private boolean debugMode;
private boolean stateReductionMode;
private final PrintWriter out;
- volatile private String detail;
- volatile private int depth;
- volatile private int id;
- Transition transition;
+ private String detail;
+ private int depth;
+ private int id;
+ private Transition transition;
// State reduction fields
private Integer[] choices;
// Stores explored backtrack lists in the form of HashSet of Strings
private HashSet<String> backtrackSet;
private HashMap<Integer, HashSet<Integer>> conflictPairMap;
- // Map choicelist with start index
- // private HashMap<Integer[],Integer> choiceListStartIndexMap;
// Map that represents graph G
// (i.e., visible operation dependency graph (VOD Graph)
// Set that represents hash table H
// (i.e., hash table that records encountered states)
// VOD graph is updated when the state has not yet been seen
- private HashSet<Integer> visitedStateSet;
// Current state
private int stateId;
+ // Previous choice number
+ private int prevChoiceValue;
+ // HashSet that stores references to unused CGs
+ private HashSet<IntChoiceFromSet> unusedCG;
+
+ // Reference to the state graph in the ConflictTracker class
+ private HashMap<Integer, ConflictTracker.Node> stateGraph;
+ // Visited states in the previous and current executions/traces for terminating condition
+ private HashSet<Integer> prevVisitedStates;
+ private HashSet<Integer> currVisitedStates;
public StateReducer(Config config, JPF jpf) {
debugMode = config.getBoolean("debug_state_transition", false);
transition = null;
isBooleanCGFlipped = false;
vodGraphMap = new HashMap<>();
- visitedStateSet = new HashSet<>();
stateId = -1;
+ prevChoiceValue = -1;
+ cgMap = new HashMap<>();
+ readWriteFieldsMap = new HashMap<>();
+ backtrackMap = new HashMap<>();
+ backtrackSet = new HashSet<>();
+ conflictPairMap = new HashMap<>();
+ unusedCG = new HashSet<>();
+ // TODO: We are assuming that the StateReducer is always used together with the ConflictTracker
+ stateGraph = ConflictTracker.nodes;
+ prevVisitedStates = new HashSet<>();
+ currVisitedStates = new HashSet<>();
initializeStateReduction();
}
maxUpperBound = 0;
isInitialized = false;
isResetAfterAnalysis = false;
- cgMap = new HashMap<>();
- readWriteFieldsMap = new HashMap<>();
- backtrackMap = new HashMap<>();
- backtrackSet = new HashSet<>();
- conflictPairMap = new HashMap<>();
+ cgMap.clear();
+ readWriteFieldsMap.clear();
+ backtrackMap.clear();
+ backtrackSet.clear();
+ conflictPairMap.clear();
}
}
isInitialized = true;
}
// Record the subsequent Integer CGs only until we hit the upper bound
- if (!isResetAfterAnalysis && choiceCounter <= choiceUpperBound && !cgMap.containsValue(choiceCounter)) {
- // Update the choices of the first CG and add '-1'
- if (choices == null) {
- // Initialize backtrack set that stores all the explored backtrack lists
- maxUpperBound = cgChoices.length;
- // All the choices are always the same so we only need to update it once
- choices = new Integer[cgChoices.length + 1];
- System.arraycopy(cgChoices, 0, choices, 0, cgChoices.length);
- choices[choices.length - 1] = -1;
- String firstChoiceListString = buildStringFromChoiceList(choices);
- backtrackSet.add(firstChoiceListString);
+ if (!isResetAfterAnalysis) {
+ if (choiceCounter <= choiceUpperBound && !cgMap.containsValue(choiceCounter)) {
+ // Update the choices of the first CG and add '-1'
+ if (choices == null) {
+ // Initialize backtrack set that stores all the explored backtrack lists
+ maxUpperBound = cgChoices.length;
+ // All the choices are always the same so we only need to update it once
+ choices = new Integer[cgChoices.length + 1];
+ System.arraycopy(cgChoices, 0, choices, 0, cgChoices.length);
+ choices[choices.length - 1] = -1;
+ String firstChoiceListString = buildStringFromChoiceList(choices);
+ backtrackSet.add(firstChoiceListString);
+ }
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // Advance the current Integer CG
+ // This way we explore all the event numbers in the first pass
+ icsCG.advance(choices[choiceCounter]);
+ cgMap.put(icsCG, choices[choiceCounter]);
+ } else {
+ // We repeat the same trace if a state match is not found yet
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // Use a modulo since choiceCounter is going to keep increasing
+ int choiceIndex = choiceCounter % (choices.length - 1);
+ icsCG.advance(choices[choiceIndex]);
+ unusedCG.add(icsCG);
}
- icsCG.setNewValues(choices);
- icsCG.reset();
- // Advance the current Integer CG
- // This way we explore all the event numbers in the first pass
- icsCG.advance(choices[choiceCounter]);
- cgMap.put(icsCG, choices[choiceCounter]);
+ //choiceCounter = choiceCounter < choiceUpperBound ? choiceCounter + 1 : 0;
choiceCounter++;
} else {
- // Set done the subsequent CGs
- // We only need n CGs (n is event numbers)
+ // Set new CGs to done so that the search algorithm explores the existing CGs
icsCG.setDone();
}
}
Set<Integer> eventSet = backtrackMap.keySet();
// Return if there is no conflict at all (highly unlikely)
if (eventSet.isEmpty()) {
+ // Set every CG to done!
+ for (IntChoiceFromSet cg : cgMap.keySet()) {
+ cg.setDone();
+ }
return;
}
// Reset every CG with the first backtrack lists
cg.setDone();
}
}
+ // Set done every CG in the unused CG set
+ for (IntChoiceFromSet cg : unusedCG) {
+ cg.setDone();
+ }
+ unusedCG.clear();
+ saveVisitedStates();
+ }
+
+ // Detect cycles in the current execution/trace
+ // We terminate the execution iff:
+ // (1) the state has been visited in the current execution
+ // (2) the state has one or more cycles that involve all the events
+ private boolean containsCyclesWithAllEvents(int stId) {
+
+ HashSet<ConflictTracker.Node> visitingStates = new HashSet<>();
+ HashSet<Integer> visitedEvents = new HashSet<>();
+ boolean containsCyclesWithAllEvts = false;
+ ConflictTracker.Node currNode = stateGraph.get(stId);
+ dfsFindCycles(currNode, visitingStates, visitedEvents, new HashSet<>());
+ if (checkIfAllEventsInvolved(visitedEvents)) {
+ containsCyclesWithAllEvts = true;
+ }
+
+ return containsCyclesWithAllEvts;
+ }
+
+ private void dfsFindCycles(ConflictTracker.Node currNode, HashSet<ConflictTracker.Node> visitingStates,
+ HashSet<Integer> visitedEvents, HashSet<Integer> visitingEvents) {
+
+ // Stop when there is a cycle and record all the events
+ if (visitingStates.contains(currNode)) {
+ visitedEvents.addAll(visitingEvents);
+ } else {
+ visitingStates.add(currNode);
+ for(ConflictTracker.Edge edge : currNode.getOutEdges()) {
+ visitingEvents.add(edge.getEventNumber());
+ dfsFindCycles(edge.getDst(), visitingStates, visitedEvents, visitingEvents);
+ visitingEvents.remove(edge.getEventNumber());
+ }
+ visitingStates.remove(currNode);
+ }
+ }
+
+ private boolean checkIfAllEventsInvolved(HashSet<Integer> visitedEvents) {
+
+ // Check if this set contains all the event choices
+ // If not then this is not the terminating condition
+ for(int i=0; i<=choiceUpperBound; i++) {
+ if (!visitedEvents.contains(i)) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ private void saveVisitedStates() {
+ // CG is being reset
+ // Save all the visited states
+ prevVisitedStates.addAll(currVisitedStates);
+ currVisitedStates.clear();
}
@Override
readWriteFieldsMap.clear();
choiceCounter = 0;
}
- // Traverse the sub-graphs
- if (isResetAfterAnalysis) {
- // Advance choice counter for sub-graphs
- choiceCounter++;
- // Do this for every CG after finishing each backtrack list
- if (icsCG.getNextChoice() == -1 || visitedStateSet.contains(stateId)) {
- int event = cgMap.get(icsCG);
- LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
- if (choiceLists != null && choiceLists.peekFirst() != null) {
- Integer[] choiceList = choiceLists.removeFirst();
- // Deploy the new choice list for this CG
- icsCG.setNewValues(choiceList);
- icsCG.reset();
- } else {
- // Set done if this was the last backtrack list
- icsCG.setDone();
+ // Check if we have seen this state or this state contains cycles that involve all events
+ if (prevVisitedStates.contains(stateId) || containsCyclesWithAllEvents(stateId)) {
+ // Traverse the sub-graphs
+ if (isResetAfterAnalysis) {
+ // Advance choice counter for sub-graphs
+ choiceCounter++;
+ // Do this for every CG after finishing each backtrack list
+ // We try to update the CG with a backtrack list if the state has been visited multiple times
+ if ((icsCG.getNextChoice() == -1 || choiceCounter > 1) && cgMap.containsKey(icsCG)) {
+ int event = cgMap.get(icsCG);
+ LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
+ if (choiceLists != null && choiceLists.peekFirst() != null) {
+ Integer[] choiceList = choiceLists.removeFirst();
+ // Deploy the new choice list for this CG
+ icsCG.setNewValues(choiceList);
+ icsCG.reset();
+ } else {
+ // Set done if this was the last backtrack list
+ icsCG.setDone();
+ }
+ saveVisitedStates();
}
+ } else {
+ // Update and reset the CG if needed (do this for the first time after the analysis)
+ // Start backtracking if this is a visited state and it is not a repeating state
+ resetAllCGs();
+ isResetAfterAnalysis = true;
}
}
- // Update and reset the CG if needed (do this for the first time after the analysis)
- if (!isResetAfterAnalysis && icsCG.getNextChoice() == -1) {
- resetAllCGs();
- isResetAfterAnalysis = true;
- }
+ // Update the VOD graph always with the latest
+ updateVODGraph(icsCG.getNextChoice());
}
}
}
- public void updateVODGraph(int prevChoice, int currChoice) {
+ private void updateVODGraph(int currChoiceValue) {
+ // Update the graph when we have the current choice value
+ updateVODGraph(prevChoiceValue, currChoiceValue);
+ prevChoiceValue = currChoiceValue;
+ }
+
+ private void updateVODGraph(int prevChoice, int currChoice) {
HashSet<Integer> choiceSet;
if (vodGraphMap.containsKey(prevChoice)) {
" which is " + detail + " Transition: " + transition + "\n");
}
if (stateReductionMode) {
- // Update vodGraph
- int currChoice = choiceCounter - 1;
- int prevChoice = currChoice - 1;
- if (currChoice < 0) {
- // Current choice has to be at least 0 (initial case can be -1)
- visitedStateSet.add(stateId);
- return;
- }
- // Current choice and previous choice values could be -1 (since we use -1 as the end-of-array condition)
- int currChoiceValue = (choices[currChoice] == -1) ? 0 : choices[currChoice];
- // When current choice is 0, previous choice could be -1
- int prevChoiceValue = (prevChoice == -1) ? -1 : choices[prevChoice];
- updateVODGraph(prevChoiceValue, currChoiceValue);
- // Line 19 in the paper page 11 (see the heading note above)
+ // Update the state ID variables
stateId = search.getStateId();
- // Add state ID into the visited state set
- visitedStateSet.add(stateId);
+ currVisitedStates.add(stateId);
}
}
transition = search.getTransition();
detail = null;
+ // Update the state variables
+ // Line 19 in the paper page 11 (see the heading note above)
+ stateId = search.getStateId();
+ currVisitedStates.add(stateId);
+
out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
" and depth: " + depth + "\n");
}
// The start index for the recursion is always 1 (from the main branch)
} else { // This is a sub-graph
// There is a case/bug that after a re-initialization, currCG is not yet initialized
- if (currCG != null) {
+ if (currCG != null && cgMap.containsKey(currCG)) {
int backtrackListIndex = cgMap.get(currCG);
backtrackChoiceLists = backtrackMap.get(backtrackListIndex);
int listLength = choices.length;
if (currChoiceNextNodes != null) {
// Add only if there is a mapping for next nodes
for (Integer nextNode : currChoiceNextNodes) {
+ // Skip cycles
+ if (nextNode == currChoice) {
+ continue;
+ }
nodesToVisit.addLast(nextNode);
}
}
public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
if (stateReductionMode) {
if (isInitialized) {
- if (choiceCounter > choices.length - 1) {
+ if (choiceCounter <= 0 || choiceCounter > choices.length - 1) {
// We do not compute the conflicts for the choice '-1'
return;
}
// If it has been serviced before, we just skip this
if (recordConflictPair(currentChoice, eventNumber)) {
// Lines 4-8 of the algorithm in the paper page 11 (see the heading note above)
- if (!visitedStateSet.contains(stateId)||
- (visitedStateSet.contains(stateId) && isReachableInVODGraph(choices[currentChoice], choices[currentChoice-1]))) {
+ if (vm.isNewState() ||
+ (!vm.isNewState() && isReachableInVODGraph(choices[currentChoice], choices[currentChoice-1]))) {
createBacktrackChoiceList(currentChoice, eventNumber);
// Break if a conflict is found!
break;
projects / jpf-core.git / blobdiff