Package org.apache.flink.sql.tests

Class StreamSQLTestProgram.Generator

java.lang.Object

org.apache.flink.sql.tests.StreamSQLTestProgram.Generator

All Implemented Interfaces:

Serializable, Function, ResultTypeQueryable<Row>, CheckpointedFunction, SourceFunction<Row>

Enclosing class:

StreamSQLTestProgram

public static class StreamSQLTestProgram.Generator
extends Object
implements SourceFunction<Row>, ResultTypeQueryable<Row>, CheckpointedFunction

Data-generating source function.

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
Generator(int numKeys, float rowsPerKeyAndSecond, int durationSeconds, int offsetSeconds)

Method Summary

Modifier and Type	Method	Description
void	cancel()	Cancels the source.
TypeInformation<Row>	getProducedType()	Gets the data type (as a TypeInformation) produced by this function or input format.
void	initializeState(FunctionInitializationContext context)	This method is called when the parallel function instance is created during distributed execution.
void	run(SourceFunction.SourceContext<Row> ctx)	Starts the source.
void	snapshotState(FunctionSnapshotContext context)	This method is called when a snapshot for a checkpoint is requested.

Methods inherited from class java.lang.Object

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

Constructor Detail

Generator

public Generator(int numKeys,
                 float rowsPerKeyAndSecond,
                 int durationSeconds,
                 int offsetSeconds)

Method Detail

run

public void run(SourceFunction.SourceContext<Row> 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.

Specified by:

run in interface SourceFunction<Row>

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.

Specified by:

cancel in interface SourceFunction<Row>

getProducedType

public TypeInformation<Row> getProducedType()

Description copied from interface: ResultTypeQueryable

Gets the data type (as a TypeInformation) produced by this function or input format.

Specified by:

getProducedType in interface ResultTypeQueryable<Row>

Returns:

The data type produced by this function or input format.

initializeState

public void initializeState(FunctionInitializationContext context)
                     throws Exception

Description copied from interface: CheckpointedFunction

This method is called when the parallel function instance is created during distributed execution. Functions typically set up their state storing data structures in this method.

Specified by:

initializeState in interface CheckpointedFunction

Parameters:

context - the context for initializing the operator

Throws:

Exception - Thrown, if state could not be created ot restored.

snapshotState

public void snapshotState(FunctionSnapshotContext context)
                   throws Exception

Description copied from interface: CheckpointedFunction

This method is called when a snapshot for a checkpoint is requested. This acts as a hook to the function to ensure that all state is exposed by means previously offered through FunctionInitializationContext when the Function was initialized, or offered now by FunctionSnapshotContext itself.

Specified by:

snapshotState in interface CheckpointedFunction

Parameters:

context - the context for drawing a snapshot of the operator

Throws:

Exception - Thrown, if state could not be created ot restored.