Package org.apache.flink.connector.file.src.impl

Class ContinuousFileSplitEnumerator

java.lang.Object

org.apache.flink.connector.file.src.impl.ContinuousFileSplitEnumerator

All Implemented Interfaces:

AutoCloseable, CheckpointListener, SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>, SupportsBatchSnapshot

@Internal
public class ContinuousFileSplitEnumerator
extends Object
implements SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>, SupportsBatchSnapshot

A continuously monitoring enumerator.

Constructor Summary

Constructors

Constructor	Description
ContinuousFileSplitEnumerator(SplitEnumeratorContext<FileSourceSplit> context, FileEnumerator enumerator, FileSplitAssigner splitAssigner, Path[] paths, Collection<Path> alreadyDiscoveredPaths, long discoveryInterval)

Method Summary

Modifier and Type	Method	Description
void	addReader(int subtaskId)	Add a new source reader with the given subtask ID.
void	addSplitsBack(List<FileSourceSplit> splits, int subtaskId)	Add splits back to the split enumerator.
void	close()	Called to close the enumerator, in case it holds on to any resources, like threads or network connections.
void	handleSourceEvent(int subtaskId, SourceEvent sourceEvent)	Handles a custom source event from the source reader.
void	handleSplitRequest(int subtaskId, String requesterHostname)	Handles the request for a split.
PendingSplitsCheckpoint<FileSourceSplit>	snapshotState(long checkpointId)	Creates a snapshot of the state of this split enumerator, to be stored in a checkpoint.
void	start()	Start the split enumerator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.flink.api.common.state.CheckpointListener

notifyCheckpointAborted

Methods inherited from interface org.apache.flink.api.connector.source.SplitEnumerator

notifyCheckpointComplete

Constructor Detail

ContinuousFileSplitEnumerator

public ContinuousFileSplitEnumerator(SplitEnumeratorContext<FileSourceSplit> context,
                                     FileEnumerator enumerator,
                                     FileSplitAssigner splitAssigner,
                                     Path[] paths,
                                     Collection<Path> alreadyDiscoveredPaths,
                                     long discoveryInterval)

Method Detail

start

public void start()

Description copied from interface: SplitEnumerator

Start the split enumerator.

The default behavior does nothing.

Specified by:

start in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

close

public void close()
           throws IOException

Description copied from interface: SplitEnumerator

Called to close the enumerator, in case it holds on to any resources, like threads or network connections.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

Throws:

IOException

addReader

public void addReader(int subtaskId)

Description copied from interface: SplitEnumerator

Add a new source reader with the given subtask ID.

Specified by:

addReader in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

Parameters:

subtaskId - the subtask ID of the new source reader.

handleSplitRequest

public void handleSplitRequest(int subtaskId,
                               @Nullable
                               String requesterHostname)

Description copied from interface: SplitEnumerator

Handles the request for a split. This method is called when the reader with the given subtask id calls the SourceReaderContext.sendSplitRequest() method.

Specified by:

handleSplitRequest in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

Parameters:

subtaskId - the subtask id of the source reader who sent the source event.

requesterHostname - Optional, the hostname where the requesting task is running. This can be used to make split assignments locality-aware.

handleSourceEvent

public void handleSourceEvent(int subtaskId,
                              SourceEvent sourceEvent)

Description copied from interface: SplitEnumerator

Handles a custom source event from the source reader.

This method has a default implementation that does nothing, because it is only required to be implemented by some sources, which have a custom event protocol between reader and enumerator. The common events for reader registration and split requests are not dispatched to this method, but rather invoke the SplitEnumerator.addReader(int) and SplitEnumerator.handleSplitRequest(int, String) methods.

Specified by:

handleSourceEvent in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

Parameters:

subtaskId - the subtask id of the source reader who sent the source event.

sourceEvent - the source event from the source reader.

addSplitsBack

public void addSplitsBack(List<FileSourceSplit> splits,
                          int subtaskId)

Description copied from interface: SplitEnumerator

Add splits back to the split enumerator. This will only happen when a SourceReader fails and there are splits assigned to it after the last successful checkpoint.

Specified by:

addSplitsBack in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

Parameters:

splits - The splits to add back to the enumerator for reassignment.

subtaskId - The id of the subtask to which the returned splits belong.

snapshotState

public PendingSplitsCheckpoint<FileSourceSplit> snapshotState(long checkpointId)
                                                       throws Exception

Description copied from interface: SplitEnumerator

Creates a snapshot of the state of this split enumerator, to be stored in a checkpoint.

The snapshot should contain the latest state of the enumerator: It should assume that all operations that happened before the snapshot have successfully completed. For example all splits assigned to readers via SplitEnumeratorContext.assignSplit(SourceSplit, int) and SplitEnumeratorContext.assignSplits(SplitsAssignment)) don't need to be included in the snapshot anymore.

This method takes the ID of the checkpoint for which the state is snapshotted. Most implementations should be able to ignore this parameter, because for the contents of the snapshot, it doesn't matter for which checkpoint it gets created. This parameter can be interesting for source connectors with external systems where those systems are themselves aware of checkpoints; for example in cases where the enumerator notifies that system about a specific checkpoint being triggered.

Specified by:

snapshotState in interface SplitEnumerator<FileSourceSplit,PendingSplitsCheckpoint<FileSourceSplit>>

Parameters:

checkpointId - The ID of the checkpoint for which the snapshot is created.

Returns:

an object containing the state of the split enumerator.

Throws:

Exception - when the snapshot cannot be taken.