chia7712 commented on code in PR #15621:
URL: https://github.com/apache/kafka/pull/15621#discussion_r1548644261
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core/src/main/scala/kafka/log/UnifiedLog.scala:
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@@ -1337,13 +1337,17 @@ class UnifiedLog(@volatile var logStartOffset: Long,
} else if (targetTimestamp == ListOffsetsRequest.MAX_TIMESTAMP) {
// Cache to avoid race conditions. `toBuffer` is faster than most
alternatives and provides
// constant time access while being safe to use with concurrent
collections unlike `toArray`.
- val segmentsCopy = logSegments.asScala.toBuffer
- val latestTimestampSegment = segmentsCopy.maxBy(_.maxTimestampSoFar)
- val latestTimestampAndOffset =
latestTimestampSegment.readMaxTimestampAndOffsetSoFar
-
- Some(new TimestampAndOffset(latestTimestampAndOffset.timestamp,
- latestTimestampAndOffset.offset,
- latestEpochAsOptional(leaderEpochCache)))
+ val latestTimestampSegment =
logSegments.asScala.toBuffer.maxBy[Long](_.maxTimestampSoFar)
+ // cache the timestamp and offset
+ val maxTimestampSoFar =
latestTimestampSegment.readMaxTimestampAndOffsetSoFar
+ // lookup the position of batch to avoid extra I/O
+ val position =
latestTimestampSegment.offsetIndex.lookup(maxTimestampSoFar.offset)
+ val lpc = latestEpochAsOptional(leaderEpochCache)
+ Some(latestTimestampSegment.log.batchesFrom(position.position).asScala
+ .find(_.maxTimestamp() == maxTimestampSoFar.timestamp)
+ .flatMap(batch => batch.offsetOfMaxTimestamp().asScala.map(new
TimestampAndOffset(batch.maxTimestamp(), _, lpc)))
+ // return the base offset for backward compatibility if there is no
batches
+ .getOrElse(new TimestampAndOffset(RecordBatch.NO_TIMESTAMP,
latestTimestampSegment.baseOffset(), lpc)))
Review Comment:
I am ok to return -1. However, it seems that we return base offset before
when we do not find the max timestamp (no batch exists). Hence, the main reason
of returning base offset is backward compatibility.
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