001package org.cpsolver.ifs.assignment;
002
003import java.util.Collection;
004import java.util.HashMap;
005import java.util.Map;
006import java.util.concurrent.locks.Lock;
007
008import org.cpsolver.ifs.assignment.context.AssignmentContextHolder;
009import org.cpsolver.ifs.assignment.context.DefaultParallelAssignmentContextHolder;
010import org.cpsolver.ifs.model.Model;
011import org.cpsolver.ifs.model.Value;
012import org.cpsolver.ifs.model.Variable;
013import org.cpsolver.ifs.solution.Solution;
014import org.cpsolver.ifs.solver.ParallelSolver;
015
016
017/**
018 * An assignment using the {@link Variable#getAssignments()} to store values of all the
019 * variables of the model. Besides of that, a set of assigned variables is kept in memory.
020 * Each extra contains an array of values, indexed by {@link Assignment#getIndex()}.
021 * Useful for a small, fixed number of assignments. Used by the {@link ParallelSolver},
022 * where there is one assignment for each thread. 
023 * 
024 * @see Assignment
025 * @see ParallelSolver
026 * 
027 * @author  Tomáš Müller
028 * @version IFS 1.3 (Iterative Forward Search)<br>
029 *          Copyright (C) 2014 Tomáš Müller<br>
030 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
031 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
032 * <br>
033 *          This library is free software; you can redistribute it and/or modify
034 *          it under the terms of the GNU Lesser General Public License as
035 *          published by the Free Software Foundation; either version 3 of the
036 *          License, or (at your option) any later version. <br>
037 * <br>
038 *          This library is distributed in the hope that it will be useful, but
039 *          WITHOUT ANY WARRANTY; without even the implied warranty of
040 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
041 *          Lesser General Public License for more details. <br>
042 * <br>
043 *          You should have received a copy of the GNU Lesser General Public
044 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
045 * @param <V> Variable
046 * @param <T> Value
047 **/
048public class DefaultParallelAssignment <V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentAbstract<V, T> {
049    private Map<V, Long> iAssignedVariables = new HashMap<V, Long>();
050    private int iIndex;
051
052    public DefaultParallelAssignment(int threadIndex) {
053        super(new DefaultParallelAssignmentContextHolder<V, T>(threadIndex));
054        iIndex = threadIndex;
055    }
056    
057    public DefaultParallelAssignment() {
058        this(0);
059    }
060    
061    public DefaultParallelAssignment(int threadIndex, Model<V, T> model, Assignment<V, T> assignment) {
062        this(threadIndex);
063        for (V variable: model.variables())
064            setValueInternal(0, variable, assignment != null ? assignment.getValue(variable) : null);
065    }
066    
067    public DefaultParallelAssignment(AssignmentContextHolder<V, T> contexts, int threadIndex, Solution<V, T> solution) {
068        super(contexts);
069        iIndex = threadIndex;
070        Lock lock = solution.getLock().readLock();
071        lock.lock();
072        try {
073            for (V variable: solution.getModel().variables())
074                setValueInternal(0, variable, solution.getAssignment().getValue(variable));
075        } finally {
076            lock.unlock();
077        }
078    }
079
080    @Override
081    public long getIteration(V variable) {
082        Long it = iAssignedVariables.get(variable);
083        return (it == null ? 0 : it.longValue());
084    }
085
086    @Override
087    public Collection<V> assignedVariables() {
088        return iAssignedVariables.keySet();
089    }
090    
091    @Override
092    @SuppressWarnings({ "deprecation", "unchecked" })
093    protected T getValueInternal(V variable) {
094        return (T) variable.getAssignments()[iIndex];
095    }
096    
097    @Override
098    @SuppressWarnings("deprecation")
099    protected void setValueInternal(long iteration, V variable, T value) {
100        variable.getAssignments()[iIndex] = value;
101        if (value == null)
102            iAssignedVariables.remove(variable);
103        else
104            iAssignedVariables.put(variable, iteration);
105    }
106
107    @Override
108    public int getIndex() {
109        return iIndex;
110    }
111}