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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 kafka.cluster
import com.yammer.metrics.core.Gauge
import java.util.concurrent.locks.ReentrantReadWriteLock
import java.util.{Optional, Properties}
import kafka.api.{ApiVersion, LeaderAndIsr, Request}
import kafka.common.UnexpectedAppendOffsetException
import kafka.controller.KafkaController
import kafka.log._
import kafka.metrics.KafkaMetricsGroup
import kafka.server._
import kafka.server.checkpoints.OffsetCheckpoints
import kafka.utils.CoreUtils.{inReadLock, inWriteLock}
import kafka.utils._
import kafka.zk.{AdminZkClient, KafkaZkClient}
import org.apache.kafka.common.TopicPartition
import org.apache.kafka.common.errors._
import org.apache.kafka.common.message.LeaderAndIsrRequestData.LeaderAndIsrPartitionState
import org.apache.kafka.common.protocol.Errors
import org.apache.kafka.common.protocol.Errors._
import org.apache.kafka.common.record.FileRecords.TimestampAndOffset
import org.apache.kafka.common.record.{MemoryRecords, RecordBatch}
import org.apache.kafka.common.requests.EpochEndOffset._
import org.apache.kafka.common.requests._
import org.apache.kafka.common.utils.Time
import scala.collection.JavaConverters._
import scala.collection.{Map, Seq}
trait PartitionStateStore {
def fetchTopicConfig(): Properties
def shrinkIsr(controllerEpoch: Int, leaderAndIsr: LeaderAndIsr): Option[Int]
def expandIsr(controllerEpoch: Int, leaderAndIsr: LeaderAndIsr): Option[Int]
}
class ZkPartitionStateStore(topicPartition: TopicPartition,
zkClient: KafkaZkClient,
replicaManager: ReplicaManager) extends PartitionStateStore {
override def fetchTopicConfig(): Properties = {
val adminZkClient = new AdminZkClient(zkClient)
adminZkClient.fetchEntityConfig(ConfigType.Topic, topicPartition.topic)
}
override def shrinkIsr(controllerEpoch: Int, leaderAndIsr: LeaderAndIsr): Option[Int] = {
val newVersionOpt = updateIsr(controllerEpoch, leaderAndIsr)
if (newVersionOpt.isDefined)
replicaManager.isrShrinkRate.mark()
newVersionOpt
}
override def expandIsr(controllerEpoch: Int, leaderAndIsr: LeaderAndIsr): Option[Int] = {
val newVersionOpt = updateIsr(controllerEpoch, leaderAndIsr)
if (newVersionOpt.isDefined)
replicaManager.isrExpandRate.mark()
newVersionOpt
}
private def updateIsr(controllerEpoch: Int, leaderAndIsr: LeaderAndIsr): Option[Int] = {
val (updateSucceeded, newVersion) = ReplicationUtils.updateLeaderAndIsr(zkClient, topicPartition,
leaderAndIsr, controllerEpoch)
if (updateSucceeded) {
replicaManager.recordIsrChange(topicPartition)
Some(newVersion)
} else {
replicaManager.failedIsrUpdatesRate.mark()
None
}
}
}
class DelayedOperations(topicPartition: TopicPartition,
produce: DelayedOperationPurgatory[DelayedProduce],
fetch: DelayedOperationPurgatory[DelayedFetch],
deleteRecords: DelayedOperationPurgatory[DelayedDeleteRecords]) {
def checkAndCompleteAll(): Unit = {
val requestKey = TopicPartitionOperationKey(topicPartition)
fetch.checkAndComplete(requestKey)
produce.checkAndComplete(requestKey)
deleteRecords.checkAndComplete(requestKey)
}
def checkAndCompleteFetch(): Unit = {
fetch.checkAndComplete(TopicPartitionOperationKey(topicPartition))
}
def checkAndCompleteProduce(): Unit = {
produce.checkAndComplete(TopicPartitionOperationKey(topicPartition))
}
def checkAndCompleteDeleteRecords(): Unit = {
deleteRecords.checkAndComplete(TopicPartitionOperationKey(topicPartition))
}
def numDelayedDelete: Int = deleteRecords.numDelayed
def numDelayedFetch: Int = fetch.numDelayed
def numDelayedProduce: Int = produce.numDelayed
}
object Partition extends KafkaMetricsGroup {
def apply(topicPartition: TopicPartition,
time: Time,
replicaManager: ReplicaManager): Partition = {
val zkIsrBackingStore = new ZkPartitionStateStore(
topicPartition,
replicaManager.zkClient,
replicaManager)
val delayedOperations = new DelayedOperations(
topicPartition,
replicaManager.delayedProducePurgatory,
replicaManager.delayedFetchPurgatory,
replicaManager.delayedDeleteRecordsPurgatory)
new Partition(topicPartition,
replicaLagTimeMaxMs = replicaManager.config.replicaLagTimeMaxMs,
interBrokerProtocolVersion = replicaManager.config.interBrokerProtocolVersion,
localBrokerId = replicaManager.config.brokerId,
time = time,
stateStore = zkIsrBackingStore,
delayedOperations = delayedOperations,
metadataCache = replicaManager.metadataCache,
logManager = replicaManager.logManager)
}
def removeMetrics(topicPartition: TopicPartition): Unit = {
val tags = Map("topic" -> topicPartition.topic, "partition" -> topicPartition.partition.toString)
removeMetric("UnderReplicated", tags)
removeMetric("UnderMinIsr", tags)
removeMetric("InSyncReplicasCount", tags)
removeMetric("ReplicasCount", tags)
removeMetric("LastStableOffsetLag", tags)
removeMetric("AtMinIsr", tags)
}
}
/**
* Data structure that represents a topic partition. The leader maintains the AR, ISR, CUR, RAR
*/
class Partition(val topicPartition: TopicPartition,
replicaLagTimeMaxMs: Long,
interBrokerProtocolVersion: ApiVersion,
localBrokerId: Int,
time: Time,
stateStore: PartitionStateStore,
delayedOperations: DelayedOperations,
metadataCache: MetadataCache,
logManager: LogManager) extends Logging with KafkaMetricsGroup {
def topic: String = topicPartition.topic
def partitionId: Int = topicPartition.partition
private val remoteReplicasMap = new Pool[Int, Replica]
// The read lock is only required when multiple reads are executed and needs to be in a consistent manner
private val leaderIsrUpdateLock = new ReentrantReadWriteLock
private var zkVersion: Int = LeaderAndIsr.initialZKVersion
@volatile private var leaderEpoch: Int = LeaderAndIsr.initialLeaderEpoch - 1
// start offset for 'leaderEpoch' above (leader epoch of the current leader for this partition),
// defined when this broker is leader for partition
@volatile private var leaderEpochStartOffsetOpt: Option[Long] = None
@volatile var leaderReplicaIdOpt: Option[Int] = None
@volatile var inSyncReplicaIds = Set.empty[Int]
// An ordered sequence of all the valid broker ids that were assigned to this topic partition
@volatile var allReplicaIds = Seq.empty[Int]
// Logs belonging to this partition. Majority of time it will be only one log, but if log directory
// is getting changed (as a result of ReplicaAlterLogDirs command), we may have two logs until copy
// completes and a switch to new location is performed.
// log and futureLog variables defined below are used to capture this
@volatile var log: Option[Log] = None
// If ReplicaAlterLogDir command is in progress, this is future location of the log
@volatile var futureLog: Option[Log] = None
/* Epoch of the controller that last changed the leader. This needs to be initialized correctly upon broker startup.
* One way of doing that is through the controller's start replica state change command. When a new broker starts up
* the controller sends it a start replica command containing the leader for each partition that the broker hosts.
* In addition to the leader, the controller can also send the epoch of the controller that elected the leader for
* each partition. */
private var controllerEpoch: Int = KafkaController.InitialControllerEpoch
this.logIdent = s"[Partition $topicPartition broker=$localBrokerId] "
private val tags = Map("topic" -> topic, "partition" -> partitionId.toString)
newGauge("UnderReplicated",
new Gauge[Int] {
def value: Int = {
if (isUnderReplicated) 1 else 0
}
},
tags
)
newGauge("InSyncReplicasCount",
new Gauge[Int] {
def value: Int = {
if (isLeader) inSyncReplicaIds.size else 0
}
},
tags
)
newGauge("UnderMinIsr",
new Gauge[Int] {
def value: Int = {
if (isUnderMinIsr) 1 else 0
}
},
tags
)
newGauge("AtMinIsr",
new Gauge[Int] {
def value: Int = {
if (isAtMinIsr) 1 else 0
}
},
tags
)
newGauge("ReplicasCount",
new Gauge[Int] {
def value: Int = {
if (isLeader) allReplicaIds.size else 0
}
},
tags
)
newGauge("LastStableOffsetLag",
new Gauge[Long] {
def value: Long = {
log.map(_.lastStableOffsetLag).getOrElse(0)
}
},
tags
)
def isUnderReplicated: Boolean =
isLeader && inSyncReplicaIds.size < allReplicaIds.size
def isUnderMinIsr: Boolean = {
leaderLogIfLocal.exists { inSyncReplicaIds.size < _.config.minInSyncReplicas }
}
def isAtMinIsr: Boolean = {
leaderLogIfLocal.exists { inSyncReplicaIds.size == _.config.minInSyncReplicas }
}
/**
* Create the future replica if 1) the current replica is not in the given log directory and 2) the future replica
* does not exist. This method assumes that the current replica has already been created.
*
* @param logDir log directory
* @param highWatermarkCheckpoints Checkpoint to load initial high watermark from
* @return true iff the future replica is created
*/
def maybeCreateFutureReplica(logDir: String, highWatermarkCheckpoints: OffsetCheckpoints): Boolean = {
// The writeLock is needed to make sure that while the caller checks the log directory of the
// current replica and the existence of the future replica, no other thread can update the log directory of the
// current replica or remove the future replica.
inWriteLock(leaderIsrUpdateLock) {
val currentLogDir = localLogOrException.dir.getParent
if (currentLogDir == logDir) {
info(s"Current log directory $currentLogDir is same as requested log dir $logDir. " +
s"Skipping future replica creation.")
false
} else {
futureLog match {
case Some(partitionFutureLog) =>
val futureLogDir = partitionFutureLog.dir.getParent
if (futureLogDir != logDir)
throw new IllegalStateException(s"The future log dir $futureLogDir of $topicPartition is " +
s"different from the requested log dir $logDir")
false
case None =>
createLogIfNotExists(Request.FutureLocalReplicaId, isNew = false, isFutureReplica = true, highWatermarkCheckpoints)
true
}
}
}
}
def createLogIfNotExists(replicaId: Int, isNew: Boolean, isFutureReplica: Boolean, offsetCheckpoints: OffsetCheckpoints): Unit = {
isFutureReplica match {
case true if futureLog.isEmpty =>
val log = createLog(replicaId, isNew, isFutureReplica, offsetCheckpoints)
this.futureLog = Option(log)
case false if log.isEmpty =>
val log = createLog(replicaId, isNew, isFutureReplica, offsetCheckpoints)
this.log = Option(log)
case _ => trace(s"${if (isFutureReplica) "Future Log" else "Log"} already exists.")
}
}
// Visible for testing
private[cluster] def createLog(replicaId: Int, isNew: Boolean, isFutureReplica: Boolean, offsetCheckpoints: OffsetCheckpoints): Log = {
val fetchLogConfig = () => {
val props = stateStore.fetchTopicConfig()
LogConfig.fromProps(logManager.currentDefaultConfig.originals, props)
}
logManager.initializingLog(topicPartition)
var maybeLog: Option[Log] = None
try {
val log = logManager.getOrCreateLog(topicPartition, fetchLogConfig(), isNew, isFutureReplica)
val checkpointHighWatermark = offsetCheckpoints.fetch(log.dir.getParent, topicPartition).getOrElse {
info(s"No checkpointed highwatermark is found for partition $topicPartition")
0L
}
val initialHighWatermark = log.updateHighWatermark(checkpointHighWatermark)
info(s"Log loaded for partition $topicPartition with initial high watermark $initialHighWatermark")
maybeLog = Some(log)
log
} finally {
logManager.finishedInitializingLog(topicPartition, maybeLog, fetchLogConfig)
}
}
def getReplica(replicaId: Int): Option[Replica] = Option(remoteReplicasMap.get(replicaId))
private def getReplicaOrException(replicaId: Int): Replica = getReplica(replicaId).getOrElse{
throw new ReplicaNotAvailableException(s"Replica with id $replicaId is not available on broker $localBrokerId")
}
private def checkCurrentLeaderEpoch(remoteLeaderEpochOpt: Optional[Integer]): Errors = {
if (!remoteLeaderEpochOpt.isPresent) {
Errors.NONE
} else {
val remoteLeaderEpoch = remoteLeaderEpochOpt.get
val localLeaderEpoch = leaderEpoch
if (localLeaderEpoch > remoteLeaderEpoch)
Errors.FENCED_LEADER_EPOCH
else if (localLeaderEpoch < remoteLeaderEpoch)
Errors.UNKNOWN_LEADER_EPOCH
else
Errors.NONE
}
}
private def getLocalLog(currentLeaderEpoch: Optional[Integer],
requireLeader: Boolean): Either[Log, Errors] = {
checkCurrentLeaderEpoch(currentLeaderEpoch) match {
case Errors.NONE =>
if (requireLeader && !isLeader) {
Right(Errors.NOT_LEADER_FOR_PARTITION)
} else {
log match {
case Some(partitionLog) =>
Left(partitionLog)
case _ =>
if (requireLeader)
Right(Errors.NOT_LEADER_FOR_PARTITION)
else
Right(Errors.REPLICA_NOT_AVAILABLE)
}
}
case error =>
Right(error)
}
}
def localLogOrException: Log = log.getOrElse {
throw new ReplicaNotAvailableException(s"Log for partition $topicPartition is not available " +
s"on broker $localBrokerId")
}
def futureLocalLogOrException: Log = futureLog.getOrElse {
throw new ReplicaNotAvailableException(s"Future log for partition $topicPartition is not available " +
s"on broker $localBrokerId")
}
def leaderLogIfLocal: Option[Log] = {
log.filter(_ => isLeader)
}
/**
* Returns true if this node is currently leader for the Partition.
*/
def isLeader: Boolean = leaderReplicaIdOpt.contains(localBrokerId)
private def localLogWithEpochOrException(currentLeaderEpoch: Optional[Integer],
requireLeader: Boolean): Log = {
getLocalLog(currentLeaderEpoch, requireLeader) match {
case Left(localLog) => localLog
case Right(error) =>
throw error.exception(s"Failed to find ${if (requireLeader) "leader " else ""} log for " +
s"partition $topicPartition with leader epoch $currentLeaderEpoch. The current leader " +
s"is $leaderReplicaIdOpt and the current epoch $leaderEpoch")
}
}
// Visible for testing -- Used by unit tests to set log for this partition
def setLog(log: Log, isFutureLog: Boolean): Unit = {
if (isFutureLog)
futureLog = Some(log)
else
this.log = Some(log)
}
// remoteReplicas will be called in the hot path, and must be inexpensive
def remoteReplicas: Iterable[Replica] =
remoteReplicasMap.values
def futureReplicaDirChanged(newDestinationDir: String): Boolean = {
inReadLock(leaderIsrUpdateLock) {
futureLog.exists(_.dir.getParent != newDestinationDir)
}
}
def removeFutureLocalReplica(deleteFromLogDir: Boolean = true): Unit = {
inWriteLock(leaderIsrUpdateLock) {
futureLog = None
if (deleteFromLogDir)
logManager.asyncDelete(topicPartition, isFuture = true)
}
}
// Return true iff the future replica exists and it has caught up with the current replica for this partition
// Only ReplicaAlterDirThread will call this method and ReplicaAlterDirThread should remove the partition
// from its partitionStates if this method returns true
def maybeReplaceCurrentWithFutureReplica(): Boolean = {
val localReplicaLEO = localLogOrException.logEndOffset
val futureReplicaLEO = futureLog.map(_.logEndOffset)
if (futureReplicaLEO.contains(localReplicaLEO)) {
// The write lock is needed to make sure that while ReplicaAlterDirThread checks the LEO of the
// current replica, no other thread can update LEO of the current replica via log truncation or log append operation.
inWriteLock(leaderIsrUpdateLock) {
futureLog match {
case Some(futurePartitionLog) =>
if (log.exists(_.logEndOffset == futurePartitionLog.logEndOffset)) {
logManager.replaceCurrentWithFutureLog(topicPartition)
log = futureLog
removeFutureLocalReplica(false)
true
} else false
case None =>
// Future replica is removed by a non-ReplicaAlterLogDirsThread before this method is called
// In this case the partition should have been removed from state of the ReplicaAlterLogDirsThread
// Return false so that ReplicaAlterLogDirsThread does not have to remove this partition from the
// state again to avoid race condition
false
}
}
} else false
}
def delete(): Unit = {
// need to hold the lock to prevent appendMessagesToLeader() from hitting I/O exceptions due to log being deleted
inWriteLock(leaderIsrUpdateLock) {
remoteReplicasMap.clear()
allReplicaIds = Seq.empty
log = None
futureLog = None
inSyncReplicaIds = Set.empty
leaderReplicaIdOpt = None
leaderEpochStartOffsetOpt = None
Partition.removeMetrics(topicPartition)
logManager.asyncDelete(topicPartition)
if (logManager.getLog(topicPartition, isFuture = true).isDefined)
logManager.asyncDelete(topicPartition, isFuture = true)
}
}
def getLeaderEpoch: Int = this.leaderEpoch
/**
* Make the local replica the leader by resetting LogEndOffset for remote replicas (there could be old LogEndOffset
* from the time when this broker was the leader last time) and setting the new leader and ISR.
* If the leader replica id does not change, return false to indicate the replica manager.
*/
def makeLeader(controllerId: Int,
partitionState: LeaderAndIsrPartitionState,
correlationId: Int,
highWatermarkCheckpoints: OffsetCheckpoints): Boolean = {
val (leaderHWIncremented, isNewLeader) = inWriteLock(leaderIsrUpdateLock) {
// record the epoch of the controller that made the leadership decision. This is useful while updating the isr
// to maintain the decision maker controller's epoch in the zookeeper path
controllerEpoch = partitionState.controllerEpoch
updateAssignmentAndIsr(
assignment = partitionState.replicas.asScala.iterator.map(_.toInt).toSeq,
isr = partitionState.isr.asScala.iterator.map(_.toInt).toSet
)
createLogIfNotExists(localBrokerId, partitionState.isNew, isFutureReplica = false, highWatermarkCheckpoints)
val leaderLog = localLogOrException
val leaderEpochStartOffset = leaderLog.logEndOffset
info(s"$topicPartition starts at Leader Epoch ${partitionState.leaderEpoch} from " +
s"offset $leaderEpochStartOffset. Previous Leader Epoch was: $leaderEpoch")
//We cache the leader epoch here, persisting it only if it's local (hence having a log dir)
leaderEpoch = partitionState.leaderEpoch
leaderEpochStartOffsetOpt = Some(leaderEpochStartOffset)
zkVersion = partitionState.zkVersion
// In the case of successive leader elections in a short time period, a follower may have
// entries in its log from a later epoch than any entry in the new leader's log. In order
// to ensure that these followers can truncate to the right offset, we must cache the new
// leader epoch and the start offset since it should be larger than any epoch that a follower
// would try to query.
leaderLog.maybeAssignEpochStartOffset(leaderEpoch, leaderEpochStartOffset)
val isNewLeader = !isLeader
val curLeaderLogEndOffset = leaderLog.logEndOffset
val curTimeMs = time.milliseconds
// initialize lastCaughtUpTime of replicas as well as their lastFetchTimeMs and lastFetchLeaderLogEndOffset.
remoteReplicas.foreach { replica =>
val lastCaughtUpTimeMs = if (inSyncReplicaIds.contains(replica.brokerId)) curTimeMs else 0L
replica.resetLastCaughtUpTime(curLeaderLogEndOffset, curTimeMs, lastCaughtUpTimeMs)
}
if (isNewLeader) {
// mark local replica as the leader after converting hw
leaderReplicaIdOpt = Some(localBrokerId)
// reset log end offset for remote replicas
remoteReplicas.foreach { replica =>
replica.updateFetchState(
followerFetchOffsetMetadata = LogOffsetMetadata.UnknownOffsetMetadata,
followerStartOffset = Log.UnknownOffset,
followerFetchTimeMs = 0L,
leaderEndOffset = Log.UnknownOffset,
lastSentHighwatermark = 0L)
}
}
// we may need to increment high watermark since ISR could be down to 1
(maybeIncrementLeaderHW(leaderLog), isNewLeader)
}
// some delayed operations may be unblocked after HW changed
if (leaderHWIncremented)
tryCompleteDelayedRequests()
isNewLeader
}
/**
* Make the local replica the follower by setting the new leader and ISR to empty
* If the leader replica id does not change and the new epoch is equal or one
* greater (that is, no updates have been missed), return false to indicate to the
* replica manager that state is already correct and the become-follower steps can be skipped
*/
def makeFollower(controllerId: Int,
partitionState: LeaderAndIsrPartitionState,
correlationId: Int,
highWatermarkCheckpoints: OffsetCheckpoints): Boolean = {
inWriteLock(leaderIsrUpdateLock) {
val newLeaderBrokerId = partitionState.leader
val oldLeaderEpoch = leaderEpoch
// record the epoch of the controller that made the leadership decision. This is useful while updating the isr
// to maintain the decision maker controller's epoch in the zookeeper path
controllerEpoch = partitionState.controllerEpoch
updateAssignmentAndIsr(
assignment = partitionState.replicas.asScala.iterator.map(_.toInt).toSeq,
isr = Set.empty[Int]
)
createLogIfNotExists(localBrokerId, partitionState.isNew, isFutureReplica = false, highWatermarkCheckpoints)
leaderEpoch = partitionState.leaderEpoch
leaderEpochStartOffsetOpt = None
zkVersion = partitionState.zkVersion
if (leaderReplicaIdOpt.contains(newLeaderBrokerId) && leaderEpoch == oldLeaderEpoch) {
false
} else {
leaderReplicaIdOpt = Some(newLeaderBrokerId)
true
}
}
}
/**
* Update the follower's state in the leader based on the last fetch request. See
* [[kafka.cluster.Replica#updateLogReadResult]] for details.
*
* @return true if the follower's fetch state was updated, false if the followerId is not recognized
*/
def updateFollowerFetchState(followerId: Int,
followerFetchOffsetMetadata: LogOffsetMetadata,
followerStartOffset: Long,
followerFetchTimeMs: Long,
leaderEndOffset: Long,
lastSentHighwatermark: Long): Boolean = {
getReplica(followerId) match {
case Some(followerReplica) =>
// No need to calculate low watermark if there is no delayed DeleteRecordsRequest
val oldLeaderLW = if (delayedOperations.numDelayedDelete > 0) lowWatermarkIfLeader else -1L
val prevFollowerEndOffset = followerReplica.logEndOffset
followerReplica.updateFetchState(
followerFetchOffsetMetadata,
followerStartOffset,
followerFetchTimeMs,
leaderEndOffset,
lastSentHighwatermark)
val newLeaderLW = if (delayedOperations.numDelayedDelete > 0) lowWatermarkIfLeader else -1L
// check if the LW of the partition has incremented
// since the replica's logStartOffset may have incremented
val leaderLWIncremented = newLeaderLW > oldLeaderLW
// check if we need to expand ISR to include this replica
// if it is not in the ISR yet
if (!inSyncReplicaIds(followerId))
maybeExpandIsr(followerReplica, followerFetchTimeMs)
// check if the HW of the partition can now be incremented
// since the replica may already be in the ISR and its LEO has just incremented
val leaderHWIncremented = if (prevFollowerEndOffset != followerReplica.logEndOffset) {
leaderLogIfLocal.exists(leaderLog => maybeIncrementLeaderHW(leaderLog, followerFetchTimeMs))
} else {
false
}
// some delayed operations may be unblocked after HW or LW changed
if (leaderLWIncremented || leaderHWIncremented)
tryCompleteDelayedRequests()
debug(s"Recorded replica $followerId log end offset (LEO) position " +
s"${followerFetchOffsetMetadata.messageOffset} and log start offset $followerStartOffset.")
true
case None =>
false
}
}
/**
* Stores the topic partition assignment and ISR.
* It creates a new Replica object for any new remote broker. The isr parameter is
* expected to be a subset of the assignment parameter.
*
* Note: public visibility for tests.
*
* @param assignment An ordered sequence of all the broker ids that were assigned to this
* topic partition
* @param isr The set of broker ids that are known to be insync with the leader
*/
def updateAssignmentAndIsr(assignment: Seq[Int], isr: Set[Int]): Unit = {
val replicaSet = assignment.toSet
val removedReplicas = remoteReplicasMap.keys -- replicaSet
assignment
.filter(_ != localBrokerId)
.foreach(id => remoteReplicasMap.getAndMaybePut(id, new Replica(id, topicPartition)))
removedReplicas.foreach(remoteReplicasMap.remove)
allReplicaIds = assignment
inSyncReplicaIds = isr
}
/**
* Check and maybe expand the ISR of the partition.
* A replica will be added to ISR if its LEO >= current hw of the partition and it is caught up to
* an offset within the current leader epoch. A replica must be caught up to the current leader
* epoch before it can join ISR, because otherwise, if there is committed data between current
* leader's HW and LEO, the replica may become the leader before it fetches the committed data
* and the data will be lost.
*
* Technically, a replica shouldn't be in ISR if it hasn't caught up for longer than replicaLagTimeMaxMs,
* even if its log end offset is >= HW. However, to be consistent with how the follower determines
* whether a replica is in-sync, we only check HW.
*
* This function can be triggered when a replica's LEO has incremented.
*/
private def maybeExpandIsr(followerReplica: Replica, followerFetchTimeMs: Long): Unit = {
inWriteLock(leaderIsrUpdateLock) {
// check if this replica needs to be added to the ISR
leaderLogIfLocal.foreach { leaderLog =>
val leaderHighwatermark = leaderLog.highWatermark
if (!inSyncReplicaIds.contains(followerReplica.brokerId) && isFollowerInSync(followerReplica, leaderHighwatermark)) {
val newInSyncReplicaIds = inSyncReplicaIds + followerReplica.brokerId
info(s"Expanding ISR from ${inSyncReplicaIds.mkString(",")} " +
s"to ${newInSyncReplicaIds.mkString(",")}")
// update ISR in ZK and cache
expandIsr(newInSyncReplicaIds)
}
}
}
}
private def isFollowerInSync(followerReplica: Replica, highWatermark: Long): Boolean = {
val followerEndOffset = followerReplica.logEndOffset
followerEndOffset >= highWatermark && leaderEpochStartOffsetOpt.exists(followerEndOffset >= _)
}
/*
* Returns a tuple where the first element is a boolean indicating whether enough replicas reached `requiredOffset`
* and the second element is an error (which would be `Errors.NONE` for no error).
*
* Note that this method will only be called if requiredAcks = -1 and we are waiting for all replicas in ISR to be
* fully caught up to the (local) leader's offset corresponding to this produce request before we acknowledge the
* produce request.
*/
def checkEnoughReplicasReachOffset(requiredOffset: Long): (Boolean, Errors) = {
leaderLogIfLocal match {
case Some(leaderLog) =>
// keep the current immutable replica list reference
val curInSyncReplicaIds = inSyncReplicaIds
if (isTraceEnabled) {
def logEndOffsetString: ((Int, Long)) => String = {
case (brokerId, logEndOffset) => s"broker $brokerId: $logEndOffset"
}
val curInSyncReplicaObjects = (curInSyncReplicaIds - localBrokerId).map(getReplicaOrException)
val replicaInfo = curInSyncReplicaObjects.map(replica => (replica.brokerId, replica.logEndOffset))
val localLogInfo = (localBrokerId, localLogOrException.logEndOffset)
val (ackedReplicas, awaitingReplicas) = (replicaInfo + localLogInfo).partition { _._2 >= requiredOffset}
trace(s"Progress awaiting ISR acks for offset $requiredOffset: " +
s"acked: ${ackedReplicas.map(logEndOffsetString)}, " +
s"awaiting ${awaitingReplicas.map(logEndOffsetString)}")
}
val minIsr = leaderLog.config.minInSyncReplicas
if (leaderLog.highWatermark >= requiredOffset) {
/*
* The topic may be configured not to accept messages if there are not enough replicas in ISR
* in this scenario the request was already appended locally and then added to the purgatory before the ISR was shrunk
*/
if (minIsr <= curInSyncReplicaIds.size)
(true, Errors.NONE)
else
(true, Errors.NOT_ENOUGH_REPLICAS_AFTER_APPEND)
} else
(false, Errors.NONE)
case None =>
(false, Errors.NOT_LEADER_FOR_PARTITION)
}
}
/**
* Check and maybe increment the high watermark of the partition;
* this function can be triggered when
*
* 1. Partition ISR changed
* 2. Any replica's LEO changed
*
* The HW is determined by the smallest log end offset among all replicas that are in sync or are considered caught-up.
* This way, if a replica is considered caught-up, but its log end offset is smaller than HW, we will wait for this
* replica to catch up to the HW before advancing the HW. This helps the situation when the ISR only includes the
* leader replica and a follower tries to catch up. If we don't wait for the follower when advancing the HW, the
* follower's log end offset may keep falling behind the HW (determined by the leader's log end offset) and therefore
* will never be added to ISR.
*
* Returns true if the HW was incremented, and false otherwise.
* Note There is no need to acquire the leaderIsrUpdate lock here
* since all callers of this private API acquire that lock
*/
private def maybeIncrementLeaderHW(leaderLog: Log, curTime: Long = time.milliseconds): Boolean = {
inReadLock(leaderIsrUpdateLock) {
// maybeIncrementLeaderHW is in the hot path, the following code is written to
// avoid unnecessary collection generation
var newHighWatermark = leaderLog.logEndOffsetMetadata
remoteReplicasMap.values.foreach { replica =>
if (replica.logEndOffsetMetadata.messageOffset < newHighWatermark.messageOffset &&
(curTime - replica.lastCaughtUpTimeMs <= replicaLagTimeMaxMs || inSyncReplicaIds.contains(replica.brokerId))) {
newHighWatermark = replica.logEndOffsetMetadata
}
}
leaderLog.maybeIncrementHighWatermark(newHighWatermark) match {
case Some(oldHighWatermark) =>
debug(s"High watermark updated from $oldHighWatermark to $newHighWatermark")
true
case None =>
def logEndOffsetString: ((Int, LogOffsetMetadata)) => String = {
case (brokerId, logEndOffsetMetadata) => s"replica $brokerId: $logEndOffsetMetadata"
}
if (isTraceEnabled) {
val replicaInfo = remoteReplicas.map(replica => (replica.brokerId, replica.logEndOffsetMetadata)).toSet
val localLogInfo = (localBrokerId, localLogOrException.logEndOffsetMetadata)
trace(s"Skipping update high watermark since new hw $newHighWatermark is not larger than old value. " +
s"All current LEOs are ${(replicaInfo + localLogInfo).map(logEndOffsetString)}")
}
false
}
}
}
/**
* The low watermark offset value, calculated only if the local replica is the partition leader
* It is only used by leader broker to decide when DeleteRecordsRequest is satisfied. Its value is minimum logStartOffset of all live replicas
* Low watermark will increase when the leader broker receives either FetchRequest or DeleteRecordsRequest.
*/
def lowWatermarkIfLeader: Long = {
if (!isLeader)
throw new NotLeaderForPartitionException(s"Leader not local for partition $topicPartition on broker $localBrokerId")
// lowWatermarkIfLeader may be called many times when a DeleteRecordsRequest is outstanding,
// care has been taken to avoid generating unnecessary collections in this code
var lowWaterMark = localLogOrException.logStartOffset
remoteReplicas.foreach { replica =>
if (metadataCache.getAliveBroker(replica.brokerId).nonEmpty && replica.logStartOffset < lowWaterMark) {
lowWaterMark = replica.logStartOffset
}
}
futureLog match {
case Some(partitionFutureLog) =>
Math.min(lowWaterMark, partitionFutureLog.logStartOffset)
case None =>
lowWaterMark
}
}
/**
* Try to complete any pending requests. This should be called without holding the leaderIsrUpdateLock.
*/
private def tryCompleteDelayedRequests(): Unit = delayedOperations.checkAndCompleteAll()
def maybeShrinkIsr(replicaMaxLagTimeMs: Long): Unit = {
val leaderHWIncremented = inWriteLock(leaderIsrUpdateLock) {
leaderLogIfLocal match {
case Some(leaderLog) =>
val outOfSyncReplicaIds = getOutOfSyncReplicas(replicaMaxLagTimeMs)
if (outOfSyncReplicaIds.nonEmpty) {
val newInSyncReplicaIds = inSyncReplicaIds -- outOfSyncReplicaIds
assert(newInSyncReplicaIds.nonEmpty)
info("Shrinking ISR from %s to %s. Leader: (highWatermark: %d, endOffset: %d). Out of sync replicas: %s."
.format(inSyncReplicaIds.mkString(","),
newInSyncReplicaIds.mkString(","),
leaderLog.highWatermark,
leaderLog.logEndOffset,
outOfSyncReplicaIds.map { replicaId =>
s"(brokerId: $replicaId, endOffset: ${getReplicaOrException(replicaId).logEndOffset})"
}.mkString(" ")
)
)
// update ISR in zk and in cache
shrinkIsr(newInSyncReplicaIds)
// we may need to increment high watermark since ISR could be down to 1
maybeIncrementLeaderHW(leaderLog)
} else {
false
}
case None => false // do nothing if no longer leader
}
}
// some delayed operations may be unblocked after HW changed
if (leaderHWIncremented)
tryCompleteDelayedRequests()
}
private def isFollowerOutOfSync(replicaId: Int,
leaderEndOffset: Long,
currentTimeMs: Long,
maxLagMs: Long): Boolean = {
val followerReplica = getReplicaOrException(replicaId)
followerReplica.logEndOffset != leaderEndOffset &&
(currentTimeMs - followerReplica.lastCaughtUpTimeMs) > maxLagMs
}
def getOutOfSyncReplicas(maxLagMs: Long): Set[Int] = {
/**
* If the follower already has the same leo as the leader, it will not be considered as out-of-sync,
* otherwise there are two cases that will be handled here -
* 1. Stuck followers: If the leo of the replica hasn't been updated for maxLagMs ms,
* the follower is stuck and should be removed from the ISR
* 2. Slow followers: If the replica has not read up to the leo within the last maxLagMs ms,
* then the follower is lagging and should be removed from the ISR
* Both these cases are handled by checking the lastCaughtUpTimeMs which represents
* the last time when the replica was fully caught up. If either of the above conditions
* is violated, that replica is considered to be out of sync
*
**/
val candidateReplicaIds = inSyncReplicaIds - localBrokerId
val currentTimeMs = time.milliseconds()
val leaderEndOffset = localLogOrException.logEndOffset
candidateReplicaIds.filter(replicaId => isFollowerOutOfSync(replicaId, leaderEndOffset, currentTimeMs, maxLagMs))
}
private def doAppendRecordsToFollowerOrFutureReplica(records: MemoryRecords, isFuture: Boolean): Option[LogAppendInfo] = {
// The read lock is needed to handle race condition if request handler thread tries to
// remove future replica after receiving AlterReplicaLogDirsRequest.
inReadLock(leaderIsrUpdateLock) {
if (isFuture) {
// Note the replica may be undefined if it is removed by a non-ReplicaAlterLogDirsThread before
// this method is called
futureLog.map { _.appendAsFollower(records) }
} else {
// The read lock is needed to prevent the follower replica from being updated while ReplicaAlterDirThread
// is executing maybeDeleteAndSwapFutureReplica() to replace follower replica with the future replica.
Some(localLogOrException.appendAsFollower(records))
}
}
}
def appendRecordsToFollowerOrFutureReplica(records: MemoryRecords, isFuture: Boolean): Option[LogAppendInfo] = {
try {
doAppendRecordsToFollowerOrFutureReplica(records, isFuture)
} catch {
case e: UnexpectedAppendOffsetException =>
val log = if (isFuture) futureLocalLogOrException else localLogOrException
val logEndOffset = log.logEndOffset
if (logEndOffset == log.logStartOffset &&
e.firstOffset < logEndOffset && e.lastOffset >= logEndOffset) {
// This may happen if the log start offset on the leader (or current replica) falls in
// the middle of the batch due to delete records request and the follower tries to
// fetch its first offset from the leader.
// We handle this case here instead of Log#append() because we will need to remove the
// segment that start with log start offset and create a new one with earlier offset
// (base offset of the batch), which will move recoveryPoint backwards, so we will need
// to checkpoint the new recovery point before we append
val replicaName = if (isFuture) "future replica" else "follower"
info(s"Unexpected offset in append to $topicPartition. First offset ${e.firstOffset} is less than log start offset ${log.logStartOffset}." +
s" Since this is the first record to be appended to the $replicaName's log, will start the log from offset ${e.firstOffset}.")
truncateFullyAndStartAt(e.firstOffset, isFuture)
doAppendRecordsToFollowerOrFutureReplica(records, isFuture)
} else
throw e
}
}
def appendRecordsToLeader(records: MemoryRecords, isFromClient: Boolean, requiredAcks: Int = 0): LogAppendInfo = {
val (info, leaderHWIncremented) = inReadLock(leaderIsrUpdateLock) {
leaderLogIfLocal match {
case Some(leaderLog) =>
val minIsr = leaderLog.config.minInSyncReplicas
val inSyncSize = inSyncReplicaIds.size
// Avoid writing to leader if there are not enough insync replicas to make it safe
if (inSyncSize < minIsr && requiredAcks == -1) {
throw new NotEnoughReplicasException(s"The size of the current ISR $inSyncReplicaIds " +
s"is insufficient to satisfy the min.isr requirement of $minIsr for partition $topicPartition")
}
val info = leaderLog.appendAsLeader(records, leaderEpoch = this.leaderEpoch, isFromClient,
interBrokerProtocolVersion)
// we may need to increment high watermark since ISR could be down to 1
(info, maybeIncrementLeaderHW(leaderLog))
case None =>
throw new NotLeaderForPartitionException("Leader not local for partition %s on broker %d"
.format(topicPartition, localBrokerId))
}
}
// some delayed operations may be unblocked after HW changed
if (leaderHWIncremented)
tryCompleteDelayedRequests()
else {
// probably unblock some follower fetch requests since log end offset has been updated
delayedOperations.checkAndCompleteFetch()
}
info
}
def readRecords(fetchOffset: Long,
currentLeaderEpoch: Optional[Integer],
maxBytes: Int,
fetchIsolation: FetchIsolation,
fetchOnlyFromLeader: Boolean,
minOneMessage: Boolean): LogReadInfo = inReadLock(leaderIsrUpdateLock) {
// decide whether to only fetch from leader
val localLog = localLogWithEpochOrException(currentLeaderEpoch, fetchOnlyFromLeader)
// Note we use the log end offset prior to the read. This ensures that any appends following
// the fetch do not prevent a follower from coming into sync.
val initialHighWatermark = localLog.highWatermark
val initialLogStartOffset = localLog.logStartOffset
val initialLogEndOffset = localLog.logEndOffset
val initialLastStableOffset = localLog.lastStableOffset
val fetchedData = localLog.read(fetchOffset, maxBytes, fetchIsolation, minOneMessage)
LogReadInfo(
fetchedData = fetchedData,
highWatermark = initialHighWatermark,
logStartOffset = initialLogStartOffset,
logEndOffset = initialLogEndOffset,
lastStableOffset = initialLastStableOffset)
}
def fetchOffsetForTimestamp(timestamp: Long,
isolationLevel: Option[IsolationLevel],
currentLeaderEpoch: Optional[Integer],
fetchOnlyFromLeader: Boolean): Option[TimestampAndOffset] = inReadLock(leaderIsrUpdateLock) {
// decide whether to only fetch from leader
val localLog = localLogWithEpochOrException(currentLeaderEpoch, fetchOnlyFromLeader)
val lastFetchableOffset = isolationLevel match {
case Some(IsolationLevel.READ_COMMITTED) => localLog.lastStableOffset
case Some(IsolationLevel.READ_UNCOMMITTED) => localLog.highWatermark
case None => localLog.logEndOffset
}
val epochLogString = if(currentLeaderEpoch.isPresent) {
s"epoch ${currentLeaderEpoch.get}"
} else {
"unknown epoch"
}
// Only consider throwing an error if we get a client request (isolationLevel is defined) and the start offset
// is lagging behind the high watermark
val maybeOffsetsError: Option[ApiException] = leaderEpochStartOffsetOpt
.filter(epochStart => isolationLevel.isDefined && epochStart > localLog.highWatermark)
.map(epochStart => Errors.OFFSET_NOT_AVAILABLE.exception(s"Failed to fetch offsets for " +
s"partition $topicPartition with leader $epochLogString as this partition's " +
s"high watermark (${localLog.highWatermark}) is lagging behind the " +
s"start offset from the beginning of this epoch ($epochStart)."))
def getOffsetByTimestamp: Option[TimestampAndOffset] = {
logManager.getLog(topicPartition).flatMap(log => log.fetchOffsetByTimestamp(timestamp))
}
// If we're in the lagging HW state after a leader election, throw OffsetNotAvailable for "latest" offset
// or for a timestamp lookup that is beyond the last fetchable offset.
timestamp match {
case ListOffsetRequest.LATEST_TIMESTAMP =>
maybeOffsetsError.map(e => throw e)
.orElse(Some(new TimestampAndOffset(RecordBatch.NO_TIMESTAMP, lastFetchableOffset, Optional.of(leaderEpoch))))
case ListOffsetRequest.EARLIEST_TIMESTAMP =>
getOffsetByTimestamp
case _ =>
getOffsetByTimestamp.filter(timestampAndOffset => timestampAndOffset.offset < lastFetchableOffset)
.orElse(maybeOffsetsError.map(e => throw e))
}
}
def fetchOffsetSnapshot(currentLeaderEpoch: Optional[Integer],
fetchOnlyFromLeader: Boolean): LogOffsetSnapshot = inReadLock(leaderIsrUpdateLock) {
// decide whether to only fetch from leader
val localLog = localLogWithEpochOrException(currentLeaderEpoch, fetchOnlyFromLeader)
localLog.fetchOffsetSnapshot
}
def legacyFetchOffsetsForTimestamp(timestamp: Long,
maxNumOffsets: Int,
isFromConsumer: Boolean,
fetchOnlyFromLeader: Boolean): Seq[Long] = inReadLock(leaderIsrUpdateLock) {
val localLog = localLogWithEpochOrException(Optional.empty(), fetchOnlyFromLeader)
val allOffsets = localLog.legacyFetchOffsetsBefore(timestamp, maxNumOffsets)
if (!isFromConsumer) {
allOffsets
} else {
val hw = localLog.highWatermark
if (allOffsets.exists(_ > hw))
hw +: allOffsets.dropWhile(_ > hw)
else
allOffsets
}
}
def logStartOffset: Long = {
inReadLock(leaderIsrUpdateLock) {
leaderLogIfLocal.map(_.logStartOffset).getOrElse(-1)
}
}
/**
* Update logStartOffset and low watermark if 1) offset <= highWatermark and 2) it is the leader replica.
* This function can trigger log segment deletion and log rolling.
*
* Return low watermark of the partition.
*/
def deleteRecordsOnLeader(offset: Long): LogDeleteRecordsResult = inReadLock(leaderIsrUpdateLock) {
leaderLogIfLocal match {
case Some(leaderLog) =>
if (!leaderLog.config.delete)
throw new PolicyViolationException(s"Records of partition $topicPartition can not be deleted due to the configured policy")
val convertedOffset = if (offset == DeleteRecordsRequest.HIGH_WATERMARK)
leaderLog.highWatermark
else
offset
if (convertedOffset < 0)
throw new OffsetOutOfRangeException(s"The offset $convertedOffset for partition $topicPartition is not valid")
leaderLog.maybeIncrementLogStartOffset(convertedOffset)
LogDeleteRecordsResult(
requestedOffset = convertedOffset,
lowWatermark = lowWatermarkIfLeader)
case None =>
throw new NotLeaderForPartitionException(s"Leader not local for partition $topicPartition on broker $localBrokerId")
}
}
/**
* Truncate the local log of this partition to the specified offset and checkpoint the recovery point to this offset
*
* @param offset offset to be used for truncation
* @param isFuture True iff the truncation should be performed on the future log of this partition
*/
def truncateTo(offset: Long, isFuture: Boolean): Unit = {
// The read lock is needed to prevent the follower replica from being truncated while ReplicaAlterDirThread
// is executing maybeDeleteAndSwapFutureReplica() to replace follower replica with the future replica.
inReadLock(leaderIsrUpdateLock) {
logManager.truncateTo(Map(topicPartition -> offset), isFuture = isFuture)
}
}
/**
* Delete all data in the local log of this partition and start the log at the new offset
*
* @param newOffset The new offset to start the log with
* @param isFuture True iff the truncation should be performed on the future log of this partition
*/
def truncateFullyAndStartAt(newOffset: Long, isFuture: Boolean): Unit = {
// The read lock is needed to prevent the follower replica from being truncated while ReplicaAlterDirThread
// is executing maybeDeleteAndSwapFutureReplica() to replace follower replica with the future replica.
inReadLock(leaderIsrUpdateLock) {
logManager.truncateFullyAndStartAt(topicPartition, newOffset, isFuture = isFuture)
}
}
/**
* Find the (exclusive) last offset of the largest epoch less than or equal to the requested epoch.
*
* @param currentLeaderEpoch The expected epoch of the current leader (if known)
* @param leaderEpoch Requested leader epoch
* @param fetchOnlyFromLeader Whether or not to require servicing only from the leader
*
* @return The requested leader epoch and the end offset of this leader epoch, or if the requested
* leader epoch is unknown, the leader epoch less than the requested leader epoch and the end offset
* of this leader epoch. The end offset of a leader epoch is defined as the start
* offset of the first leader epoch larger than the leader epoch, or else the log end
* offset if the leader epoch is the latest leader epoch.
*/
def lastOffsetForLeaderEpoch(currentLeaderEpoch: Optional[Integer],
leaderEpoch: Int,
fetchOnlyFromLeader: Boolean): EpochEndOffset = {
inReadLock(leaderIsrUpdateLock) {
val localLogOrError = getLocalLog(currentLeaderEpoch, fetchOnlyFromLeader)
localLogOrError match {
case Left(localLog) =>
localLog.endOffsetForEpoch(leaderEpoch) match {
case Some(epochAndOffset) => new EpochEndOffset(NONE, epochAndOffset.leaderEpoch, epochAndOffset.offset)
case None => new EpochEndOffset(NONE, UNDEFINED_EPOCH, UNDEFINED_EPOCH_OFFSET)
}
case Right(error) =>
new EpochEndOffset(error, UNDEFINED_EPOCH, UNDEFINED_EPOCH_OFFSET)
}
}
}
private def expandIsr(newIsr: Set[Int]): Unit = {
val newLeaderAndIsr = new LeaderAndIsr(localBrokerId, leaderEpoch, newIsr.toList, zkVersion)
val zkVersionOpt = stateStore.expandIsr(controllerEpoch, newLeaderAndIsr)
maybeUpdateIsrAndVersion(newIsr, zkVersionOpt)
}
private def shrinkIsr(newIsr: Set[Int]): Unit = {
val newLeaderAndIsr = new LeaderAndIsr(localBrokerId, leaderEpoch, newIsr.toList, zkVersion)
val zkVersionOpt = stateStore.shrinkIsr(controllerEpoch, newLeaderAndIsr)
maybeUpdateIsrAndVersion(newIsr, zkVersionOpt)
}
private def maybeUpdateIsrAndVersion(isr: Set[Int], zkVersionOpt: Option[Int]): Unit = {
zkVersionOpt match {
case Some(newVersion) =>
inSyncReplicaIds = isr
zkVersion = newVersion
info("ISR updated to [%s] and zkVersion updated to [%d]".format(isr.mkString(","), zkVersion))
case None =>
info(s"Cached zkVersion $zkVersion not equal to that in zookeeper, skip updating ISR")
}
}
override def equals(that: Any): Boolean = that match {
case other: Partition => partitionId == other.partitionId && topic == other.topic
case _ => false
}
override def hashCode: Int =
31 + topic.hashCode + 17 * partitionId
override def toString: String = {
val partitionString = new StringBuilder
partitionString.append("Topic: " + topic)
partitionString.append("; Partition: " + partitionId)
partitionString.append("; Leader: " + leaderReplicaIdOpt)
partitionString.append("; AllReplicaIds: " + allReplicaIds.mkString(","))
partitionString.append("; InSyncReplicaIds: " + inSyncReplicaIds.mkString(","))
partitionString.toString
}
}
