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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 * Unless required by applicable law or agreed to in writing, software
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package org.apache.cassandra.gms;

import java.net.InetAddress;

An interface that provides an application with the ability
to query liveness information of a node in the cluster. It
also exposes methods which help an application register callbacks
for notifications of liveness information of nodes.
/**
 * An interface that provides an application with the ability
 * to query liveness information of a node in the cluster. It
 * also exposes methods which help an application register callbacks
 * for notifications of liveness information of nodes.
 */

public interface IFailureDetector
{
    
Failure Detector's knowledge of whether a node is up or
down.
Params:
ep – endpoint in question.
Returns:
true if UP and false if DOWN./**
     * Failure Detector's knowledge of whether a node is up or
     * down.
     *
     * @param ep endpoint in question.
     * @return true if UP and false if DOWN.
     */
    public boolean isAlive(InetAddress ep);

    
This method is invoked by any entity wanting to interrogate the status of an endpoint.
In our case it would be the Gossiper. The Failure Detector will then calculate Phi and
deem an endpoint as suspicious or alive as explained in the Hayashibara paper.
param ep endpoint for which we interpret the inter arrival times.
/**
     * This method is invoked by any entity wanting to interrogate the status of an endpoint.
     * In our case it would be the Gossiper. The Failure Detector will then calculate Phi and
     * deem an endpoint as suspicious or alive as explained in the Hayashibara paper.
     *
     * param ep endpoint for which we interpret the inter arrival times.
     */
    public void interpret(InetAddress ep);

    
This method is invoked by the receiver of the heartbeat. In our case it would be
the Gossiper. Gossiper inform the Failure Detector on receipt of a heartbeat. The
FailureDetector will then sample the arrival time as explained in the paper.
param ep endpoint being reported.
/**
     * This method is invoked by the receiver of the heartbeat. In our case it would be
     * the Gossiper. Gossiper inform the Failure Detector on receipt of a heartbeat. The
     * FailureDetector will then sample the arrival time as explained in the paper.
     *
     * param ep endpoint being reported.
     */
    public void report(InetAddress ep);

    
remove endpoint from failure detector
/**
     * remove endpoint from failure detector
     */
    public void remove(InetAddress ep);

    
force conviction of endpoint in the failure detector
/**
     * force conviction of endpoint in the failure detector
     */
    public void forceConviction(InetAddress ep);

    
Register interest for Failure Detector events.
Params:
listener – implementation of an application provided IFailureDetectionEventListener/**
     * Register interest for Failure Detector events.
     *
     * @param listener implementation of an application provided IFailureDetectionEventListener
     */
    public void registerFailureDetectionEventListener(IFailureDetectionEventListener listener);

    
Un-register interest for Failure Detector events.
Params:
listener – implementation of an application provided IFailureDetectionEventListener/**
     * Un-register interest for Failure Detector events.
     *
     * @param listener implementation of an application provided IFailureDetectionEventListener
     */
    public void unregisterFailureDetectionEventListener(IFailureDetectionEventListener listener);
}