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.Config;
22: import gov.nasa.jpf.VM;
23: import gov.nasa.jpf.jvm.TrailInfo;
24:
25: /**
26: * heuristic state prioritizer that tries to minimize re-scheduling
27: */
28: public class GlobalSwitchThread implements Heuristic {
29: private int[] threads;
30: VM vm;
31:
32: public GlobalSwitchThread(Config config, HeuristicSearch hSearch) {
33: int threadHistorySize = config.getInt(
34: "search.heuristic.thread_history_size", 10);
35:
36: vm = hSearch.getVM();
37: threads = new int[threadHistorySize];
38:
39: for (int i = 0; i < threads.length; i++) {
40: threads[i] = -1;
41: }
42: }
43:
44: public int heuristicValue() {
45: int aliveThreads = vm.getAliveThreadCount();
46:
47: int lastRun = ((TrailInfo) vm.getLastTransition()).getThread();
48: int h_value = 0;
49:
50: if (aliveThreads > 1) {
51: for (int i = 0; i < threads.length; i++) {
52: if (lastRun == threads[i]) {
53: h_value += ((threads.length - i) * aliveThreads);
54: }
55: }
56: }
57:
58: int temp0 = threads[0];
59: int temp1;
60: threads[0] = lastRun;
61:
62: for (int i = 1; i < threads.length; i++) {
63: temp1 = threads[i];
64: threads[i] = temp0;
65: temp0 = temp1;
66: }
67:
68: return h_value;
69: }
70:
71: public void processParent() {
72: }
73: }
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