org.apache.gobblin.stream

Class ControlMessageInjector<SI,DI>

java.lang.Object

org.apache.gobblin.stream.ControlMessageInjector<SI,DI>

Type Parameters:

SI -

DI -

All Implemented Interfaces:

Closeable, AutoCloseable, RecordStreamProcessor<SI,SI,DI,DI>

public abstract class ControlMessageInjector<SI,DI>
extends Object
implements Closeable, RecordStreamProcessor<SI,SI,DI,DI>

A RecordStreamProcessor that inspects an input record and outputs control messages before, after, or around the input record

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.gobblin.records.RecordStreamProcessor

RecordStreamProcessor.StreamProcessingException

Constructor Summary

Constructors

Constructor and Description
ControlMessageInjector()

Method Summary

Modifier and Type	Method and Description
void	close()
protected ControlMessageHandler	getMessageHandler()
protected ControlMessageInjector<SI,DI>	init(WorkUnitState workUnitState) Initialize this ControlMessageInjector.
protected abstract Iterable<ControlMessage<DI>>	injectControlMessagesAfter(RecordEnvelope<DI> inputRecordEnvelope, WorkUnitState workUnitState) Inject ControlMessages after the record
protected abstract Iterable<ControlMessage<DI>>	injectControlMessagesBefore(RecordEnvelope<DI> inputRecordEnvelope, WorkUnitState workUnitState) Inject ControlMessages before the record
RecordStreamWithMetadata<DI,SI>	processStream(RecordStreamWithMetadata<DI,SI> inputStream, WorkUnitState workUnitState) Apply injections to the input RecordStreamWithMetadata.
protected void	setInputGlobalMetadata(GlobalMetadata<SI> inputGlobalMetadata, WorkUnitState workUnitState) Set the global metadata of the input messages.

Methods inherited from class java.lang.Object

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

Constructor Detail

ControlMessageInjector

public ControlMessageInjector()

Method Detail

init

protected ControlMessageInjector<SI,DI> init(WorkUnitState workUnitState)

Initialize this ControlMessageInjector.

Parameters:

workUnitState - a WorkUnitState object carrying configuration properties

Returns:

an initialized ControlMessageInjector instance

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

setInputGlobalMetadata

protected void setInputGlobalMetadata(GlobalMetadata<SI> inputGlobalMetadata,
                                      WorkUnitState workUnitState)

Set the global metadata of the input messages. The base implementation is empty and should be overridden by the subclasses that need to store the input GlobalMetadata

Parameters:

inputGlobalMetadata - the global metadata for input messages

workUnitState -

injectControlMessagesBefore

protected abstract Iterable<ControlMessage<DI>> injectControlMessagesBefore(RecordEnvelope<DI> inputRecordEnvelope,
                                                                            WorkUnitState workUnitState)

Inject ControlMessages before the record

Parameters:

inputRecordEnvelope -

workUnitState -

Returns:

The ControlMessages to inject before the record

injectControlMessagesAfter

protected abstract Iterable<ControlMessage<DI>> injectControlMessagesAfter(RecordEnvelope<DI> inputRecordEnvelope,
                                                                           WorkUnitState workUnitState)

Inject ControlMessages after the record

Parameters:

inputRecordEnvelope -

workUnitState -

Returns:

The ControlMessages to inject after the record

processStream

public RecordStreamWithMetadata<DI,SI> processStream(RecordStreamWithMetadata<DI,SI> inputStream,
                                                     WorkUnitState workUnitState)
                                              throws RecordStreamProcessor.StreamProcessingException

Apply injections to the input RecordStreamWithMetadata. ControlMessages may be injected before, after, or around the input record. A MetadataUpdateControlMessage will update the current input GlobalMetadata and pass the updated input GlobalMetadata to the next processor to propagate the metadata update down the pipeline.

Specified by:

processStream in interface RecordStreamProcessor<SI,SI,DI,DI>

Throws:

RecordStreamProcessor.StreamProcessingException

getMessageHandler

protected ControlMessageHandler getMessageHandler()

Returns:

ControlMessageHandler to call for each ControlMessage received.