me.prettyprint.cassandra.connection
Class DynamicLoadBalancingPolicy

java.lang.Object
  me.prettyprint.cassandra.connection.DynamicLoadBalancingPolicy

All Implemented Interfaces:

Serializable, LoadBalancingPolicy

public class DynamicLoadBalancingPolicy
extends Object
implements LoadBalancingPolicy

This LB Algorithm has the Phi algo which Dynamic snitch uses, LB is based on the probablity of failure of the node. TODO: Make cassandra code abstracted enough so we can inherit from the same.

Author:

Vijay Parthasarathy

See Also:

Serialized Form

Constructor Summary

DynamicLoadBalancingPolicy()

Method Summary

HClientPool	createConnection(HClientFactory clientFactory, CassandraHost host, CassandraClientMonitor monitor) Creates a connection pool for host.
double	getBadnessThreshold()
HClientPool	getPool(Collection<HClientPool> pools, Set<CassandraHost> excludeHosts) Retrieves a pool from the collection of pools excluding excludeHosts.
int	getResetInterval()
int	getUpdateInterval()
void	setBadnessThreshold(double badness) This is the percentage of badness which is acceptable...
void	setResetInterval(int resetInterval) Set the configured interval for the stats to be reset so that the new stats are allowed and we can get rid of bad nodes value.
void	setUpdateInterval(int updateInterval) Set the configured interval for the stats to be recalculated (until this time it is been cached.

Methods inherited from class java.lang.Object

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

Constructor Detail

DynamicLoadBalancingPolicy

public DynamicLoadBalancingPolicy()

Method Detail

getPool

public HClientPool getPool(Collection<HClientPool> pools,
                           Set<CassandraHost> excludeHosts)

Description copied from interface: LoadBalancingPolicy

Retrieves a pool from the collection of pools excluding excludeHosts.

Specified by:

getPool in interface LoadBalancingPolicy

Parameters:

pools - collection of all available pools

excludeHosts - excluded pools

Returns:

a pool based on this load balancing policy

createConnection

public HClientPool createConnection(HClientFactory clientFactory,
                                    CassandraHost host,
                                    CassandraClientMonitor monitor)

Description copied from interface: LoadBalancingPolicy

Creates a connection pool for host.

Specified by:

createConnection in interface LoadBalancingPolicy

Parameters:

clientFactory - an instance of HClientFactory

host - an instance of CassandraHost representing the host this pool will represent

monitor - the monitor exposing JMX methods

Returns:

a connection pool

getUpdateInterval

public int getUpdateInterval()

setUpdateInterval

public void setUpdateInterval(int updateInterval)

Set the configured interval for the stats to be recalculated (until this time it is been cached.

Parameters:

updateInterval - In ms.

getResetInterval

public int getResetInterval()

setResetInterval

public void setResetInterval(int resetInterval)

Set the configured interval for the stats to be reset so that the new stats are allowed and we can get rid of bad nodes value. This is under the assumption that the bad nodes will eventually get better....

Parameters:

resetInterval - in ms

getBadnessThreshold

public double getBadnessThreshold()

setBadnessThreshold

public void setBadnessThreshold(double badness)

This is the percentage of badness which is acceptable... Example: A should be 0.20 (20%) bad than B before B is choosen rathar than A.

Parameters:

badness - in %