private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
private HashMap<Integer, HashSet<Integer>> stateToEventMap;
// Data structure to analyze field Read/Write accesses and conflicts
- private HashMap<Integer, LinkedList<Integer[]>> backtrackMap; // Track created backtracking points
- private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
- private ArrayList<BacktrackPoint> backtrackPointList; // Record backtrack points (CG and choice)
- private HashMap<Integer, IntChoiceFromSet> cgMap; // Maps state IDs to CGs
- private HashMap<Integer, HashSet<Integer>> conflictPairMap; // Record conflicting events
- private HashSet<String> doneBacktrackSet; // Record state ID and trace that are done
- private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
+ private HashMap<Integer, LinkedList<Integer[]>> backtrackMap; // Track created backtracking points
+ private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
+ 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, 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 prevChoiceValue;
out = null;
}
isBooleanCGFlipped = false;
+ restorableStateMap = new HashMap<>();
initializeStatesVariables();
}
// Use a modulo since choiceCounter is going to keep increasing
int choiceIndex = choiceCounter % choices.length;
icsCG.advance(choices[choiceIndex]);
- // Index the ChoiceGenerator to set backtracking points
- BacktrackPoint backtrackPoint = new BacktrackPoint(icsCG, choices[choiceIndex]);
- backtrackPointList.add(backtrackPoint);
} else {
// Set done all CGs while transitioning to a new execution
icsCG.setDone();
if (currentCG instanceof IntChoiceFromSet) {
IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
// If this is a new CG then we need to update data structures
- resetStatesForNewExecution(icsCG);
+ resetStatesForNewExecution(icsCG, vm);
// If we don't see a fair scheduling of events/choices then we have to enforce it
- checkAndEnforceFairScheduling(icsCG);
+ 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()) {
- exploreNextBacktrackPoints(icsCG);
+ exploreNextBacktrackPoints(vm, icsCG);
}
justVisitedStates.clear();
choiceCounter++;
}
}
- // This class compactly stores backtracking points: 1) backtracking ChoiceGenerator, and 2) backtracking choices
+ // This class compactly stores backtrack points: 1) backtrack state ID, and 2) backtracking choices
private class BacktrackPoint {
- private IntChoiceFromSet backtrackCG; // CG to backtrack from
+ private IntChoiceFromSet backtrackCG; // CG at this backtrack point
+ private int stateId; // State at this backtrack point
private int choice; // Choice chosen at this backtrack point
- public BacktrackPoint(IntChoiceFromSet cg, int cho) {
+ public BacktrackPoint(IntChoiceFromSet cg, int stId, int cho) {
backtrackCG = cg;
+ stateId = stId;
choice = cho;
}
- public IntChoiceFromSet getBacktrackCG() {
- return backtrackCG;
+ public IntChoiceFromSet getBacktrackCG() { return backtrackCG; }
+
+ public int getStateId() {
+ return stateId;
}
public int getChoice() {
private final static String JAVA_STRING_LIB = "java.lang.String";
// -- FUNCTIONS
- private void checkAndEnforceFairScheduling(IntChoiceFromSet icsCG) {
+ private void fairSchedulingAndBacktrackPoint(IntChoiceFromSet icsCG, VM vm) {
// Check the next choice and if the value is not the same as the expected then force the expected value
int choiceIndex = choiceCounter % refChoices.length;
int nextChoice = icsCG.getNextChoice();
icsCG.setChoice(currCGIndex, expectedChoice);
}
}
+ // Record state ID and choice/event as backtrack point
+ backtrackPointList.add(new BacktrackPoint(icsCG, vm.getStateId(), refChoices[choiceIndex]));
}
private Integer[] copyChoices(Integer[] choicesToCopy) {
backtrackMap = new HashMap<>();
backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
backtrackPointList = new ArrayList<>();
- cgMap = new HashMap<>();
conflictPairMap = new HashMap<>();
doneBacktrackSet = new HashSet<>();
readWriteFieldsMap = new HashMap<>();
stateToEventMap.put(stateId, eventSet);
}
justVisitedStates.add(stateId);
+ // Store restorable state object for this state (always store the latest)
+ RestorableVMState restorableState = search.getVM().getRestorableState();
+ restorableStateMap.put(stateId, restorableState);
}
// --- Functions related to Read/Write access analysis on shared fields
- private void addNewBacktrackPoint(IntChoiceFromSet backtrackCG, Integer[] newChoiceList) {
- int stateId = backtrackCG.getStateId();
+ private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList) {
// Insert backtrack point to the right state ID
LinkedList<Integer[]> backtrackList;
if (backtrackMap.containsKey(stateId)) {
backtrackMap.put(stateId, backtrackList);
}
backtrackList.addFirst(newChoiceList);
- // Add CG for this state ID if there isn't one yet
- if (!cgMap.containsKey(stateId)) {
- cgMap.put(stateId, backtrackCG);
- }
// Add to priority queue
if (!backtrackStateQ.contains(stateId)) {
backtrackStateQ.add(stateId);
// If current choice is not the same, then this is caused by the firing of IntIntervalGenerator
// for certain method calls in the infrastructure, e.g., eventSince()
int currChoiceInd = currentChoice % refChoices.length;
- int currChoiceFromCG = getCurrentChoice(vm);
+ int currChoiceFromCG = 0;
+ ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
+ // This is the main event CG
+ if (currentCG instanceof IntChoiceFromSet) {
+ currChoiceFromCG = currChoiceInd;
+ } else {
+ // This is the interval CG used in device handlers
+ ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
+ currChoiceFromCG = ((IntChoiceFromSet) parentCG).getNextChoiceIndex();
+ }
if (currChoiceInd != currChoiceFromCG) {
currentChoice = (currentChoice - currChoiceInd) + currChoiceFromCG;
}
}
}
// Get the backtrack CG for this backtrack point
- IntChoiceFromSet backtrackCG = backtrackPointList.get(confEvtNum).getBacktrackCG();
+ int stateId = backtrackPointList.get(confEvtNum).getStateId();
// Check if this trace has been done starting from this state
- if (isTraceConstructed(newChoiceList, backtrackCG)) {
+ if (isTraceAlreadyConstructed(newChoiceList, stateId)) {
return;
}
//BacktrackPoint backtrackPoint = new BacktrackPoint(backtrackCG, newChoiceList);
- addNewBacktrackPoint(backtrackCG, newChoiceList);
+ addNewBacktrackPoint(stateId, newChoiceList);
}
private boolean excludeThisForItContains(String[] excludedStrings, String className) {
return false;
}
- private void exploreNextBacktrackPoints(IntChoiceFromSet icsCG) {
+ 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 (icsCG.getNextChoiceIndex() > 0) {
- HashSet<IntChoiceFromSet> backtrackCGs = new HashSet<>(cgMap.values());
+ 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()) {
- // Reset the next CG with the latest state
- int hiStateId = backtrackStateQ.peek();
- // Check with the current state and if it's lower than the highest state, we defer to this lower state
- int currStateId = icsCG.getStateId();
- if (currStateId < hiStateId && cgMap.keySet().contains(currStateId)) {
- hiStateId = currStateId;
+ // Set done all the other backtrack points
+ for (BacktrackPoint backtrackPoint : backtrackPointList) {
+ backtrackPoint.getBacktrackCG().setDone();
}
- setBacktrackCG(hiStateId, backtrackCGs);
- }
- // Clear unused CGs
- for (BacktrackPoint backtrackPoint : backtrackPointList) {
- IntChoiceFromSet cg = backtrackPoint.getBacktrackCG();
- if (!backtrackCGs.contains(cg)) {
- cg.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();
}
- backtrackPointList.clear();
// Save all the visited states when starting a new execution of trace
prevVisitedStates.addAll(currVisitedStates);
currVisitedStates.clear();
}
}
- private int getCurrentChoice(VM vm) {
- ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
- // This is the main event CG
- if (currentCG instanceof IntChoiceFromSet) {
- return ((IntChoiceFromSet) currentCG).getNextChoiceIndex();
- } else {
- // This is the interval CG used in device handlers
- ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
- return ((IntChoiceFromSet) parentCG).getNextChoiceIndex();
- }
- }
-
private ReadWriteSet getReadWriteSet(int currentChoice) {
// Do the analysis to get Read and Write accesses to fields
ReadWriteSet rwSet;
return true;
}
- private boolean isTraceConstructed(Integer[] choiceList, IntChoiceFromSet backtrackCG) {
- // Concatenate state ID and trace in a string, e.g., "1:10234"
- int stateId = backtrackCG.getStateId();
+ private boolean isTraceAlreadyConstructed(Integer[] choiceList, int stateId) {
+ // Concatenate state ID and only the first event in the string, e.g., "1:1 for the trace 10234 at state 1"
+ // TODO: THIS IS AN OPTIMIZATION!
+ // This is the optimized version because after we execute, e.g., the trace 1:10234, we don't need to try
+ // another trace that starts with event 1 at state 1, e.g., the trace 1:13024
+ // The second time this event 1 is explored, it will generate the same state as the first one
StringBuilder sb = new StringBuilder();
sb.append(stateId);
sb.append(':');
- for(Integer choice : choiceList) {
- sb.append(choice);
- }
+ sb.append(choiceList[0]);
// Check if the trace has been constructed as a backtrack point for this state
if (doneBacktrackSet.contains(sb.toString())) {
return true;
return false;
}
- private void resetStatesForNewExecution(IntChoiceFromSet icsCG) {
+ private void resetStatesForNewExecution(IntChoiceFromSet icsCG, VM vm) {
if (choices == null || choices != icsCG.getAllChoices()) {
// Reset state variables
choiceCounter = 0;
readWriteFieldsMap.clear();
stateToEventMap.clear();
isEndOfExecution = false;
- // Adding this CG as the first backtrack point for this execution
- backtrackPointList.add(new BacktrackPoint(icsCG, choices[0]));
+ backtrackPointList.clear();
}
}
- private void setBacktrackCG(int stateId, HashSet<IntChoiceFromSet> backtrackCGs) {
+ private void setBacktrackCG(int stateId, IntChoiceFromSet backtrackCG) {
// Set a backtrack CG based on a state ID
- IntChoiceFromSet backtrackCG = cgMap.get(stateId);
- // Need to reset the CGs first so that the CG last reset will be chosen next
- for (IntChoiceFromSet cg : backtrackCGs) {
- if (cg != backtrackCG && cg.getNextChoiceIndex() > -1) {
- cg.reset();
- }
- }
LinkedList<Integer[]> backtrackChoices = backtrackMap.get(stateId);
backtrackCG.setNewValues(backtrackChoices.removeLast()); // Get the last from the queue
+ backtrackCG.setStateId(stateId);
backtrackCG.reset();
// Remove from the queue if we don't have more backtrack points for that state
if (backtrackChoices.isEmpty()) {
- cgMap.remove(stateId);
backtrackMap.remove(stateId);
backtrackStateQ.remove(stateId);
}
private boolean isReachableInVODGraph(int currentChoice) {
// Extract previous and current events
int choiceIndex = currentChoice % refChoices.length;
+ int prevChoIndex = (currentChoice - 1) % refChoices.length;
int currEvent = refChoices[choiceIndex];
- int prevEvent = refChoices[choiceIndex - 1];
+ int prevEvent = refChoices[prevChoIndex];
// Record visited choices as we search in the graph
HashSet<Integer> visitedChoice = new HashSet<>();
visitedChoice.add(prevEvent);
projects / jpf-core.git / blobdiff