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CloudSim Plus: A modern, highly extensible and easier-to-use Java 8 Framework for Modeling and Simulation of Cloud Computing Infrastructures and Services
/*
* CloudSim Plus: A modern, highly-extensible and easier-to-use Framework for
* Modeling and Simulation of Cloud Computing Infrastructures and Services.
* http://cloudsimplus.org
*
* Copyright (C) 2015-2021 Universidade da Beira Interior (UBI, Portugal) and
* the Instituto Federal de Educação Ciência e Tecnologia do Tocantins (IFTO, Brazil).
*
* This file is part of CloudSim Plus.
*
* CloudSim Plus is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* CloudSim Plus is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with CloudSim Plus. If not, see This scaling type will resize the resource capacity in the following way:
*
* - in underload conditions: it decreases the resource capacity to be equal to
* the current load of the resource being scaled;
* - in overload conditions: it increases the resource capacity to be equal to
* the current load of the resource being scaled.
*
*
* Finally it adds an extra amount of resource, defined by the
* {@link VerticalVmScaling#getScalingFactor() scaling factor}, for safety.
* This extra amount added is to enable the resource usage to grow up to the scaling factor
* without needing to resize the resource again. If it grows up to the scaling factor,
* a new up scaling request will be sent.
*
*
* If the scaling factor for this type of scaling is zero, it means that the scaling object
* will always resize the resource to the exact amount that is being used.
*
* @author Manoel Campos da Silva Filho
* @since CloudSim Plus 1.2.0
*/
public class ResourceScalingInstantaneous implements ResourceScaling {
private static final ResourceScaling GRADUAL = new ResourceScalingGradual();
@Override
public double getResourceAmountToScale(final VerticalVmScaling vmScaling) {
final Function thresholdFunc = vmScaling.getResourceUsageThresholdFunction();
/* Computes the size to which the resource has to be scaled to move it from the
* under or overload state.*/
final Resource res = vmScaling.getResource();
//The new total capacity to move the VM resource from under/overloaded.
final double newTotalCapacity = Math.ceil(res.getAllocatedResource() / thresholdFunc.apply(vmScaling.getVm()));
//The difference to add/remove from the current capacity so that the resource capacity will be equal to that just computed.
final double scaleCapacity = newTotalCapacity - res.getCapacity();
/*Includes and additional resource amount for safety, according to the scaling factor.
* This way, if the resource usage increases again up to this extra amount,
* there is no need to re-scale the resource.
* If the scale factor is zero, no extra safety amount is included.*/
final double extraSafetyCapacity = GRADUAL.getResourceAmountToScale(vmScaling);
return scaleCapacity + extraSafetyCapacity;
}
}