org.apache.flink.streaming.runtime.tasks

Class SourceStreamTask<OUT,SRC extends SourceFunction<OUT>,OP extends StreamSource<OUT,SRC>>

java.lang.Object

org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable

org.apache.flink.streaming.runtime.tasks.StreamTask<OUT,OP>

org.apache.flink.streaming.runtime.tasks.SourceStreamTask<OUT,SRC,OP>

Type Parameters:

OUT - Type of the output elements of this source.

SRC - Type of the source function for the stream source operator

OP - Type of the stream source operator

All Implemented Interfaces:

AsyncExceptionHandler

Direct Known Subclasses:

StoppableSourceStreamTask

@Internal
public class SourceStreamTask<OUT,SRC extends SourceFunction<OUT>,OP extends StreamSource<OUT,SRC>>
extends StreamTask<OUT,OP>

StreamTask for executing a StreamSource.

One important aspect of this is that the checkpointing and the emission of elements must never occur at the same time. The execution must be serial. This is achieved by having the contract with the StreamFunction that it must only modify its state or emit elements in a synchronized block that locks on the lock Object. Also, the modification of the state and the emission of elements must happen in the same block of code that is protected by the synchronized block.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.streaming.runtime.tasks.StreamTask

StreamTask.AsyncCheckpointRunnable

Field Summary

Fields inherited from class org.apache.flink.streaming.runtime.tasks.StreamTask

configuration, headOperator, operatorChain, stateBackend, timerService, TRIGGER_THREAD_GROUP

Constructor Summary

Constructors

Constructor and Description
SourceStreamTask(Environment env)

Method Summary

Modifier and Type	Method and Description
protected void	cancelTask()
protected void	cleanup()
protected void	init()
protected void	run()
boolean	triggerCheckpoint(CheckpointMetaData checkpointMetaData, CheckpointOptions checkpointOptions) This method is called to trigger a checkpoint, asynchronously by the checkpoint coordinator.

Methods inherited from class org.apache.flink.streaming.runtime.tasks.StreamTask

abortCheckpointOnBarrier, cancel, createCheckpointExceptionHandlerFactory, createStreamRecordWriters, createStreamTaskStateInitializer, finalize, getAccumulatorMap, getAsyncOperationsThreadPool, getCancelables, getCheckpointLock, getCheckpointStorage, getConfiguration, getName, getProcessingTimeService, getStreamStatusMaintainer, handleAsyncException, invoke, isCanceled, isRunning, notifyCheckpointComplete, toString, triggerCheckpointOnBarrier

Methods inherited from class org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable

getCurrentNumberOfSubtasks, getEnvironment, getExecutionConfig, getIndexInSubtaskGroup, getJobConfiguration, getTaskConfiguration, getUserCodeClassLoader

Methods inherited from class java.lang.Object

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

Constructor Detail

SourceStreamTask

public SourceStreamTask(Environment env)

Method Detail

init

protected void init()

Specified by:

init in class StreamTask<OUT,OP extends StreamSource<OUT,SRC>>

cleanup

protected void cleanup()

Specified by:

cleanup in class StreamTask<OUT,OP extends StreamSource<OUT,SRC>>

run

protected void run()
            throws Exception

Specified by:

run in class StreamTask<OUT,OP extends StreamSource<OUT,SRC>>

Throws:

Exception

cancelTask

protected void cancelTask()
                   throws Exception

Specified by:

cancelTask in class StreamTask<OUT,OP extends StreamSource<OUT,SRC>>

Throws:

Exception

triggerCheckpoint

public boolean triggerCheckpoint(CheckpointMetaData checkpointMetaData,
                                 CheckpointOptions checkpointOptions)
                          throws Exception

Description copied from class: AbstractInvokable

This method is called to trigger a checkpoint, asynchronously by the checkpoint coordinator.

This method is called for tasks that start the checkpoints by injecting the initial barriers, i.e., the source tasks. In contrast, checkpoints on downstream operators, which are the result of receiving checkpoint barriers, invoke the AbstractInvokable.triggerCheckpointOnBarrier(CheckpointMetaData, CheckpointOptions, CheckpointMetrics) method.

Overrides:

triggerCheckpoint in class StreamTask<OUT,OP extends StreamSource<OUT,SRC>>

Parameters:

checkpointMetaData - Meta data for about this checkpoint

checkpointOptions - Options for performing this checkpoint

Returns:

false if the checkpoint can not be carried out, true otherwise

Throws:

Exception