org.apache.hadoop.hbase.master.balancer

Class CostFunction

java.lang.Object

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

Direct Known Subclasses:

CostFromRegionLoadFunction, HeterogeneousRegionCountCostFunction, LocalityBasedCostFunction, MoveCostFunction, PrimaryRegionCountSkewCostFunction, RegionCountSkewCostFunction, RegionReplicaGroupingCostFunction, TableSkewCostFunction

@InterfaceAudience.Private
abstract class CostFunction
extends Object

Base class of StochasticLoadBalancer's Cost Functions.

Field Summary

Fields

Modifier and Type	Field and Description
protected BalancerClusterState	cluster
static double	COST_EPSILON
private float	multiplier

Constructor Summary

Constructors

Constructor and Description
CostFunction()

Method Summary

Modifier and Type	Method and Description
protected abstract double	cost()
(package private) float	getMultiplier()
(package private) boolean	isNeeded()
(package private) void	postAction(BalanceAction action) Called once per cluster Action to give the cost function an opportunity to update it's state.
(package private) void	prepare(BalancerClusterState cluster) Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.
protected void	regionMoved(int region, int oldServer, int newServer)
protected static double	scale(double min, double max, double value) Scale the value between 0 and 1.
(package private) void	setMultiplier(float m)
void	updateWeight(double[] weights) Add the cost of this cost function to the weight of the candidate generator that is optimized for this cost function.

Methods inherited from class java.lang.Object

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

Field Detail

COST_EPSILON

public static final double COST_EPSILON

See Also:

Constant Field Values

multiplier

private float multiplier

cluster

protected BalancerClusterState cluster

Constructor Detail

CostFunction

CostFunction()

Method Detail

isNeeded

boolean isNeeded()

getMultiplier

float getMultiplier()

setMultiplier

void setMultiplier(float m)

prepare

void prepare(BalancerClusterState cluster)

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

postAction

void postAction(BalanceAction 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

protected abstract double cost()

scale

protected static 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.

updateWeight

public void updateWeight(double[] weights)

Add the cost of this cost function to the weight of the candidate generator that is optimized for this cost function. By default it is the RandomCandiateGenerator for a cost function. Called once per init or after postAction.

Parameters:

weights - the weights for every generator.