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 * @version IFS 1.3 (Iterative Forward Search)<br>
028 *          Copyright (C) 2014 Tomáš Müller<br>
029 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
030 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
031 * <br>
032 *          This library is free software; you can redistribute it and/or modify
033 *          it under the terms of the GNU Lesser General Public License as
034 *          published by the Free Software Foundation; either version 3 of the
035 *          License, or (at your option) any later version. <br>
036 * <br>
037 *          This library is distributed in the hope that it will be useful, but
038 *          WITHOUT ANY WARRANTY; without even the implied warranty of
039 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
040 *          Lesser General Public License for more details. <br>
041 * <br>
042 *          You should have received a copy of the GNU Lesser General Public
043 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
044 * @param <V> Variable
045 * @param <T> Value
046 **/
047public class DefaultParallelAssignment <V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentAbstract<V, T> {
048    private Map<V, Long> iAssignedVariables = new HashMap<V, Long>();
049    private int iIndex;
050
051    public DefaultParallelAssignment(int threadIndex) {
052        super(new DefaultParallelAssignmentContextHolder<V, T>(threadIndex));
053        iIndex = threadIndex;
054    }
055    
056    public DefaultParallelAssignment() {
057        this(0);
058    }
059    
060    public DefaultParallelAssignment(int threadIndex, Model<V, T> model, Assignment<V, T> assignment) {
061        this(threadIndex);
062        for (V variable: model.variables())
063            setValueInternal(0, variable, assignment != null ? assignment.getValue(variable) : null);
064    }
065    
066    public DefaultParallelAssignment(AssignmentContextHolder<V, T> contexts, int threadIndex, Solution<V, T> solution) {
067        super(contexts);
068        iIndex = threadIndex;
069        Lock lock = solution.getLock().readLock();
070        lock.lock();
071        try {
072            for (V variable: solution.getModel().variables())
073                setValueInternal(0, variable, solution.getAssignment().getValue(variable));
074        } finally {
075            lock.unlock();
076        }
077    }
078
079    @Override
080    public long getIteration(V variable) {
081        Long it = iAssignedVariables.get(variable);
082        return (it == null ? 0 : it.longValue());
083    }
084
085    @Override
086    public Collection<V> assignedVariables() {
087        return iAssignedVariables.keySet();
088    }
089    
090    @Override
091    @SuppressWarnings({ "deprecation", "unchecked" })
092    protected T getValueInternal(V variable) {
093        return (T) variable.getAssignments()[iIndex];
094    }
095    
096    @Override
097    @SuppressWarnings("deprecation")
098    protected void setValueInternal(long iteration, V variable, T value) {
099        variable.getAssignments()[iIndex] = value;
100        if (value == null)
101            iAssignedVariables.remove(variable);
102        else
103            iAssignedVariables.put(variable, iteration);
104    }
105
106    @Override
107    public int getIndex() {
108        return iIndex;
109    }
110}