Package com.elastisys.autoscaler.metricstreamers.streamjoiner

Class MetricStreamJoiner

java.lang.Object

com.elastisys.autoscaler.metricstreamers.streamjoiner.MetricStreamJoiner

All Implemented Interfaces:

com.elastisys.autoscaler.core.api.Configurable<MetricStreamJoinerConfig>, com.elastisys.autoscaler.core.api.Service<MetricStreamJoinerConfig>, com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<MetricStreamJoinerConfig>

public class MetricStreamJoiner
extends java.lang.Object
implements com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<MetricStreamJoinerConfig>

A MetricStreamJoiner is a "meta metric streamer", which consumes one or more metric streams and produces a single new metric stream by applying a join script to the consumed stream values. The `MetricStreamJoiner`'s operation can be illustrated by the following schematical image:

 
 MetricStream a -> |
                   |
 MetricStream b -> | MetricStreamJoiner d: joinScript(${a}, ${b}, ${c})
                   |
 MetricStream c -> |
 
 

MetricStreamJoiner listens for values from existing MetricStreams `a`, `b`, `c` and whenever a new value is received from either stream (and at least one value has been observed on every stream and their timestamps are within `maxTimeDifference` distance of each other) the joiner stream `d` produces a new metric value being its "join function" applied to the most recently observed value from every stream.

The `joinScript` can be an arbitrary JavaScript expression like

 
   a + b + c
 
 

or

 
   if (a + b > c) {
     a + b;
   } else {
     c;
   }
 
 

The only requirement that the `joinScript` must satisfy is that the end result of executing the last script statement/expression must be a single numerical value.

Constructor Summary

Constructors

Constructor	Description
MetricStreamJoiner(org.slf4j.Logger logger, com.elastisys.scale.commons.eventbus.EventBus eventBus, java.util.List<com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<?>> priorDeclaredMetricStreamers)	Creates a MetricStreamJoiner.

Method Summary

Modifier and Type	Method	Description
void	configure(MetricStreamJoinerConfig newConfig)
void	fetch()
MetricStreamJoinerConfig	getConfiguration()
java.lang.Class<MetricStreamJoinerConfig>	getConfigurationClass()
com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStream	getMetricStream(java.lang.String id)
java.util.List<com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStream>	getMetricStreams()
com.elastisys.autoscaler.core.api.types.ServiceStatus	getStatus()
void	start()
void	stop()
void	validate(MetricStreamJoinerConfig configuration)

Methods inherited from class java.lang.Object

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

Constructor Detail

MetricStreamJoiner

@Inject
public MetricStreamJoiner(org.slf4j.Logger logger,
                          com.elastisys.scale.commons.eventbus.EventBus eventBus,
                          java.util.List<com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<?>> priorDeclaredMetricStreamers)

Creates a MetricStreamJoiner.

Parameters:

logger - Logger instance.

eventBus - EventBus on which to listen for metrics.

priorDeclaredMetricStreamers - The list of MetricStreamers declared prior to this MetricStreamer and which can be used as references in input streams. May be null, which is interpreted as an empty list.

Method Detail

validate

public void validate(MetricStreamJoinerConfig configuration)
              throws java.lang.IllegalArgumentException

Specified by:

validate in interface com.elastisys.autoscaler.core.api.Configurable<MetricStreamJoinerConfig>

Throws:

java.lang.IllegalArgumentException

configure

public void configure(MetricStreamJoinerConfig newConfig)
               throws java.lang.IllegalArgumentException

Specified by:

configure in interface com.elastisys.autoscaler.core.api.Configurable<MetricStreamJoinerConfig>

Throws:

java.lang.IllegalArgumentException

start

public void start()
           throws java.lang.IllegalStateException

Specified by:

start in interface com.elastisys.autoscaler.core.api.Service<MetricStreamJoinerConfig>

Throws:

java.lang.IllegalStateException

stop

public void stop()

Specified by:

stop in interface com.elastisys.autoscaler.core.api.Service<MetricStreamJoinerConfig>

getStatus

public com.elastisys.autoscaler.core.api.types.ServiceStatus getStatus()

Specified by:

getStatus in interface com.elastisys.autoscaler.core.api.Service<MetricStreamJoinerConfig>

getConfiguration

public MetricStreamJoinerConfig getConfiguration()

Specified by:

getConfiguration in interface com.elastisys.autoscaler.core.api.Configurable<MetricStreamJoinerConfig>

getConfigurationClass

public java.lang.Class<MetricStreamJoinerConfig> getConfigurationClass()

Specified by:

getConfigurationClass in interface com.elastisys.autoscaler.core.api.Configurable<MetricStreamJoinerConfig>

getMetricStreams

public java.util.List<com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStream> getMetricStreams()

Specified by:

getMetricStreams in interface com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<MetricStreamJoinerConfig>

getMetricStream

public com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStream getMetricStream(java.lang.String id)
                                                                                         throws java.lang.IllegalArgumentException

Specified by:

getMetricStream in interface com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<MetricStreamJoinerConfig>

Throws:

java.lang.IllegalArgumentException

fetch

public void fetch()
           throws com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamException,
                  java.lang.IllegalStateException

Specified by:

fetch in interface com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamer<MetricStreamJoinerConfig>

Throws:

com.elastisys.autoscaler.core.monitoring.metricstreamer.api.MetricStreamException

java.lang.IllegalStateException