kafka-log-TransactionIndex.adoc

TransactionIndex

TransactionIndex is a transaction index of a LogSegment.

TransactionIndex is created when:

• LogSegment utility is used to open a log segment

• DumpLogSegments tool is used (to dump a transaction index (of a log segment))

Creating TransactionIndex Instance

TransactionIndex takes the following to be created:

• Start offset

• Underlying file (Java’s File)

TransactionIndex initializes the internal properties.

While being created, TransactionIndex opens a channel to the file if exists already.

append Method

append(
  abortedTxn: AbortedTxn): Unit

append…​FIXME

Note	append is used when: CleanedTransactionMetadata is requested to onControlBatchRead LogSegment is requested to updateTxnIndex

flush Method

flush(): Unit

flush…​FIXME

Note	flush is used when LogSegment is requested to flush.

truncateTo Method

truncateTo(
  offset: Long): Unit

truncateTo…​FIXME

Note	truncateTo is used when LogSegment is requested to truncate (to a given offset).

deleteIfExists Method

deleteIfExists(): Boolean

deleteIfExists…​FIXME

Note	deleteIfExists is used when LogSegment is requested to deleteIfExists.

collectAbortedTxns Method

collectAbortedTxns(
  fetchOffset: Long,
  upperBoundOffset: Long): TxnIndexSearchResult

collectAbortedTxns…​FIXME

Note	collectAbortedTxns is used when LogSegment is requested to collectAbortedTxns.

Opening FileChannel — openChannel Internal Method

openChannel(): FileChannel

openChannel uses Java’s FileChannel utility to open a file channel to the underlying file for read and write access (and creating a new file unless it exists already).

openChannel registers the FileChannel with the maybeChannel internal registry.

openChannel sets the file position of the FileChannel to be the very end of the file.

Note	openChannel is used when TransactionIndex is created (and the underlying file is available) and requested for the FileChannel.

channel Internal Method

channel(): FileChannel

channel takes the FileChannel out from the maybeChannel internal registry (if available) or opens a new FileChannel.

Note	channel is used when TransactionIndex is requested to append and truncateTo.

Internal Properties

Name	Description
lastOffset	lastOffset: Option[Long] = None Used when…​FIXME
maybeChannel	maybeChannel: Option[FileChannel] = None FileChannel Used when…​FIXME