org.apache.cassandra.gms
Class Gossiper

java.lang.Object
  org.apache.cassandra.gms.Gossiper

All Implemented Interfaces:

IEndPointStateChangePublisher, IFailureDetectionEventListener

public class Gossiper
extends java.lang.Object
implements IFailureDetectionEventListener, IEndPointStateChangePublisher

This module is responsible for Gossiping information for the local endpoint. This abstraction maintains the list of live and dead endpoints. Periodically i.e. every 1 second this module chooses a random node and initiates a round of Gossip with it. A round of Gossip involves 3 rounds of messaging. For instance if node A wants to initiate a round of Gossip with node B it starts off by sending node B a GossipDigestSynMessage. Node B on receipt of this message sends node A a GossipDigestAckMessage. On receipt of this message node A sends node B a GossipDigestAck2Message which completes a round of Gossip. This module as and when it hears one of the three above mentioned messages updates the Failure Detector with the liveness information.

Nested Class Summary

static class	Gossiper.GossipDigestAck2VerbHandler
static class	Gossiper.GossipDigestAckVerbHandler
static class	Gossiper.GossipDigestSynVerbHandler
static class	Gossiper.JoinVerbHandler

Field Summary

static Gossiper	instance
static int	intervalInMillis_

Method Summary

void	addLocalApplicationState(java.lang.String key, ApplicationState appState)
void	convict(java.net.InetAddress endpoint) This method is part of IFailureDetectionEventListener interface.
int	getCurrentGenerationNumber(java.net.InetAddress endpoint)
java.util.Set<java.net.InetAddress>	getLiveMembers()
java.util.Set<java.net.InetAddress>	getUnreachableMembers()
boolean	isKnownEndpoint(java.net.InetAddress endpoint)
void	register(IEndPointStateChangeSubscriber subscriber) Register with the Gossiper for EndPointState notifications
void	removeEndPoint(java.net.InetAddress endpoint) Removes the endpoint completely from Gossip
void	start(java.net.InetAddress localEndPoint, int generationNbr) Start the gossiper with the generation # retrieved from the System table
void	stop()
void	unregister(IEndPointStateChangeSubscriber subscriber) Unregister interest for state changes.

Methods inherited from class java.lang.Object

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

Field Detail

intervalInMillis_

public static final int intervalInMillis_

See Also:

Constant Field Values

instance

public static final Gossiper instance

Method Detail

register

public void register(IEndPointStateChangeSubscriber subscriber)

Register with the Gossiper for EndPointState notifications

Specified by:

register in interface IEndPointStateChangePublisher

Parameters:

subscriber - module which implements the IEndPointStateChangeSubscriber

unregister

public void unregister(IEndPointStateChangeSubscriber subscriber)

Description copied from interface: IEndPointStateChangePublisher

Unregister interest for state changes.

Specified by:

unregister in interface IEndPointStateChangePublisher

Parameters:

subscriber - module which implements the IEndPointStateChangeSubscriber

getLiveMembers

public java.util.Set<java.net.InetAddress> getLiveMembers()

getUnreachableMembers

public java.util.Set<java.net.InetAddress> getUnreachableMembers()

convict

public void convict(java.net.InetAddress endpoint)

This method is part of IFailureDetectionEventListener interface. This is invoked by the Failure Detector when it convicts an end point. param @ endpoint end point that is convicted.

Specified by:

convict in interface IFailureDetectionEventListener

Parameters:

endpoint - endpoint to be convicted

removeEndPoint

public void removeEndPoint(java.net.InetAddress endpoint)

Removes the endpoint completely from Gossip

isKnownEndpoint

public boolean isKnownEndpoint(java.net.InetAddress endpoint)

getCurrentGenerationNumber

public int getCurrentGenerationNumber(java.net.InetAddress endpoint)

start

public void start(java.net.InetAddress localEndPoint,
                  int generationNbr)

Start the gossiper with the generation # retrieved from the System table

addLocalApplicationState

public void addLocalApplicationState(java.lang.String key,
                                     ApplicationState appState)

stop

public void stop()