SupportsWriterState (Flink : 2.0-SNAPSHOT API)

Type Parameters:

InputT - The type of the sink's input

WriterStateT - The type of the sink writer's state

All Known Implementing Classes:

AsyncSinkBase, FileSink
```
@Public
public interface SupportsWriterState<InputT,WriterStateT>
```
A mixin interface for a Sink which supports a stateful StatefulSinkWriter.
The Sink needs to be serializable. All configuration should be validated eagerly. The respective sink writers are transient and will only be created in the subtasks on the taskmanagers.

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static interface`	`SupportsWriterState.WithCompatibleState`	A mix-in for `SupportsWriterState` that allows users to migrate from a sink with a compatible state to this sink.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`SimpleVersionedSerializer<WriterStateT>`	`getWriterStateSerializer()`	Any stateful sink needs to provide this state serializer and implement `StatefulSinkWriter.snapshotState(long)` properly.
`StatefulSinkWriter<InputT,WriterStateT>`	`restoreWriter(WriterInitContext context, Collection<WriterStateT> recoveredState)`	Create a `StatefulSinkWriter` from a recovered state.

- Method Detail
  - restoreWriter
```
StatefulSinkWriter<InputT,WriterStateT> restoreWriter(WriterInitContext context,
                                                            Collection<WriterStateT> recoveredState)
                                                     throws IOException
```
    Create a StatefulSinkWriter from a recovered state.
    
    Parameters:
    
    context - the runtime context.
    
    recoveredState - the state to recover from.
    
    Returns:
    
    A sink writer.
    
    Throws:
    
    IOException - for any failure during creation.
  - getWriterStateSerializer
```
SimpleVersionedSerializer<WriterStateT> getWriterStateSerializer()
```
    Any stateful sink needs to provide this state serializer and implement StatefulSinkWriter.snapshotState(long) properly. The respective state is used in restoreWriter(WriterInitContext, Collection) on recovery.
    
    Returns:
    
    the serializer of the writer's state type.