org.eclipse.equinox.p2.cudf.solver.ParanoidOptimizationFunction.java Source code

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Here is the source code for org.eclipse.equinox.p2.cudf.solver.ParanoidOptimizationFunction.java

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/*******************************************************************************
 * Copyright (c) 2009 Daniel Le Berre and others. All rights reserved. This
 * program and the accompanying materials are made available under the terms of
 * the Eclipse Public License v1.0 which accompanies this distribution, and is
 * available at http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Daniel Le Berre - initial API and implementation
 ******************************************************************************/
package org.eclipse.equinox.p2.cudf.solver;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.equinox.p2.cudf.metadata.InstallableUnit;
import org.eclipse.equinox.p2.cudf.solver.Projector.AbstractVariable;
import org.sat4j.pb.tools.WeightedObject;

//   PARANOID: we want to answer the user request, minimizing the number
//    of packages removed in the solution, and also the packages
//    changed by the solution; the optimization criterion is
//
//         lex( min #removed, min #changed)
//
//    Hence, two solutions S1 and S2 will be compared as follows:
//
//    i) compute ri = #removed(U,Si), ci = #changed(U,Si)
//
//    ii) S1 is better than S2 iff r1 < r2 or (r1=r2 and c1<c2)
public class ParanoidOptimizationFunction extends OptimizationFunction {
    @SuppressWarnings("unused")
    private static final Log log = LogFactory.getLog(ParanoidOptimizationFunction.class);

    public List<WeightedObject<Object>> createOptimizationFunction(InstallableUnit metaIu) {
        List<WeightedObject<Object>> weightedObjects = new ArrayList<WeightedObject<Object>>();
        BigInteger weight = BigInteger.valueOf(slice.size() + 1);
        removed(weightedObjects, weight, metaIu);
        changed(weightedObjects, BigInteger.ONE, metaIu);
        if (!weightedObjects.isEmpty()) {
            return weightedObjects;
        }
        return null;
    }

    public String getName() {
        return "misc 2010 paranoid";
    }

    public String printSolutionValue() {
        StringBuilder sb = new StringBuilder();
        int removed = 0, changed = 0;
        List<AbstractVariable> proof = new ArrayList<AbstractVariable>();
        for (int i = 0; i < removalVariables.size(); i++) {
            AbstractVariable var = removalVariables.get(i);
            if (dependencyHelper.getBooleanValueFor(var)) {
                removed++;
                proof.add(var);
            }
        }
        for (int i = 0; i < changeVariables.size(); i++) {
            AbstractVariable var = changeVariables.get(i);
            if (dependencyHelper.getBooleanValueFor(var)) {
                changed++;
                proof.add(var);
            }
        }
        sb.append("# Paranoid criteria value: -" + removed + ", -" + changed + "\n");
        sb.append("# Proof: " + proof + "\n");
        return sb.toString();
    }
}