/**
* Copyright 2016 LinkedIn Corp. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*/
package com.github.ambry.clustermap;
/** ResourceStatePolicy is used to determine if the state of a resource is "up" or "down". For resources like data nodes
* and disks, up and down mean available and unavailable, respectively.
*/
public interface ResourceStatePolicy {
/**
* Checks to see if the state is permanently down.
*
* @return true if the state is permanently down, false otherwise.
*/
boolean isHardDown();
/**
* Checks to see if the state is down (soft or hard).
*
* @return true if the state is down, false otherwise.
*/
boolean isDown();
/**
* Should be called by the caller every time an error is encountered for the corresponding resource.
*/
void onError();
/**
* May be called by the caller when the resource is responsive.
*/
void onSuccess();
/**
* Should be called if the caller knows outside of the policy that the resource has gone down.
*/
void onHardDown();
/**
* Should be called if the caller knows outside of the policy that the resource is up.
*/
void onHardUp();
}