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Java > Open Source Codes > gov > nasa > jpf > search > heuristic > MostBlocked


1 //
2 // Copyright (C) 2005 United States Government as represented by the
3 // Administrator of the National Aeronautics and Space Administration
4 // (NASA). All Rights Reserved.
5 //
6 // This software is distributed under the NASA Open Source Agreement
7 // (NOSA), version 1.3. The NOSA has been approved by the Open Source
8 // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
9 // directory tree for the complete NOSA document.
10 //
11 // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12 // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13 // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14 // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15 // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16 // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17 // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18 //
19 package gov.nasa.jpf.search.heuristic;
20
21 import gov.nasa.jpf.VM;
22
23
24 /**
25  * Heuristic state prioriizer that maximizes number of blocked states. This
26  * is a classic heuristic for finding deadlocks, since a deadlock requires
27  * all threads to be blocked.
28  */
29 public class MostBlocked implements Heuristic {
30   VM vm;
31
32   public MostBlocked (HeuristicSearch hSearch) {
33     vm = hSearch.getVM();
34   }
35
36   public int heuristicValue () {
37     int alive = vm.getAliveThreadCount();
38     int runnable = vm.getRunnableThreadCount();
39
40     // pcm - the (iSystemState based) condition was "!runnable && alive"
41 // the '10000' is just a potential max thread count
42 int h_value = (10000 - (alive - runnable));
43
44     return h_value;
45   }
46
47   public void processParent () {
48   }
49 }
50
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