云计算仿真工具中文注释VmAllocationPolicySimple.java

/*
 * 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) 2009-2010, The University of Melbourne, Australia
 */

package org.cloudbus.cloudsim;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.cloudbus.cloudsim.core.CloudSim;

/**
 * 虚拟机分配策略,分配满足条件的最少的pe的主机
 * 字段里继承了一个主机列表，vm和主机映射，主机usedpes，主机freepes
 * VmAllocationPolicySimple is an VmAllocationPolicy that
 * chooses, as the host for a VM, the host with
 * less PEs in use.
 *
 * @author		Rodrigo N. Calheiros
 * @author		Anton Beloglazov
 * @since		CloudSim Toolkit 1.0
 */
public class VmAllocationPolicySimple extends VmAllocationPolicy {

	/** The vm table. */
	private Map<String, Host> vmTable;

	/** The used pes. */
	private Map<String, Integer> usedPes;

	/** The free pes. 记录了每一台主机空闲的pe*/
	private List<Integer> freePes;

	/**
	 * Creates the new VmAllocationPolicySimple object.
	 *
	 * @param list the list
	 *
	 * @pre $none
	 * @post $none
	 */
	public VmAllocationPolicySimple(List<? extends Host> list) {
		super(list);

		setFreePes(new ArrayList<Integer>());
		for (Host host : getHostList()) {
			getFreePes().add(host.getPesNumber());

		}

		setVmTable(new HashMap<String, Host>());
		setUsedPes(new HashMap<String, Integer>());
	}

	/**
	 * 对一个给定 的vm分配一个host
	 * Allocates a host for a given VM.
	 *
	 * @param vm VM specification
	 *
	 * @return $true if the host could be allocated; $false otherwise
	 *
	 * @pre $none
	 * @post $none
	 */
	@Override
	public boolean allocateHostForVm(Vm vm) {
		int requiredPes = vm.getPesNumber();
		boolean result = false;
		int tries = 0;
		List<Integer> freePesTmp = new ArrayList<Integer>();
		for (Integer freePes : getFreePes()) {
			freePesTmp.add(freePes);
		}

		if (!getVmTable().containsKey(vm.getUid())) { //if this vm was not created
			do {//we still trying until we find a host or until we try all of them
				int moreFree = Integer.MIN_VALUE;
				int idx = -1;

				//we want the host with less pes in use
				for (int i=0; i < freePesTmp.size(); i++) { //寻找具有最大空闲pe的host
					if (freePesTmp.get(i) > moreFree) {
						moreFree = freePesTmp.get(i);
						idx = i;
					}
				}

				Host host = getHostList().get(idx);
				result = host.vmCreate(vm);              //在此host上创建vm

				if (result) { //if vm were succesfully created in the host
					//Log.printLine("VmAllocationPolicy: VM #"+vm.getVmId()+ "Chosen host: #"+host.getMachineID()+" idx:"+idx);
					getVmTable().put(vm.getUid(), host);       //vm和host的对应表
					getUsedPes().put(vm.getUid(), requiredPes);  //vm和使用的pe对应表
					getFreePes().set(idx, getFreePes().get(idx) - requiredPes);   //修改对应主机空闲的pe
					result = true;
					break;
				} else {
					freePesTmp.set(idx, Integer.MIN_VALUE);
				}
				tries++;
			} while (!result && tries < getFreePes().size());

		}

		return result;
	}

	/**
	 * 回收host
	 * Releases the host used by a VM.
	 *
	 * @param vm the vm
	 *
	 * @pre $none
	 * @post none
	 */
	@Override
	public void deallocateHostForVm(Vm vm) {
		Host host = getVmTable().remove(vm.getUid());
		int idx = getHostList().indexOf(host);
		int pes = getUsedPes().remove(vm.getUid());
		if (host != null) {
			host.vmDestroy(vm);
			getFreePes().set(idx, getFreePes().get(idx) + pes);
		}
	}

	/**
	 * Gets the host that is executing the given VM belonging to the
	 * given user.
	 *
	 * @param vm the vm
	 *
	 * @return the Host with the given vmID and userID; $null if not found
	 *
	 * @pre $none
	 * @post $none
	 */
	@Override
	public Host getHost(Vm vm) {
		return getVmTable().get(vm.getUid());
	}

	/**
	 * Gets the host that is executing the given VM belonging to the
	 * given user.
	 *
	 * @param vmId the vm id
	 * @param userId the user id
	 *
	 * @return the Host with the given vmID and userID; $null if not found
	 *
	 * @pre $none
	 * @post $none
	 */
	@Override
	public Host getHost(int vmId, int userId) {
		return getVmTable().get(Vm.getUid(userId, vmId));
	}

	/**
	 * Gets the vm table.
	 *
	 * @return the vm table
	 */
	public Map<String, Host> getVmTable() {
		return vmTable;
	}

	/**
	 * Sets the vm table.
	 *
	 * @param vmTable the vm table
	 */
	protected void setVmTable(Map<String, Host> vmTable) {
		this.vmTable = vmTable;
	}

	/**
	 * Gets the used pes.
	 *
	 * @return the used pes
	 */
	protected Map<String, Integer> getUsedPes() {
		return usedPes;
	}

	/**
	 * Sets the used pes.
	 *
	 * @param usedPes the used pes
	 */
	protected void setUsedPes(Map<String, Integer> usedPes) {
		this.usedPes = usedPes;
	}

	/**
	 * Gets the free pes.
	 *
	 * @return the free pes
	 */
	protected List<Integer> getFreePes() {
		return freePes;
	}

	/**
	 * Sets the free pes.
	 *
	 * @param freePes the new free pes
	 */
	protected void setFreePes(List<Integer> freePes) {
		this.freePes = freePes;
	}

	/* (non-Javadoc)
	 * @see cloudsim.VmAllocationPolicy#optimizeAllocation(double, cloudsim.VmList, double)
	 */
	@Override
	public List<Map<String, Object>> optimizeAllocation(List<? extends Vm> vmList) {
		// TODO Auto-generated method stub
		return null;
	}

	/* (non-Javadoc)
	 * 分配特定主机一个特定的vm
	 * @see org.cloudbus.cloudsim.VmAllocationPolicy#allocateHostForVm(org.cloudbus.cloudsim.Vm, org.cloudbus.cloudsim.Host)
	 */
	@Override
	public boolean allocateHostForVm(Vm vm, Host host) {
		if (host.vmCreate(vm)) { //if vm has been succesfully created in the host
			getVmTable().put(vm.getUid(), host);
			Log.formatLine("%.2f: VM #" + vm.getId() + " has been allocated to the host #" + host.getId(), CloudSim.clock());
			return true;
		}

		return false;
	}
}