mumrah commented on a change in pull request #10864:
URL: https://github.com/apache/kafka/pull/10864#discussion_r662505337
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File path: core/src/main/scala/kafka/raft/KafkaMetadataLog.scala
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@@ -312,26 +315,142 @@ final class KafkaMetadataLog private (
}
}
- override def deleteBeforeSnapshot(logStartSnapshotId: OffsetAndEpoch):
Boolean = {
- val (deleted, forgottenSnapshots) = snapshots synchronized {
- latestSnapshotId().asScala match {
- case Some(snapshotId) if (snapshots.contains(logStartSnapshotId) &&
- startOffset < logStartSnapshotId.offset &&
- logStartSnapshotId.offset <= snapshotId.offset &&
- log.maybeIncrementLogStartOffset(logStartSnapshotId.offset,
SnapshotGenerated)) =>
+ /**
+ * Delete a snapshot, advance the log start offset, and clean old log
segments. This will only happen if the
+ * following invariants all hold true:
+ *
+ * <li>This is not the latest snapshot (i.e., another snapshot proceeds this
one)</li>
+ * <li>The offset of the next snapshot is greater than the log start
offset</li>
+ * <li>The log can be advanced to the offset of the next snapshot</li>
+ *
+ * This method is not thread safe and assumes a lock on the snapshots
collection is held
+ */
+ private[raft] def deleteSnapshot(snapshotId: OffsetAndEpoch, nextSnapshotId:
OffsetAndEpoch): Boolean = {
+ if (snapshots.contains(snapshotId) &&
+ snapshots.contains(nextSnapshotId) &&
+ startOffset < nextSnapshotId.offset &&
+ snapshotId.offset < nextSnapshotId.offset &&
+ log.maybeIncrementLogStartOffset(nextSnapshotId.offset,
SnapshotGenerated)) {
+ log.deleteOldSegments()
+ val forgotten = mutable.TreeMap.empty[OffsetAndEpoch,
Option[FileRawSnapshotReader]]
+ snapshots.remove(snapshotId) match {
+ case Some(removedSnapshot) => forgotten.put(snapshotId,
removedSnapshot)
+ case None => throw new IllegalStateException(s"Could not remove
snapshot $snapshotId from our cache.")
+ }
+ removeSnapshots(forgotten)
+ true
+ } else {
+ false
+ }
+ }
- // Delete all segments that have a "last offset" less than the log
start offset
- log.deleteOldSegments()
+ /**
+ * Force all known snapshots to have an open reader so we can know their
sizes. This method is not thread-safe
+ */
+ private def loadSnapshotSizes(): Seq[(OffsetAndEpoch, Long)] = {
Review comment:
This is calling `FileRawSnapshotReader#sizeInBytes` which in turn calls
`FileRecords#sizeInBytes` which is just calling the `FileChannel` method you
mention. The readSnapshot method doesn't actually read the snapshot, it just
returns the reader object (maybe we should rename that for clarity)
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