hachikuji commented on a change in pull request #9275:
URL: https://github.com/apache/kafka/pull/9275#discussion_r488850209
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File path: core/src/main/scala/kafka/server/epoch/LeaderEpochFileCache.scala
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@@ -47,63 +47,81 @@ class LeaderEpochFileCache(topicPartition: TopicPartition,
private val epochs = new util.TreeMap[Int, EpochEntry]()
inWriteLock(lock) {
- checkpoint.read().foreach { entry =>
- epochs.put(entry.epoch, entry)
- }
+ checkpoint.read().foreach(assign)
}
/**
* Assigns the supplied Leader Epoch to the supplied Offset
* Once the epoch is assigned it cannot be reassigned
*/
def assign(epoch: Int, startOffset: Long): Unit = {
- inWriteLock(lock) {
- val updateNeeded = if (epochs.isEmpty) {
- true
- } else {
- val lastEntry = epochs.lastEntry.getValue
- lastEntry.epoch != epoch || startOffset < lastEntry.startOffset
- }
+ val entry = EpochEntry(epoch, startOffset)
+ if (assign(entry)) {
+ debug(s"Appended new epoch entry $entry. Cache now contains
${epochs.size} entries.")
+ flush()
+ }
+ }
- if (updateNeeded) {
- truncateAndAppend(EpochEntry(epoch, startOffset))
- flush()
+ private def assign(entry: EpochEntry): Boolean = {
+ if (entry.epoch < 0 || entry.startOffset < 0) {
+ throw new IllegalArgumentException(s"Received invalid partition leader
epoch entry $entry")
+ }
+
+ // Check whether the append is needed before acquiring the write lock
+ // in order to avoid contention with readers in the common case
+ latestEntry.foreach { lastEntry =>
+ if (entry.epoch == lastEntry.epoch && entry.startOffset >=
lastEntry.startOffset) {
+ return false
Review comment:
Yeah, let me add it. I had debated it and convinced myself it was not
needed, but that probably relies a bit too heavily on locking at higher layers.
Probably better to err on the safe side.
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