StochasticLoadBalancer.RegionReplicaHostCostFunction (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction
- - org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.RegionReplicaHostCostFunction

Direct Known Subclasses:

StochasticLoadBalancer.RegionReplicaRackCostFunction

Enclosing class:

StochasticLoadBalancer
```
static class StochasticLoadBalancer.RegionReplicaHostCostFunction
extends StochasticLoadBalancer.CostFunction
```
A cost function for region replicas. We give a very high cost to hosting replicas of the same region in the same host. We do not prevent the case though, since if numReplicas > numRegionServers, we still want to keep the replica open.

Field Summary

Fields
Modifier and Type	Field and Description
`(package private) long[]`	`costsPerGroup`
`private static float`	`DEFAULT_REGION_REPLICA_HOST_COST_KEY`
`(package private) long`	`maxCost`
`(package private) int[][]`	`primariesOfRegionsPerGroup`
`private static String`	`REGION_REPLICA_HOST_COST_KEY`

Fields inherited from class org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction
cluster

Constructor Summary

Constructors
Constructor and Description

StochasticLoadBalancer.RegionReplicaHostCostFunction(org.apache.hadoop.conf.Configuration conf)

Constructors
Constructor and Description
`StochasticLoadBalancer.RegionReplicaHostCostFunction(org.apache.hadoop.conf.Configuration conf)`

Method Summary

Methods
Modifier and Type	Method and Description
`(package private) double`	`cost()`
`protected long`	`costPerGroup(int[] primariesOfRegions)` For each primary region, it computes the total number of replicas in the array (numReplicas) and returns a sum of numReplicas-1 squared.
`(package private) long`	`getMaxCost(BaseLoadBalancer.Cluster cluster)`
`(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.
`protected void`	`regionMoved(int region, int oldServer, int newServer)`

Methods inherited from class org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction
costFromArray, getMultiplier, postAction, scale, setMultiplier

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - REGION_REPLICA_HOST_COST_KEY
```
private static final String REGION_REPLICA_HOST_COST_KEY
```
    See Also:
    Constant Field Values
  - DEFAULT_REGION_REPLICA_HOST_COST_KEY
```
private static final float DEFAULT_REGION_REPLICA_HOST_COST_KEY
```
    See Also:
    Constant Field Values
  - maxCost
```
long maxCost
```
  - costsPerGroup
```
long[] costsPerGroup
```
  - primariesOfRegionsPerGroup
```
int[][] primariesOfRegionsPerGroup
```
- Constructor Detail
  - StochasticLoadBalancer.RegionReplicaHostCostFunction
```
public StochasticLoadBalancer.RegionReplicaHostCostFunction(org.apache.hadoop.conf.Configuration conf)
```
- Method Detail
  - init
```
void init(BaseLoadBalancer.Cluster cluster)
```
    Description copied from class: StochasticLoadBalancer.CostFunction
    
    Called once per LB invocation to give the cost function to initialize it's state, and perform any costly calculation.
    
    Overrides:
    
    init in class StochasticLoadBalancer.CostFunction
  - getMaxCost
```
long getMaxCost(BaseLoadBalancer.Cluster cluster)
```
  - cost
```
double cost()
```
    Specified by:
    
    cost in class StochasticLoadBalancer.CostFunction
  - costPerGroup
```
protected long costPerGroup(int[] primariesOfRegions)
```
    For each primary region, it computes the total number of replicas in the array (numReplicas) and returns a sum of numReplicas-1 squared. For example, if the server hosts regions a, b, c, d, e, f where a and b are same replicas, and c,d,e are same replicas, it returns (2-1) * (2-1) + (3-1) * (3-1) + (1-1) * (1-1).
    
    Parameters:
    primariesOfRegions - a sorted array of primary regions ids for the regions hosted
    
    Returns:
    a sum of numReplicas-1 squared for each primary region in the group.
  - regionMoved
```
protected void regionMoved(int region,
               int oldServer,
               int newServer)
```
    Overrides:
    
    regionMoved in class StochasticLoadBalancer.CostFunction

Class StochasticLoadBalancer.RegionReplicaHostCostFunction

Field Summary

Fields inherited from class org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction

Constructor Summary

Method Summary

Methods inherited from class org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.CostFunction

Methods inherited from class java.lang.Object

Field Detail

REGION_REPLICA_HOST_COST_KEY

DEFAULT_REGION_REPLICA_HOST_COST_KEY

maxCost

costsPerGroup

primariesOfRegionsPerGroup

Constructor Detail

StochasticLoadBalancer.RegionReplicaHostCostFunction

Method Detail

init

getMaxCost

cost

costPerGroup

regionMoved