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Java > Open Source Codes > gov > nasa > jpf > jvm > bytecode > MONITORENTER


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.jvm.bytecode;
20
21 import gov.nasa.jpf.jvm.KernelState;
22 import gov.nasa.jpf.jvm.SystemState;
23 import gov.nasa.jpf.jvm.ThreadInfo;
24
25 import org.apache.bcel.classfile.ConstantPool;
26 import gov.nasa.jpf.jvm.ElementInfo;
27
28
29 /**
30  * Enter monitor for object
31  * ..., objectref => ...
32  */
33 public class MONITORENTER extends Instruction {
34   public boolean isExecutable (SystemState ss, KernelState ks, ThreadInfo th) {
35     int objref = th.peek();
36     boolean isExec = ks.da.get(objref).canLock(th);
37
38     return isExec;
39   }
40
41   public void setPeer (org.apache.bcel.generic.Instruction i, ConstantPool cp) {
42   }
43
44   public Instruction execute (SystemState ss, KernelState ks, ThreadInfo th) {
45     int objref = th.pop();
46
47     ks.da.get(objref).lock(th);
48
49     return getNext(th);
50   }
51
52   public boolean isSchedulingRelevant (SystemState ss, KernelState ks, ThreadInfo ti) {
53     int objref = ti.peek();
54     ElementInfo ei = ks.da.get(objref);
55     
56     if (mi.isBodySchedulingRelevant(ti,ei) && (ei.getLockCount() == 0)) {
57       // only relevant if there are other runnables
58 return ti.hasOtherRunnables();
59     } else {
60       // it's either not executable, or we already have the lock, or we don't care
61 return false;
62     }
63   }
64   
65   public int getByteCode () {
66     return 0xC2;
67   }
68 }
69
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