RoundRobinDatacenterBroker.java

package org.cloudbus.cloudsim.examples;

import java.util.List;

import org.cloudbus.cloudsim.DatacenterBroker;
import org.cloudbus.cloudsim.DatacenterCharacteristics;
import org.cloudbus.cloudsim.Log;
import org.cloudbus.cloudsim.Vm;
import org.cloudbus.cloudsim.core.CloudSim;
import org.cloudbus.cloudsim.core.CloudSimTags;
import org.cloudbus.cloudsim.core.SimEvent;

import java.util.List;

import org.cloudbus.cloudsim.DatacenterBroker;
import org.cloudbus.cloudsim.DatacenterCharacteristics;
import org.cloudbus.cloudsim.Log;
import org.cloudbus.cloudsim.Vm;
import org.cloudbus.cloudsim.core.CloudSim;
import org.cloudbus.cloudsim.core.CloudSimTags;
import org.cloudbus.cloudsim.core.SimEvent;

/**
 * This broker allocates VMs to data centers following the 
 * <a href="http://en.wikipedia.org/wiki/Round-robin_scheduling">Round-robin</a> algorithm.
 * @author alessandro
 */
public class RoundRobinDatacenterBroker extends DatacenterBroker 
{

    /**
     * Creates an instance of this class associating to it a given name.
     * @param name The name to be associated to this broker. It might not be <code>null</code> or empty.
     * @throws Exception If the name contains spaces.
     */
    public RoundRobinDatacenterBroker(String name) throws Exception 
    {
        super(name);
    }

    @Override
    protected void processResourceCharacteristics(SimEvent ev) 
    {        
        DatacenterCharacteristics characteristics = (DatacenterCharacteristics) ev.getData();
        getDatacenterCharacteristicsList().put(characteristics.getId(), characteristics);

        if (getDatacenterCharacteristicsList().size() == getDatacenterIdsList().size()) 
        {
            distributeRequestsForNewVmsAcrossDatacentersUsingTheRoundRobinApproach();
        }
    }

    /**
     * Distributes the VMs across the data centers using the round-robin approach. A VM is allocated to a data center only if there isn't  
     * a VM in the data center with the same id.     
     */
    protected void distributeRequestsForNewVmsAcrossDatacentersUsingTheRoundRobinApproach() 
    {
        int numberOfVmsAllocated = 0;
        int i = 0;
        
        final List<Integer> availableDatacenters = getDatacenterIdsList();
        
        for (Vm vm : getVmList()) 
        {
            int datacenterId = availableDatacenters.get(i++ % availableDatacenters.size());
            String datacenterName = CloudSim.getEntityName(datacenterId);
            
            if (!getVmsToDatacentersMap().containsKey(vm.getId())) 
            {
                Log.printLine(CloudSim.clock() + ": " + getName() + ": Trying to Create VM #" + vm.getId() + " in " + datacenterName);
                sendNow(datacenterId, CloudSimTags.VM_CREATE_ACK, vm);
                numberOfVmsAllocated++;
            }
        }
        
        setVmsRequested(numberOfVmsAllocated);
        setVmsAcks(0);
    }
}