Package org.apache.flink.test

Class StatefulStreamingJob.MySource

java.lang.Object

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

org.apache.flink.streaming.api.functions.source.legacy.RichParallelSourceFunction<Integer>

org.apache.flink.test.StatefulStreamingJob.MySource

All Implemented Interfaces:

Serializable, Function, RichFunction, ParallelSourceFunction<Integer>, SourceFunction<Integer>

Enclosing class:

StatefulStreamingJob

public static class StatefulStreamingJob.MySource
extends RichParallelSourceFunction<Integer>

Stub source that emits one record per second.

See Also:

Serialized Form

Nested Class Summary

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

SourceFunction.SourceContext<T>

Constructor Summary

Constructors

Constructor	Description
MySource()

Method Summary

Modifier and Type	Method	Description
void	cancel()	Cancels the source.
void	run(SourceFunction.SourceContext<Integer> ctx)	Starts the source.

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

MySource

public MySource()

Method Detail

run

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

Description copied from interface: SourceFunction

Starts the source. Implementations use the SourceFunction.SourceContext to emit elements. Sources that checkpoint their state for fault tolerance should use the checkpoint lock to ensure consistency between the bookkeeping and emitting the elements.

Sources that implement CheckpointedFunction must lock on the checkpoint lock checkpoint lock (using a synchronized block) before updating internal state and emitting elements, to make both an atomic operation.

Refer to the top-level class docs for an example.

Parameters:

ctx - The context to emit elements to and for accessing locks.

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(SourceContext) method. The implementation needs to ensure that the source will break out of that loop after this method is called.

A typical pattern is to have an "volatile boolean isRunning" flag that is set to false in this method. That flag is checked in the loop condition.

In case of an ungraceful shutdown (cancellation of the source operator, possibly for failover), the thread that calls SourceFunction.run(SourceContext) will also be interrupted) by the Flink runtime, in order to speed up the cancellation (to ensure threads exit blocking methods fast, like I/O, blocking queues, etc.). The interruption happens strictly after this method has been called, so any interruption handler can rely on the fact that this method has completed (for example to ignore exceptions that happen after cancellation).

During graceful shutdown (for example stopping a job with a savepoint), the program must cleanly exit the SourceFunction.run(SourceContext) method soon after this method was called. The Flink runtime will NOT interrupt the source thread during graceful shutdown. Source implementors must ensure that no thread interruption happens on any thread that emits records through the SourceContext from the SourceFunction.run(SourceContext) method; otherwise the clean shutdown may fail when threads are interrupted while processing the final records.

Because the SourceFunction cannot easily differentiate whether the shutdown should be graceful or ungraceful, we recommend that implementors refrain from interrupting any threads that interact with the SourceContext at all. You can rely on the Flink runtime to interrupt the source thread in case of ungraceful cancellation. Any additionally spawned threads that directly emit records through the SourceContext should use a shutdown method that does not rely on thread interruption.