*/
public class DPORStateReducer extends ListenerAdapter {
- // Debug info fields
+ // Information printout fields for verbose mode
private boolean verboseMode;
private boolean stateReductionMode;
private final PrintWriter out;
private int id;
private Transition transition;
+ // DPOR-related fields
+ // Basic information
+ private Integer[] choices;
+ private Integer[] refChoices; // Second reference to a copy of choices (choices may be modified for fair scheduling)
+ 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 HashMap<Integer, HashSet<Integer>> stateToEventMap;
+ // Data structure to analyze field Read/Write accesses and conflicts
+ private HashMap<Integer, LinkedList<Integer[]>> backtrackMap; // Track created backtracking points
+ private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
+ private ArrayList<BacktrackPoint> backtrackPointList; // Record backtrack points (CG, state Id, and choice)
+ private HashMap<Integer, HashSet<Integer>> conflictPairMap; // Record conflicting events
+ private HashSet<String> doneBacktrackSet; // Record state ID and trace already constructed
+ private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
+ private HashMap<Integer, RestorableVMState> restorableStateMap; // Maps state IDs to the restorable state object
+
+ // Visible operation dependency graph implementation (SPIN paper) related fields
+ private int prevChoiceValue;
+ private HashMap<Integer, HashSet<Integer>> vodGraphMap; // Visible operation dependency graph (VOD graph)
+
+ // Boolean states
+ private boolean isBooleanCGFlipped;
+ private boolean isEndOfExecution;
+
public DPORStateReducer(Config config, JPF jpf) {
verboseMode = config.getBoolean("printout_state_transition", false);
stateReductionMode = config.getBoolean("activate_state_reduction", true);
} else {
out = null;
}
+ isBooleanCGFlipped = false;
+ restorableStateMap = new HashMap<>();
+ initializeStatesVariables();
}
@Override
out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
" which is " + detail + " Transition: " + transition + "\n");
}
+ if (stateReductionMode) {
+ updateStateInfo(search);
+ }
}
@Override
out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
" and depth: " + depth + "\n");
}
+ if (stateReductionMode) {
+ updateStateInfo(search);
+ }
}
@Override
out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
}
}
+
+ @Override
+ public void choiceGeneratorRegistered(VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
+ if (stateReductionMode) {
+ // Initialize with necessary information from the CG
+ if (nextCG instanceof IntChoiceFromSet) {
+ IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
+ 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]);
+ } else {
+ // Set done all CGs while transitioning to a new execution
+ icsCG.setDone();
+ }
+ }
+ }
+ }
+
+ @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 {
+ // 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, vm);
+ // If we don't see a fair scheduling of events/choices then we have to enforce it
+ fairSchedulingAndBacktrackPoint(icsCG, vm);
+ // Map state to event
+ mapStateToEvent(icsCG.getNextChoice());
+ // Update the VOD graph always with the latest
+ updateVODGraph(icsCG.getNextChoice());
+ // Check if we have seen this state or this state contains cycles that involve all events
+ if (terminateCurrentExecution()) {
+ exploreNextBacktrackPoints(vm, icsCG);
+ }
+ justVisitedStates.clear();
+ choiceCounter++;
+ }
+ }
+ }
+
+ @Override
+ public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
+ if (stateReductionMode) {
+ 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;
+ }
+ 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);
+ }
+ } 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);
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+
+
+ // == HELPERS
+
+ // -- INNER CLASSES
+
+ // 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<String, Integer> readSet;
+ private HashMap<String, Integer> writeSet;
+
+ public ReadWriteSet() {
+ readSet = new HashMap<>();
+ writeSet = new HashMap<>();
+ }
+
+ public void addReadField(String field, int objectId) {
+ readSet.put(field, objectId);
+ }
+
+ public void addWriteField(String field, int objectId) {
+ writeSet.put(field, objectId);
+ }
+
+ public boolean readFieldExists(String field) {
+ return readSet.containsKey(field);
+ }
+
+ public boolean writeFieldExists(String field) {
+ return writeSet.containsKey(field);
+ }
+
+ public int readFieldObjectId(String field) {
+ return readSet.get(field);
+ }
+
+ public int writeFieldObjectId(String field) {
+ return writeSet.get(field);
+ }
+ }
+
+ // 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
+
+ public BacktrackPoint(IntChoiceFromSet cg, int stId, int cho) {
+ backtrackCG = cg;
+ stateId = stId;
+ choice = cho;
+ }
+
+ public IntChoiceFromSet getBacktrackCG() { return backtrackCG; }
+
+ public int getStateId() {
+ return stateId;
+ }
+
+ public int getChoice() {
+ return choice;
+ }
+ }
+
+ // -- CONSTANTS
+ private final static String DO_CALL_METHOD = "doCall";
+ // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
+ private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
+ private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST =
+ // Groovy library created fields
+ {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__",
+ // Infrastructure
+ "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList",
+ "eventList", "valueList", "settings", "printToConsole", "app1", "app2"};
+ private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST =
+ // Java and Groovy libraries
+ { "java", "org", "sun", "com", "gov", "groovy"};
+ private final static String[] EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
+ private final static String GET_PROPERTY_METHOD =
+ "invokeinterface org.codehaus.groovy.runtime.callsite.CallSite.callGetProperty";
+ private final static String GROOVY_CALLSITE_LIB = "org.codehaus.groovy.runtime.callsite";
+ private final static String JAVA_INTEGER = "int";
+ private final static String JAVA_STRING_LIB = "java.lang.String";
+
+ // -- FUNCTIONS
+ private void fairSchedulingAndBacktrackPoint(IntChoiceFromSet icsCG, VM vm) {
+ // Check the next choice and if the value is not the same as the expected then force the expected value
+ int choiceIndex = choiceCounter % refChoices.length;
+ int nextChoice = icsCG.getNextChoice();
+ if (refChoices[choiceIndex] != nextChoice) {
+ int expectedChoice = refChoices[choiceIndex];
+ int currCGIndex = icsCG.getNextChoiceIndex();
+ if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
+ icsCG.setChoice(currCGIndex, expectedChoice);
+ }
+ }
+ // Record state ID and choice/event as backtrack point
+ backtrackPointList.add(new BacktrackPoint(icsCG, vm.getStateId(), refChoices[choiceIndex]));
+ }
+
+ private Integer[] copyChoices(Integer[] choicesToCopy) {
+
+ Integer[] copyOfChoices = new Integer[choicesToCopy.length];
+ System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
+ return copyOfChoices;
+ }
+
+ // --- Functions related to cycle detection
+
+ // 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
+ // 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) {
+
+ // False if the state ID hasn't been recorded
+ if (!stateToEventMap.containsKey(stId)) {
+ return false;
+ }
+ HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
+ // Check if this set contains all the event choices
+ // If not then this is not the terminating condition
+ for(int i=0; i<=maxEventChoice; i++) {
+ if (!visitedEvents.contains(i)) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ private void initializeStatesVariables() {
+ // 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<>();
+ backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
+ backtrackPointList = new ArrayList<>();
+ conflictPairMap = new HashMap<>();
+ doneBacktrackSet = new HashSet<>();
+ readWriteFieldsMap = new HashMap<>();
+ // VOD graph
+ prevChoiceValue = -1;
+ vodGraphMap = new HashMap<>();
+ // Booleans
+ isEndOfExecution = false;
+ }
+
+ private void mapStateToEvent(int nextChoiceValue) {
+ // Update all states with this event/choice
+ // This means that all past states now see this transition
+ Set<Integer> stateSet = stateToEventMap.keySet();
+ for(Integer stateId : stateSet) {
+ HashSet<Integer> eventSet = stateToEventMap.get(stateId);
+ eventSet.add(nextChoiceValue);
+ }
+ }
+
+ private boolean terminateCurrentExecution() {
+ // 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)) {
+ return true;
+ }
+ }
+ return 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();
+ currVisitedStates.add(stateId);
+ // Insert state ID into the map if it is new
+ if (!stateToEventMap.containsKey(stateId)) {
+ HashSet<Integer> eventSet = new HashSet<>();
+ stateToEventMap.put(stateId, eventSet);
+ }
+ justVisitedStates.add(stateId);
+ // Store restorable state object for this state (always store the latest)
+ RestorableVMState restorableState = search.getVM().getRestorableState();
+ restorableStateMap.put(stateId, restorableState);
+ }
+
+ // --- Functions related to Read/Write access analysis on shared fields
+
+ private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList) {
+ // 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 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
+ ReadWriteSet rwSet = getReadWriteSet(currentChoice);
+ int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().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;
+ }
+ }
+ rwSet.addWriteField(fieldClass, objectId);
+ } else if (executedInsn instanceof ReadInstruction) {
+ rwSet.addReadField(fieldClass, objectId);
+ }
+ }
+
+ // Analyze Read accesses that are indirect (performed through iterators)
+ // These accesses are marked by certain bytecode instructions, e.g., INVOKEINTERFACE
+ private void analyzeReadWriteAccesses(Instruction instruction, ThreadInfo ti, int currentChoice) {
+ // Get method name
+ INVOKEINTERFACE insn = (INVOKEINTERFACE) instruction;
+ if (insn.toString().startsWith(GET_PROPERTY_METHOD) &&
+ insn.getMethodInfo().getName().equals(DO_CALL_METHOD)) {
+ // Extract info from the stack frame
+ StackFrame frame = ti.getTopFrame();
+ int[] frameSlots = frame.getSlots();
+ // Get the Groovy callsite library at index 0
+ ElementInfo eiCallsite = VM.getVM().getHeap().get(frameSlots[0]);
+ if (!eiCallsite.getClassInfo().getName().startsWith(GROOVY_CALLSITE_LIB)) {
+ return;
+ }
+ // Get the iterated object whose property is accessed
+ ElementInfo eiAccessObj = VM.getVM().getHeap().get(frameSlots[1]);
+ if (eiAccessObj == null) {
+ 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)) {
+ return;
+ }
+ // Extract fields from this object and put them into the read write
+ int numOfFields = eiAccessObj.getNumberOfFields();
+ for(int i=0; i<numOfFields; i++) {
+ FieldInfo fieldInfo = eiAccessObj.getFieldInfo(i);
+ if (fieldInfo.getType().equals(JAVA_STRING_LIB) || fieldInfo.getType().equals(JAVA_INTEGER)) {
+ String fieldClass = fieldInfo.getFullName();
+ ReadWriteSet rwSet = getReadWriteSet(currentChoice);
+ int objectId = fieldInfo.getClassInfo().getClassObjectRef();
+ // Record the field in the map
+ rwSet.addReadField(fieldClass, objectId);
+ }
+ }
+ }
+ }
+
+ 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 = 0;
+ ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
+ // This is the main event CG
+ if (currentCG instanceof IntChoiceFromSet) {
+ currChoiceFromCG = currChoiceInd;
+ } else {
+ // This is the interval CG used in device handlers
+ ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
+ currChoiceFromCG = ((IntChoiceFromSet) parentCG).getNextChoiceIndex();
+ }
+ if (currChoiceInd != currChoiceFromCG) {
+ currentChoice = (currentChoice - currChoiceInd) + currChoiceFromCG;
+ }
+ return currentChoice;
+ }
+
+ private void createBacktrackingPoint(int currentChoice, int confEvtNum) {
+
+ // 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}
+ Integer[] newChoiceList = new Integer[refChoices.length];
+ // Put the conflicting event numbers first and reverse the order
+ int actualCurrCho = currentChoice % refChoices.length;
+ // We use the actual choices here in case they have been modified/adjusted by the fair scheduling method
+ newChoiceList[0] = choices[actualCurrCho];
+ newChoiceList[1] = backtrackPointList.get(confEvtNum).getChoice();
+ // 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]) {
+ 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;
+ }
+ //BacktrackPoint backtrackPoint = new BacktrackPoint(backtrackCG, newChoiceList);
+ addNewBacktrackPoint(stateId, newChoiceList);
+ }
+
+ private boolean excludeThisForItContains(String[] excludedStrings, String className) {
+ for (String excludedField : excludedStrings) {
+ if (className.contains(excludedField)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private boolean excludeThisForItEndsWith(String[] excludedStrings, String className) {
+ for (String excludedField : excludedStrings) {
+ if (className.endsWith(excludedField)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private boolean excludeThisForItStartsWith(String[] excludedStrings, String className) {
+ for (String excludedField : excludedStrings) {
+ if (className.startsWith(excludedField)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private void exploreNextBacktrackPoints(VM vm, IntChoiceFromSet icsCG) {
+
+ // We can start exploring the next backtrack point after the current CG is advanced at least once
+ if (choiceCounter > 0) {
+ // Check if we are reaching the end of our execution: no more backtracking points to explore
+ // cgMap, backtrackMap, backtrackStateQ are updated simultaneously (checking backtrackStateQ is enough)
+ if (!backtrackStateQ.isEmpty()) {
+ // Set done all the other backtrack points
+ for (BacktrackPoint backtrackPoint : backtrackPointList) {
+ backtrackPoint.getBacktrackCG().setDone();
+ }
+ // Reset the next backtrack point with the latest state
+ int hiStateId = backtrackStateQ.peek();
+ // Restore the state first if necessary
+ if (vm.getStateId() != hiStateId) {
+ RestorableVMState restorableState = restorableStateMap.get(hiStateId);
+ vm.restoreState(restorableState);
+ }
+ // Set the backtrack CG
+ IntChoiceFromSet backtrackCG = (IntChoiceFromSet) vm.getChoiceGenerator();
+ setBacktrackCG(hiStateId, backtrackCG);
+ } else {
+ // Set done this last CG (we save a few rounds)
+ icsCG.setDone();
+ }
+ // 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(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;
+ }
+ return false;
+ }
+
+ private boolean isFieldExcluded(String field) {
+ // 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)) {
+ return true;
+ }
+
+ return false;
+ }
+
+ private boolean isNewConflict(int currentEvent, int eventNumber) {
+ HashSet<Integer> 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) {
+ // 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;
+ }
+ doneBacktrackSet.add(sb.toString());
+ return false;
+ }
+
+ private void resetStatesForNewExecution(IntChoiceFromSet icsCG, VM vm) {
+ if (choices == null || choices != icsCG.getAllChoices()) {
+ // Reset state variables
+ choiceCounter = 0;
+ choices = icsCG.getAllChoices();
+ refChoices = copyChoices(choices);
+ // Clearing data structures
+ conflictPairMap.clear();
+ readWriteFieldsMap.clear();
+ stateToEventMap.clear();
+ isEndOfExecution = false;
+ backtrackPointList.clear();
+ }
+ }
+
+ private void setBacktrackCG(int stateId, IntChoiceFromSet backtrackCG) {
+ // Set a backtrack CG based on a state ID
+ LinkedList<Integer[]> backtrackChoices = backtrackMap.get(stateId);
+ backtrackCG.setNewValues(backtrackChoices.removeLast()); // Get the last from the queue
+ backtrackCG.setStateId(stateId);
+ backtrackCG.reset();
+ // Remove from the queue if we don't have more backtrack points for that state
+ if (backtrackChoices.isEmpty()) {
+ backtrackMap.remove(stateId);
+ backtrackStateQ.remove(stateId);
+ }
+ }
+
+ // --- 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)
+ //private boolean isReachableInVODGraph(int checkedChoice, int referenceChoice) {
+ private boolean isReachableInVODGraph(int currentChoice) {
+ // Extract previous and current events
+ int choiceIndex = currentChoice % refChoices.length;
+ int prevChoIndex = (currentChoice - 1) % refChoices.length;
+ int currEvent = refChoices[choiceIndex];
+ int prevEvent = refChoices[prevChoIndex];
+ // Record visited choices as we search in the graph
+ HashSet<Integer> visitedChoice = new HashSet<>();
+ visitedChoice.add(prevEvent);
+ LinkedList<Integer> nodesToVisit = new LinkedList<>();
+ // If the state doesn't advance as the threads/sub-programs are executed (basically there is no new state),
+ // there is a chance that the graph doesn't have new nodes---thus this check will return a null.
+ if (vodGraphMap.containsKey(prevEvent)) {
+ nodesToVisit.addAll(vodGraphMap.get(prevEvent));
+ while(!nodesToVisit.isEmpty()) {
+ int choice = nodesToVisit.getFirst();
+ if (choice == currEvent) {
+ return true;
+ }
+ if (visitedChoice.contains(choice)) { // If there is a loop then we don't find it
+ return false;
+ }
+ // Continue searching
+ visitedChoice.add(choice);
+ HashSet<Integer> choiceNextNodes = vodGraphMap.get(choice);
+ if (choiceNextNodes != null) {
+ // Add only if there is a mapping for next nodes
+ for (Integer nextNode : choiceNextNodes) {
+ // Skip cycles
+ if (nextNode == choice) {
+ continue;
+ }
+ nodesToVisit.addLast(nextNode);
+ }
+ }
+ }
+ }
+ return false;
+ }
+
+ private void updateVODGraph(int currChoiceValue) {
+ // Update the graph when we have the current choice value
+ HashSet<Integer> choiceSet;
+ if (vodGraphMap.containsKey(prevChoiceValue)) {
+ // If the key already exists, just retrieve it
+ choiceSet = vodGraphMap.get(prevChoiceValue);
+ } else {
+ // Create a new entry
+ choiceSet = new HashSet<>();
+ vodGraphMap.put(prevChoiceValue, choiceSet);
+ }
+ choiceSet.add(currChoiceValue);
+ prevChoiceValue = currChoiceValue;
+ }
}
projects / jpf-core.git / blobdiff