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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

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/*
 * Title:        CloudSim Toolkit
 * Description:  CloudSim (Cloud Simulation) Toolkit for Modeling and Simulation of Clouds
 * Licence:      GPL - http://www.gnu.org/copyleft/gpl.html
 *
 * Copyright (c) 2009-2012, The University of Melbourne, Australia
 */
package org.cloudbus.cloudsim.allocationpolicies.migration;

import org.cloudbus.cloudsim.allocationpolicies.VmAllocationPolicy;
import org.cloudbus.cloudsim.hosts.Host;
import org.cloudbus.cloudsim.selectionpolicies.power.PowerVmSelectionPolicy;
import org.cloudbus.cloudsim.vms.Vm;

import java.util.Comparator;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.stream.Stream;

/**
 * A {@link VmAllocationPolicy} that uses a Static CPU utilization Threshold (THR) to
 * detect host {@link #getUnderUtilizationThreshold() under} and
 * {@link #getOverUtilizationThreshold(Host)} over} utilization.
 *
 * It's a Best Fit policy which selects the Host having the most used amount of CPU
 * MIPS to place a given VM, disregarding energy consumption.
 *
 * @author Anton Beloglazov
 * @author Manoel Campos da Silva Filho
 * @since CloudSim Plus 1.0
 */
public class VmAllocationPolicyMigrationBestFitStaticThreshold extends VmAllocationPolicyMigrationStaticThreshold {

    public VmAllocationPolicyMigrationBestFitStaticThreshold(
        final PowerVmSelectionPolicy vmSelectionPolicy,
        final double overUtilizationThreshold)
    {
        this(vmSelectionPolicy, overUtilizationThreshold, null);
    }

    /**
     * Creates a new VmAllocationPolicy, changing the {@link Function} to select a Host for a Vm.
     * @param vmSelectionPolicy the policy that defines how VMs are selected for migration
     * @param overUtilizationThreshold the over utilization threshold
     * @param findHostForVmFunction a {@link Function} to select a Host for a given Vm.
     *                              Passing null makes the Function to be set as the default {@link #findHostForVm(Vm)}.
     * @see VmAllocationPolicy#setFindHostForVmFunction(java.util.function.BiFunction)
     */
    public VmAllocationPolicyMigrationBestFitStaticThreshold(
        final PowerVmSelectionPolicy vmSelectionPolicy,
        final double overUtilizationThreshold,
        final BiFunction> findHostForVmFunction)
    {
        super(vmSelectionPolicy, overUtilizationThreshold, findHostForVmFunction);
    }

    /**
     * Gets the Host having the least available MIPS capacity (max used MIPS).
     *
     * This method is ignoring the additional filtering performed by the super class.
     * This way, Host selection is performed ignoring energy consumption.
     * However, all the basic filters defined in the super class are ensured, since
     * this method is called just after they are applied.
     * 
     *
     * @param vm {@inheritDoc}
     * @param hostStream {@inheritDoc}
     * @return {@inheritDoc}
     */
    @Override
    protected Optional findHostForVmInternal(final Vm vm, final Stream hostStream) {
        /*It's ignoring the super class intentionally to avoid the additional filtering performed there
        * and to apply a different method to select the Host to place the VM.*/
        return hostStream.max(Comparator.comparingDouble(Host::getUtilizationOfCpuMips));
    }
}