org.apache.hadoop.hbase.master.balancer

Class StochasticLoadBalancer.CostFunction

java.lang.Object

org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction

Direct Known Subclasses:

StochasticLoadBalancer.CostFromRegionLoadFunction, StochasticLoadBalancer.LocalityBasedCostFunction, StochasticLoadBalancer.MoveCostFunction, StochasticLoadBalancer.PrimaryRegionCountSkewCostFunction, StochasticLoadBalancer.RegionCountSkewCostFunction, StochasticLoadBalancer.RegionReplicaHostCostFunction, StochasticLoadBalancer.TableSkewCostFunction

Enclosing class:

StochasticLoadBalancer

abstract static class StochasticLoadBalancer.CostFunction
extends Object

Base class of StochasticLoadBalancer's Cost Functions.

Field Summary

Fields

Modifier and Type	Field and Description
protected BaseLoadBalancer.Cluster	cluster
private float	multiplier

Constructor Summary

Constructors

Constructor and Description
CostFunction(org.apache.hadoop.conf.Configuration c)

Method Summary

Modifier and Type	Method and Description
(package private) abstract double	cost()
protected double	costFromArray(double[] stats) Function to compute a scaled cost using org.apache.commons.math3.stat.descriptive.DescriptiveStatistics.
(package private) float	getMultiplier()
private double	getSum(double[] stats)
(package private) void	init(BaseLoadBalancer.Cluster cluster) Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.
(package private) boolean	isNeeded()
(package private) void	postAction(BaseLoadBalancer.Cluster.Action action) Called once per cluster Action to give the cost function an opportunity to update it's state.
protected void	regionMoved(int region, int oldServer, int newServer)
protected double	scale(double min, double max, double value) Scale the value between 0 and 1.
(package private) void	setMultiplier(float m)

Methods inherited from class java.lang.Object

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

Field Detail

multiplier

private float multiplier

cluster

protected BaseLoadBalancer.Cluster cluster

Constructor Detail

CostFunction

CostFunction(org.apache.hadoop.conf.Configuration c)

Method Detail

isNeeded

boolean isNeeded()

getMultiplier

float getMultiplier()

setMultiplier

void setMultiplier(float m)

init

void init(BaseLoadBalancer.Cluster cluster)

Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.

postAction

void postAction(BaseLoadBalancer.Cluster.Action action)

Called once per cluster Action to give the cost function an opportunity to update it's state. postAction() is always called at least once before cost() is called with the cluster that this action is performed on.

regionMoved

protected void regionMoved(int region,
                           int oldServer,
                           int newServer)

cost

abstract double cost()

costFromArray

protected double costFromArray(double[] stats)

Function to compute a scaled cost using org.apache.commons.math3.stat.descriptive.DescriptiveStatistics. It assumes that this is a zero sum set of costs. It assumes that the worst case possible is all of the elements in one region server and the rest having 0.

Parameters:

stats - the costs

Returns:

a scaled set of costs.

getSum

private double getSum(double[] stats)

scale

protected double scale(double min,
                       double max,
                       double value)

Scale the value between 0 and 1.

Parameters:

min - Min value

max - The Max value

value - The value to be scaled.

Returns:

The scaled value.