kafka.coordinator.group.GroupMetadata.scala Maven / Gradle / Ivy
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* 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.coordinator.group
import java.util.UUID
import java.util.concurrent.locks.ReentrantLock
import kafka.common.OffsetAndMetadata
import kafka.utils.{CoreUtils, Logging, nonthreadsafe}
import org.apache.kafka.common.TopicPartition
import org.apache.kafka.common.utils.Time
import scala.collection.{Seq, immutable, mutable}
private[group] sealed trait GroupState
/**
* Group is preparing to rebalance
*
* action: respond to heartbeats with REBALANCE_IN_PROGRESS
* respond to sync group with REBALANCE_IN_PROGRESS
* remove member on leave group request
* park join group requests from new or existing members until all expected members have joined
* allow offset commits from previous generation
* allow offset fetch requests
* transition: some members have joined by the timeout => CompletingRebalance
* all members have left the group => Empty
* group is removed by partition emigration => Dead
*/
private[group] case object PreparingRebalance extends GroupState
/**
* Group is awaiting state assignment from the leader
*
* action: respond to heartbeats with REBALANCE_IN_PROGRESS
* respond to offset commits with REBALANCE_IN_PROGRESS
* park sync group requests from followers until transition to Stable
* allow offset fetch requests
* transition: sync group with state assignment received from leader => Stable
* join group from new member or existing member with updated metadata => PreparingRebalance
* leave group from existing member => PreparingRebalance
* member failure detected => PreparingRebalance
* group is removed by partition emigration => Dead
*/
private[group] case object CompletingRebalance extends GroupState
/**
* Group is stable
*
* action: respond to member heartbeats normally
* respond to sync group from any member with current assignment
* respond to join group from followers with matching metadata with current group metadata
* allow offset commits from member of current generation
* allow offset fetch requests
* transition: member failure detected via heartbeat => PreparingRebalance
* leave group from existing member => PreparingRebalance
* leader join-group received => PreparingRebalance
* follower join-group with new metadata => PreparingRebalance
* group is removed by partition emigration => Dead
*/
private[group] case object Stable extends GroupState
/**
* Group has no more members and its metadata is being removed
*
* action: respond to join group with UNKNOWN_MEMBER_ID
* respond to sync group with UNKNOWN_MEMBER_ID
* respond to heartbeat with UNKNOWN_MEMBER_ID
* respond to leave group with UNKNOWN_MEMBER_ID
* respond to offset commit with UNKNOWN_MEMBER_ID
* allow offset fetch requests
* transition: Dead is a final state before group metadata is cleaned up, so there are no transitions
*/
private[group] case object Dead extends GroupState
/**
* Group has no more members, but lingers until all offsets have expired. This state
* also represents groups which use Kafka only for offset commits and have no members.
*
* action: respond normally to join group from new members
* respond to sync group with UNKNOWN_MEMBER_ID
* respond to heartbeat with UNKNOWN_MEMBER_ID
* respond to leave group with UNKNOWN_MEMBER_ID
* respond to offset commit with UNKNOWN_MEMBER_ID
* allow offset fetch requests
* transition: last offsets removed in periodic expiration task => Dead
* join group from a new member => PreparingRebalance
* group is removed by partition emigration => Dead
* group is removed by expiration => Dead
*/
private[group] case object Empty extends GroupState
private object GroupMetadata {
private val validPreviousStates: Map[GroupState, Set[GroupState]] =
Map(Dead -> Set(Stable, PreparingRebalance, CompletingRebalance, Empty, Dead),
CompletingRebalance -> Set(PreparingRebalance),
Stable -> Set(CompletingRebalance),
PreparingRebalance -> Set(Stable, CompletingRebalance, Empty),
Empty -> Set(PreparingRebalance))
def loadGroup(groupId: String,
initialState: GroupState,
generationId: Int,
protocolType: String,
protocol: String,
leaderId: String,
currentStateTimestamp: Option[Long],
members: Iterable[MemberMetadata],
time: Time): GroupMetadata = {
val group = new GroupMetadata(groupId, initialState, time)
group.generationId = generationId
group.protocolType = if (protocolType == null || protocolType.isEmpty) None else Some(protocolType)
group.protocol = Option(protocol)
group.leaderId = Option(leaderId)
group.currentStateTimestamp = currentStateTimestamp
members.foreach(group.add(_, null))
group
}
}
/**
* Case class used to represent group metadata for the ListGroups API
*/
case class GroupOverview(groupId: String,
protocolType: String)
/**
* Case class used to represent group metadata for the DescribeGroup API
*/
case class GroupSummary(state: String,
protocolType: String,
protocol: String,
members: List[MemberSummary])
/**
* We cache offset commits along with their commit record offset. This enables us to ensure that the latest offset
* commit is always materialized when we have a mix of transactional and regular offset commits. Without preserving
* information of the commit record offset, compaction of the offsets topic it self may result in the wrong offset commit
* being materialized.
*/
case class CommitRecordMetadataAndOffset(appendedBatchOffset: Option[Long], offsetAndMetadata: OffsetAndMetadata) {
def olderThan(that: CommitRecordMetadataAndOffset) : Boolean = appendedBatchOffset.get < that.appendedBatchOffset.get
}
/**
* Group contains the following metadata:
*
* Membership metadata:
* 1. Members registered in this group
* 2. Current protocol assigned to the group (e.g. partition assignment strategy for consumers)
* 3. Protocol metadata associated with group members
*
* State metadata:
* 1. group state
* 2. generation id
* 3. leader id
*/
@nonthreadsafe
private[group] class GroupMetadata(val groupId: String, initialState: GroupState, time: Time) extends Logging {
type JoinCallback = JoinGroupResult => Unit
private[group] val lock = new ReentrantLock
private var state: GroupState = initialState
var currentStateTimestamp: Option[Long] = Some(time.milliseconds())
var protocolType: Option[String] = None
var generationId = 0
private var leaderId: Option[String] = None
private var protocol: Option[String] = None
private val members = new mutable.HashMap[String, MemberMetadata]
private var numMembersAwaitingJoin = 0
private val supportedProtocols = new mutable.HashMap[String, Integer]().withDefaultValue(0)
private val offsets = new mutable.HashMap[TopicPartition, CommitRecordMetadataAndOffset]
private val pendingOffsetCommits = new mutable.HashMap[TopicPartition, OffsetAndMetadata]
private val pendingTransactionalOffsetCommits = new mutable.HashMap[Long, mutable.Map[TopicPartition, CommitRecordMetadataAndOffset]]()
private var receivedTransactionalOffsetCommits = false
private var receivedConsumerOffsetCommits = false
var newMemberAdded: Boolean = false
def inLock[T](fun: => T): T = CoreUtils.inLock(lock)(fun)
def is(groupState: GroupState) = state == groupState
def not(groupState: GroupState) = state != groupState
def has(memberId: String) = members.contains(memberId)
def get(memberId: String) = members(memberId)
def isLeader(memberId: String): Boolean = leaderId.contains(memberId)
def leaderOrNull: String = leaderId.orNull
def protocolOrNull: String = protocol.orNull
def currentStateTimestampOrDefault: Long = currentStateTimestamp.getOrElse(-1)
def add(member: MemberMetadata, callback: JoinCallback = null) {
if (members.isEmpty)
this.protocolType = Some(member.protocolType)
assert(groupId == member.groupId)
assert(this.protocolType.orNull == member.protocolType)
assert(supportsProtocols(member.protocols))
if (leaderId.isEmpty)
leaderId = Some(member.memberId)
members.put(member.memberId, member)
member.supportedProtocols.foreach{ case (protocol, _) => supportedProtocols(protocol) += 1 }
member.awaitingJoinCallback = callback
if (member.awaitingJoinCallback != null)
numMembersAwaitingJoin += 1
}
def remove(memberId: String) {
members.remove(memberId).foreach { member =>
member.supportedProtocols.foreach{ case (protocol, _) => supportedProtocols(protocol) -= 1 }
if (member.awaitingJoinCallback != null)
numMembersAwaitingJoin -= 1
}
if (isLeader(memberId)) {
leaderId = if (members.isEmpty) {
None
} else {
Some(members.keys.head)
}
}
}
def currentState = state
def notYetRejoinedMembers = members.values.filter(_.awaitingJoinCallback == null).toList
def hasAllMembersJoined = members.size <= numMembersAwaitingJoin
def allMembers = members.keySet
def allMemberMetadata = members.values.toList
def rebalanceTimeoutMs = members.values.foldLeft(0) { (timeout, member) =>
timeout.max(member.rebalanceTimeoutMs)
}
// TODO: decide if ids should be predictable or random
def generateMemberIdSuffix = UUID.randomUUID().toString
def canRebalance = GroupMetadata.validPreviousStates(PreparingRebalance).contains(state)
def transitionTo(groupState: GroupState) {
assertValidTransition(groupState)
state = groupState
currentStateTimestamp = Some(time.milliseconds())
}
def selectProtocol: String = {
if (members.isEmpty)
throw new IllegalStateException("Cannot select protocol for empty group")
// select the protocol for this group which is supported by all members
val candidates = candidateProtocols
// let each member vote for one of the protocols and choose the one with the most votes
val votes: List[(String, Int)] = allMemberMetadata
.map(_.vote(candidates))
.groupBy(identity)
.mapValues(_.size)
.toList
votes.maxBy(_._2)._1
}
private def candidateProtocols = {
// get the set of protocols that are commonly supported by all members
val numMembers = members.size
supportedProtocols.filter(_._2 == numMembers).map(_._1).toSet
}
def supportsProtocols(memberProtocols: Set[String]) = {
val numMembers = members.size
members.isEmpty || memberProtocols.exists(supportedProtocols(_) == numMembers)
}
def updateMember(member: MemberMetadata,
protocols: List[(String, Array[Byte])],
callback: JoinCallback) = {
member.supportedProtocols.foreach{ case (protocol, _) => supportedProtocols(protocol) -= 1 }
protocols.foreach{ case (protocol, _) => supportedProtocols(protocol) += 1 }
member.supportedProtocols = protocols
if (callback != null && member.awaitingJoinCallback == null) {
numMembersAwaitingJoin += 1
} else if (callback == null && member.awaitingJoinCallback != null) {
numMembersAwaitingJoin -= 1
}
member.awaitingJoinCallback = callback
}
def maybeInvokeJoinCallback(member: MemberMetadata,
joinGroupResult: JoinGroupResult) : Unit = {
if (member.awaitingJoinCallback != null) {
member.awaitingJoinCallback(joinGroupResult)
member.awaitingJoinCallback = null
numMembersAwaitingJoin -= 1
}
}
def initNextGeneration() = {
assert(notYetRejoinedMembers == List.empty[MemberMetadata])
if (members.nonEmpty) {
generationId += 1
protocol = Some(selectProtocol)
transitionTo(CompletingRebalance)
} else {
generationId += 1
protocol = None
transitionTo(Empty)
}
receivedConsumerOffsetCommits = false
receivedTransactionalOffsetCommits = false
}
def currentMemberMetadata: Map[String, Array[Byte]] = {
if (is(Dead) || is(PreparingRebalance))
throw new IllegalStateException("Cannot obtain member metadata for group in state %s".format(state))
members.map{ case (memberId, memberMetadata) => (memberId, memberMetadata.metadata(protocol.get))}.toMap
}
def summary: GroupSummary = {
if (is(Stable)) {
val protocol = protocolOrNull
if (protocol == null)
throw new IllegalStateException("Invalid null group protocol for stable group")
val members = this.members.values.map { member => member.summary(protocol) }
GroupSummary(state.toString, protocolType.getOrElse(""), protocol, members.toList)
} else {
val members = this.members.values.map{ member => member.summaryNoMetadata() }
GroupSummary(state.toString, protocolType.getOrElse(""), GroupCoordinator.NoProtocol, members.toList)
}
}
def overview: GroupOverview = {
GroupOverview(groupId, protocolType.getOrElse(""))
}
def initializeOffsets(offsets: collection.Map[TopicPartition, CommitRecordMetadataAndOffset],
pendingTxnOffsets: Map[Long, mutable.Map[TopicPartition, CommitRecordMetadataAndOffset]]) {
this.offsets ++= offsets
this.pendingTransactionalOffsetCommits ++= pendingTxnOffsets
}
def onOffsetCommitAppend(topicPartition: TopicPartition, offsetWithCommitRecordMetadata: CommitRecordMetadataAndOffset) {
if (pendingOffsetCommits.contains(topicPartition)) {
if (offsetWithCommitRecordMetadata.appendedBatchOffset.isEmpty)
throw new IllegalStateException("Cannot complete offset commit write without providing the metadata of the record " +
"in the log.")
if (!offsets.contains(topicPartition) || offsets(topicPartition).olderThan(offsetWithCommitRecordMetadata))
offsets.put(topicPartition, offsetWithCommitRecordMetadata)
}
pendingOffsetCommits.get(topicPartition) match {
case Some(stagedOffset) if offsetWithCommitRecordMetadata.offsetAndMetadata == stagedOffset =>
pendingOffsetCommits.remove(topicPartition)
case _ =>
// The pendingOffsetCommits for this partition could be empty if the topic was deleted, in which case
// its entries would be removed from the cache by the `removeOffsets` method.
}
}
def failPendingOffsetWrite(topicPartition: TopicPartition, offset: OffsetAndMetadata): Unit = {
pendingOffsetCommits.get(topicPartition) match {
case Some(pendingOffset) if offset == pendingOffset => pendingOffsetCommits.remove(topicPartition)
case _ =>
}
}
def prepareOffsetCommit(offsets: Map[TopicPartition, OffsetAndMetadata]) {
receivedConsumerOffsetCommits = true
pendingOffsetCommits ++= offsets
}
def prepareTxnOffsetCommit(producerId: Long, offsets: Map[TopicPartition, OffsetAndMetadata]) {
trace(s"TxnOffsetCommit for producer $producerId and group $groupId with offsets $offsets is pending")
receivedTransactionalOffsetCommits = true
val producerOffsets = pendingTransactionalOffsetCommits.getOrElseUpdate(producerId,
mutable.Map.empty[TopicPartition, CommitRecordMetadataAndOffset])
offsets.foreach { case (topicPartition, offsetAndMetadata) =>
producerOffsets.put(topicPartition, CommitRecordMetadataAndOffset(None, offsetAndMetadata))
}
}
def hasReceivedConsistentOffsetCommits : Boolean = {
!receivedConsumerOffsetCommits || !receivedTransactionalOffsetCommits
}
/* Remove a pending transactional offset commit if the actual offset commit record was not written to the log.
* We will return an error and the client will retry the request, potentially to a different coordinator.
*/
def failPendingTxnOffsetCommit(producerId: Long, topicPartition: TopicPartition): Unit = {
pendingTransactionalOffsetCommits.get(producerId) match {
case Some(pendingOffsets) =>
val pendingOffsetCommit = pendingOffsets.remove(topicPartition)
trace(s"TxnOffsetCommit for producer $producerId and group $groupId with offsets $pendingOffsetCommit failed " +
s"to be appended to the log")
if (pendingOffsets.isEmpty)
pendingTransactionalOffsetCommits.remove(producerId)
case _ =>
// We may hit this case if the partition in question has emigrated already.
}
}
def onTxnOffsetCommitAppend(producerId: Long, topicPartition: TopicPartition,
commitRecordMetadataAndOffset: CommitRecordMetadataAndOffset) {
pendingTransactionalOffsetCommits.get(producerId) match {
case Some(pendingOffset) =>
if (pendingOffset.contains(topicPartition)
&& pendingOffset(topicPartition).offsetAndMetadata == commitRecordMetadataAndOffset.offsetAndMetadata)
pendingOffset.update(topicPartition, commitRecordMetadataAndOffset)
case _ =>
// We may hit this case if the partition in question has emigrated.
}
}
/* Complete a pending transactional offset commit. This is called after a commit or abort marker is fully written
* to the log.
*/
def completePendingTxnOffsetCommit(producerId: Long, isCommit: Boolean): Unit = {
val pendingOffsetsOpt = pendingTransactionalOffsetCommits.remove(producerId)
if (isCommit) {
pendingOffsetsOpt.foreach { pendingOffsets =>
pendingOffsets.foreach { case (topicPartition, commitRecordMetadataAndOffset) =>
if (commitRecordMetadataAndOffset.appendedBatchOffset.isEmpty)
throw new IllegalStateException(s"Trying to complete a transactional offset commit for producerId $producerId " +
s"and groupId $groupId even though the offset commit record itself hasn't been appended to the log.")
val currentOffsetOpt = offsets.get(topicPartition)
if (currentOffsetOpt.forall(_.olderThan(commitRecordMetadataAndOffset))) {
trace(s"TxnOffsetCommit for producer $producerId and group $groupId with offset $commitRecordMetadataAndOffset " +
"committed and loaded into the cache.")
offsets.put(topicPartition, commitRecordMetadataAndOffset)
} else {
trace(s"TxnOffsetCommit for producer $producerId and group $groupId with offset $commitRecordMetadataAndOffset " +
s"committed, but not loaded since its offset is older than current offset $currentOffsetOpt.")
}
}
}
} else {
trace(s"TxnOffsetCommit for producer $producerId and group $groupId with offsets $pendingOffsetsOpt aborted")
}
}
def activeProducers = pendingTransactionalOffsetCommits.keySet
def hasPendingOffsetCommitsFromProducer(producerId: Long) =
pendingTransactionalOffsetCommits.contains(producerId)
def removeAllOffsets(): immutable.Map[TopicPartition, OffsetAndMetadata] = removeOffsets(offsets.keySet.toSeq)
def removeOffsets(topicPartitions: Seq[TopicPartition]): immutable.Map[TopicPartition, OffsetAndMetadata] = {
topicPartitions.flatMap { topicPartition =>
pendingOffsetCommits.remove(topicPartition)
pendingTransactionalOffsetCommits.foreach { case (_, pendingOffsets) =>
pendingOffsets.remove(topicPartition)
}
val removedOffset = offsets.remove(topicPartition)
removedOffset.map(topicPartition -> _.offsetAndMetadata)
}.toMap
}
def removeExpiredOffsets(currentTimestamp: Long, offsetRetentionMs: Long) : Map[TopicPartition, OffsetAndMetadata] = {
def getExpiredOffsets(baseTimestamp: CommitRecordMetadataAndOffset => Long): Map[TopicPartition, OffsetAndMetadata] = {
offsets.filter {
case (topicPartition, commitRecordMetadataAndOffset) =>
!pendingOffsetCommits.contains(topicPartition) && {
commitRecordMetadataAndOffset.offsetAndMetadata.expireTimestamp match {
case None =>
// current version with no per partition retention
currentTimestamp - baseTimestamp(commitRecordMetadataAndOffset) >= offsetRetentionMs
case Some(expireTimestamp) =>
// older versions with explicit expire_timestamp field => old expiration semantics is used
currentTimestamp >= expireTimestamp
}
}
}.map {
case (topicPartition, commitRecordOffsetAndMetadata) =>
(topicPartition, commitRecordOffsetAndMetadata.offsetAndMetadata)
}.toMap
}
val expiredOffsets: Map[TopicPartition, OffsetAndMetadata] = protocolType match {
case Some(_) if is(Empty) =>
// no consumer exists in the group =>
// - if current state timestamp exists and retention period has passed since group became Empty,
// expire all offsets with no pending offset commit;
// - if there is no current state timestamp (old group metadata schema) and retention period has passed
// since the last commit timestamp, expire the offset
getExpiredOffsets(commitRecordMetadataAndOffset =>
currentStateTimestamp.getOrElse(commitRecordMetadataAndOffset.offsetAndMetadata.commitTimestamp))
case None =>
// protocolType is None => standalone (simple) consumer, that uses Kafka for offset storage only
// expire offsets with no pending offset commit that retention period has passed since their last commit
getExpiredOffsets(_.offsetAndMetadata.commitTimestamp)
case _ =>
Map()
}
if (expiredOffsets.nonEmpty)
debug(s"Expired offsets from group '$groupId': ${expiredOffsets.keySet}")
offsets --= expiredOffsets.keySet
expiredOffsets
}
def allOffsets = offsets.map { case (topicPartition, commitRecordMetadataAndOffset) =>
(topicPartition, commitRecordMetadataAndOffset.offsetAndMetadata)
}.toMap
def offset(topicPartition: TopicPartition): Option[OffsetAndMetadata] = offsets.get(topicPartition).map(_.offsetAndMetadata)
// visible for testing
private[group] def offsetWithRecordMetadata(topicPartition: TopicPartition): Option[CommitRecordMetadataAndOffset] = offsets.get(topicPartition)
def numOffsets = offsets.size
def hasOffsets = offsets.nonEmpty || pendingOffsetCommits.nonEmpty || pendingTransactionalOffsetCommits.nonEmpty
private def assertValidTransition(targetState: GroupState) {
if (!GroupMetadata.validPreviousStates(targetState).contains(state))
throw new IllegalStateException("Group %s should be in the %s states before moving to %s state. Instead it is in %s state"
.format(groupId, GroupMetadata.validPreviousStates(targetState).mkString(","), targetState, state))
}
override def toString: String = {
"GroupMetadata(" +
s"groupId=$groupId, " +
s"generation=$generationId, " +
s"protocolType=$protocolType, " +
s"currentState=$currentState, " +
s"members=$members)"
}
}
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