org.apache.flink.runtime.state.changelog

Interface StateChangelogWriter<Handle extends ChangelogStateHandle>

All Superinterfaces:

AutoCloseable

@Internal
public interface StateChangelogWriter<Handle extends ChangelogStateHandle>
extends AutoCloseable

Allows to write data to the log. Scoped to a single writer (e.g. state backend).

Method Summary

Modifier and Type	Method and Description
void	append(int keyGroup, byte[] value) Appends the provided data to this log.
void	appendMeta(byte[] value) Appends the provided **metadata** to this log.
void	close() Close this log.
void	confirm(SequenceNumber from, SequenceNumber to, long checkpointId) Mark the given state changes as confirmed by the JM.
SequenceNumber	initialSequenceNumber() Get the initial SequenceNumber that is used for the first element.
SequenceNumber	nextSequenceNumber() Get SequenceNumber to be used for the next element added by append.
CompletableFuture<SnapshotResult<Handle>>	persist(SequenceNumber from, long checkpointId) Durably persist previously appended data starting from the provided SequenceNumber and up to the latest change added.
void	reset(SequenceNumber from, SequenceNumber to, long checkpointId) Reset the state the given state changes.
void	truncate(SequenceNumber to) Truncate this state changelog to free up the resources and collect any garbage.
void	truncateAndClose(SequenceNumber from) Truncate the tail of log and close it.

Method Detail

initialSequenceNumber

SequenceNumber initialSequenceNumber()

Get the initial SequenceNumber that is used for the first element.

nextSequenceNumber

SequenceNumber nextSequenceNumber()

Get SequenceNumber to be used for the next element added by append.

appendMeta

void appendMeta(byte[] value)
         throws IOException

Appends the provided **metadata** to this log. No persistency guarantees.

Throws:

IOException

append

void append(int keyGroup,
            byte[] value)
     throws IOException

Appends the provided data to this log. No persistency guarantees.

Throws:

IOException

persist

CompletableFuture<SnapshotResult<Handle>> persist(SequenceNumber from,
                                                  long checkpointId)
                                           throws IOException

Durably persist previously appended data starting from the provided SequenceNumber and up to the latest change added. After this call, one of confirm, reset, or truncate eventually must be called for the corresponding change set. with reset/truncate/confirm methods?

Parameters:

from - inclusive

checkpointId - to persist

Throws:

IOException

truncate

void truncate(SequenceNumber to)

Truncate this state changelog to free up the resources and collect any garbage. That means:

• Discard the written state changes - in the provided range [from; to)
• Truncate the in-memory view of this changelog - in the range [0; to)

Called upon state materialization. Any ongoing persist calls will not be affected.

WARNING: the range [from; to) must not include any range that is included into any checkpoint that is not subsumed or aborted.

Parameters:

to - exclusive

confirm

void confirm(SequenceNumber from,
             SequenceNumber to,
             long checkpointId)

Mark the given state changes as confirmed by the JM.

Parameters:

from - inclusive

to - exclusive

checkpointId - to confirm

reset

void reset(SequenceNumber from,
           SequenceNumber to,
           long checkpointId)

Reset the state the given state changes. Called upon abortion so that if requested later then these changes will be re-uploaded.

truncateAndClose

void truncateAndClose(SequenceNumber from)

Truncate the tail of log and close it. No new appends will be possible. Any appended but not persisted records will be lost.

Parameters:

from - SequenceNumber from which to truncate the changelog, inclusive

close

void close()

Close this log. No new appends will be possible. Any appended but not persisted records will be lost.

Specified by:

close in interface AutoCloseable