wipool.java

与postgresql数据库结合的数据库水印软件包

/*
 * 
 * Copyright 2003,2004 The Watermill Team
 *
 * This file is part of Watermill.
 *
 *    Watermill 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 2 of the License, or
 *    (at your option) any later version.
 *
 *    Watermill 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 Watermill; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
package Watermill.kernel;

import java.io.*;
import java.util.*;

public class WIPool extends Pool implements Serializable {
    /** A Precompiled pool for weight independent queries **/

    public Identifiers identifiers;
    public DependencyMatrix depMatrix;
    public HashMap classes=new HashMap();
    public Pairs pairs=new Pairs();

    public WIPool(String ipn,Document id,WSchema iws){
	super(ipn,id,iws);

	identifiers=id.getModifiableValuesIdentifiers(wschema.getLocalConstraints());
	Msg.verbose("Identifiers:"+identifiers.toString());
		
	depMatrix=id.getDependency(wschema.getGlobalConstraints());
	Msg.verbose("DepMatrix:"+depMatrix.toString());

	reductMatrix(1,2);
	Msg.debug("Warning : constant maxlocal=1 and minglobal=2 in reductmatrix");

	computeMap();
	Msg.verbose("Classes:"+classes.toString());
	computePairs();
	Msg.verbose("Pairs:"+pairs.toString());
    }

    public void reductMatrix(int maxLocal,int minGlobal){
	if (depMatrix.size()<=1) return; // nothing to do

	DependencyMatrix dep=(DependencyMatrix)depMatrix.clone();

	int currentPos=-1;
	int targetPos;

	do {
	    currentPos++;
	    targetPos=currentPos;
	    
	    Identifiers current=(Identifiers)dep.get(currentPos);
	    Identifiers target;
	    do {
		targetPos++;
		Msg.verbose("positions:"+currentPos+","+targetPos);
		target=(Identifiers)dep.get(targetPos);
		
		if (delta(current,target)*maxLocal<=minGlobal){
		    Msg.verbose("Dependency "+currentPos+":"+current+"  and "+targetPos+":"+target+" are similar");
		    Msg.verbose("Removing "+targetPos);
		    dep.remove(targetPos);
		}
	    }while((targetPos+1<dep.size()));
	}while(currentPos+2<dep.size());

	depMatrix=dep;
    }

    public int delta(Identifiers a,Identifiers b){
	int res=0;

	for(Enumeration e=a.elements();e.hasMoreElements();){
	    Identifier i=(Identifier)e.nextElement();
	    if (!(b.contains(i)))
		res++;
	}

	for(Enumeration e=b.elements();e.hasMoreElements();){
	    Identifier i=(Identifier)e.nextElement();
	    if (!(a.contains(i)))
		res++;
	}
	return res;
    }

    public boolean anyInclusion(Set a,Set b){
	return ((a.containsAll(b))||(b.containsAll(a)));
    }

    public void computePairs(){
	Identifiers ids=(Identifiers)identifiers.clone();
	Msg.verbose("computePairs : "+ids.toString());

	while(ids.size()>1) {
	    Msg.verbose("Current size "+ids.size());
	    int currentPos=0,targetPos=0;
	    Identifier current=(Identifier)ids.get(currentPos);
	    Identifier target;
	    do {
		targetPos++;
		Msg.verbose("positions:"+currentPos+","+targetPos);
		target=(Identifier)ids.get(targetPos);
	    }while((targetPos+1<ids.size())&&!(classes.get(current).equals(classes.get(target))));
	    
	    if (targetPos+1<ids.size()){
		pairs.add(new Pair(current,target));
		Msg.verbose("adding "+currentPos+","+targetPos);
		Msg.verbose("Removing "+targetPos);
		ids.remove(targetPos);
	    }
	    Msg.verbose("Removing "+currentPos);
	    ids.remove(currentPos);
	    
	}
    }

    public void computeMap(){
	for(Enumeration e=identifiers.elements();e.hasMoreElements();){
	    Identifier id=(Identifier)e.nextElement();

	    Msg.verbose("Looking queries depending on "+id.toString());

	    int i=0;
	    for(Enumeration e2=depMatrix.elements();e2.hasMoreElements();i++){
		Identifiers dep=(Identifiers)e2.nextElement();
		int pos=dep.indexOf(id);
		if(pos==-1)
		    Msg.verbose("no match !");
		if (pos!=-1){
		    HashSet s=(HashSet)classes.get(id);
		    if (s==null){
			s=new HashSet();
			s.add(new Integer(i));
			classes.put(id,s);
		    }
		    else {
			s.add(new Integer(i));
			classes.put(id,s);
		    }
		}
	    }
	}
    }


    public Watermark watermark(Document doc,int seed){
	Random r=new Random(seed);
	Watermark res=new Watermark();
	Msg.verbose("Watermark");
	Msg.verbose("Pairs : "+pairs.toString());

	for(Enumeration e=pairs.elements();e.hasMoreElements();){
	    Pair p=(Pair)e.nextElement();
	    Msg.verbose("watermarking in pair "+p.toString());
	    boolean b=r.nextBoolean();
	    int d=p.first.maxDistortion;
	    if (p.second.maxDistortion<d)
		d=p.second.maxDistortion;
	    if (b) 
		d=-d;
	    res.put(p.first,new Value(d));
	    res.put(p.second,new Value(-d));
	    doc.addValue(p.first,new Value(d));
	    doc.addValue(p.second,new Value(-d));

	}
	return res;
    }
}