--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/tests/gov/nasa/jpf/test/mc/basic/CascadedCGTest.java	Fri Jan 23 10:14:01 2015 -0800
@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2014, United States Government, as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All rights reserved.
+ *
+ * The Java Pathfinder core (jpf-core) platform is licensed under the
+ * Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ *        http://www.apache.org/licenses/LICENSE-2.0. 
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and 
+ * limitations under the License.
+ */
+
+package gov.nasa.jpf.test.mc.basic;
+
+
+import gov.nasa.jpf.ListenerAdapter;
+import gov.nasa.jpf.jvm.bytecode.EXECUTENATIVE;
+import gov.nasa.jpf.jvm.bytecode.GETFIELD;
+import gov.nasa.jpf.search.Search;
+import gov.nasa.jpf.util.test.TestJPF;
+import gov.nasa.jpf.vm.ChoiceGenerator;
+import gov.nasa.jpf.vm.FieldInfo;
+import gov.nasa.jpf.vm.Instruction;
+import gov.nasa.jpf.vm.VM;
+import gov.nasa.jpf.vm.StackFrame;
+import gov.nasa.jpf.vm.SystemState;
+import gov.nasa.jpf.vm.ThreadInfo;
+import gov.nasa.jpf.vm.Verify;
+import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
+import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
+
+import org.junit.Test;
+
+/**
+ * regression test for cascaded ChoiceGenerators
+ */
+public class CascadedCGTest extends TestJPF {
+
+  public static class IntChoiceCascader extends ListenerAdapter {
+    static int result;
+
+    @Override
+    public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
+      SystemState ss = vm.getSystemState();
+
+      if (executedInsn instanceof EXECUTENATIVE) { // break on native method exec
+        EXECUTENATIVE exec = (EXECUTENATIVE) executedInsn;
+
+        if (exec.getExecutedMethodName().equals("getInt")){// this insn did create a CG
+          if (!ti.isFirstStepInsn()){
+            result = 0;
+
+            IntIntervalGenerator cg = new IntIntervalGenerator("listenerCG", 3,4);
+            ss.setNextChoiceGenerator(cg);
+            System.out.println("# listener registered " + cg);
+
+          } else { // reexecution
+
+            ChoiceGenerator<?>[] curCGs = ss.getCurrentChoiceGenerators();
+            assert curCGs.length == 2;
+
+            IntIntervalGenerator cg = ss.getCurrentChoiceGenerator("listenerCG", IntIntervalGenerator.class);
+            assert cg != null : "no 'listenerCG' IntIntervalGenerator found";
+            int i = cg.getNextChoice();
+            System.out.println("# current listener CG choice: " + i);
+
+            cg = ss.getCurrentChoiceGenerator("verifyGetInt(II)", IntIntervalGenerator.class);
+            assert cg != null : "no 'verifyGetInt(II)' IntIntervalGenerator found";
+            int j = cg.getNextChoice();
+            System.out.println("# current insn CG choice: " + j);
+
+            result += i * j;
+          }
+        }
+      }
+    }
+  }
+
+  @Test
+  public void testCascadedIntIntervals () {
+    if (verifyNoPropertyViolation("+listener=.test.mc.basic.CascadedCGTest$IntChoiceCascader")){
+      int i = Verify.getInt( 1, 2);
+      System.out.print("i=");
+      System.out.println(i);
+    } else {
+      assert IntChoiceCascader.result == 21;
+    }
+  }
+
+
+  //--- mixed data and thread CG
+
+  // this listener replaces all GETFIELD "mySharedField" results with configured
+  // choice values (i.e. it is a simplified field Perturbator).
+  // The demo point is that it is not aware of that such GETFIELDs might also be
+  // scheduling points because of shared object field access, and it should work
+  // the same no matter if there also was a ThreadChoice/context switch or not
+
+  // NOTE: while the cascaded CG interface is easy to use (almost the same as the
+  // single CG interface), the context can be quite tricky because the cascaded
+  // CG (the scheduling point in this case) means the corresponding instruction
+  // is already rescheduled and might have been cut short in insn specific ways
+  // (in this case before pushing the field value on the operand stack). For this
+  // reason a simple ti.isFirstStepInsn() check is not sufficient. There might not
+  // have been a reschedule if there was only one thread, or even if this is the
+  // first step insn, the corresponding CG might have been not related to the
+  // getfield but some action in the preceeding thread (e.g. a terminate).
+  // In this case, the simple solution is based on that we want the data CG
+  // unconditionally, so we check if there is a corresponding current CG
+  // (which means this is not the first step insn)
+
+  public static class FieldAccessCascader extends ListenerAdapter {
+
+    @Override
+    public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
+      SystemState ss = vm.getSystemState();
+
+      if (executedInsn instanceof GETFIELD){
+        GETFIELD getInsn = (GETFIELD) executedInsn;
+        FieldInfo fi = getInsn.getFieldInfo();
+        if (fi.getName().equals("mySharedField")){
+
+          IntChoiceFromSet cg = ss.getCurrentChoiceGenerator("fieldReplace", IntChoiceFromSet.class);
+          if (cg == null){
+
+            // we might get here after a preceding rescheduling exec, i.e.
+            // partial execution (with successive re-execution), or after
+            // non-rescheduling exec has been completed (only one runnable thread).
+            // In the first case we have to restore the operand stack so that
+            // we can reexecute
+            if (!ti.willReExecuteInstruction()){
+              // restore old operand stack contents
+              StackFrame frame = ti.getModifiableTopFrame();
+
+              frame.pop();
+              frame.pushRef( getInsn.getLastThis());
+            }
+
+            cg = new IntChoiceFromSet("fieldReplace", 42, 43);
+            ss.setNextChoiceGenerator(cg);
+            ti.reExecuteInstruction();
+
+            System.out.println("# listener registered CG: " + cg);
+
+          } else {
+            StackFrame frame = ti.getModifiableTopFrame();
+
+            int v = cg.getNextChoice();
+            int n = frame.pop();
+            frame.push(v);
+
+            System.out.println("# listener replacing " + n + " with " + v);
+          }
+        }
+      }
+    }
+
+    //--- those are just for debugging purposes
+    @Override
+    public void stateBacktracked(Search search) {
+      System.out.println("#------ [" + search.getDepth() + "] backtrack: " + search.getStateId());
+    }
+    
+    @Override
+    public void stateAdvanced(Search search){
+      System.out.println("#------ " + search.getStateId() + " isNew: " + search.isNewState() + ", isEnd: " + search.isEndState());
+    }
+    
+    @Override
+    public void threadScheduled(VM vm, ThreadInfo ti){
+      System.out.println("# running thread: " + ti);
+    }
+    
+    @Override
+    public void threadTerminated(VM vm, ThreadInfo ti){
+      System.out.println("# terminated thread: " + ti);
+    }
+    
+    @Override
+    public void threadStarted(VM vm, ThreadInfo ti){
+      System.out.println("# started thread: " + ti);
+    }
+    
+    @Override
+    public void choiceGeneratorAdvanced (VM vm, ChoiceGenerator<?> currentCG) {
+      System.out.println("# choice: " + currentCG);
+    }
+  }
+
+  int mySharedField = -1;
+
+  @Test
+  public void testMixedThreadDataCGs () {
+    if (verifyNoPropertyViolation("+listener=.test.mc.basic.CascadedCGTest$FieldAccessCascader")){
+      Thread t = new Thread(){
+        @Override
+		public void run() {
+          int n = mySharedField;
+          System.out.print("<thread> mySharedField read: ");
+          System.out.println( n);
+          assert n == 42 || n == 43; // regardless of main thread exec state
+        }
+      };
+      t.start();
+
+      mySharedField = 7;
+      System.out.println("<main> mySharedField write: 7");
+    }
+  }
+}