Package org.apache.flink.streaming.api.functions.source

Class ContinuousFileReaderOperator<OUT,T extends TimestampedInputSplit>

java.lang.Object

org.apache.flink.streaming.api.operators.AbstractStreamOperator<OUT>

org.apache.flink.streaming.api.functions.source.ContinuousFileReaderOperator<OUT,T>

All Implemented Interfaces:

Serializable, CheckpointListener, Input<T>, KeyContext, KeyContextHandler, OneInputStreamOperator<T,OUT>, OutputTypeConfigurable<OUT>, StreamOperator<OUT>, StreamOperatorStateHandler.CheckpointedStreamOperator, YieldingOperator<OUT>

@Internal
public class ContinuousFileReaderOperator<OUT,T extends TimestampedInputSplit>
extends AbstractStreamOperator<OUT>
implements OneInputStreamOperator<T,OUT>, OutputTypeConfigurable<OUT>

The operator that reads the splits received from the preceding ContinuousFileMonitoringFunction. Contrary to the ContinuousFileMonitoringFunction which has a parallelism of 1, this operator can have DOP > 1.

This implementation uses MailboxExecutor to execute each action and state machine approach. The workflow is the following:

1. start in IDLE
2. upon receiving a split add it to the queue, switch to OPENING and enqueue a mail to process it
3. open file, switch to READING, read one record, re-enqueue self
4. if no more records or splits available, switch back to IDLE

On close:

1. if IDLE then close immediately
2. otherwise switch to CLOSING, call yield in a loop until state is CLOSED
3. yield() causes remaining records (and splits) to be processed in the same way as above

Using MailboxExecutor allows to avoid explicit synchronization. At most one mail should be enqueued at any given time.

Using FSM approach allows to explicitly define states and enforce transitions between them.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.flink.streaming.api.operators.AbstractStreamOperator

config, lastRecordAttributes1, lastRecordAttributes2, latencyStats, metrics, output, processingTimeService, stateHandler, stateKeySelector1, stateKeySelector2, timeServiceManager

Method Summary

Modifier and Type	Method	Description
void	close()	This method is called at the very end of the operator's life, both in the case of a successful completion of the operation, and in the case of a failure and canceling.
void	finish()	This method is called at the end of data processing.
void	initializeState(StateInitializationContext context)	Stream operators with state which can be restored need to override this hook method.
void	open()	This method is called immediately before any elements are processed, it should contain the operator's initialization logic, e.g. state initialization.
void	processElement(StreamRecord<T> element)	Processes one element that arrived on this input of the MultipleInputStreamOperator.
void	processWatermark(Watermark mark)	Processes a Watermark that arrived on the first input of this two-input operator.
void	setOutputType(TypeInformation<OUT> outTypeInfo, ExecutionConfig executionConfig)	Is called by the org.apache.flink.streaming.api.graph.StreamGraph#addOperator(Integer, String, StreamOperator, TypeInformation, TypeInformation, String) method when the org.apache.flink.streaming.api.graph.StreamGraph is generated.
void	snapshotState(StateSnapshotContext context)	Stream operators with state, which want to participate in a snapshot need to override this hook method.

Methods inherited from class org.apache.flink.streaming.api.operators.AbstractStreamOperator

getContainingTask, getCurrentKey, getExecutionConfig, getInternalTimerService, getKeyedStateBackend, getKeyedStateStore, getMetricGroup, getOperatorConfig, getOperatorID, getOperatorName, getOperatorStateBackend, getOrCreateKeyedState, getPartitionedState, getPartitionedState, getProcessingTimeService, getRuntimeContext, getStateKeySelector1, getStateKeySelector2, getTimeServiceManager, getUserCodeClassloader, hasKeyContext1, hasKeyContext2, initializeState, isUsingCustomRawKeyedState, notifyCheckpointAborted, notifyCheckpointComplete, prepareSnapshotPreBarrier, processLatencyMarker, processLatencyMarker1, processLatencyMarker2, processRecordAttributes, processRecordAttributes1, processRecordAttributes2, processWatermark1, processWatermark2, processWatermarkStatus, processWatermarkStatus1, processWatermarkStatus2, reportOrForwardLatencyMarker, setCurrentKey, setKeyContextElement1, setKeyContextElement2, setMailboxExecutor, setProcessingTimeService, setup, snapshotState, useSplittableTimers

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, notifyCheckpointComplete

Methods inherited from interface org.apache.flink.streaming.api.operators.Input

processLatencyMarker, processRecordAttributes, processWatermarkStatus

Methods inherited from interface org.apache.flink.streaming.api.operators.KeyContext

getCurrentKey, setCurrentKey

Methods inherited from interface org.apache.flink.streaming.api.operators.KeyContextHandler

hasKeyContext

Methods inherited from interface org.apache.flink.streaming.api.operators.OneInputStreamOperator

setKeyContextElement

Methods inherited from interface org.apache.flink.streaming.api.operators.StreamOperator

getMetricGroup, getOperatorAttributes, getOperatorID, initializeState, prepareSnapshotPreBarrier, setKeyContextElement1, setKeyContextElement2, snapshotState

Method Detail

initializeState

public void initializeState(StateInitializationContext context)
                     throws Exception

Description copied from class: AbstractStreamOperator

Stream operators with state which can be restored need to override this hook method.

Specified by:

initializeState in interface StreamOperatorStateHandler.CheckpointedStreamOperator

Overrides:

initializeState in class AbstractStreamOperator<OUT>

Parameters:

context - context that allows to register different states.

Throws:

Exception

open

public void open()
          throws Exception

Description copied from class: AbstractStreamOperator

This method is called immediately before any elements are processed, it should contain the operator's initialization logic, e.g. state initialization.

The default implementation does nothing.

Specified by:

open in interface StreamOperator<OUT>

Overrides:

open in class AbstractStreamOperator<OUT>

Throws:

Exception - An exception in this method causes the operator to fail.

processElement

public void processElement(StreamRecord<T> element)
                    throws Exception

Description copied from interface: Input

Processes one element that arrived on this input of the MultipleInputStreamOperator. This method is guaranteed to not be called concurrently with other methods of the operator.

Specified by:

processElement in interface Input<OUT>

Throws:

Exception

processWatermark

public void processWatermark(Watermark mark)
                      throws Exception

Description copied from interface: Input

Processes a Watermark that arrived on the first input of this two-input operator. This method is guaranteed to not be called concurrently with other methods of the operator.

Specified by:

processWatermark in interface Input<OUT>

Overrides:

processWatermark in class AbstractStreamOperator<OUT>

Throws:

Exception

See Also:

Watermark

finish

public void finish()
            throws Exception

Description copied from interface: StreamOperator

This method is called at the end of data processing.

The method is expected to flush all remaining buffered data. Exceptions during this flushing of buffered data should be propagated, in order to cause the operation to be recognized as failed, because the last data items are not processed properly.

After this method is called, no more records can be produced for the downstream operators.

WARNING: It is not safe to use this method to commit any transactions or other side effects! You can use this method to flush any buffered data that can later on be committed e.g. in a CheckpointListener.notifyCheckpointComplete(long).

NOTE:This method does not need to close any resources. You should release external resources in the StreamOperator.close() method.

Specified by:

finish in interface StreamOperator<OUT>

Overrides:

finish in class AbstractStreamOperator<OUT>

Throws:

Exception - An exception in this method causes the operator to fail.

close

public void close()
           throws Exception

Description copied from interface: StreamOperator

This method is called at the very end of the operator's life, both in the case of a successful completion of the operation, and in the case of a failure and canceling.

This method is expected to make a thorough effort to release all resources that the operator has acquired.

NOTE:It can not emit any records! If you need to emit records at the end of processing, do so in the StreamOperator.finish() method.

Specified by:

close in interface StreamOperator<OUT>

Overrides:

close in class AbstractStreamOperator<OUT>

Throws:

Exception

snapshotState

public void snapshotState(StateSnapshotContext context)
                   throws Exception

Description copied from class: AbstractStreamOperator

Stream operators with state, which want to participate in a snapshot need to override this hook method.

Specified by:

snapshotState in interface StreamOperatorStateHandler.CheckpointedStreamOperator

Overrides:

snapshotState in class AbstractStreamOperator<OUT>

Parameters:

context - context that provides information and means required for taking a snapshot

Throws:

Exception

setOutputType

public void setOutputType(TypeInformation<OUT> outTypeInfo,
                          ExecutionConfig executionConfig)

Description copied from interface: OutputTypeConfigurable

Is called by the org.apache.flink.streaming.api.graph.StreamGraph#addOperator(Integer, String, StreamOperator, TypeInformation, TypeInformation, String) method when the org.apache.flink.streaming.api.graph.StreamGraph is generated. The method is called with the output TypeInformation which is also used for the org.apache.flink.streaming.runtime.tasks.StreamTask output serializer.

Specified by:

setOutputType in interface OutputTypeConfigurable<OUT>

Parameters:

outTypeInfo - Output type information of the org.apache.flink.streaming.runtime.tasks.StreamTask

executionConfig - Execution configuration