satishd commented on code in PR #11390:
URL: https://github.com/apache/kafka/pull/11390#discussion_r1032944075
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core/src/main/scala/kafka/server/ReplicaFetcherThread.scala:
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@@ -169,4 +181,140 @@ class ReplicaFetcherThread(name: String,
partition.truncateFullyAndStartAt(offset, isFuture = false)
}
+ /**
+ * It tries to build the required state for this partition from leader and
remote storage so that it can start
+ * fetching records from the leader.
+ */
+ override protected def buildRemoteLogAuxState(partition: TopicPartition,
+ currentLeaderEpoch: Int,
+ leaderLocalLogStartOffset:
Long,
+
epochForLeaderLocalLogStartOffset: Int,
+ leaderLogStartOffset: Long):
Long = {
+
+ def fetchEarlierEpochEndOffset(epoch:Int): EpochEndOffset = {
+ val previousEpoch = epoch - 1
+ // Find the end-offset for the epoch earlier to the given epoch from
the leader
+ val partitionsWithEpochs = Map(partition -> new
EpochData().setPartition(partition.partition())
+ .setCurrentLeaderEpoch(currentLeaderEpoch)
+ .setLeaderEpoch(previousEpoch))
+ val maybeEpochEndOffset =
leader.fetchEpochEndOffsets(partitionsWithEpochs).get(partition)
+ if (maybeEpochEndOffset.isEmpty) {
+ throw new KafkaException("No response received for partition: " +
partition);
+ }
+
+ val epochEndOffset = maybeEpochEndOffset.get
+ if (epochEndOffset.errorCode() != Errors.NONE.code()) {
+ throw Errors.forCode(epochEndOffset.errorCode()).exception()
+ }
+
+ epochEndOffset
+ }
+
+ val log = replicaMgr.localLogOrException(partition)
+ val nextOffset = {
+ if (log.remoteStorageSystemEnable &&
log.config.remoteLogConfig.remoteStorageEnable) {
+ if (replicaMgr.remoteLogManager.isEmpty) throw new
IllegalStateException("RemoteLogManager is not yet instantiated")
+
+ val rlm = replicaMgr.remoteLogManager.get
+
+ // Find the respective leader epoch for (leaderLocalLogStartOffset -
1). We need to build the leader epoch cache
+ // until that offset
+ val previousOffsetToLeaderLocalLogStartOffset =
leaderLocalLogStartOffset - 1
+ val targetEpoch: Int = {
+ // If the existing epoch is 0, no need to fetch from earlier epoch
as the desired offset(leaderLogStartOffset - 1)
+ // will have the same epoch.
+ if (epochForLeaderLocalLogStartOffset == 0) {
+ epochForLeaderLocalLogStartOffset
+ } else {
+ // Fetch the earlier epoch/end-offset(exclusive) from the leader.
+ val earlierEpochEndOffset =
fetchEarlierEpochEndOffset(epochForLeaderLocalLogStartOffset)
+ // Check if the target offset lies with in the range of earlier
epoch. Here, epoch's end-offset is exclusive.
+ if (earlierEpochEndOffset.endOffset >
previousOffsetToLeaderLocalLogStartOffset) {
+ // Always use the leader epoch from returned
earlierEpochEndOffset.
+ // This gives the respective leader epoch, that will handle any
gaps in epochs.
+ // For ex, leader epoch cache contains:
+ // leader-epoch start-offset
+ // 0 20
+ // 1 85
+ // <2> - gap no messages were appended in this leader epoch.
+ // 3 90
+ // 4 98
+ // There is a gap in leader epoch. For leaderLocalLogStartOffset
as 90, leader-epoch is 3.
+ // fetchEarlierEpochEndOffset(2) will return leader-epoch as 1,
end-offset as 90.
+ // So, for offset 89, we should return leader epoch as 1 like
below.
+ earlierEpochEndOffset.leaderEpoch()
+ } else epochForLeaderLocalLogStartOffset
+ }
+ }
+
+ val maybeRlsm = rlm.fetchRemoteLogSegmentMetadata(partition,
targetEpoch, previousOffsetToLeaderLocalLogStartOffset)
+
+ if (maybeRlsm.isPresent) {
+ val remoteLogSegmentMetadata = maybeRlsm.get()
+ // Build leader epoch cache, producer snapshots until
remoteLogSegmentMetadata.endOffset() and start
+ // segments from (remoteLogSegmentMetadata.endOffset() + 1)
+ val nextOffset = remoteLogSegmentMetadata.endOffset() + 1
+ val epochStream =
rlm.storageManager().fetchIndex(remoteLogSegmentMetadata,
RemoteStorageManager.IndexType.LEADER_EPOCH)
+ val epochs = readLeaderEpochCheckpoint(epochStream)
+
+ // Truncate the existing local log before restoring the leader epoch
cache and producer snapshots.
+ truncateFullyAndStartAt(partition, nextOffset)
+
+ log.maybeIncrementLogStartOffset(leaderLogStartOffset,
LeaderOffsetIncremented)
+ log.leaderEpochCache.foreach { cache =>
Review Comment:
leaderepochcache is already cleaned up by the earlier
`truncateFullyAndStartAt` call.
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