X-Git-Url: http://plrg.eecs.uci.edu/git/?p=jpf-core.git;a=blobdiff_plain;f=src%2Fmain%2Fgov%2Fnasa%2Fjpf%2Flistener%2FDPORStateReducer.java;h=5b0359ed5a92198f351200cda526b7ab573b3e2e;hp=4645d2c5745e5cc568d1db93eadff74b448424c9;hb=8a8c10ed55dfd4dcd299af66c2f418bbd41241c5;hpb=9adeb9b41d1ca24612350f1b055af8d9e0f65e8b diff --git a/src/main/gov/nasa/jpf/listener/DPORStateReducer.java b/src/main/gov/nasa/jpf/listener/DPORStateReducer.java index 4645d2c..5b0359e 100644 --- a/src/main/gov/nasa/jpf/listener/DPORStateReducer.java +++ b/src/main/gov/nasa/jpf/listener/DPORStateReducer.java @@ -20,8 +20,9 @@ package gov.nasa.jpf.listener; 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; @@ -29,24 +30,14 @@ import gov.nasa.jpf.vm.choice.IntChoiceFromSet; 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; -// TODO: Fix for Groovy's model-checking -// TODO: This is a setter to change the values of the ChoiceGenerator to implement POR /** - * Simple tool to log state changes. - * - * This DPOR implementation is augmented by the algorithm presented in this SPIN paper: - * http://spinroot.com/spin/symposia/ws08/spin2008_submission_33.pdf - * - * The algorithm is presented on page 11 of the paper. Basically, we have a graph G - * (i.e., visible operation dependency graph). - * This DPOR implementation actually fixes the algorithm in the SPIN paper that does not - * consider cases where a state could be matched early. In this new algorithm/implementation, - * each run is terminated iff: + * This a DPOR implementation for event-driven applications with loops that create cycles of state matching + * In this new DPOR algorithm/implementation, each run is terminated iff: * - we find a state that matches a state in a previous run, or * - we have a matched state in the current run that consists of cycles that contain all choices/events. */ @@ -69,29 +60,28 @@ public class DPORStateReducer extends ListenerAdapter { 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 currVisitedStates; // States being visited in the current execution - private HashSet justVisitedStates; // States just visited in the previous choice/event - private HashSet prevVisitedStates; // States visited in the previous execution + private HashSet currVisitedStates; // States being visited in the current execution + private HashSet justVisitedStates; // States just visited in the previous choice/event + private HashSet prevVisitedStates; // States visited in the previous execution + private HashSet nonRelevantClasses;// Class info objects of non-relevant classes + private HashSet nonRelevantFields; // Field info objects of non-relevant fields + private HashSet relevantFields; // Field info objects of relevant fields private HashMap> stateToEventMap; // Data structure to analyze field Read/Write accesses and conflicts - private HashMap> backtrackMap; // Track created backtracking points + private HashMap> backtrackMap; // Track created backtracking points private PriorityQueue backtrackStateQ; // Heap that returns the latest state - private ArrayList backtrackPointList; // Record backtrack points (CG, state Id, and choice) - private HashMap> conflictPairMap; // Record conflicting events - private HashSet doneBacktrackSet; // Record state ID and trace already constructed - private HashMap readWriteFieldsMap; // Record fields that are accessed + private Execution currentExecution; // Holds the information about the current execution + private HashMap> doneBacktrackMap; // Record state ID and trace already constructed private HashMap restorableStateMap; // Maps state IDs to the restorable state object - private HashMap stateToChoiceCounterMap; // Maps state IDs to the choice counter - private HashMap stateToRGraph; // Maps state IDs to a ReachabilityGraph + 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); @@ -108,8 +98,10 @@ public class DPORStateReducer extends ListenerAdapter { } } isBooleanCGFlipped = false; - numOfConflicts = 0; numOfTransitions = 0; + nonRelevantClasses = new HashSet<>(); + nonRelevantFields = new HashSet<>(); + relevantFields = new HashSet<>(); restorableStateMap = new HashMap<>(); initializeStatesVariables(); } @@ -177,19 +169,13 @@ public class DPORStateReducer extends ListenerAdapter { @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(); @@ -202,6 +188,8 @@ public class DPORStateReducer extends ListenerAdapter { // 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(); @@ -228,15 +216,12 @@ public class DPORStateReducer extends ListenerAdapter { @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(); } @@ -247,12 +232,13 @@ public class DPORStateReducer extends ListenerAdapter { // If this is a new CG then we need to update data structures resetStatesForNewExecution(icsCG, vm); // If we don't see a fair scheduling of events/choices then we have to enforce it - fairSchedulingAndBacktrackPoint(icsCG, vm); - // Explore the next backtrack point: + ensureFairSchedulingAndSetupTransition(icsCG, vm); + // Update backtrack set of an executed event (transition): one transition before this one + updateBacktrackSet(currentExecution, choiceCounter - 1); + // 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) { - saveExecutionInfo(); exploreNextBacktrackPoints(vm, icsCG); } else { numOfTransitions++; @@ -281,34 +267,14 @@ public class DPORStateReducer extends ListenerAdapter { 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 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("")) { - 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)) { - createBacktrackingPoint(currentChoice, eventCounter); - } - } - } - } - } } } } @@ -319,91 +285,335 @@ public class DPORStateReducer extends ListenerAdapter { // -- INNER CLASSES + // This class compactly stores backtrack execution: + // 1) backtrack choice list, and + // 2) first backtrack point (linking with predecessor execution) + private class BacktrackExecution { + private Integer[] choiceList; + private TransitionEvent firstTransition; + + public BacktrackExecution(Integer[] choList, TransitionEvent fTransition) { + choiceList = choList; + firstTransition = fTransition; + } + + public Integer[] getChoiceList() { + return choiceList; + } + + public TransitionEvent getFirstTransition() { + return firstTransition; + } + } + + // 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 + // TODO: (2) last state with two or more incoming events/transitions + private class Execution { + private HashMap cgToChoiceMap; // Map between CG to choice numbers for O(1) access + private ArrayList executionTrace; // The BacktrackPoint objects of this execution + private boolean isNew; // Track if this is the first time it is accessed + private HashMap readWriteFieldsMap; // Record fields that are accessed + + public Execution() { + cgToChoiceMap = new HashMap<>(); + executionTrace = new ArrayList<>(); + isNew = true; + readWriteFieldsMap = new HashMap<>(); + } + + public void addTransition(TransitionEvent newBacktrackPoint) { + executionTrace.add(newBacktrackPoint); + } + + public void clearCGToChoiceMap() { + cgToChoiceMap = null; + } + + public int getChoiceFromCG(IntChoiceFromSet icsCG) { + return cgToChoiceMap.get(icsCG); + } + + public ArrayList getExecutionTrace() { + return executionTrace; + } + + public TransitionEvent getFirstTransition() { + return executionTrace.get(0); + } + + public TransitionEvent getLastTransition() { + return executionTrace.get(executionTrace.size() - 1); + } + + public HashMap getReadWriteFieldsMap() { + return readWriteFieldsMap; + } + + public boolean isNew() { + if (isNew) { + // Right after this is accessed, it is no longer new + isNew = false; + return true; + } + return false; + } + + public void mapCGToChoice(IntChoiceFromSet icsCG, int choice) { + cgToChoiceMap.put(icsCG, choice); + } + } + + // This class compactly stores a predecessor + // 1) a predecessor execution + // 2) the predecessor choice in that predecessor execution + private class Predecessor { + private int choice; // Predecessor choice + private Execution execution; // Predecessor execution + + public Predecessor(int predChoice, Execution predExec) { + choice = predChoice; + execution = predExec; + } + + public int getChoice() { + return choice; + } + + public Execution getExecution() { + return execution; + } + } + + // 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> graph; // Reachable transitions from past executions + + public RGraph() { + hiStateId = 0; + graph = new HashMap<>(); + } + + public void addReachableTransition(int stateId, TransitionEvent transition) { + HashSet transitionSet; + if (graph.containsKey(stateId)) { + transitionSet = graph.get(stateId); + } else { + transitionSet = new HashSet<>(); + graph.put(stateId, transitionSet); + } + // Insert into the set if it does not contain it yet + if (!transitionSet.contains(transition)) { + transitionSet.add(transition); + } + // Update highest state ID + if (hiStateId < stateId) { + hiStateId = stateId; + } + } + + public HashSet getReachableTransitionsAtState(int stateId) { + if (!graph.containsKey(stateId)) { + // This is a loop from a transition to itself, so just return the current transition + HashSet transitionSet = new HashSet<>(); + transitionSet.add(currentExecution.getLastTransition()); + return transitionSet; + } + return graph.get(stateId); + } + + public HashSet getReachableTransitions(int stateId) { + HashSet 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++) { + // 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 Read and Write field sets // We store the field name and its object ID // Sharing the same field means the same field name and object ID private class ReadWriteSet { - private HashMap readSet; - private HashMap writeSet; + private HashMap readMap; + private HashMap writeMap; public ReadWriteSet() { - readSet = new HashMap<>(); - writeSet = new HashMap<>(); + readMap = new HashMap<>(); + writeMap = new HashMap<>(); } public void addReadField(String field, int objectId) { - readSet.put(field, objectId); + readMap.put(field, objectId); } public void addWriteField(String field, int objectId) { - writeSet.put(field, objectId); + writeMap.put(field, objectId); + } + + public void removeReadField(String field) { + readMap.remove(field); + } + + public void removeWriteField(String field) { + writeMap.remove(field); + } + + public boolean isEmpty() { + return readMap.isEmpty() && writeMap.isEmpty(); + } + + public ReadWriteSet getCopy() { + ReadWriteSet copyRWSet = new ReadWriteSet(); + // Copy the maps in the set into the new object copy + copyRWSet.setReadMap(new HashMap<>(this.getReadMap())); + copyRWSet.setWriteMap(new HashMap<>(this.getWriteMap())); + return copyRWSet; } public Set getReadSet() { - return readSet.keySet(); + return readMap.keySet(); } public Set getWriteSet() { - return writeSet.keySet(); + return writeMap.keySet(); } public boolean readFieldExists(String field) { - return readSet.containsKey(field); + return readMap.containsKey(field); } public boolean writeFieldExists(String field) { - return writeSet.containsKey(field); + return writeMap.containsKey(field); } public int readFieldObjectId(String field) { - return readSet.get(field); + return readMap.get(field); } public int writeFieldObjectId(String field) { - return writeSet.get(field); + return writeMap.get(field); + } + + private HashMap getReadMap() { + return readMap; + } + + private HashMap getWriteMap() { + return writeMap; + } + + private void setReadMap(HashMap rMap) { + readMap = rMap; + } + + private void setWriteMap(HashMap wMap) { + writeMap = wMap; } } - // This class compactly stores backtrack points: 1) backtrack state ID, and 2) backtracking choices - private class BacktrackPoint { - 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 + // This class compactly stores transitions: + // 1) CG, + // 2) state ID, + // 3) choice, + // 4) predecessors (for backward DFS). + private class TransitionEvent { + private int choice; // Choice chosen at this transition + private int choiceCounter; // Choice counter at this transition + private Execution execution; // The execution where this transition belongs + private HashSet predecessors; // Maps incoming events/transitions (execution and choice) + private HashMap> 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 + + public TransitionEvent() { + choice = 0; + choiceCounter = 0; + execution = null; + predecessors = new HashSet<>(); + recordedPredecessors = new HashMap<>(); + stateId = 0; + transitionCG = null; + } - public BacktrackPoint(IntChoiceFromSet cg, int stId, int cho) { - backtrackCG = cg; - stateId = stId; - choice = cho; + public int getChoice() { + return choice; + } + + public int getChoiceCounter() { + return choiceCounter; + } + + public Execution getExecution() { + return execution; } - public IntChoiceFromSet getBacktrackCG() { return backtrackCG; } + public HashSet getPredecessors() { + return predecessors; + } public int getStateId() { return stateId; } - public int getChoice() { - return choice; + public IntChoiceFromSet getTransitionCG() { return transitionCG; } + + private boolean isRecordedPredecessor(Execution execution, int choice) { + // See if we have recorded this predecessor earlier + HashSet 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; } - } - // This class stores a compact representation of a reachability graph for past executions - private class ReachabilityGraph { - private ArrayList pastBacktrackPointList; - private HashMap pastReadWriteFieldsMap; + public void recordPredecessor(Execution execution, int choice) { + if (!isRecordedPredecessor(execution, choice)) { + predecessors.add(new Predecessor(choice, execution)); + } + } + + public void setChoice(int cho) { + choice = cho; + } + + public void setChoiceCounter(int choCounter) { + choiceCounter = choCounter; + } - public ReachabilityGraph(ArrayList btrackPointList, - HashMap rwFieldsMap) { - pastBacktrackPointList = btrackPointList; - pastReadWriteFieldsMap = rwFieldsMap; + public void setExecution(Execution exec) { + execution = exec; } - public ArrayList getPastBacktrackPointList() { - return pastBacktrackPointList; + public void setPredecessors(HashSet preds) { + predecessors = new HashSet<>(preds); } - public HashMap getPastReadWriteFieldsMap() { - return pastReadWriteFieldsMap; + public void setStateId(int stId) { + stateId = stId; + } + + public void setTransitionCG(IntChoiceFromSet cg) { + transitionCG = cg; } } @@ -428,7 +638,14 @@ public class DPORStateReducer extends ListenerAdapter { private final static String JAVA_STRING_LIB = "java.lang.String"; // -- FUNCTIONS - private void fairSchedulingAndBacktrackPoint(IntChoiceFromSet icsCG, VM vm) { + private Integer[] copyChoices(Integer[] choicesToCopy) { + + Integer[] copyOfChoices = new Integer[choicesToCopy.length]; + System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length); + return copyOfChoices; + } + + private void ensureFairSchedulingAndSetupTransition(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(); @@ -439,22 +656,42 @@ public class DPORStateReducer extends ListenerAdapter { icsCG.setChoice(currCGIndex, expectedChoice); } } - // Record state ID and choice/event as backtrack point + // Get state ID and associate it with this transition int stateId = vm.getStateId(); - backtrackPointList.add(new BacktrackPoint(icsCG, stateId, refChoices[choiceIndex])); + TransitionEvent transition = setupTransition(icsCG, stateId, choiceIndex); + // 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 + 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 Integer[] copyChoices(Integer[] choicesToCopy) { + private TransitionEvent setupTransition(IntChoiceFromSet icsCG, int stateId, int choiceIndex) { + // Get a new transition + TransitionEvent transition; + if (currentExecution.isNew()) { + // We need to handle the first transition differently because this has a predecessor execution + transition = currentExecution.getFirstTransition(); + } else { + transition = new TransitionEvent(); + currentExecution.addTransition(transition); + transition.recordPredecessor(currentExecution, choiceCounter - 1); + } + transition.setExecution(currentExecution); + transition.setTransitionCG(icsCG); + transition.setStateId(stateId); + transition.setChoice(refChoices[choiceIndex]); + transition.setChoiceCounter(choiceCounter); - Integer[] copyOfChoices = new Integer[choicesToCopy.length]; - System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length); - return copyOfChoices; + return transition; } - // --- Functions related to cycle detection + // --- Functions related to cycle detection and reachability graph // Detect cycles in the current execution/trace // We terminate the execution iff: @@ -462,8 +699,7 @@ public class DPORStateReducer extends ListenerAdapter { // (2) the state has one or more cycles that involve all the events // 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 containsCyclesWithAllEvents(int stId) { - + private boolean completeFullCycle(int stId) { // False if the state ID hasn't been recorded if (!stateToEventMap.containsKey(stId)) { return false; @@ -493,12 +729,10 @@ public class DPORStateReducer extends ListenerAdapter { // Backtracking backtrackMap = new HashMap<>(); backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder()); - backtrackPointList = new ArrayList<>(); - conflictPairMap = new HashMap<>(); - doneBacktrackSet = new HashSet<>(); - readWriteFieldsMap = new HashMap<>(); - stateToChoiceCounterMap = new HashMap<>(); - stateToRGraph = new HashMap<>(); + currentExecution = new Execution(); + currentExecution.addTransition(new TransitionEvent()); // Always start with 1 backtrack point + doneBacktrackMap = new HashMap<>(); + rGraph = new RGraph(); // Booleans isEndOfExecution = false; } @@ -517,7 +751,7 @@ public class DPORStateReducer extends ListenerAdapter { // We need to check all the states that have just been visited // Often a transition (choice/event) can result into forwarding/backtracking to a number of states for(Integer stateId : justVisitedStates) { - if (prevVisitedStates.contains(stateId) || containsCyclesWithAllEvents(stateId)) { + if (prevVisitedStates.contains(stateId) || completeFullCycle(stateId)) { return true; } } @@ -526,31 +760,35 @@ public class DPORStateReducer extends ListenerAdapter { 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)) { HashSet eventSet = new HashSet<>(); stateToEventMap.put(stateId, eventSet); } - stateToChoiceCounterMap.put(stateId, choiceCounter); analyzeReachabilityAndCreateBacktrackPoints(search.getVM(), stateId); justVisitedStates.add(stateId); - currVisitedStates.add(stateId); + if (!prevVisitedStates.contains(stateId)) { + // It is a currently visited states if the state has not been seen in previous executions + currVisitedStates.add(stateId); + } } // --- Functions related to Read/Write access analysis on shared fields - private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList) { + private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList, TransitionEvent conflictTransition) { // Insert backtrack point to the right state ID - LinkedList backtrackList; + LinkedList backtrackExecList; if (backtrackMap.containsKey(stateId)) { - backtrackList = backtrackMap.get(stateId); + backtrackExecList = backtrackMap.get(stateId); } else { - backtrackList = new LinkedList<>(); - backtrackMap.put(stateId, backtrackList); + backtrackExecList = new LinkedList<>(); + backtrackMap.put(stateId, backtrackExecList); } - backtrackList.addFirst(newChoiceList); + // Add the new backtrack execution object + TransitionEvent backtrackTransition = new TransitionEvent(); + backtrackTransition.setPredecessors(conflictTransition.getPredecessors()); + backtrackExecList.addFirst(new BacktrackExecution(newChoiceList, backtrackTransition)); // Add to priority queue if (!backtrackStateQ.contains(stateId)) { backtrackStateQ.add(stateId); @@ -558,17 +796,28 @@ public class DPORStateReducer extends ListenerAdapter { } // 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) { @@ -597,9 +846,17 @@ public class DPORStateReducer extends ListenerAdapter { 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 @@ -620,8 +877,6 @@ public class DPORStateReducer extends ListenerAdapter { private int checkAndAdjustChoice(int currentChoice, VM vm) { // 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 = currChoiceInd; ChoiceGenerator currentCG = vm.getChoiceGenerator(); // This is the main event CG if (currentCG instanceof IntIntervalGenerator) { @@ -631,45 +886,40 @@ public class DPORStateReducer extends ListenerAdapter { while (!(parentCG instanceof IntChoiceFromSet)) { parentCG = ((IntIntervalGenerator) parentCG).getPreviousChoiceGenerator(); } - int actualEvtNum = ((IntChoiceFromSet) parentCG).getNextChoice(); - // Find the index of the event/choice in refChoices - for (int i = 0; i currentTrace = execution.getExecutionTrace(); + ArrayList conflictTrace = conflictExecution.getExecutionTrace(); + int currChoice = currentTrace.get(currentChoice).getChoice(); + int stateId = conflictTrace.get(conflictChoice).getStateId(); + // Check if this trace has been done from this state + if (isTraceAlreadyConstructed(currChoice, stateId)) { + return; + } // Put the conflicting event numbers first and reverse the order - // We use the actual choices here in case they have been modified/adjusted by the fair scheduling method - newChoiceList[0] = backtrackPointList.get(currentChoice).getChoice(); - newChoiceList[1] = backtrackPointList.get(confEvtNum).getChoice(); + newChoiceList[0] = currChoice; // 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]) { + for (int i = 0, j = 1; i < refChoices.length; i++) { + if (refChoices[i] != newChoiceList[0]) { newChoiceList[j] = refChoices[i]; j++; } } - // Get the backtrack CG for this backtrack point - int stateId = backtrackPointList.get(confEvtNum).getStateId(); - // Check if this trace has been done starting from this state - if (isTraceAlreadyConstructed(newChoiceList, stateId)) { - return; - } - addNewBacktrackPoint(stateId, newChoiceList); + // Predecessor of the new backtrack point is the same as the conflict point's + addNewBacktrackPoint(stateId, newChoiceList, conflictTrace.get(conflictChoice)); } private boolean excludeThisForItContains(String[] excludedStrings, String className) { @@ -700,13 +950,12 @@ public class DPORStateReducer extends ListenerAdapter { } private void exploreNextBacktrackPoints(VM vm, IntChoiceFromSet icsCG) { - // 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(); + for (TransitionEvent backtrackTransition : currentExecution.getExecutionTrace()) { + backtrackTransition.getTransitionCG().setDone(); } // Reset the next backtrack point with the latest state int hiStateId = backtrackStateQ.peek(); @@ -724,41 +973,31 @@ public class DPORStateReducer extends ListenerAdapter { } // 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) { - // Do the analysis to get Read and Write accesses to fields - ReadWriteSet rwSet; - // We already have an entry - if (readWriteFieldsMap.containsKey(currentChoice)) { - rwSet = readWriteFieldsMap.get(currentChoice); - } else { // We need to create a new entry - rwSet = new ReadWriteSet(); - readWriteFieldsMap.put(currentChoice, rwSet); - } - return rwSet; - } - - private boolean isConflictFound(int eventCounter, int currentChoice) { - + 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 executionTrace = execution.getExecutionTrace(); + ArrayList conflictTrace = conflictExecution.getExecutionTrace(); + HashMap 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 (!readWriteFieldsMap.containsKey(eventCounter) || - backtrackPointList.get(currentChoice).getChoice() == backtrackPointList.get(eventCounter).getChoice()) { + if (!confRWFieldsMap.containsKey(conflictChoice) || + executionTrace.get(reachableChoice).getChoice() == conflictTrace.get(conflictChoice).getChoice()) { return false; } - // Current R/W set - ReadWriteSet currRWSet = readWriteFieldsMap.get(currentChoice); // R/W set of choice/event that may have a potential conflict - ReadWriteSet evtRWSet = readWriteFieldsMap.get(eventCounter); + ReadWriteSet confRWSet = confRWFieldsMap.get(conflictChoice); // Check for conflicts with Read and Write fields for Write instructions Set 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; } } @@ -766,7 +1005,9 @@ public class DPORStateReducer extends ListenerAdapter { Set 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; } } @@ -774,73 +1015,65 @@ public class DPORStateReducer extends ListenerAdapter { return false; } - private boolean isConflictFound(Instruction nextInsn, int eventCounter, int currentChoice, String fieldClass) { - - 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] == backtrackPointList.get(eventCounter).getChoice()) { - return false; - } - ReadWriteSet rwSet = readWriteFieldsMap.get(eventCounter); - int currObjId = ((JVMFieldInstruction) nextInsn).getFieldInfo().getClassInfo().getClassObjectRef(); - // Check for conflicts with Write fields for both Read and Write instructions - if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) && - rwSet.writeFieldExists(fieldClass) && rwSet.writeFieldObjectId(fieldClass) == currObjId) || - (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass) && - rwSet.readFieldObjectId(fieldClass) == currObjId)) { - return true; + private ReadWriteSet getReadWriteSet(int currentChoice) { + // Do the analysis to get Read and Write accesses to fields + ReadWriteSet rwSet; + // We already have an entry + HashMap currReadWriteFieldsMap = currentExecution.getReadWriteFieldsMap(); + if (currReadWriteFieldsMap.containsKey(currentChoice)) { + rwSet = currReadWriteFieldsMap.get(currentChoice); + } else { // We need to create a new entry + rwSet = new ReadWriteSet(); + currReadWriteFieldsMap.put(currentChoice, rwSet); } - return false; + 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; } - private boolean isNewConflict(int currentEvent, int eventNumber) { - HashSet conflictSet; - if (!conflictPairMap.containsKey(currentEvent)) { - conflictSet = new HashSet<>(); - conflictPairMap.put(currentEvent, conflictSet); - } else { - conflictSet = conflictPairMap.get(currentEvent); - } - // If this conflict has been recorded before, we return false because - // we don't want to save this backtrack point twice - if (conflictSet.contains(eventNumber)) { - return false; - } - // If it hasn't been recorded, then do otherwise - conflictSet.add(eventNumber); - return true; - } - - private boolean isTraceAlreadyConstructed(Integer[] choiceList, int stateId) { + // 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(choiceList[0]); // 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 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; } + // Reset data structure for each new execution private void resetStatesForNewExecution(IntChoiceFromSet icsCG, VM vm) { if (choices == null || choices != icsCG.getAllChoices()) { // Reset state variables @@ -848,122 +1081,146 @@ public class DPORStateReducer extends ListenerAdapter { choices = icsCG.getAllChoices(); refChoices = copyChoices(choices); // Clear data structures - backtrackPointList = new ArrayList<>(); - conflictPairMap = new HashMap<>(); - readWriteFieldsMap = new HashMap<>(); - stateToChoiceCounterMap = new HashMap<>(); + currVisitedStates = new HashSet<>(); stateToEventMap = new HashMap<>(); isEndOfExecution = false; } } + // Set a backtrack point for a particular state private void setBacktrackCG(int stateId, IntChoiceFromSet backtrackCG) { // Set a backtrack CG based on a state ID - LinkedList backtrackChoices = backtrackMap.get(stateId); - backtrackCG.setNewValues(backtrackChoices.removeLast()); // Get the last from the queue + LinkedList backtrackExecutions = backtrackMap.get(stateId); + BacktrackExecution backtrackExecution = backtrackExecutions.removeLast(); + backtrackCG.setNewValues(backtrackExecution.getChoiceList()); // Get the last from the queue backtrackCG.setStateId(stateId); backtrackCG.reset(); + // Update current execution with this new execution + Execution newExecution = new Execution(); + TransitionEvent firstTransition = backtrackExecution.getFirstTransition(); + newExecution.addTransition(firstTransition); + // Try to free some memory since this map is only used for the current execution + currentExecution.clearCGToChoiceMap(); + currentExecution = newExecution; // Remove from the queue if we don't have more backtrack points for that state - if (backtrackChoices.isEmpty()) { + if (backtrackExecutions.isEmpty()) { backtrackMap.remove(stateId); backtrackStateQ.remove(stateId); } } + // Update backtrack sets + // 1) recursively, and + // 2) track accesses per memory location (per shared variable/field) + private void updateBacktrackSet(Execution execution, int currentChoice) { + // Copy ReadWriteSet object + HashMap currRWFieldsMap = execution.getReadWriteFieldsMap(); + ReadWriteSet currRWSet = currRWFieldsMap.get(currentChoice); + if (currRWSet == null) { + return; + } + currRWSet = currRWSet.getCopy(); + // Memorize visited TransitionEvent object while performing backward DFS to avoid getting caught up in a cycle + HashSet visited = new HashSet<>(); + // Update backtrack set recursively + // TODO: The following is the call to the original version of the method +// updateBacktrackSetRecursive(execution, currentChoice, execution, currentChoice, currRWSet, visited); + // TODO: The following is the call to the version of the method with pushing up happens-before transitions + updateBacktrackSetRecursive(execution, currentChoice, execution, currentChoice, currRWSet, visited); + } + +// TODO: This is the original version of the recursive method +// private void updateBacktrackSetRecursive(Execution execution, int currentChoice, +// Execution conflictExecution, int conflictChoice, +// ReadWriteSet currRWSet, HashSet 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, + ReadWriteSet currRWSet, HashSet visited) { + // Halt when we have found the first read/write conflicts for all memory locations + if (currRWSet.isEmpty()) { + return; + } + TransitionEvent currTrans = execution.getExecutionTrace().get(currentChoice); + // Halt when we have visited this transition (in a cycle) + if (visited.contains(currTrans)) { + return; + } + visited.add(currTrans); + // Explore all predecessors + for (Predecessor predecessor : currTrans.getPredecessors()) { + // Get the predecessor (previous conflict choice) + int predecessorChoice = predecessor.getChoice(); + Execution predecessorExecution = predecessor.getExecution(); + // Push up one happens-before transition + int newConflictChoice = conflictChoice; + Execution newConflictExecution = conflictExecution; + // Check if a conflict is found + 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(predecessorExecution, predecessorChoice, newConflictExecution, newConflictChoice, + currRWSet, visited); + } + // Remove the transition after being explored + // TODO: Seems to cause a lot of loops---commented out for now + //visited.remove(confTrans); + } + // --- Functions related to the reachability analysis when there is a state match - // We use backtrackPointsList to analyze the reachable states/events when there is a state match: - // 1) Whenever there is state match, there is a cycle of events - // 2) We need to analyze and find conflicts for the reachable choices/events in the cycle - // 3) Then we create a new backtrack point for every new conflict private void analyzeReachabilityAndCreateBacktrackPoints(VM vm, int stateId) { // Perform this analysis only when: - // 1) there is a state match, - // 2) this is not during a switch to a new execution, - // 3) at least 2 choices/events have been explored (choiceCounter > 1), - // 4) the matched state has been encountered in the current execution, and - // 5) state > 0 (state 0 is for boolean CG) - if (!vm.isNewState() && !isEndOfExecution && choiceCounter > 1 && (stateId > 0)) { - if (currVisitedStates.contains(stateId)) { - // Update the backtrack sets in the cycle - updateBacktrackSetsInCycle(stateId); - } else if (prevVisitedStates.contains(stateId)) { // We visit a state in a previous execution - // Update the backtrack sets in a previous execution - updateBacktrackSetsInPreviousExecution(stateId); - } - } - } - - // Save the information from this execution for future reachability analysis - private void saveExecutionInfo() { - Set states = stateToChoiceCounterMap.keySet(); - ReachabilityGraph reachabilityGraph = new - ReachabilityGraph(backtrackPointList, readWriteFieldsMap); - // Map all the states visited in this execution to the same ReachabilityGraph object for fast access - for(Integer state : states) { - if (!prevVisitedStates.contains(state)) { - stateToRGraph.put(state, reachabilityGraph); - } - } - } - - // Update the backtrack sets in the cycle - private void updateBacktrackSetsInCycle(int stateId) { - // Find the choice/event that marks the start of this cycle: first choice we explore for conflicts - int conflictChoice = stateToChoiceCounterMap.get(stateId); - int currentChoice = choiceCounter - 1; - // Find conflicts between choices/events in this cycle (we scan forward in the cycle, not backward) - while (conflictChoice < currentChoice) { - for (int eventCounter = conflictChoice + 1; eventCounter <= currentChoice; eventCounter++) { - if (isConflictFound(eventCounter, conflictChoice) && isNewConflict(conflictChoice, eventCounter)) { - createBacktrackingPoint(conflictChoice, eventCounter); - } - } - conflictChoice++; - } - } - - private int getPastConflictChoice(int stateId, ArrayList pastBacktrackPointList) { - // Iterate and find the first occurrence of the state ID - // It is guaranteed that a choice should be found because the state ID is in the list - int pastConfChoice = 0; - for(int i = 0; i pastBacktrackPointList = rGraph.getPastBacktrackPointList(); - HashMap pastReadWriteFieldsMap = rGraph.getPastReadWriteFieldsMap(); - int pastConfChoice = getPastConflictChoice(stateId, pastBacktrackPointList); - int conflictChoice = choiceCounter; - // Iterate from the starting point until the end of the past execution trace - while (pastConfChoice < pastBacktrackPointList.size() - 1) { // BacktrackPoint list always has a surplus of 1 - // Get the info of the event from the past execution trace - BacktrackPoint confBtrackPoint = pastBacktrackPointList.get(pastConfChoice); - ReadWriteSet rwSet = pastReadWriteFieldsMap.get(pastConfChoice); - // Append this event to the current list and map - backtrackPointList.add(confBtrackPoint); - readWriteFieldsMap.put(choiceCounter, rwSet); - for (int eventCounter = conflictChoice - 1; eventCounter >= 0; eventCounter--) { - if (isConflictFound(eventCounter, conflictChoice) && isNewConflict(conflictChoice, eventCounter)) { - createBacktrackingPoint(conflictChoice, eventCounter); + // 1) this is not during a switch to a new execution, + // 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) || prevVisitedStates.contains(stateId)) { + // Update reachable transitions in the graph with a predecessor + HashSet reachableTransitions = rGraph.getReachableTransitionsAtState(stateId); + for(TransitionEvent transition : reachableTransitions) { + transition.recordPredecessor(currentExecution, choiceCounter - 1); } + updateBacktrackSetsFromPreviousExecution(stateId); } - // Remove this event to replace it with a new one - backtrackPointList.remove(backtrackPointList.size() - 1); - readWriteFieldsMap.remove(choiceCounter); - pastConfChoice++; + } + } + + // Update the backtrack sets from previous executions + private void updateBacktrackSetsFromPreviousExecution(int stateId) { + // Collect all the reachable transitions from R-Graph + HashSet reachableTransitions = rGraph.getReachableTransitions(stateId); + for(TransitionEvent transition : reachableTransitions) { + Execution execution = transition.getExecution(); + int currentChoice = transition.getChoiceCounter(); + updateBacktrackSet(execution, currentChoice); } } }