Module io.inverno.mod.discovery.http

Package io.inverno.mod.discovery.http

Class LeastRequestTrafficLoadBalancer

java.lang.Object

io.inverno.mod.discovery.http.LeastRequestTrafficLoadBalancer

All Implemented Interfaces:

TrafficLoadBalancer<HttpServiceInstance,UnboundExchange<?>>

public class LeastRequestTrafficLoadBalancer
extends Object
implements TrafficLoadBalancer<HttpServiceInstance,UnboundExchange<?>>

An HTTP traffic load balancer that selects the service instance with the least current active requests from a random subset of instances.

In order to select a service instance, the load balancer first selects getChoiceCount() instances and calculates a score to each of them based on the following formula:

 score = instance_weight / (instance_active_requests + 1) ^ bias
 

The getBias() is used to increase the importance of active requests: the greater it is, the more instances with lower active requests count are selected.

The instance with the highest score is eventually then selected.

Since:

1.12

Author:

Jeremy Kuhn

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LeastRequestTrafficLoadBalancer.Factory	A Least request traffic load balancer factory.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_BIAS	The default bias on active requests.
static final int	DEFAULT_CHOICE_COUNT	The default choice count.

Constructor Summary

Constructors

Constructor	Description
LeastRequestTrafficLoadBalancer(Collection<HttpServiceInstance> weightedInstances)	Creates a least request traffic load balancer.
LeastRequestTrafficLoadBalancer(Collection<HttpServiceInstance> weightedInstances, int choiceCount, int bias)	Creates a least request traffic load balancer with the specified choice count and active request bias.

Method Summary

Modifier and Type	Method	Description
int	getBias()	Returns the active requests bias used to increase the importance of active requests when selecting an instance.
int	getChoiceCount()	Returns the number of service instances to consider when selecting an instance.
Mono<HttpServiceInstance>	next(UnboundExchange<?> serviceRequest)	Returns the next service instance to use to process the specified service request.

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_CHOICE_COUNT

public static final int DEFAULT_CHOICE_COUNT

The default choice count.

See Also:

• Constant Field Values

DEFAULT_BIAS

public static final int DEFAULT_BIAS

The default bias on active requests.

See Also:

• Constant Field Values

Constructor Details

LeastRequestTrafficLoadBalancer

public LeastRequestTrafficLoadBalancer(Collection<HttpServiceInstance> weightedInstances)

Creates a least request traffic load balancer.

Parameters:

weightedInstances - a collection of HTTP service instances

LeastRequestTrafficLoadBalancer

public LeastRequestTrafficLoadBalancer(Collection<HttpServiceInstance> weightedInstances,
 int choiceCount,
 int bias)

Creates a least request traffic load balancer with the specified choice count and active request bias.

Parameters:

weightedInstances - a collection of weighted instances

choiceCount - the choice count

bias - the bias on active requests

Method Details

getChoiceCount

public int getChoiceCount()

Returns the number of service instances to consider when selecting an instance.

Returns:

the choice count

getBias

public int getBias()

Returns the active requests bias used to increase the importance of active requests when selecting an instance.

The greater it is, the more instances with lower active requests count are selected.

Returns:

the active requests bias

next

public Mono<HttpServiceInstance> next(UnboundExchange<?> serviceRequest)

Description copied from interface: TrafficLoadBalancer

Returns the next service instance to use to process the specified service request.

Specified by:

next in interface TrafficLoadBalancer<HttpServiceInstance,UnboundExchange<?>>

Parameters:

serviceRequest - a service request

Returns:

a Mono emitting the next service instance