Package org.voltdb.stream.function

Class CancelingFunction<I,O extends Comparable<O>>

java.lang.Object

org.voltdb.stream.function.CancelingFunction<I,O>

Type Parameters:

I - the type of input elements to be processed

O - the type of the accumulator, which must be Comparable to allow threshold comparison

All Implemented Interfaces:

VoltFunction<I,I>, VoltLifecycle

public class CancelingFunction<I,O extends Comparable<O>>
extends Object
implements VoltFunction<I,I>

This identity function, but it accumulates value with given accumulatorFunction, and cancels the execution once the accumulated value exceeds given threshold.

Usage Example

 // Creating a function that will cancel the execution after processing 1024 bytes worth of strings.
 CancelingFunction<String, Integer> cancelingFunction = new CancelingFunction<>(0, 1024, (bytes, string) -> bytes + string.length());

 // Use it as a function in a pipeline.
 stream
   .withName("cancelable infinite stream stream")
   .consumeFromSource(...)
   .processWith(cancelingFunction)
   .terminateWithSink(Sinks.collection());
 

Constructor Summary

Constructors

Constructor	Description
CancelingFunction(O accumulator, O threshold, BiFunction<O,I,O> accumulatorFunction)	Constructs a CancelingFunction with the specified initial accumulator, threshold, and accumulator function.

Method Summary

Modifier and Type	Method	Description
void	process(I input, Consumer<I> consumer, ExecutionContext context)	processes input and emits output messages to a consumer

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.voltdb.stream.api.pipeline.VoltFunction

batchProcessed, initialize, nextBatchStarts

Methods inherited from interface org.voltdb.stream.api.pipeline.VoltLifecycle

configure, destroy

Constructor Details

CancelingFunction

public CancelingFunction(O accumulator,
 O threshold,
 BiFunction<O,I,O> accumulatorFunction)

Constructs a CancelingFunction with the specified initial accumulator, threshold, and accumulator function.

The accumulator function defines how each input item is combined with the current accumulator to produce a new accumulator value. If the updated accumulator meets or exceeds the threshold, the execution context is canceled.

Parameters:

accumulator - the initial value of the accumulator

threshold - the threshold value at which the execution context should be canceled

accumulatorFunction - a BiFunction that combines the current accumulator with an input item

Method Details

process

public void process(I input,
 Consumer<I> consumer,
 ExecutionContext context)

Description copied from interface: VoltFunction

processes input and emits output messages to a consumer

Specified by:

process in interface VoltFunction<I,O extends Comparable<O>>

Parameters:

input - message

consumer - binds this function with next step

context - of the execution