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LockLit.java

package edu.ksu.cis.bandera.bir;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Bandera, a Java(TM) analysis and transformation toolkit           *
 * Copyright (C) 1998, 1999   James Corbett (corbett@hawaii.edu)     *
 * All rights reserved.                                              *
 *                                                                   *
 * This work was done as a project in the SAnToS Laboratory,         *
 * Department of Computing and Information Sciences, Kansas State    *
 * University, USA (http://www.cis.ksu.edu/santos).                  *
 * It is understood that any modification not identified as such is  *
 * not covered by the preceding statement.                           *
 *                                                                   *
 * This work is free software; you can redistribute it and/or        *
 * modify it under the terms of the GNU Library General Public       *
 * License as published by the Free Software Foundation; either      *
 * version 2 of the License, or (at your option) any later version.  *
 *                                                                   *
 * This work 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 *
 * Library General Public License for more details.                  *
 *                                                                   *
 * You should have received a copy of the GNU Library General Public *
 * License along with this toolkit; if not, write to the             *
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,      *
 * Boston, MA  02111-1307, USA.                                      *
 *                                                                   *
 * Java is a trademark of Sun Microsystems, Inc.                     *
 *                                                                   *
 * To submit a bug report, send a comment, or get the latest news on *
 * this project and other SAnToS projects, please visit the web-site *
 *                http://www.cis.ksu.edu/santos                      *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
import ca.mcgill.sable.util.*;

import java.util.*;

/**
 * A lock literal value.
 * <p>
 * Can only appear in a BirState (not in transition system source).
 */

public class LockLit implements Literal, BirConstants, Cloneable {

    int heldCount = 0;       // number of times acquired (0 if free)
    BirThread owner = null;  // acquiring thread
    boolean [] waiting;
    int [] waitHeldCount;
    TransSystem system;
    int numThreads;

    public LockLit(TransSystem system) {
    this.system = system;
    numThreads = system.getThreads().size();
    waiting = new boolean[numThreads];
    waitHeldCount = new int[numThreads];
    }
    public void apply(Switch sw)
    {
        ((ExprSwitch) sw).caseLockLit(this);
    }
    public BirThread getOwner() { return owner; }
    public TransSystem getSystem() { return system; }
    public Type getType() { return Type.WR_lockType; }
    public ThreadVector getWaitingThreads() {
    ThreadVector waitThreads = new ThreadVector();
    ThreadVector threads = system.getThreads();
    for (int i = 0; i < threads.size(); i++) {
        BirThread thread = threads.elementAt(i);
        if (waiting[thread.getId()])
        waitThreads.addElement(thread);
    }
    return waitThreads;
    }
    public LockLit nextState(int operation, BirThread thread, int choice) {
    LockLit nextState;
    try {
        nextState = (LockLit) this.clone();
    } catch (CloneNotSupportedException e) { return null; }
    switch (operation) {
    case LOCK: 
        if (owner == null)
        nextState.owner = thread;
        else 
        nextState.heldCount++;
        break;
    case UNLOCK: 
        if (heldCount == 0)
        nextState.owner = null;
        else 
        nextState.heldCount--;
        break;
    case WAIT: 
        nextState.waiting = (boolean []) waiting.clone();
        nextState.waiting[thread.getId()] = true;
        nextState.waitHeldCount = (int []) waitHeldCount.clone();
        nextState.waitHeldCount[thread.getId()] = heldCount;
        nextState.owner = null;
        break;
    case UNWAIT:
        nextState.heldCount = waitHeldCount[thread.getId()];
        nextState.owner = thread;
        break;
    case NOTIFY:
        nextState.waiting = (boolean []) waiting.clone();
        if (choice < numThreads)
        nextState.waiting[choice] = false;
        break;
    case NOTIFYALL:
        nextState.waiting = (boolean []) waiting.clone();
        for (int i = 0; i < numThreads; i++)
        nextState.waiting[i] = false;
        break;
    default:
        throw new RuntimeException("Bad operation code");
    }
    return nextState;
    }
    public boolean queryState(int operation, BirThread thread) {
    switch (operation) {
    case LOCK_AVAILABLE: 
        return owner == null;
    case HAS_LOCK: 
        return owner == thread;
    case WAS_NOTIFIED: 
        return ! waiting[thread.getId()];
    default:
        throw new RuntimeException("Bad operation code");
    }
    }
    public String toString() {
    String result = (owner == null) ? "Lock:*" : "Lock:" + owner.getName();
    for (int i = 0; i < numThreads; i++)
        if (waiting[i])
        result += "," + i;
    return "<" + result + ">";
    }
}

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