org.ballerina.gateway.siddhi.extension

Class EmitOnStateChange

java.lang.Object

org.ballerinalang.siddhi.core.query.processor.stream.AbstractStreamProcessor

org.ballerinalang.siddhi.core.query.processor.stream.StreamProcessor

org.ballerina.gateway.siddhi.extension.EmitOnStateChange

All Implemented Interfaces:

org.ballerinalang.siddhi.core.query.processor.Processor, org.ballerinalang.siddhi.core.util.extension.holder.EternalReferencedHolder, org.ballerinalang.siddhi.core.util.snapshot.Snapshotable

public class EmitOnStateChange
extends org.ballerinalang.siddhi.core.query.processor.stream.StreamProcessor

This is a custom extension, written for a certain throttler. Upon arrival of a request, looking at the key in the request, this throttler first decides whether to throttle the request or not. If that decision is different to what it was for the previous request (with the same key), then this processor emits this request as an event; hence the name emitOnStateChange.

If this request is the first request from a certain key, then that requested will be emitted out.

This is useful when the throttler needs to alert only when the throttling decision is changed, in contrast to alerting about every decision taken.

Usage: throttler:emitOnStateChange(key, isThrottled)

Parameters: key: The key coming in the request, based on which throttling decision was made. isThrottled: The throttling decision made.

Example on usage: from DecisionStream#throttler:emitOnStateChange(key, isThrottled) select * insert into AlertStream;

Field Summary

Fields inherited from class org.ballerinalang.siddhi.core.query.processor.stream.StreamProcessor

outputExpectsExpiredEvents

Fields inherited from class org.ballerinalang.siddhi.core.query.processor.stream.AbstractStreamProcessor

additionalAttributes, attributeExpressionExecutors, attributeExpressionLength, complexEventPopulater, elementId, inputDefinition, nextProcessor, queryName, siddhiAppContext, streamEventCloner

Constructor Summary

Constructors

Constructor and Description
EmitOnStateChange()

Method Summary

Modifier and Type	Method and Description
Map<String,Object>	currentState()
protected List<org.ballerinalang.siddhi.query.api.definition.Attribute>	init(org.ballerinalang.siddhi.query.api.definition.AbstractDefinition abstractDefinition, org.ballerinalang.siddhi.core.executor.ExpressionExecutor[] expressionExecutors, org.ballerinalang.siddhi.core.util.config.ConfigReader configReader, org.ballerinalang.siddhi.core.config.SiddhiAppContext siddhiAppContext)
protected void	process(org.ballerinalang.siddhi.core.event.ComplexEventChunk<org.ballerinalang.siddhi.core.event.stream.StreamEvent> streamEventChunk, org.ballerinalang.siddhi.core.query.processor.Processor processor, org.ballerinalang.siddhi.core.event.stream.StreamEventCloner streamEventCloner, org.ballerinalang.siddhi.core.event.stream.populater.ComplexEventPopulater complexEventPopulater)
void	restoreState(Map<String,Object> map)
void	start()
void	stop()

Methods inherited from class org.ballerinalang.siddhi.core.query.processor.stream.StreamProcessor

init, processEventChunk

Methods inherited from class org.ballerinalang.siddhi.core.query.processor.stream.AbstractStreamProcessor

cloneProcessor, constructStreamEventPopulater, getElementId, getNextProcessor, initProcessor, process, setNextProcessor, setStreamEventCloner, setToLast

Methods inherited from class java.lang.Object

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

Constructor Detail

EmitOnStateChange

public EmitOnStateChange()

Method Detail

start

public void start()

stop

public void stop()

currentState

public Map<String,Object> currentState()

restoreState

public void restoreState(Map<String,Object> map)

process

protected void process(org.ballerinalang.siddhi.core.event.ComplexEventChunk<org.ballerinalang.siddhi.core.event.stream.StreamEvent> streamEventChunk,
                       org.ballerinalang.siddhi.core.query.processor.Processor processor,
                       org.ballerinalang.siddhi.core.event.stream.StreamEventCloner streamEventCloner,
                       org.ballerinalang.siddhi.core.event.stream.populater.ComplexEventPopulater complexEventPopulater)

Specified by:

process in class org.ballerinalang.siddhi.core.query.processor.stream.StreamProcessor

init

protected List<org.ballerinalang.siddhi.query.api.definition.Attribute> init(org.ballerinalang.siddhi.query.api.definition.AbstractDefinition abstractDefinition,
                                                                             org.ballerinalang.siddhi.core.executor.ExpressionExecutor[] expressionExecutors,
                                                                             org.ballerinalang.siddhi.core.util.config.ConfigReader configReader,
                                                                             org.ballerinalang.siddhi.core.config.SiddhiAppContext siddhiAppContext)

Specified by:

init in class org.ballerinalang.siddhi.core.query.processor.stream.StreamProcessor