import gov.nasa.jpf.Config;
import gov.nasa.jpf.JPF;
import gov.nasa.jpf.ListenerAdapter;
+import gov.nasa.jpf.jvm.bytecode.INVOKEINTERFACE;
+import gov.nasa.jpf.jvm.bytecode.JVMFieldInstruction;
import gov.nasa.jpf.search.Search;
-import gov.nasa.jpf.jvm.bytecode.*;
import gov.nasa.jpf.vm.*;
import gov.nasa.jpf.vm.bytecode.ReadInstruction;
import gov.nasa.jpf.vm.bytecode.WriteInstruction;
import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
import java.io.FileWriter;
+import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
import java.util.logging.Logger;
-import java.io.IOException;
/**
* This a DPOR implementation for event-driven applications with loops that create cycles of state matching
private int choiceCounter;
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> justVisitedStates; // States just visited in the previous choice/event
- private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
+ private HashSet<Integer> currVisitedStates; // States being visited in the current execution
+ private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
+ private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
+ private HashSet<ClassInfo> nonRelevantClasses;// Class info objects of non-relevant classes
+ private HashSet<FieldInfo> nonRelevantFields; // Field info objects of non-relevant fields
+ private HashSet<FieldInfo> relevantFields; // Field info objects of relevant fields
private HashMap<Integer, HashSet<Integer>> stateToEventMap;
// Data structure to analyze field Read/Write accesses and conflicts
private HashMap<Integer, LinkedList<BacktrackExecution>> backtrackMap; // Track created backtracking points
private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
private Execution currentExecution; // Holds the information about the current execution
- private HashSet<String> doneBacktrackSet; // Record state ID and trace already constructed
+ private HashMap<Integer, HashSet<Integer>> doneBacktrackMap; // Record state ID and trace already constructed
private HashMap<Integer, RestorableVMState> restorableStateMap; // Maps state IDs to the restorable state object
- private ReachabilityGraph rGraph; // Reachability graph for past executions
+ private RGraph rGraph; // R-Graph for past executions
// Boolean states
private boolean isBooleanCGFlipped;
private boolean isEndOfExecution;
// Statistics
- private int numOfConflicts;
private int numOfTransitions;
-
+
public DPORStateReducer(Config config, JPF jpf) {
verboseMode = config.getBoolean("printout_state_transition", false);
stateReductionMode = config.getBoolean("activate_state_reduction", true);
}
}
isBooleanCGFlipped = false;
- numOfConflicts = 0;
numOfTransitions = 0;
+ nonRelevantClasses = new HashSet<>();
+ nonRelevantFields = new HashSet<>();
+ relevantFields = new HashSet<>();
restorableStateMap = new HashMap<>();
initializeStatesVariables();
}
@Override
public void searchFinished(Search search) {
- if (stateReductionMode) {
- // Number of conflicts = first trace + subsequent backtrack points
- numOfConflicts += 1 + doneBacktrackSet.size();
- }
if (verboseMode) {
out.println("\n==> DEBUG: ----------------------------------- search finished");
out.println("\n==> DEBUG: State reduction mode : " + stateReductionMode);
- out.println("\n==> DEBUG: Number of conflicts : " + numOfConflicts);
out.println("\n==> DEBUG: Number of transitions : " + numOfTransitions);
out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
fileWriter.println("==> DEBUG: State reduction mode : " + stateReductionMode);
- fileWriter.println("==> DEBUG: Number of conflicts : " + numOfConflicts);
fileWriter.println("==> DEBUG: Number of transitions : " + numOfTransitions);
fileWriter.println();
fileWriter.close();
// Initialize with necessary information from the CG
if (nextCG instanceof IntChoiceFromSet) {
IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
+ // Tell JPF that we are performing DPOR
+ icsCG.setDpor();
if (!isEndOfExecution) {
// Check if CG has been initialized, otherwise initialize it
Integer[] cgChoices = icsCG.getAllChoices();
@Override
public void choiceGeneratorAdvanced(VM vm, ChoiceGenerator<?> currentCG) {
-
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 {
- // Number of conflicts = first trace + subsequent backtrack points
- numOfConflicts = 1 + doneBacktrackSet.size();
// Allocate new objects for data structure when the boolean is flipped from "false" to "true"
initializeStatesVariables();
}
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 (!isFieldExcluded(executedInsn)) {
+ analyzeReadWriteAccesses(executedInsn, currentChoice);
}
} else if (executedInsn instanceof INVOKEINTERFACE) {
// Handle the read/write accesses that occur through iterators
}
}
- // This class stores a representation of the execution graph node
+ // This class stores a representation of an execution
// TODO: We can modify this class to implement some optimization (e.g., clock-vector)
// TODO: We basically need to keep track of:
// TODO: (1) last read/write access to each memory location
private ArrayList<TransitionEvent> executionTrace; // The BacktrackPoint objects of this execution
private boolean isNew; // Track if this is the first time it is accessed
private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
- private HashMap<Integer, TransitionEvent> stateToTransitionMap; // For O(1) access to backtrack point
public Execution() {
cgToChoiceMap = new HashMap<>();
executionTrace = new ArrayList<>();
isNew = true;
readWriteFieldsMap = new HashMap<>();
- stateToTransitionMap = new HashMap<>();
}
public void addTransition(TransitionEvent newBacktrackPoint) {
return executionTrace.get(0);
}
- public HashMap<Integer, ReadWriteSet> getReadWriteFieldsMap() {
- return readWriteFieldsMap;
+ public TransitionEvent getLastTransition() {
+ return executionTrace.get(executionTrace.size() - 1);
}
- public TransitionEvent getTransitionFromState(int stateId) {
- if (stateToTransitionMap.containsKey(stateId)) {
- return stateToTransitionMap.get(stateId);
- }
- // Return the latest transition for unseen states (that have just been encountered in this transition)
- return executionTrace.get(executionTrace.size() - 1);
+ public HashMap<Integer, ReadWriteSet> getReadWriteFieldsMap() {
+ return readWriteFieldsMap;
}
public boolean isNew() {
public void mapCGToChoice(IntChoiceFromSet icsCG, int choice) {
cgToChoiceMap.put(icsCG, choice);
}
-
- public void mapStateToTransition(int stateId, TransitionEvent backtrackPoint) {
- stateToTransitionMap.put(stateId, backtrackPoint);
- }
}
// This class compactly stores a predecessor
}
}
- // This class represents a Reachability Graph
- private class ReachabilityGraph {
+ // This class represents a R-Graph (in the paper it is a state transition graph R)
+ // This implementation stores reachable transitions from and connects with past executions
+ private class RGraph {
private int hiStateId; // Maximum state Id
- private HashMap<Integer, HashSet<TransitionEvent>> graph; // Reachability graph for past executions
+ private HashMap<Integer, HashSet<TransitionEvent>> graph; // Reachable transitions from past executions
- public ReachabilityGraph() {
+ public RGraph() {
hiStateId = 0;
graph = new HashMap<>();
}
}
public HashSet<TransitionEvent> getReachableTransitionsAtState(int stateId) {
+ if (!graph.containsKey(stateId)) {
+ // This is a loop from a transition to itself, so just return the current transition
+ HashSet<TransitionEvent> transitionSet = new HashSet<>();
+ transitionSet.add(currentExecution.getLastTransition());
+ return transitionSet;
+ }
return graph.get(stateId);
}
HashSet<TransitionEvent> reachableTransitions = new HashSet<>();
// All transitions from states higher than the given state ID (until the highest state ID) are reachable
for(int stId = stateId; stId <= hiStateId; stId++) {
- reachableTransitions.addAll(graph.get(stId));
+ // We might encounter state IDs from the first round of Boolean CG
+ // The second round of Boolean CG should consider these new states
+ if (graph.containsKey(stId)) {
+ reachableTransitions.addAll(graph.get(stId));
+ }
}
return reachableTransitions;
}
}
}
- // This class compactly stores backtrack points:
+ // This class compactly stores transitions:
// 1) CG,
// 2) state ID,
// 3) choice,
private int choiceCounter; // Choice counter at this transition
private Execution execution; // The execution where this transition belongs
private HashSet<Predecessor> predecessors; // Maps incoming events/transitions (execution and choice)
+ private HashMap<Execution, HashSet<Integer>> recordedPredecessors;
+ // Memorize event and choice number to not record them twice
private int stateId; // State at this transition
private IntChoiceFromSet transitionCG; // CG at this transition
choiceCounter = 0;
execution = null;
predecessors = new HashSet<>();
+ recordedPredecessors = new HashMap<>();
stateId = 0;
transitionCG = null;
}
public IntChoiceFromSet getTransitionCG() { return transitionCG; }
+ private boolean isRecordedPredecessor(Execution execution, int choice) {
+ // See if we have recorded this predecessor earlier
+ HashSet<Integer> recordedChoices;
+ if (recordedPredecessors.containsKey(execution)) {
+ recordedChoices = recordedPredecessors.get(execution);
+ if (recordedChoices.contains(choice)) {
+ return true;
+ }
+ } else {
+ recordedChoices = new HashSet<>();
+ recordedPredecessors.put(execution, recordedChoices);
+ }
+ // Record the choice if we haven't seen it
+ recordedChoices.add(choice);
+
+ return false;
+ }
+
public void recordPredecessor(Execution execution, int choice) {
- predecessors.add(new Predecessor(choice, execution));
+ if (!isRecordedPredecessor(execution, choice)) {
+ predecessors.add(new Predecessor(choice, execution));
+ }
}
public void setChoice(int cho) {
// Get state ID and associate it with this transition
int stateId = vm.getStateId();
TransitionEvent transition = setupTransition(icsCG, stateId, choiceIndex);
- // Add new transition to the current execution
+ // Add new transition to the current execution and map it in R-Graph
for (Integer stId : justVisitedStates) { // Map this transition to all the previously passed states
- currentExecution.mapStateToTransition(stId, transition);
+ rGraph.addReachableTransition(stId, transition);
}
currentExecution.mapCGToChoice(icsCG, choiceCounter);
// Store restorable state object for this state (always store the latest)
- RestorableVMState restorableState = vm.getRestorableState();
- restorableStateMap.put(stateId, restorableState);
+ if (!restorableStateMap.containsKey(stateId)) {
+ RestorableVMState restorableState = vm.getRestorableState();
+ restorableStateMap.put(stateId, restorableState);
+ }
}
private TransitionEvent setupTransition(IntChoiceFromSet icsCG, int stateId, int choiceIndex) {
transition.setStateId(stateId);
transition.setChoice(refChoices[choiceIndex]);
transition.setChoiceCounter(choiceCounter);
- // Add transition into R-Graph
- for (Integer stId : justVisitedStates) {
- rGraph.addReachableTransition(stId, transition);
- }
return transition;
}
// With simple approach we only need to check for a re-visited state.
// Basically, we have to check that we have executed all events between two occurrences of such state.
private boolean completeFullCycle(int stId) {
-
// False if the state ID hasn't been recorded
if (!stateToEventMap.containsKey(stId)) {
return false;
backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
currentExecution = new Execution();
currentExecution.addTransition(new TransitionEvent()); // Always start with 1 backtrack point
- doneBacktrackSet = new HashSet<>();
- rGraph = new ReachabilityGraph();
+ doneBacktrackMap = new HashMap<>();
+ rGraph = new RGraph();
// Booleans
isEndOfExecution = false;
}
private void updateStateInfo(Search search) {
// Update the state variables
- // Line 19 in the paper page 11 (see the heading note above)
int stateId = search.getStateId();
// Insert state ID into the map if it is new
if (!stateToEventMap.containsKey(stateId)) {
}
// Analyze Read/Write accesses that are directly invoked on fields
- private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
+ private void analyzeReadWriteAccesses(Instruction executedInsn, int currentChoice) {
+ // Get the field info
+ FieldInfo fieldInfo = ((JVMFieldInstruction) executedInsn).getFieldInfo();
+ // Analyze only after being initialized
+ String fieldClass = fieldInfo.getFullName();
// Do the analysis to get Read and Write accesses to fields
ReadWriteSet rwSet = getReadWriteSet(currentChoice);
- int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().getClassInfo().getClassObjectRef();
+ int objectId = fieldInfo.getClassInfo().getClassObjectRef();
// Record the field in the map
if (executedInsn instanceof WriteInstruction) {
- // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
- for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
- if (fieldClass.startsWith(str)) {
- return;
+ // We first check the non-relevant fields set
+ if (!nonRelevantFields.contains(fieldInfo)) {
+ // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
+ for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
+ if (fieldClass.startsWith(str)) {
+ nonRelevantFields.add(fieldInfo);
+ return;
+ }
}
+ } else {
+ // If we have this field in the non-relevant fields set then we return right away
+ return;
}
rwSet.addWriteField(fieldClass, objectId);
} else if (executedInsn instanceof ReadInstruction) {
return;
}
// We exclude library classes (they start with java, org, etc.) and some more
- String objClassName = eiAccessObj.getClassInfo().getName();
- if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName) ||
- excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName)) {
+ ClassInfo classInfo = eiAccessObj.getClassInfo();
+ String objClassName = classInfo.getName();
+ // Check if this class info is part of the non-relevant classes set already
+ if (!nonRelevantClasses.contains(classInfo)) {
+ if (excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName) ||
+ excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName)) {
+ nonRelevantClasses.add(classInfo);
+ return;
+ }
+ } else {
+ // If it is part of the non-relevant classes set then return immediately
return;
}
// Extract fields from this object and put them into the read write
// Create a new list of choices for backtrack based on the current choice and conflicting event number
// E.g. if we have a conflict between 1 and 3, then we create the list {3, 1, 0, 2}
// for the original set {0, 1, 2, 3}
+
+ // execution/currentChoice represent the event/transaction that will be put into the backtracking set of
+ // conflictExecution/conflictChoice
Integer[] newChoiceList = new Integer[refChoices.length];
ArrayList<TransitionEvent> currentTrace = execution.getExecutionTrace();
ArrayList<TransitionEvent> conflictTrace = conflictExecution.getExecutionTrace();
private boolean isConflictFound(Execution execution, int reachableChoice, Execution conflictExecution, int conflictChoice,
ReadWriteSet currRWSet) {
+ // conflictExecution/conflictChoice represent a predecessor event/transaction that can potentially have a conflict
ArrayList<TransitionEvent> executionTrace = execution.getExecutionTrace();
- HashMap<Integer, ReadWriteSet> execRWFieldsMap = execution.getReadWriteFieldsMap();
ArrayList<TransitionEvent> conflictTrace = conflictExecution.getExecutionTrace();
+ HashMap<Integer, ReadWriteSet> confRWFieldsMap = conflictExecution.getReadWriteFieldsMap();
// Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
- if (!execRWFieldsMap.containsKey(conflictChoice) ||
+ if (!confRWFieldsMap.containsKey(conflictChoice) ||
executionTrace.get(reachableChoice).getChoice() == conflictTrace.get(conflictChoice).getChoice()) {
return false;
}
// R/W set of choice/event that may have a potential conflict
- ReadWriteSet evtRWSet = execRWFieldsMap.get(conflictChoice);
+ ReadWriteSet confRWSet = confRWFieldsMap.get(conflictChoice);
// Check for conflicts with Read and Write fields for Write instructions
Set<String> currWriteSet = currRWSet.getWriteSet();
for(String writeField : currWriteSet) {
int currObjId = currRWSet.writeFieldObjectId(writeField);
- if ((evtRWSet.readFieldExists(writeField) && evtRWSet.readFieldObjectId(writeField) == currObjId) ||
- (evtRWSet.writeFieldExists(writeField) && evtRWSet.writeFieldObjectId(writeField) == currObjId)) {
+ if ((confRWSet.readFieldExists(writeField) && confRWSet.readFieldObjectId(writeField) == currObjId) ||
+ (confRWSet.writeFieldExists(writeField) && confRWSet.writeFieldObjectId(writeField) == currObjId)) {
// Remove this from the write set as we are tracking per memory location
currRWSet.removeWriteField(writeField);
return true;
Set<String> currReadSet = currRWSet.getReadSet();
for(String readField : currReadSet) {
int currObjId = currRWSet.readFieldObjectId(readField);
- if (evtRWSet.writeFieldExists(readField) && evtRWSet.writeFieldObjectId(readField) == currObjId) {
+ if (confRWSet.writeFieldExists(readField) && confRWSet.writeFieldObjectId(readField) == currObjId) {
// Remove this from the read set as we are tracking per memory location
currRWSet.removeReadField(readField);
return true;
return rwSet;
}
- private boolean isFieldExcluded(String field) {
+ private boolean isFieldExcluded(Instruction executedInsn) {
+ // Get the field info
+ FieldInfo fieldInfo = ((JVMFieldInstruction) executedInsn).getFieldInfo();
+ // Check if the non-relevant fields set already has it
+ if (nonRelevantFields.contains(fieldInfo)) {
+ return true;
+ }
+ // Check if the relevant fields set already has it
+ if (relevantFields.contains(fieldInfo)) {
+ return false;
+ }
+ // Analyze only after being initialized
+ String field = fieldInfo.getFullName();
// Check against "starts-with", "ends-with", and "contains" list
if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, field) ||
excludeThisForItEndsWith(EXCLUDED_FIELDS_ENDS_WITH_LIST, field) ||
excludeThisForItContains(EXCLUDED_FIELDS_CONTAINS_LIST, field)) {
+ nonRelevantFields.add(fieldInfo);
return true;
}
-
+ relevantFields.add(fieldInfo);
return false;
}
// Check if this trace is already constructed
private boolean isTraceAlreadyConstructed(int firstChoice, 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(':');
- sb.append(firstChoice);
// Check if the trace has been constructed as a backtrack point for this state
- if (doneBacktrackSet.contains(sb.toString())) {
- return true;
+ // TODO: THIS IS AN OPTIMIZATION!
+ HashSet<Integer> choiceSet;
+ if (doneBacktrackMap.containsKey(stateId)) {
+ choiceSet = doneBacktrackMap.get(stateId);
+ if (choiceSet.contains(firstChoice)) {
+ return true;
+ }
+ } else {
+ choiceSet = new HashSet<>();
+ doneBacktrackMap.put(stateId, choiceSet);
}
- doneBacktrackSet.add(sb.toString());
+ choiceSet.add(firstChoice);
+
return false;
}
// 1) recursively, and
// 2) track accesses per memory location (per shared variable/field)
private void updateBacktrackSet(Execution execution, int currentChoice) {
- // Choice/event we want to check for conflict against (start from actual choice)
- int conflictChoice = currentChoice;
// Copy ReadWriteSet object
HashMap<Integer, ReadWriteSet> currRWFieldsMap = execution.getReadWriteFieldsMap();
ReadWriteSet currRWSet = currRWFieldsMap.get(currentChoice);
// Memorize visited TransitionEvent object while performing backward DFS to avoid getting caught up in a cycle
HashSet<TransitionEvent> visited = new HashSet<>();
// Update backtrack set recursively
-// updateBacktrackSetRecursive(execution, currentChoice, execution, conflictChoice, currRWSet, visited);
- int hbChoice = currentChoice;
- updateBacktrackSetRecursive(execution, currentChoice, execution, conflictChoice, execution, hbChoice, currRWSet, visited);
+ updateBacktrackSetRecursive(execution, currentChoice, execution, currentChoice, currRWSet, visited);
}
-// private void updateBacktrackSetRecursive(Execution execution, int currentChoice,
-// Execution conflictExecution, int conflictChoice,
-// ReadWriteSet currRWSet, HashSet<TransitionEvent> visited) {
-// // Halt when we have found the first read/write conflicts for all memory locations
-// if (currRWSet.isEmpty()) {
-// return;
-// }
-// TransitionEvent confTrans = conflictExecution.getExecutionTrace().get(conflictChoice);
-// // Halt when we have visited this transition (in a cycle)
-// if (visited.contains(confTrans)) {
-// return;
-// }
-// visited.add(confTrans);
-// // Explore all predecessors
-// for (Predecessor predecessor : confTrans.getPredecessors()) {
-// // Get the predecessor (previous conflict choice)
-// conflictChoice = predecessor.getChoice();
-// conflictExecution = predecessor.getExecution();
-// // Check if a conflict is found
-// if (isConflictFound(execution, currentChoice, conflictExecution, conflictChoice, currRWSet)) {
-// createBacktrackingPoint(execution, currentChoice, conflictExecution, conflictChoice);
-// }
-// // Continue performing DFS if conflict is not found
-// updateBacktrackSetRecursive(execution, currentChoice, conflictExecution, conflictChoice, currRWSet, visited);
-// }
-// }
-
- // TODO: This is the version of the method with pushing up happens-before transitions
private void updateBacktrackSetRecursive(Execution execution, int currentChoice,
Execution conflictExecution, int conflictChoice,
- Execution hbExecution, int hbChoice,
ReadWriteSet currRWSet, HashSet<TransitionEvent> visited) {
// Halt when we have found the first read/write conflicts for all memory locations
if (currRWSet.isEmpty()) {
return;
}
- TransitionEvent confTrans = conflictExecution.getExecutionTrace().get(conflictChoice);
+ TransitionEvent currTrans = execution.getExecutionTrace().get(currentChoice);
// Halt when we have visited this transition (in a cycle)
- if (visited.contains(confTrans)) {
+ if (visited.contains(currTrans)) {
return;
}
- visited.add(confTrans);
+ visited.add(currTrans);
// Explore all predecessors
- for (Predecessor predecessor : confTrans.getPredecessors()) {
+ for (Predecessor predecessor : currTrans.getPredecessors()) {
// Get the predecessor (previous conflict choice)
- conflictChoice = predecessor.getChoice();
- conflictExecution = predecessor.getExecution();
+ int predecessorChoice = predecessor.getChoice();
+ Execution predecessorExecution = predecessor.getExecution();
// Push up one happens-before transition
- int pushedChoice = hbChoice;
- Execution pushedExecution = hbExecution;
+ int newConflictChoice = conflictChoice;
+ Execution newConflictExecution = conflictExecution;
// Check if a conflict is found
- if (isConflictFound(execution, currentChoice, conflictExecution, conflictChoice, currRWSet)) {
- createBacktrackingPoint(pushedExecution, pushedChoice, conflictExecution, conflictChoice);
- pushedChoice = conflictChoice;
- pushedExecution = conflictExecution;
+ if (isConflictFound(conflictExecution, conflictChoice, predecessorExecution, predecessorChoice, currRWSet)) {
+ createBacktrackingPoint(conflictExecution, conflictChoice, predecessorExecution, predecessorChoice);
+ newConflictChoice = predecessorChoice;
+ newConflictExecution = predecessorExecution;
}
// Continue performing DFS if conflict is not found
- updateBacktrackSetRecursive(execution, currentChoice, conflictExecution, conflictChoice,
- pushedExecution, pushedChoice, currRWSet, visited);
+ updateBacktrackSetRecursive(predecessorExecution, predecessorChoice, newConflictExecution, newConflictChoice,
+ currRWSet, visited);
}
}
// 2) at least 2 choices/events have been explored (choiceCounter > 1),
// 3) state > 0 (state 0 is for boolean CG)
if (!isEndOfExecution && choiceCounter > 1 && stateId > 0) {
- if (currVisitedStates.contains(stateId)) {
- // Get the backtrack point from the current execution
- TransitionEvent transition = currentExecution.getTransitionFromState(stateId);
- transition.recordPredecessor(currentExecution, choiceCounter - 1);
- updateBacktrackSetsFromPreviousExecution(stateId);
- } else if (prevVisitedStates.contains(stateId)) { // We visit a state in a previous execution
- // Update past executions with a predecessor
+ if (currVisitedStates.contains(stateId) || prevVisitedStates.contains(stateId)) {
+ // Update reachable transitions in the graph with a predecessor
HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitionsAtState(stateId);
for(TransitionEvent transition : reachableTransitions) {
transition.recordPredecessor(currentExecution, choiceCounter - 1);
}
- updateBacktrackSetsFromPreviousExecution(stateId);
+ updateBacktrackSetsFromGraph(stateId);
}
}
}
// Update the backtrack sets from previous executions
- private void updateBacktrackSetsFromPreviousExecution(int stateId) {
+ private void updateBacktrackSetsFromGraph(int stateId) {
// Collect all the reachable transitions from R-Graph
HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitions(stateId);
for(TransitionEvent transition : reachableTransitions) {
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