file while it is being
* read.
*
* This method does not need to convert IOException to KafkaStorageException because it is either
* called before all logs are loaded or the immediate caller will catch and handle IOException
*
* @param segmentsToDelete The log segments to schedule for deletion
*/
private def removeAndDeleteSegmentsAsync(segmentsToDelete: Iterable[LogSegment]): Unit = {
if (segmentsToDelete.nonEmpty) {
// Most callers hold an iterator into the `params.segments` collection and
// `removeAndDeleteSegmentAsync` mutates it by removing the deleted segment. Therefore,
// we should force materialization of the iterator here, so that results of the iteration
// remain valid and deterministic. We should also pass only the materialized view of the
// iterator to the logic that deletes the segments.
val toDelete = segmentsToDelete.toList
info(s"Deleting segments as part of log recovery: ${toDelete.mkString(",")}")
toDelete.foreach { segment =>
segments.remove(segment.baseOffset)
}
UnifiedLog.deleteSegmentFiles(
toDelete,
asyncDelete = true,
dir,
topicPartition,
config,
scheduler,
logDirFailureChannel,
logIdent)
deleteProducerSnapshotsAsync(segmentsToDelete)
}
}
private def deleteProducerSnapshotsAsync(segments: Iterable[LogSegment]): Unit = {
UnifiedLog.deleteProducerSnapshots(segments,
producerStateManager,
asyncDelete = true,
scheduler,
config,
logDirFailureChannel,
dir.getParent,
topicPartition)
}
}
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