org.jboss.cache.buddyreplication
Class NextMemberBuddyLocator

java.lang.Object
  org.jboss.cache.buddyreplication.NextMemberBuddyLocator

All Implemented Interfaces:

BuddyLocator

@ThreadSafe
public class NextMemberBuddyLocator
extends Object
implements BuddyLocator

This buddy locator uses a next-in-line algorithm to select buddies for a buddy group. This algorithm allows for the following properties, all of which are optional.

• More than one buddy per group - the numBuddies property, defaulting to 1 if ommitted.
• Ability to skip buddies on the same host when selecting buddies - the ignoreColocatedBuddies property, defaulting to true if ommitted. Note that this is just a hint though, and if all nstances in a cluster are colocated, the algorithm will be forced to pick a colocated instance even if this is property set to true.

Author:

Manik Surtani (manik AT jboss DOT org)

Constructor Summary

NextMemberBuddyLocator()

Method Summary

BuddyReplicationConfig.BuddyLocatorConfig	getConfig() Gets the configuration for this BuddyLocator.
void	init(BuddyReplicationConfig.BuddyLocatorConfig buddyLocatorConfig) Initialize this BuddyLocator.
List<org.jgroups.Address>	locateBuddies(Map<org.jgroups.Address,String> buddyPoolMap, List<org.jgroups.Address> currentMembership, org.jgroups.Address dataOwner) Choose a set of buddies for the given node.

Methods inherited from class java.lang.Object

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

Constructor Detail

NextMemberBuddyLocator

public NextMemberBuddyLocator()

Method Detail

getConfig

public BuddyReplicationConfig.BuddyLocatorConfig getConfig()

Description copied from interface: BuddyLocator

Gets the configuration for this BuddyLocator.

Specified by:

getConfig in interface BuddyLocator

Returns:

object encapsulating this object's configuration. Should not return null. If BuddyLocator.init(org.jboss.cache.config.BuddyReplicationConfig.BuddyLocatorConfig) has not been called or null was passed to it, the returned value should be the default config for the given BuddyLocator implementation.

init

public void init(BuddyReplicationConfig.BuddyLocatorConfig buddyLocatorConfig)

Description copied from interface: BuddyLocator

Initialize this BuddyLocator.

Specified by:

init in interface BuddyLocator

Parameters:

buddyLocatorConfig - configuration for this BuddyLocator. May be null, in which case the implementation should use its default configuration.

locateBuddies

public List<org.jgroups.Address> locateBuddies(Map<org.jgroups.Address,String> buddyPoolMap,
                                               List<org.jgroups.Address> currentMembership,
                                               org.jgroups.Address dataOwner)

Description copied from interface: BuddyLocator

Choose a set of buddies for the given node. Invoked when a change in cluster membership is detected.

Specified by:

locateBuddies in interface BuddyLocator

Parameters:

buddyPoolMap - Map mapping nodes in the cluster to the "buddy pool" they have identified themselves as belonging too. A BuddyLocator implementation can use this information to preferentially assign buddies from the same buddy pool as dataOwner. May be null if buddy pools aren't configured.

currentMembership - List

of the current cluster members

dataOwner - Address of the node for which buddies should be selected

Returns:

List

of the nodes that should serve as buddies for dataOwner. Will not be null, may be empty.