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

Class StatefulSequenceSource

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction<Long>

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

All Implemented Interfaces:

Serializable, Function, RichFunction, Checkpointed<Long>, ParallelSourceFunction<Long>, SourceFunction<Long>

public class StatefulSequenceSource
extends RichParallelSourceFunction<Long>
implements Checkpointed<Long>

A stateful streaming source that emits each number from a given interval exactly once, possibly in parallel.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.streaming.api.functions.source.SourceFunction

SourceFunction.SourceContext<T>

Constructor Summary

Constructors

Constructor and Description
StatefulSequenceSource(long start, long end) Creates a source that emits all numbers from the given interval exactly once.

Method Summary

Methods

Modifier and Type	Method and Description
void	cancel() Cancels the source.
void	restoreState(Long state) Restores the state of the function or operator to that of a previous checkpoint.
void	run(SourceFunction.SourceContext<Long> ctx) Starts the source.
Long	snapshotState(long checkpointId, long checkpointTimestamp) Gets the current state of the function of operator.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContext

Methods inherited from class java.lang.Object

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

Constructor Detail

StatefulSequenceSource

public StatefulSequenceSource(long start,
                      long end)

Creates a source that emits all numbers from the given interval exactly once.

Parameters:

start - Start of the range of numbers to emit.

end - End of the range of numbers to emit.

Method Detail

run

public void run(SourceFunction.SourceContext<Long> ctx)
         throws Exception

Description copied from interface: SourceFunction

Starts the source. You can use the Collector parameter to emit elements. Sources that implement Checkpointed must lock on the checkpoint lock (using a synchronized block) before updating internal state and/or emitting elements. Also, the update of state and emission of elements must happen in the same synchronized block.

Specified by:

run in interface SourceFunction<Long>

Parameters:

ctx - The context for interaction with the outside world.

Throws:

Exception

cancel

public void cancel()

Description copied from interface: SourceFunction

Cancels the source. Most sources will have a while loop inside the SourceFunction.run(org.apache.flink.streaming.api.functions.source.SourceFunction.SourceContext<T>) method. You need to ensure that the source will break out of this loop. This can be achieved by having a volatile field "isRunning" that is checked in the loop and that is set to false in this method.

Specified by:

cancel in interface SourceFunction<Long>

snapshotState

public Long snapshotState(long checkpointId,
                 long checkpointTimestamp)

Description copied from interface: Checkpointed

Gets the current state of the function of operator. The state must reflect the result of all prior invocations to this function.

Specified by:

snapshotState in interface Checkpointed<Long>

Parameters:

checkpointId - The ID of the checkpoint.

checkpointTimestamp - The timestamp of the checkpoint, as derived by System.currentTimeMillis() on the JobManager.

Returns:

A snapshot of the operator state.

restoreState

public void restoreState(Long state)

Description copied from interface: Checkpointed

Restores the state of the function or operator to that of a previous checkpoint. This method is invoked when a function is executed as part of a recovery run. Note that restoreState() is called before open().

Specified by:

restoreState in interface Checkpointed<Long>

Parameters:

state - The state to be restored.