Package org.apache.flink.runtime.checkpoint.channel

Interface ChannelStateWriter

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

ChannelStateWriter.NoOpChannelStateWriter, ChannelStateWriterImpl

@Internal
public interface ChannelStateWriter
extends Closeable

Writes channel state during checkpoint/savepoint.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	ChannelStateWriter.ChannelStateWriteResult	Channel state write result.
static class	ChannelStateWriter.NoOpChannelStateWriter	No-op implementation of ChannelStateWriter.

Field Summary

Fields

Modifier and Type	Field	Description
static final ChannelStateWriter	NO_OP
static final int	SEQUENCE_NUMBER_RESTORED	Sequence number for the buffers that were saved during the previous execution attempt; then restored; and now are to be saved again (as opposed to the buffers received from the upstream or from the operator).
static final int	SEQUENCE_NUMBER_UNKNOWN	Signifies that buffer sequence number is unknown (e.g. if passing sequence numbers is not implemented).

Method Summary

Modifier and Type	Method	Description
void	abort(long checkpointId, Throwable cause, boolean cleanup)	Aborts the checkpoint and fails pending result for this checkpoint.
void	addInputData(long checkpointId, InputChannelInfo info, int startSeqNum, org.apache.flink.util.CloseableIterator<Buffer> data)	Add in-flight buffers from the InputChannel.
void	addOutputData(long checkpointId, ResultSubpartitionInfo info, int startSeqNum, Buffer... data)	Add in-flight buffers from the ResultSubpartition.
void	addOutputDataFuture(long checkpointId, ResultSubpartitionInfo info, int startSeqNum, CompletableFuture<List<Buffer>> data)	Add in-flight bufferFuture from the ResultSubpartition.
void	finishInput(long checkpointId)	Finalize write of channel state data for the given checkpoint id.
void	finishOutput(long checkpointId)	Finalize write of channel state data for the given checkpoint id.
ChannelStateWriter.ChannelStateWriteResult	getAndRemoveWriteResult(long checkpointId)	Must be called after start(long, CheckpointOptions) once.
void	start(long checkpointId, CheckpointOptions checkpointOptions)	Initiate write of channel state for the given checkpoint id.

Methods inherited from interface java.io.Closeable

close

Field Details

SEQUENCE_NUMBER_RESTORED

static final int SEQUENCE_NUMBER_RESTORED

Sequence number for the buffers that were saved during the previous execution attempt; then restored; and now are to be saved again (as opposed to the buffers received from the upstream or from the operator).

See Also:

• Constant Field Values

SEQUENCE_NUMBER_UNKNOWN

static final int SEQUENCE_NUMBER_UNKNOWN

Signifies that buffer sequence number is unknown (e.g. if passing sequence numbers is not implemented).

See Also:

• Constant Field Values

NO_OP

static final ChannelStateWriter NO_OP

Method Details

start

void start(long checkpointId,
 CheckpointOptions checkpointOptions)

Initiate write of channel state for the given checkpoint id.

addInputData

void addInputData(long checkpointId,
 InputChannelInfo info,
 int startSeqNum,
 org.apache.flink.util.CloseableIterator<Buffer> data)

Add in-flight buffers from the InputChannel. Must be called after start(long,CheckpointOptions) and before finishInput(long). Buffers are recycled after they are written or exception occurs.

Parameters:

startSeqNum - sequence number of the 1st passed buffer. It is intended to use for incremental snapshots. If no data is passed it is ignored.

data - zero or more data buffers ordered by their sequence numbers

See Also:

• SEQUENCE_NUMBER_RESTORED
• SEQUENCE_NUMBER_UNKNOWN

addOutputData

void addOutputData(long checkpointId,
 ResultSubpartitionInfo info,
 int startSeqNum,
 Buffer... data)
            throws IllegalArgumentException

Add in-flight buffers from the ResultSubpartition. Must be called after start(long, org.apache.flink.runtime.checkpoint.CheckpointOptions) and before finishOutput(long). Buffers are recycled after they are written or exception occurs.

Parameters:

startSeqNum - sequence number of the 1st passed buffer. It is intended to use for incremental snapshots. If no data is passed it is ignored.

data - zero or more data buffers ordered by their sequence numbers

Throws:

IllegalArgumentException - if one or more passed buffers isn't a buffer

See Also:

• SEQUENCE_NUMBER_RESTORED
• SEQUENCE_NUMBER_UNKNOWN

addOutputDataFuture

void addOutputDataFuture(long checkpointId,
 ResultSubpartitionInfo info,
 int startSeqNum,
 CompletableFuture<List<Buffer>> data)
                  throws IllegalArgumentException

Add in-flight bufferFuture from the ResultSubpartition. Must be called after start(long, org.apache.flink.runtime.checkpoint.CheckpointOptions) and before finishOutput(long). Buffers are recycled after they are written or exception occurs.

The method will be called when the unaligned checkpoint is enabled and received an aligned barrier.

Throws:

IllegalArgumentException

finishInput

void finishInput(long checkpointId)

Finalize write of channel state data for the given checkpoint id. Must be called after start(long, CheckpointOptions) and all of the input data of the given checkpoint added. When both finishInput(long) and finishOutput(long) were called the results can be (eventually) obtained using getAndRemoveWriteResult(long)

finishOutput

void finishOutput(long checkpointId)

Finalize write of channel state data for the given checkpoint id. Must be called after start(long, CheckpointOptions) and all of the output data of the given checkpoint added. When both finishInput(long) and finishOutput(long) were called the results can be (eventually) obtained using getAndRemoveWriteResult(long)

abort

void abort(long checkpointId,
 Throwable cause,
 boolean cleanup)

Aborts the checkpoint and fails pending result for this checkpoint.

Parameters:

cleanup - true if getAndRemoveWriteResult(long) is not supposed to be called afterwards.

getAndRemoveWriteResult

ChannelStateWriter.ChannelStateWriteResult getAndRemoveWriteResult(long checkpointId)
                                                            throws IllegalArgumentException

Must be called after start(long, CheckpointOptions) once.

Throws:

IllegalArgumentException - if the passed checkpointId is not known.