01: //
02: // Copyright (C) 2005 United States Government as represented by the
03: // Administrator of the National Aeronautics and Space Administration
04: // (NASA). All Rights Reserved.
05: //
06: // This software is distributed under the NASA Open Source Agreement
07: // (NOSA), version 1.3. The NOSA has been approved by the Open Source
08: // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
09: // 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: * Heuristic state prioriizer that maximizes number of blocked states. This
25: * is a classic heuristic for finding deadlocks, since a deadlock requires
26: * all threads to be blocked.
27: */
28: public class MostBlocked implements Heuristic {
29: VM vm;
30:
31: public MostBlocked(HeuristicSearch hSearch) {
32: vm = hSearch.getVM();
33: }
34:
35: public int heuristicValue() {
36: int alive = vm.getAliveThreadCount();
37: int runnable = vm.getRunnableThreadCount();
38:
39: // pcm - the (iSystemState based) condition was "!runnable && alive"
40: // the '10000' is just a potential max thread count
41: int h_value = (10000 - (alive - runnable));
42:
43: return h_value;
44: }
45:
46: public void processParent() {
47: }
48: }
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