genevents.java

p2p仿真器。开发者可以工作在覆盖层中进行创造和测试逻辑算法或者创建和测试新的服务。PlanetSim还可以将仿真代码平稳转换为在Internet上的实验代码

package planet.simulate;

import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;

import planet.commonapi.Id;
import planet.commonapi.exception.InitializationException;
import planet.generic.commonapi.factory.GenericFactory;

/**
 * This class permits to build events in a programming way, without any event file.
 * @author <a href="mailto: [e-mail]">Ruben Mondejar</a>
 * @author <a href="mailto: [e-mail]">Jordi Pujol</a>
 * 08-jul-2005
 */
public class GenEvents {
	
	/**
	 * Generate a set of random ids for nodes to insert to the overlay.
	 * The generated values are node's id and nodes' bootstrap.
	 * @param num Number of nodes to generate.
	 * @return An array of two positions with: in first position the
	 * id node bootstrap of the node 'i'th; in second position the id of
	 * node 'i'th. 
	 */
	public static Object[] genRandomIds(int num) {
		
		Hashtable values = new Hashtable();
		HashSet control = new HashSet();
		
		Id value = null;

		//build all node Ids randomly
		int j=0;
		while(values.size()<num) {
		  do {
		    try {
		        value = GenericFactory.buildRandomId();
		    } catch (InitializationException e){
		        e.printStackTrace();
		    }
		  } while (control.contains(value));	         		      	 
		  control.add(value);
		  values.put(new Integer(j),value);
		  j++;	      
		}	     			
		
		//select all bootstrap Id
		Id[] node = new Id[num];
		Id[] boot = new Id[num];
		int pos;
		
		for(int i=0;i<num;i++) {	 
		  node[i] = (Id) values.get(new Integer(i));
		  pos = (int) (Math.random()*(double)i);
		  boot[i] = node[pos];
		}		
		
		//build the returned value.
		Object[] ids = new Object[2];
		ids[0]=boot;
		ids[1]=node;
		return ids;
	}
	
	/**
	 * Returns an array with two positions. The first one contains an array of Id of 
	 * the bootstraps. The second one contains an array of Id with the node Id itself.
	 * The Ids are built equidistant. It means that the increment between any two
	 * consecutive Ids are the same.
	 * @param num Number of nodes to build.
	 * @return An array of two positions of Object, with an Id[] in any position. The first
	 * position contains the bootstrap Ids for any node, that appear in the second position.
	 */
	public static Object[] genDistribEvents(int num)  {
	    try {
	        Iterator it   = GenericFactory.buildDistributedIds(num);
	        Object[] toReturn = new Object[2];
	        Id[] node     = new Id[num];
	        Id[] boot     = new Id[num];
	        Id value      = (Id)it.next();
	        int index     = 0;
	        int bootIndex = 0;
	        
	        node[0]      = value;
	        boot[0]      = value;
	        while (it.hasNext())
	        {
	            node[bootIndex+1] = (Id)it.next();
	            index = (int)(Math.random()*(double)bootIndex);
	            bootIndex++;
	            boot[bootIndex] = node[index];
	        }
	        
	        toReturn[0]=boot;
	        toReturn[1]=node;
	        return toReturn;
	        
	    } catch (Exception e)
	    {
	        e.printStackTrace();
	        return null;
	    }
	}
}