private Integer[] choices;
private Integer[] refChoices;
private int choiceCounter;
+ private int lastCGStateId; // Record the state of the currently active CG
private int maxEventChoice;
// Data structure to track the events seen by each state to track cycles (containing all events) for termination
private HashSet<Integer> currVisitedStates; // States being visited in the current execution
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 Stack<BacktrackPoint> btrckPtsStack; // Stack that stores backtracking points
- private List<IntChoiceFromSet> cgList; // Record CGs for backtracking points
- private HashSet<IntChoiceFromSet> btrckCGSet; // Set that records all the backtrack CGs
- private HashMap<Integer, HashSet<Integer>> conflictPairMap; // Record conflicting events
- 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<IntChoiceFromSet> cgList; // Record CGs for backtracking points
+ 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
// Visible operation dependency graph implementation (SPIN paper) related fields
private int prevChoiceValue;
// Boolean states
private boolean isBooleanCGFlipped;
+ private boolean isFirstResetDone;
+ private boolean isEndOfExecution;
public DPORStateReducer(Config config, JPF jpf) {
verboseMode = config.getBoolean("printout_state_transition", false);
} else {
out = null;
}
- // DPOR-related
- choices = null;
- refChoices = null;
- choiceCounter = 0;
- maxEventChoice = 0;
- // Cycle tracking
- currVisitedStates = new HashSet<>();
- justVisitedStates = new HashSet<>();
- prevVisitedStates = new HashSet<>();
- stateToEventMap = new HashMap<>();
- // Backtracking
- backtrackMap = new HashMap<>();
- btrckPtsStack = new Stack<>();
- btrckCGSet = new HashSet<>();
- cgList = new ArrayList<>();
- conflictPairMap = new HashMap<>();
- readWriteFieldsMap = new HashMap<>();
- // VOD graph
- prevChoiceValue = -1;
- vodGraphMap = new HashMap<>();
- // Booleans
isBooleanCGFlipped = false;
+ initializeStatesVariables();
}
@Override
// Initialize with necessary information from the CG
if (nextCG instanceof IntChoiceFromSet) {
IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
- // Check if CG has been initialized, otherwise initialize it
- Integer[] cgChoices = icsCG.getAllChoices();
- // Record the events (from choices)
- if (choices == null) {
- choices = cgChoices;
- // Make a copy of choices as reference
- refChoices = copyChoices(choices);
- // Record the max event choice (the last element of the choice array)
- maxEventChoice = choices[choices.length - 1];
+ if (!isEndOfExecution) {
+ // Check if CG has been initialized, otherwise initialize it
+ Integer[] cgChoices = icsCG.getAllChoices();
+ // Record the events (from choices)
+ if (choices == null) {
+ choices = cgChoices;
+ // Make a copy of choices as reference
+ refChoices = copyChoices(choices);
+ // Record the max event choice (the last element of the choice array)
+ maxEventChoice = choices[choices.length - 1];
+ }
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // 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
+ cgList.add(icsCG);
+ } else {
+ // Set done all CGs while transitioning to a new execution
+ icsCG.setDone();
}
- icsCG.setNewValues(choices);
- icsCG.reset();
- // 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
- cgList.add(icsCG);
}
}
}
if (stateReductionMode) {
// Check the boolean CG and if it is flipped, we are resetting the analysis
-// if (currentCG instanceof BooleanChoiceGenerator) {
-// if (!isBooleanCGFlipped) {
-// isBooleanCGFlipped = true;
-// } else {
-// initializeStateReduction();
-// }
-// }
+ if (currentCG instanceof BooleanChoiceGenerator) {
+ if (!isBooleanCGFlipped) {
+ isBooleanCGFlipped = true;
+ } else {
+ // Allocate new objects for data structure when the boolean is flipped from "false" to "true"
+ initializeStatesVariables();
+ }
+ }
// Check every choice generated and ensure fair scheduling!
if (currentCG instanceof IntChoiceFromSet) {
IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
+ // If this is a new CG then we need to update data structures
+ resetStatesForNewExecution(icsCG);
// If we don't see a fair scheduling of events/choices then we have to enforce it
checkAndEnforceFairScheduling(icsCG);
// Map state to event
updateVODGraph(icsCG.getNextChoice());
// Check if we have seen this state or this state contains cycles that involve all events
if (terminateCurrentExecution()) {
- exploreNextBacktrackSets(icsCG);
+ exploreNextBacktrackPoints(icsCG, vm);
}
justVisitedStates.clear();
choiceCounter++;
@Override
public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
if (stateReductionMode) {
- // Has to be initialized and a integer CG
- ChoiceGenerator<?> cg = vm.getChoiceGenerator();
- if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
- int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
- if (currentChoice < 0) { // If choice is -1 then skip
- return;
- }
- currentChoice = checkAndAdjustChoice(currentChoice, vm);
- // Record accesses from executed instructions
- if (executedInsn instanceof JVMFieldInstruction) {
- // Analyze only after being initialized
- String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
- // We don't care about libraries
- if (!isFieldExcluded(fieldClass)) {
- analyzeReadWriteAccesses(executedInsn, fieldClass, currentChoice);
+ if (!isEndOfExecution) {
+ // Has to be initialized and a integer CG
+ ChoiceGenerator<?> cg = vm.getChoiceGenerator();
+ if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
+ int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
+ if (currentChoice < 0) { // If choice is -1 then skip
+ return;
}
- } else if (executedInsn instanceof INVOKEINTERFACE) {
- // Handle the read/write accesses that occur through iterators
- analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
- }
- // Analyze conflicts from next instructions
- if (nextInsn instanceof JVMFieldInstruction) {
- // Skip the constructor because it is called once and does not have shared access with other objects
- if (!nextInsn.getMethodInfo().getName().equals("<init>")) {
- String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
+ currentChoice = checkAndAdjustChoice(currentChoice, vm);
+ // Record accesses from executed instructions
+ if (executedInsn instanceof JVMFieldInstruction) {
+ // Analyze only after being initialized
+ String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
+ // We don't care about libraries
if (!isFieldExcluded(fieldClass)) {
- // Check for conflict (go backward from current choice and get the first conflict)
- for (int eventCounter = currentChoice - 1; eventCounter >= 0; eventCounter--) {
- // Check for conflicts with Write fields for both Read and Write instructions
- // Check and record a backtrack set for just once!
- if (isConflictFound(nextInsn, eventCounter, 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)) {
- createBacktrackingPoint(currentChoice, eventCounter);
+ analyzeReadWriteAccesses(executedInsn, fieldClass, currentChoice);
+ }
+ } else if (executedInsn instanceof INVOKEINTERFACE) {
+ // Handle the read/write accesses that occur through iterators
+ analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
+ }
+ // Analyze conflicts from next instructions
+ if (nextInsn instanceof JVMFieldInstruction) {
+ // Skip the constructor because it is called once and does not have shared access with other objects
+ if (!nextInsn.getMethodInfo().getName().equals("<init>")) {
+ String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
+ if (!isFieldExcluded(fieldClass)) {
+ // Check for conflict (go backward from current choice and get the first conflict)
+ for (int eventCounter = currentChoice - 1; eventCounter >= 0; eventCounter--) {
+ // Check for conflicts with Write fields for both Read and Write instructions
+ // Check and record a backtrack set for just once!
+ 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)) {
+ createBacktrackingPoint(currentChoice, eventCounter);
+ }
}
}
}
return true;
}
+ private void initializeStatesVariables() {
+ // DPOR-related
+ choices = null;
+ refChoices = null;
+ choiceCounter = 0;
+ lastCGStateId = 0;
+ maxEventChoice = 0;
+ // Cycle tracking
+ currVisitedStates = new HashSet<>();
+ justVisitedStates = new HashSet<>();
+ prevVisitedStates = new HashSet<>();
+ stateToEventMap = new HashMap<>();
+ // Backtracking
+ backtrackMap = new HashMap<>();
+ backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
+ cgList = new ArrayList<>();
+ cgMap = new HashMap<>();
+ conflictPairMap = new HashMap<>();
+ doneBacktrackSet = new HashSet<>();
+ readWriteFieldsMap = new HashMap<>();
+ // VOD graph
+ prevChoiceValue = -1;
+ vodGraphMap = new HashMap<>();
+ // Booleans
+ isEndOfExecution = false;
+ isFirstResetDone = false;
+ }
+
private void mapStateToEvent(int nextChoiceValue) {
// Update all states with this event/choice
// This means that all past states now see this transition
// --- Functions related to Read/Write access analysis on shared fields
+ private void addNewBacktrackPoint(IntChoiceFromSet backtrackCG, Integer[] newChoiceList) {
+ int stateId = backtrackCG.getStateId();
+ // Insert backtrack point to the right state ID
+ LinkedList<Integer[]> backtrackList;
+ if (backtrackMap.containsKey(stateId)) {
+ backtrackList = backtrackMap.get(stateId);
+ } else {
+ backtrackList = new LinkedList<>();
+ 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);
+ }
+ }
+
// Analyze Read/Write accesses that are directly invoked on fields
private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
// Do the analysis to get Read and Write accesses to fields
// Put the conflicting event numbers first and reverse the order
int actualCurrCho = currentChoice % refChoices.length;
int actualConfEvtNum = confEvtNum % refChoices.length;
- newChoiceList[0] = refChoices[actualCurrCho];
- newChoiceList[1] = refChoices[actualConfEvtNum];
+ // We use the actual choices here in case they have been modified/adjusted
+ newChoiceList[0] = choices[actualCurrCho];
+ newChoiceList[1] = choices[actualConfEvtNum];
// Put the rest of the event numbers into the array starting from the minimum to the upper bound
for (int i = 0, j = 2; i < refChoices.length; i++) {
if (refChoices[i] != newChoiceList[0] && refChoices[i] != newChoiceList[1]) {
}
// Record the backtracking point in the stack as well
IntChoiceFromSet backtrackCG = cgList.get(confEvtNum);
- BacktrackPoint backtrackPoint = new BacktrackPoint(backtrackCG, newChoiceList);
- btrckPtsStack.push(backtrackPoint);
- // Also record the CG in the set
- btrckCGSet.add(backtrackCG);
+ // Check if this trace has been done starting from this state
+ if (isTraceConstructed(newChoiceList, backtrackCG)) {
+ return;
+ }
+ //BacktrackPoint backtrackPoint = new BacktrackPoint(backtrackCG, newChoiceList);
+ addNewBacktrackPoint(backtrackCG, newChoiceList);
}
private boolean excludeThisForItContains(String[] excludedStrings, String className) {
return false;
}
- // TODO: THIS METHOD IS STILL UNTESTED AT THIS POINT
- private void exploreNextBacktrackSets(IntChoiceFromSet icsCG) {
- // We try to update the CG with a backtrack list if the state has been visited multiple times
+ private void exploreNextBacktrackPoints(IntChoiceFromSet icsCG, VM vm) {
+ // We can start exploring the next backtrack point after the current CG is advanced at least once
if (icsCG.getNextChoiceIndex() > 0) {
- if (btrckPtsStack.empty()) {
- // TODO: PROBABLY NEED TO DO CONTEXT SWITCHING HERE
- return;
+ // Check if we are reaching the end of our execution: no more backtracking points to explore
+ if (!backtrackMap.isEmpty()) {
+ setNextBacktrackPoint(icsCG);
}
- BacktrackPoint backtrackPoint = btrckPtsStack.pop();
- Integer[] choiceList = backtrackPoint.getBacktrackChoices();
- IntChoiceFromSet backtrackCG = backtrackPoint.getBacktrackCG();
- // Deploy the new choice list for this CG
- backtrackCG.setNewValues(choiceList);
- backtrackCG.reset();
- // Clear unused CGs
- for(IntChoiceFromSet cg : cgList) {
- if (!btrckCGSet.contains(cg)) {
- cg.setDone();
- }
- }
- cgList.clear();
- btrckCGSet.clear();
// 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;
}
}
return rwSet;
}
- private boolean isConflictFound(Instruction nextInsn, int eventCounter, String fieldClass) {
- // Skip if this event does not have any Read/Write set
- if (!readWriteFieldsMap.containsKey(eventCounter)) {
+ private boolean isConflictFound(Instruction nextInsn, int eventCounter, int currentChoice, String fieldClass) {
+ int actualEvtCntr = eventCounter % refChoices.length;
+ int actualCurrCho = currentChoice % refChoices.length;
+ // Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
+ if (!readWriteFieldsMap.containsKey(eventCounter) || choices[actualCurrCho] == choices[actualEvtCntr]) {
return false;
}
ReadWriteSet rwSet = readWriteFieldsMap.get(eventCounter);
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();
+ StringBuilder sb = new StringBuilder();
+ sb.append(stateId);
+ sb.append(':');
+ for(Integer choice : choiceList) {
+ sb.append(choice);
+ }
+ // Check if the trace has been constructed as a backtrack point for this state
+ if (doneBacktrackSet.contains(sb.toString())) {
+ return true;
+ }
+ doneBacktrackSet.add(sb.toString());
+ return false;
+ }
+
+ private void resetStatesForNewExecution(IntChoiceFromSet icsCG) {
+ if (choices == null || choices != icsCG.getAllChoices()) {
+ // Reset state variables
+ choiceCounter = 0;
+ choices = icsCG.getAllChoices();
+ refChoices = copyChoices(choices);
+ lastCGStateId = icsCG.getStateId();
+ // Clearing data structures
+ conflictPairMap.clear();
+ readWriteFieldsMap.clear();
+ stateToEventMap.clear();
+ isEndOfExecution = false;
+ // Adding this CG as the first CG for this execution
+ cgList.add(icsCG);
+ }
+ }
+
+ private void setBacktrackCG(int stateId) {
+ // Set a backtrack CG based on a state ID
+ IntChoiceFromSet backtrackCG = cgMap.get(stateId);
+ LinkedList<Integer[]> backtrackChoices = backtrackMap.get(stateId);
+ backtrackCG.setNewValues(backtrackChoices.removeLast()); // Get the last from the queue
+ 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 void setNextBacktrackPoint(IntChoiceFromSet icsCG) {
+
+ HashSet<IntChoiceFromSet> backtrackCGs = new HashSet<>(cgMap.values());
+ if (!isFirstResetDone) {
+ // Reset the last CG of every LinkedList in the map and set done everything else
+ for (Integer stateId : cgMap.keySet()) {
+ setBacktrackCG(stateId);
+ }
+ isFirstResetDone = true;
+ } else {
+ // Check if we still have backtrack points for the last state after the last backtrack
+ if (backtrackMap.containsKey(lastCGStateId)) {
+ setBacktrackCG(lastCGStateId);
+ } else {
+ // We try to reset new CGs (if we do have) when we are running out of active CGs
+ if (!backtrackStateQ.isEmpty()) {
+ // Reset the next CG with the latest state
+ int hiStateId = backtrackStateQ.peek();
+ setBacktrackCG(hiStateId);
+ }
+ }
+ }
+ // Clear unused CGs
+ for(IntChoiceFromSet cg : cgList) {
+ if (!backtrackCGs.contains(cg)) {
+ cg.setDone();
+ }
+ }
+ cgList.clear();
+ }
+
// --- 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)
projects / jpf-core.git / blobdiff