import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
-import java.awt.*;
import java.io.PrintWriter;
import java.util.*;
private ArrayList<BacktrackPoint> backtrackPointList; // Record backtrack points (CG, state Id, and choice)
private HashMap<Integer, HashSet<Integer>> conflictPairMap; // Record conflicting events
private HashSet<String> doneBacktrackSet; // Record state ID and trace already constructed
+ private HashMap<Integer,Integer> newStateEventMap; // Record event producing a new state ID
private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
private HashMap<Integer, RestorableVMState> restorableStateMap; // Maps state IDs to the restorable state object
// Visible operation dependency graph implementation (SPIN paper) related fields
+ private int currChoiceValue;
private int prevChoiceValue;
private HashMap<Integer, HashSet<Integer>> vodGraphMap; // Visible operation dependency graph (VOD graph)
private boolean isBooleanCGFlipped;
private boolean isEndOfExecution;
+ // Statistics
+ private int numOfTransitions;
+
public DPORStateReducer(Config config, JPF jpf) {
verboseMode = config.getBoolean("printout_state_transition", false);
stateReductionMode = config.getBoolean("activate_state_reduction", true);
out = null;
}
isBooleanCGFlipped = false;
+ numOfTransitions = 0;
restorableStateMap = new HashMap<>();
initializeStatesVariables();
}
@Override
public void searchFinished(Search search) {
if (verboseMode) {
+ out.println("\n==> DEBUG: ----------------------------------- search finished");
+ out.println("\n==> DEBUG: State reduction mode : " + stateReductionMode);
+ out.println("\n==> DEBUG: Number of transitions : " + numOfTransitions);
out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
}
}
fairSchedulingAndBacktrackPoint(icsCG, vm);
// Map state to event
mapStateToEvent(icsCG.getNextChoice());
- // Update the VOD graph always with the latest
- updateVODGraph(icsCG.getNextChoice());
- // Check if we have seen this state or this state contains cycles that involve all events
- if (terminateCurrentExecution()) {
+ // Explore the next backtrack point:
+ // 1) if we have seen this state or this state contains cycles that involve all events, and
+ // 2) after the current CG is advanced at least once
+ if (terminateCurrentExecution() && choiceCounter > 0) {
exploreNextBacktrackPoints(vm, icsCG);
+ } else {
+ numOfTransitions++;
}
justVisitedStates.clear();
choiceCounter++;
}
+ } else {
+ numOfTransitions++;
}
}
if (isConflictFound(nextInsn, eventCounter, currentChoice, fieldClass) &&
isNewConflict(currentChoice, eventCounter)) {
// Lines 4-8 of the algorithm in the paper page 11 (see the heading note above)
- if (vm.isNewState() || isReachableInVODGraph(currentChoice)) {
+ if (vm.isNewState() || isReachableInVODGraph(currentChoice, vm)) {
createBacktrackingPoint(currentChoice, eventCounter);
}
}
icsCG.setChoice(currCGIndex, expectedChoice);
}
}
+ // Update current choice
+ currChoiceValue = refChoices[choiceIndex];
// Record state ID and choice/event as backtrack point
int stateId = vm.getStateId();
backtrackPointList.add(new BacktrackPoint(icsCG, stateId, refChoices[choiceIndex]));
backtrackPointList = new ArrayList<>();
conflictPairMap = new HashMap<>();
doneBacktrackSet = new HashSet<>();
+ newStateEventMap = new HashMap<>();
readWriteFieldsMap = new HashMap<>();
// VOD graph
+ currChoiceValue = 0;
prevChoiceValue = -1;
vodGraphMap = new HashMap<>();
// Booleans
stateToEventMap.put(stateId, eventSet);
}
justVisitedStates.add(stateId);
+ // Update the VOD graph when there is a new state
+ updateVODGraph(search.getVM());
}
// --- Functions related to Read/Write access analysis on shared fields
private void exploreNextBacktrackPoints(VM vm, IntChoiceFromSet icsCG) {
- // We can start exploring the next backtrack point after the current CG is advanced at least once
- if (choiceCounter > 0) {
- // Check if we are reaching the end of our execution: no more backtracking points to explore
- // cgMap, backtrackMap, backtrackStateQ are updated simultaneously (checking backtrackStateQ is enough)
- if (!backtrackStateQ.isEmpty()) {
- // Set done all the other backtrack points
- for (BacktrackPoint backtrackPoint : backtrackPointList) {
- backtrackPoint.getBacktrackCG().setDone();
- }
- // Reset the next backtrack point with the latest state
- int hiStateId = backtrackStateQ.peek();
- // Restore the state first if necessary
- if (vm.getStateId() != hiStateId) {
- RestorableVMState restorableState = restorableStateMap.get(hiStateId);
- vm.restoreState(restorableState);
- }
- // Set the backtrack CG
- IntChoiceFromSet backtrackCG = (IntChoiceFromSet) vm.getChoiceGenerator();
- setBacktrackCG(hiStateId, backtrackCG);
- } else {
- // Set done this last CG (we save a few rounds)
- icsCG.setDone();
- }
- // Save all the visited states when starting a new execution of trace
- prevVisitedStates.addAll(currVisitedStates);
- currVisitedStates.clear();
- // This marks a transitional period to the new CG
- isEndOfExecution = true;
- }
+ // Check if we are reaching the end of our execution: no more backtracking points to explore
+ // cgMap, backtrackMap, backtrackStateQ are updated simultaneously (checking backtrackStateQ is enough)
+ if (!backtrackStateQ.isEmpty()) {
+ // Set done all the other backtrack points
+ for (BacktrackPoint backtrackPoint : backtrackPointList) {
+ backtrackPoint.getBacktrackCG().setDone();
+ }
+ // Reset the next backtrack point with the latest state
+ int hiStateId = backtrackStateQ.peek();
+ // Restore the state first if necessary
+ if (vm.getStateId() != hiStateId) {
+ RestorableVMState restorableState = restorableStateMap.get(hiStateId);
+ vm.restoreState(restorableState);
+ }
+ // Set the backtrack CG
+ IntChoiceFromSet backtrackCG = (IntChoiceFromSet) vm.getChoiceGenerator();
+ setBacktrackCG(hiStateId, backtrackCG);
+ } else {
+ // Set done this last CG (we save a few rounds)
+ icsCG.setDone();
+ }
+ // Save all the visited states when starting a new execution of trace
+ prevVisitedStates.addAll(currVisitedStates);
+ currVisitedStates.clear();
+ // This marks a transitional period to the new CG
+ isEndOfExecution = true;
}
private ReadWriteSet getReadWriteSet(int currentChoice) {
// --- Functions related to the visible operation dependency graph implementation discussed in the SPIN paper
- // This method checks whether a choice is reachable in the VOD graph from a reference choice (BFS algorithm)
- //private boolean isReachableInVODGraph(int checkedChoice, int referenceChoice) {
- private boolean isReachableInVODGraph(int currentChoice) {
- // Extract previous and current events
+ // This method checks whether a choice/event (transition) is reachable from the choice/event that produces
+ // the state right before this state in the VOD graph
+ // We use a BFS algorithm for this purpose
+ private boolean isReachableInVODGraph(int currentChoice, VM vm) {
+ // Current event
int choiceIndex = currentChoice % refChoices.length;
- int prevChoIndex = (currentChoice - 1) % refChoices.length;
int currEvent = refChoices[choiceIndex];
- int prevEvent = refChoices[prevChoIndex];
- // Record visited choices as we search in the graph
- HashSet<Integer> visitedChoice = new HashSet<>();
- visitedChoice.add(prevEvent);
- LinkedList<Integer> nodesToVisit = new LinkedList<>();
- // If the state doesn't advance as the threads/sub-programs are executed (basically there is no new state),
- // there is a chance that the graph doesn't have new nodes---thus this check will return a null.
+ // Previous event
+ int stateId = vm.getStateId(); // A state that has been seen
+ int prevEvent = newStateEventMap.get(stateId);
+ // Only start traversing the graph if prevEvent has an outgoing edge
if (vodGraphMap.containsKey(prevEvent)) {
+ // Record visited choices as we search in the graph
+ HashSet<Integer> visitedChoice = new HashSet<>();
+ visitedChoice.add(prevEvent);
+ // Get the first nodes to visit (the neighbors of prevEvent)
+ LinkedList<Integer> nodesToVisit = new LinkedList<>();
nodesToVisit.addAll(vodGraphMap.get(prevEvent));
- while(!nodesToVisit.isEmpty()) {
- int choice = nodesToVisit.getFirst();
+ // Traverse the graph using BFS
+ while (!nodesToVisit.isEmpty()) {
+ int choice = nodesToVisit.removeFirst();
if (choice == currEvent) {
return true;
}
- if (visitedChoice.contains(choice)) { // If there is a loop then we don't find it
- return false;
+ if (visitedChoice.contains(choice)) { // If there is a loop then just continue the exploration
+ continue;
}
// Continue searching
visitedChoice.add(choice);
return false;
}
- private void updateVODGraph(int currChoiceValue) {
- // Update the graph when we have the current choice value
- HashSet<Integer> choiceSet;
- if (vodGraphMap.containsKey(prevChoiceValue)) {
- // If the key already exists, just retrieve it
- choiceSet = vodGraphMap.get(prevChoiceValue);
- } else {
- // Create a new entry
- choiceSet = new HashSet<>();
- vodGraphMap.put(prevChoiceValue, choiceSet);
+ private void updateVODGraph(VM vm) {
+ // Do this only if it is a new state
+ if (vm.isNewState()) {
+ // Update the graph when we have the current choice value
+ HashSet<Integer> choiceSet;
+ if (vodGraphMap.containsKey(prevChoiceValue)) {
+ // If the key already exists, just retrieve it
+ choiceSet = vodGraphMap.get(prevChoiceValue);
+ } else {
+ // Create a new entry
+ choiceSet = new HashSet<>();
+ vodGraphMap.put(prevChoiceValue, choiceSet);
+ }
+ choiceSet.add(currChoiceValue);
+ prevChoiceValue = currChoiceValue;
+ // Map this state ID to the event (transition) that produces it
+ newStateEventMap.put(vm.getStateId(), currChoiceValue);
}
- choiceSet.add(currChoiceValue);
- prevChoiceValue = currChoiceValue;
}
}
projects / jpf-core.git / blobdiff