2 * Copyright (C) 2014, United States Government, as represented by the
3 * Administrator of the National Aeronautics and Space Administration.
6 * The Java Pathfinder core (jpf-core) platform is licensed under the
7 * Apache License, Version 2.0 (the "License"); you may not use this file except
8 * in compliance with the License. You may obtain a copy of the License at
10 * http://www.apache.org/licenses/LICENSE-2.0.
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
18 package gov.nasa.jpf.listener;
20 import gov.nasa.jpf.Config;
21 import gov.nasa.jpf.JPF;
22 import gov.nasa.jpf.ListenerAdapter;
23 import gov.nasa.jpf.jvm.bytecode.INVOKEINTERFACE;
24 import gov.nasa.jpf.jvm.bytecode.JVMFieldInstruction;
25 import gov.nasa.jpf.search.Search;
26 import gov.nasa.jpf.vm.*;
27 import gov.nasa.jpf.vm.bytecode.ReadInstruction;
28 import gov.nasa.jpf.vm.bytecode.WriteInstruction;
29 import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
30 import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
32 import java.io.FileWriter;
33 import java.io.IOException;
34 import java.io.PrintWriter;
36 import java.util.logging.Logger;
39 * This a DPOR implementation for event-driven applications with loops that create cycles of state matching
40 * In this new DPOR algorithm/implementation, each run is terminated iff:
41 * - we find a state that matches a state in a previous run, or
42 * - we have a matched state in the current run that consists of cycles that contain all choices/events.
44 public class DPORStateReducerEfficient extends ListenerAdapter {
46 // Information printout fields for verbose mode
47 private boolean verboseMode;
48 private boolean stateReductionMode;
49 private final PrintWriter out;
50 private PrintWriter fileWriter;
51 private String detail;
54 private Transition transition;
56 // DPOR-related fields
58 private Integer[] choices;
59 private Integer[] refChoices; // Second reference to a copy of choices (choices may be modified for fair scheduling)
60 private int choiceCounter;
61 private int maxEventChoice;
62 // Data structure to track the events seen by each state to track cycles (containing all events) for termination
63 private HashSet<Integer> currVisitedStates; // States being visited in the current execution
64 private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
65 private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
66 private HashSet<ClassInfo> nonRelevantClasses;// Class info objects of non-relevant classes
67 private HashSet<FieldInfo> nonRelevantFields; // Field info objects of non-relevant fields
68 private HashSet<FieldInfo> relevantFields; // Field info objects of relevant fields
69 private HashMap<Integer, HashSet<Integer>> stateToEventMap;
70 // Data structure to analyze field Read/Write accesses and conflicts
71 private HashMap<Integer, LinkedList<BacktrackExecution>> backtrackMap; // Track created backtracking points
72 private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
73 private Execution currentExecution; // Holds the information about the current execution
74 private HashMap<Integer, HashSet<Integer>> doneBacktrackMap; // Record state ID and trace already constructed
75 private HashMap<Integer, RestorableVMState> restorableStateMap; // Maps state IDs to the restorable state object
76 private RGraph rGraph; // R-Graph for past executions
79 private boolean isBooleanCGFlipped;
80 private boolean isEndOfExecution;
83 private int numOfTransitions;
85 public DPORStateReducerEfficient(Config config, JPF jpf) {
86 verboseMode = config.getBoolean("printout_state_transition", false);
87 stateReductionMode = config.getBoolean("activate_state_reduction", true);
89 out = new PrintWriter(System.out, true);
93 String outputFile = config.getString("file_output");
94 if (!outputFile.isEmpty()) {
96 fileWriter = new PrintWriter(new FileWriter(outputFile, true), true);
97 } catch (IOException e) {
100 isBooleanCGFlipped = false;
101 numOfTransitions = 0;
102 nonRelevantClasses = new HashSet<>();
103 nonRelevantFields = new HashSet<>();
104 relevantFields = new HashSet<>();
105 restorableStateMap = new HashMap<>();
106 initializeStatesVariables();
110 public void stateRestored(Search search) {
112 id = search.getStateId();
113 depth = search.getDepth();
114 transition = search.getTransition();
116 out.println("\n==> DEBUG: The state is restored to state with id: " + id + " -- Transition: " + transition +
117 " and depth: " + depth + "\n");
122 public void searchStarted(Search search) {
124 out.println("\n==> DEBUG: ----------------------------------- search started" + "\n");
129 public void stateAdvanced(Search search) {
131 id = search.getStateId();
132 depth = search.getDepth();
133 transition = search.getTransition();
134 if (search.isNewState()) {
140 if (search.isEndState()) {
141 out.println("\n==> DEBUG: This is the last state!\n");
144 out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
145 " which is " + detail + " Transition: " + transition + "\n");
147 if (stateReductionMode) {
148 updateStateInfo(search);
153 public void stateBacktracked(Search search) {
155 id = search.getStateId();
156 depth = search.getDepth();
157 transition = search.getTransition();
160 out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
161 " and depth: " + depth + "\n");
163 if (stateReductionMode) {
164 updateStateInfo(search);
168 static Logger log = JPF.getLogger("report");
171 public void searchFinished(Search search) {
173 out.println("\n==> DEBUG: ----------------------------------- search finished");
174 out.println("\n==> DEBUG: State reduction mode : " + stateReductionMode);
175 out.println("\n==> DEBUG: Number of transitions : " + numOfTransitions);
176 out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
178 fileWriter.println("==> DEBUG: State reduction mode : " + stateReductionMode);
179 fileWriter.println("==> DEBUG: Number of transitions : " + numOfTransitions);
180 fileWriter.println();
186 public void choiceGeneratorRegistered(VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
187 if (stateReductionMode) {
188 // Initialize with necessary information from the CG
189 if (nextCG instanceof IntChoiceFromSet) {
190 IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
191 // Tell JPF that we are performing DPOR
193 if (!isEndOfExecution) {
194 // Check if CG has been initialized, otherwise initialize it
195 Integer[] cgChoices = icsCG.getAllChoices();
196 // Record the events (from choices)
197 if (choices == null) {
199 // Make a copy of choices as reference
200 refChoices = copyChoices(choices);
201 // Record the max event choice (the last element of the choice array)
202 maxEventChoice = choices[choices.length - 1];
204 icsCG.setNewValues(choices);
206 // Use a modulo since choiceCounter is going to keep increasing
207 int choiceIndex = choiceCounter % choices.length;
208 icsCG.advance(choices[choiceIndex]);
210 // Set done all CGs while transitioning to a new execution
218 public void choiceGeneratorAdvanced(VM vm, ChoiceGenerator<?> currentCG) {
219 if (stateReductionMode) {
220 // Check the boolean CG and if it is flipped, we are resetting the analysis
221 if (currentCG instanceof BooleanChoiceGenerator) {
222 if (!isBooleanCGFlipped) {
223 isBooleanCGFlipped = true;
225 // Allocate new objects for data structure when the boolean is flipped from "false" to "true"
226 initializeStatesVariables();
229 // Check every choice generated and ensure fair scheduling!
230 if (currentCG instanceof IntChoiceFromSet) {
231 IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
232 // If this is a new CG then we need to update data structures
233 resetStatesForNewExecution(icsCG, vm);
234 // If we don't see a fair scheduling of events/choices then we have to enforce it
235 ensureFairSchedulingAndSetupTransition(icsCG, vm);
236 // Update backtrack set of an executed event (transition): one transition before this one
237 updateBacktrackSet(currentExecution, choiceCounter - 1);
238 // Explore the next backtrack point:
239 // 1) if we have seen this state or this state contains cycles that involve all events, and
240 // 2) after the current CG is advanced at least once
241 if (terminateCurrentExecution() && choiceCounter > 0) {
242 exploreNextBacktrackPoints(vm, icsCG);
246 // Map state to event
247 mapStateToEvent(icsCG.getNextChoice());
248 justVisitedStates.clear();
257 public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
258 if (stateReductionMode) {
259 if (!isEndOfExecution) {
260 // Has to be initialized and a integer CG
261 ChoiceGenerator<?> cg = vm.getChoiceGenerator();
262 if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
263 int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
264 if (currentChoice < 0) { // If choice is -1 then skip
267 currentChoice = checkAndAdjustChoice(currentChoice, vm);
268 // Record accesses from executed instructions
269 if (executedInsn instanceof JVMFieldInstruction) {
270 // We don't care about libraries
271 if (!isFieldExcluded(executedInsn)) {
272 analyzeReadWriteAccesses(executedInsn, currentChoice);
274 } else if (executedInsn instanceof INVOKEINTERFACE) {
275 // Handle the read/write accesses that occur through iterators
276 analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
288 // This class compactly stores backtrack execution:
289 // 1) backtrack choice list, and
290 // 2) first backtrack point (linking with predecessor execution)
291 private class BacktrackExecution {
292 private Integer[] choiceList;
293 private TransitionEvent firstTransition;
295 public BacktrackExecution(Integer[] choList, TransitionEvent fTransition) {
296 choiceList = choList;
297 firstTransition = fTransition;
300 public Integer[] getChoiceList() {
304 public TransitionEvent getFirstTransition() {
305 return firstTransition;
309 // This class stores a representation of an execution
310 // TODO: We can modify this class to implement some optimization (e.g., clock-vector)
311 // TODO: We basically need to keep track of:
312 // TODO: (1) last read/write access to each memory location
313 // TODO: (2) last state with two or more incoming events/transitions
314 private class Execution {
315 private HashMap<IntChoiceFromSet, Integer> cgToChoiceMap; // Map between CG to choice numbers for O(1) access
316 private ArrayList<TransitionEvent> executionTrace; // The BacktrackPoint objects of this execution
317 private boolean isNew; // Track if this is the first time it is accessed
318 private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
321 cgToChoiceMap = new HashMap<>();
322 executionTrace = new ArrayList<>();
324 readWriteFieldsMap = new HashMap<>();
327 public void addTransition(TransitionEvent newBacktrackPoint) {
328 executionTrace.add(newBacktrackPoint);
331 public void clearCGToChoiceMap() {
332 cgToChoiceMap = null;
335 public int getChoiceFromCG(IntChoiceFromSet icsCG) {
336 return cgToChoiceMap.get(icsCG);
339 public ArrayList<TransitionEvent> getExecutionTrace() {
340 return executionTrace;
343 public TransitionEvent getFirstTransition() {
344 return executionTrace.get(0);
347 public TransitionEvent getLastTransition() {
348 return executionTrace.get(executionTrace.size() - 1);
351 public HashMap<Integer, ReadWriteSet> getReadWriteFieldsMap() {
352 return readWriteFieldsMap;
355 public boolean isNew() {
357 // Right after this is accessed, it is no longer new
364 public void mapCGToChoice(IntChoiceFromSet icsCG, int choice) {
365 cgToChoiceMap.put(icsCG, choice);
369 // This class compactly stores a predecessor
370 // 1) a predecessor execution
371 // 2) the predecessor choice in that predecessor execution
372 private class Predecessor {
373 private int choice; // Predecessor choice
374 private Execution execution; // Predecessor execution
376 public Predecessor(Execution predExec, int predChoice) {
378 execution = predExec;
381 public int getChoice() {
385 public Execution getExecution() {
390 // This class represents a R-Graph (in the paper it is a state transition graph R)
391 // This implementation stores reachable transitions from and connects with past executions
392 private class RGraph {
393 private int hiStateId; // Maximum state Id
394 private HashMap<Integer, HashSet<TransitionEvent>> graph; // Reachable transitions from past executions
395 // TODO: THIS IS THE ACCESS SUMMARY
396 private HashMap<Integer, HashMap<Integer, SummaryNode>> graphSummary;
400 graph = new HashMap<>();
401 graphSummary = new HashMap<>();
404 public void addReachableTransition(int stateId, TransitionEvent transition) {
405 // Record transition into graph
406 HashSet<TransitionEvent> transitionSet;
407 if (graph.containsKey(stateId)) {
408 transitionSet = graph.get(stateId);
410 transitionSet = new HashSet<>();
411 graph.put(stateId, transitionSet);
413 // Insert into the set if it does not contain it yet
414 if (!transitionSet.contains(transition)) {
415 transitionSet.add(transition);
417 // Update highest state ID
418 if (hiStateId < stateId) {
423 public HashSet<TransitionEvent> getReachableTransitionsAtState(int stateId) {
424 if (!graph.containsKey(stateId)) {
425 // This is a loop from a transition to itself, so just return the current transition
426 HashSet<TransitionEvent> transitionSet = new HashSet<>();
427 transitionSet.add(currentExecution.getLastTransition());
428 return transitionSet;
430 return graph.get(stateId);
433 // public HashSet<TransitionEvent> getReachableTransitions(int stateId) {
434 // HashSet<TransitionEvent> reachableTransitions = new HashSet<>();
435 // // All transitions from states higher than the given state ID (until the highest state ID) are reachable
436 // for(int stId = stateId; stId <= hiStateId; stId++) {
437 // // We might encounter state IDs from the first round of Boolean CG
438 // // The second round of Boolean CG should consider these new states
439 // if (graph.containsKey(stId)) {
440 // reachableTransitions.addAll(graph.get(stId));
443 // return reachableTransitions;
446 public HashMap<Integer, SummaryNode> getReachableTransitionSummary(int stateId) {
447 // Just return an empty map if the state ID is not recorded yet
448 // This means that there is no reachable transition from this state
449 if (!graphSummary.containsKey(stateId)) {
450 return new HashMap<>();
452 return graphSummary.get(stateId);
455 // private ReadWriteSet performUnion(ReadWriteSet recordedRWSet, ReadWriteSet rwSet) {
456 // // Combine the same write accesses and record in the recordedRWSet
457 // HashMap<String, Integer> recordedWriteMap = recordedRWSet.getWriteMap();
458 // HashMap<String, Integer> writeMap = rwSet.getWriteMap();
459 // for(Map.Entry<String, Integer> entry : recordedWriteMap.entrySet()) {
460 // String writeField = entry.getKey();
461 // // Remove the entry from rwSet if both field and object ID are the same
462 // if (writeMap.containsKey(writeField) &&
463 // (writeMap.get(writeField) == recordedWriteMap.get(writeField))) {
464 // writeMap.remove(writeField);
467 // // Then add everything into the recorded map because these will be traversed
468 // recordedWriteMap.putAll(writeMap);
469 // // Combine the same read accesses and record in the recordedRWSet
470 // HashMap<String, Integer> recordedReadMap = recordedRWSet.getReadMap();
471 // HashMap<String, Integer> readMap = rwSet.getReadMap();
472 // for(Map.Entry<String, Integer> entry : recordedReadMap.entrySet()) {
473 // String readField = entry.getKey();
474 // // Remove the entry from rwSet if both field and object ID are the same
475 // if (readMap.containsKey(readField) &&
476 // (readMap.get(readField) == recordedReadMap.get(readField))) {
477 // readMap.remove(readField);
480 // // Then add everything into the recorded map because these will be traversed
481 // recordedReadMap.putAll(readMap);
486 // public ReadWriteSet recordTransitionSummary(int stateId, TransitionEvent transition, ReadWriteSet rwSet) {
487 // // Record transition into graphSummary
488 // // TransitionMap maps event (choice) number to a R/W set
489 // HashMap<Integer, SummaryNode> transitionSummary;
490 // if (graphSummary.containsKey(stateId)) {
491 // transitionSummary = graphSummary.get(stateId);
493 // transitionSummary = new HashMap<>();
494 // graphSummary.put(stateId, transitionSummary);
496 // int choice = transition.getChoice();
497 // SummaryNode summaryNode;
498 // // Insert transition into the map if we haven't had this event number recorded
499 // if (!transitionSummary.containsKey(choice)) {
500 // summaryNode = new SummaryNode(transition, rwSet.getCopy());
501 // transitionSummary.put(choice, summaryNode);
503 // summaryNode = transitionSummary.get(choice);
504 // // Perform union and subtraction between the recorded and the given R/W sets
505 // rwSet = performUnion(summaryNode.getReadWriteSet(), rwSet);
510 public void recordTransitionSummaryAtState(int stateId, HashMap<Integer, SummaryNode> transitionSummary) {
511 // Record transition summary into graphSummary
512 graphSummary.put(stateId, transitionSummary);
516 // This class compactly stores Read and Write field sets
517 // We store the field name and its object ID
518 // Sharing the same field means the same field name and object ID
519 private class ReadWriteSet {
520 private HashMap<String, Integer> readMap;
521 private HashMap<String, Integer> writeMap;
523 public ReadWriteSet() {
524 readMap = new HashMap<>();
525 writeMap = new HashMap<>();
528 public void addReadField(String field, int objectId) {
529 readMap.put(field, objectId);
532 public void addWriteField(String field, int objectId) {
533 writeMap.put(field, objectId);
536 public void removeReadField(String field) {
537 readMap.remove(field);
540 public void removeWriteField(String field) {
541 writeMap.remove(field);
544 public boolean isEmpty() {
545 return readMap.isEmpty() && writeMap.isEmpty();
548 public ReadWriteSet getCopy() {
549 ReadWriteSet copyRWSet = new ReadWriteSet();
550 // Copy the maps in the set into the new object copy
551 copyRWSet.setReadMap(new HashMap<>(this.getReadMap()));
552 copyRWSet.setWriteMap(new HashMap<>(this.getWriteMap()));
556 public Set<String> getReadSet() {
557 return readMap.keySet();
560 public Set<String> getWriteSet() {
561 return writeMap.keySet();
564 public boolean readFieldExists(String field) {
565 return readMap.containsKey(field);
568 public boolean writeFieldExists(String field) {
569 return writeMap.containsKey(field);
572 public int readFieldObjectId(String field) {
573 return readMap.get(field);
576 public int writeFieldObjectId(String field) {
577 return writeMap.get(field);
580 private HashMap<String, Integer> getReadMap() {
584 private HashMap<String, Integer> getWriteMap() {
588 private void setReadMap(HashMap<String, Integer> rMap) {
592 private void setWriteMap(HashMap<String, Integer> wMap) {
597 // This class provides a data structure to store TransitionEvent and ReadWriteSet for a summary
598 private class SummaryNode {
599 private TransitionEvent transitionEvent;
600 private ReadWriteSet readWriteSet;
602 public SummaryNode(TransitionEvent transEvent, ReadWriteSet rwSet) {
603 transitionEvent = transEvent;
604 readWriteSet = rwSet;
607 public TransitionEvent getTransitionEvent() {
608 return transitionEvent;
611 public ReadWriteSet getReadWriteSet() {
616 // This class compactly stores transitions:
620 // 4) predecessors (for backward DFS).
621 private class TransitionEvent {
622 private int choice; // Choice chosen at this transition
623 private int choiceCounter; // Choice counter at this transition
624 private Execution execution; // The execution where this transition belongs
625 private HashSet<Predecessor> predecessors; // Maps incoming events/transitions (execution and choice)
626 // TODO: THIS IS THE ACCESS SUMMARY
627 private HashMap<Integer, SummaryNode> transitionSummary;
628 // Summary of pushed transitions at the current transition
629 private HashMap<Execution, HashSet<Integer>> recordedPredecessors;
630 // Memorize event and choice number to not record them twice
631 private int stateId; // State at this transition
632 private IntChoiceFromSet transitionCG; // CG at this transition
634 public TransitionEvent() {
638 predecessors = new HashSet<>();
639 transitionSummary = new HashMap<>();
640 recordedPredecessors = new HashMap<>();
645 public int getChoice() {
649 public int getChoiceCounter() {
650 return choiceCounter;
653 public Execution getExecution() {
657 public HashSet<Predecessor> getPredecessors() {
661 public int getStateId() {
665 public HashMap<Integer, SummaryNode> getTransitionSummary() {
666 return transitionSummary;
669 public IntChoiceFromSet getTransitionCG() { return transitionCG; }
671 private boolean isRecordedPredecessor(Execution execution, int choice) {
672 // See if we have recorded this predecessor earlier
673 HashSet<Integer> recordedChoices;
674 if (recordedPredecessors.containsKey(execution)) {
675 recordedChoices = recordedPredecessors.get(execution);
676 if (recordedChoices.contains(choice)) {
680 recordedChoices = new HashSet<>();
681 recordedPredecessors.put(execution, recordedChoices);
683 // Record the choice if we haven't seen it
684 recordedChoices.add(choice);
689 private ReadWriteSet performUnion(ReadWriteSet recordedRWSet, ReadWriteSet rwSet) {
690 // Combine the same write accesses and record in the recordedRWSet
691 HashMap<String, Integer> recordedWriteMap = recordedRWSet.getWriteMap();
692 HashMap<String, Integer> writeMap = rwSet.getWriteMap();
693 for(Map.Entry<String, Integer> entry : recordedWriteMap.entrySet()) {
694 String writeField = entry.getKey();
695 // Remove the entry from rwSet if both field and object ID are the same
696 if (writeMap.containsKey(writeField) &&
697 (writeMap.get(writeField) == recordedWriteMap.get(writeField))) {
698 writeMap.remove(writeField);
701 // Then add everything into the recorded map because these will be traversed
702 recordedWriteMap.putAll(writeMap);
703 // Combine the same read accesses and record in the recordedRWSet
704 HashMap<String, Integer> recordedReadMap = recordedRWSet.getReadMap();
705 HashMap<String, Integer> readMap = rwSet.getReadMap();
706 for(Map.Entry<String, Integer> entry : recordedReadMap.entrySet()) {
707 String readField = entry.getKey();
708 // Remove the entry from rwSet if both field and object ID are the same
709 if (readMap.containsKey(readField) &&
710 (readMap.get(readField) == recordedReadMap.get(readField))) {
711 readMap.remove(readField);
714 // Then add everything into the recorded map because these will be traversed
715 recordedReadMap.putAll(readMap);
720 public void recordPredecessor(Execution execution, int choice) {
721 if (!isRecordedPredecessor(execution, choice)) {
722 predecessors.add(new Predecessor(execution, choice));
726 public ReadWriteSet recordTransitionSummary(TransitionEvent transition, ReadWriteSet rwSet) {
727 // Record transition into reachability summary
728 // TransitionMap maps event (choice) number to a R/W set
729 int choice = transition.getChoice();
730 SummaryNode summaryNode;
731 // Insert transition into the map if we haven't had this event number recorded
732 if (!transitionSummary.containsKey(choice)) {
733 summaryNode = new SummaryNode(transition, rwSet.getCopy());
734 transitionSummary.put(choice, summaryNode);
736 summaryNode = transitionSummary.get(choice);
737 // Perform union and subtraction between the recorded and the given R/W sets
738 rwSet = performUnion(summaryNode.getReadWriteSet(), rwSet);
743 public void setChoice(int cho) {
747 public void setChoiceCounter(int choCounter) {
748 choiceCounter = choCounter;
751 public void setExecution(Execution exec) {
755 public void setPredecessors(HashSet<Predecessor> preds) {
756 predecessors = new HashSet<>(preds);
759 public void setStateId(int stId) {
763 public void setTransitionCG(IntChoiceFromSet cg) {
769 private final static String DO_CALL_METHOD = "doCall";
770 // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
771 private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
772 private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST =
773 // Groovy library created fields
774 {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__",
776 "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList",
777 "eventList", "valueList", "settings", "printToConsole", "app1", "app2"};
778 private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST =
779 // Java and Groovy libraries
780 { "java", "org", "sun", "com", "gov", "groovy"};
781 private final static String[] EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
782 private final static String GET_PROPERTY_METHOD =
783 "invokeinterface org.codehaus.groovy.runtime.callsite.CallSite.callGetProperty";
784 private final static String GROOVY_CALLSITE_LIB = "org.codehaus.groovy.runtime.callsite";
785 private final static String JAVA_INTEGER = "int";
786 private final static String JAVA_STRING_LIB = "java.lang.String";
789 private Integer[] copyChoices(Integer[] choicesToCopy) {
791 Integer[] copyOfChoices = new Integer[choicesToCopy.length];
792 System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
793 return copyOfChoices;
796 private void ensureFairSchedulingAndSetupTransition(IntChoiceFromSet icsCG, VM vm) {
797 // Check the next choice and if the value is not the same as the expected then force the expected value
798 int choiceIndex = choiceCounter % refChoices.length;
799 int nextChoice = icsCG.getNextChoice();
800 if (refChoices[choiceIndex] != nextChoice) {
801 int expectedChoice = refChoices[choiceIndex];
802 int currCGIndex = icsCG.getNextChoiceIndex();
803 if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
804 icsCG.setChoice(currCGIndex, expectedChoice);
807 // Get state ID and associate it with this transition
808 int stateId = vm.getStateId();
809 TransitionEvent transition = setupTransition(icsCG, stateId, choiceIndex);
810 // Add new transition to the current execution and map it in R-Graph
811 for (Integer stId : justVisitedStates) { // Map this transition to all the previously passed states
812 rGraph.addReachableTransition(stId, transition);
814 currentExecution.mapCGToChoice(icsCG, choiceCounter);
815 // Store restorable state object for this state (always store the latest)
816 if (!restorableStateMap.containsKey(stateId)) {
817 RestorableVMState restorableState = vm.getRestorableState();
818 restorableStateMap.put(stateId, restorableState);
822 private TransitionEvent setupTransition(IntChoiceFromSet icsCG, int stateId, int choiceIndex) {
823 // Get a new transition
824 TransitionEvent transition;
825 if (currentExecution.isNew()) {
826 // We need to handle the first transition differently because this has a predecessor execution
827 transition = currentExecution.getFirstTransition();
829 transition = new TransitionEvent();
830 currentExecution.addTransition(transition);
831 transition.recordPredecessor(currentExecution, choiceCounter - 1);
833 transition.setExecution(currentExecution);
834 transition.setTransitionCG(icsCG);
835 transition.setStateId(stateId);
836 transition.setChoice(refChoices[choiceIndex]);
837 transition.setChoiceCounter(choiceCounter);
842 // --- Functions related to cycle detection and reachability graph
844 // Detect cycles in the current execution/trace
845 // We terminate the execution iff:
846 // (1) the state has been visited in the current execution
847 // (2) the state has one or more cycles that involve all the events
848 // With simple approach we only need to check for a re-visited state.
849 // Basically, we have to check that we have executed all events between two occurrences of such state.
850 private boolean completeFullCycle(int stId) {
851 // False if the state ID hasn't been recorded
852 if (!stateToEventMap.containsKey(stId)) {
855 HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
856 // Check if this set contains all the event choices
857 // If not then this is not the terminating condition
858 for(int i=0; i<=maxEventChoice; i++) {
859 if (!visitedEvents.contains(i)) {
866 private void initializeStatesVariables() {
873 currVisitedStates = new HashSet<>();
874 justVisitedStates = new HashSet<>();
875 prevVisitedStates = new HashSet<>();
876 stateToEventMap = new HashMap<>();
878 backtrackMap = new HashMap<>();
879 backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
880 currentExecution = new Execution();
881 currentExecution.addTransition(new TransitionEvent()); // Always start with 1 backtrack point
882 doneBacktrackMap = new HashMap<>();
883 rGraph = new RGraph();
885 isEndOfExecution = false;
888 private void mapStateToEvent(int nextChoiceValue) {
889 // Update all states with this event/choice
890 // This means that all past states now see this transition
891 Set<Integer> stateSet = stateToEventMap.keySet();
892 for(Integer stateId : stateSet) {
893 HashSet<Integer> eventSet = stateToEventMap.get(stateId);
894 eventSet.add(nextChoiceValue);
898 private boolean terminateCurrentExecution() {
899 // We need to check all the states that have just been visited
900 // Often a transition (choice/event) can result into forwarding/backtracking to a number of states
901 for(Integer stateId : justVisitedStates) {
902 if (prevVisitedStates.contains(stateId) || completeFullCycle(stateId)) {
909 private void updateStateInfo(Search search) {
910 // Update the state variables
911 int stateId = search.getStateId();
912 // Insert state ID into the map if it is new
913 if (!stateToEventMap.containsKey(stateId)) {
914 HashSet<Integer> eventSet = new HashSet<>();
915 stateToEventMap.put(stateId, eventSet);
917 analyzeReachabilityAndCreateBacktrackPoints(search.getVM(), stateId);
918 justVisitedStates.add(stateId);
919 if (!prevVisitedStates.contains(stateId)) {
920 // It is a currently visited states if the state has not been seen in previous executions
921 currVisitedStates.add(stateId);
925 // --- Functions related to Read/Write access analysis on shared fields
927 private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList, TransitionEvent conflictTransition) {
928 // Insert backtrack point to the right state ID
929 LinkedList<BacktrackExecution> backtrackExecList;
930 if (backtrackMap.containsKey(stateId)) {
931 backtrackExecList = backtrackMap.get(stateId);
933 backtrackExecList = new LinkedList<>();
934 backtrackMap.put(stateId, backtrackExecList);
936 // Add the new backtrack execution object
937 TransitionEvent backtrackTransition = new TransitionEvent();
938 backtrackTransition.setPredecessors(conflictTransition.getPredecessors());
939 backtrackExecList.addFirst(new BacktrackExecution(newChoiceList, backtrackTransition));
940 // Add to priority queue
941 if (!backtrackStateQ.contains(stateId)) {
942 backtrackStateQ.add(stateId);
946 // Analyze Read/Write accesses that are directly invoked on fields
947 private void analyzeReadWriteAccesses(Instruction executedInsn, int currentChoice) {
948 // Get the field info
949 FieldInfo fieldInfo = ((JVMFieldInstruction) executedInsn).getFieldInfo();
950 // Analyze only after being initialized
951 String fieldClass = fieldInfo.getFullName();
952 // Do the analysis to get Read and Write accesses to fields
953 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
954 int objectId = fieldInfo.getClassInfo().getClassObjectRef();
955 // Record the field in the map
956 if (executedInsn instanceof WriteInstruction) {
957 // We first check the non-relevant fields set
958 if (!nonRelevantFields.contains(fieldInfo)) {
959 // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
960 for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
961 if (fieldClass.startsWith(str)) {
962 nonRelevantFields.add(fieldInfo);
967 // If we have this field in the non-relevant fields set then we return right away
970 rwSet.addWriteField(fieldClass, objectId);
971 } else if (executedInsn instanceof ReadInstruction) {
972 rwSet.addReadField(fieldClass, objectId);
976 // Analyze Read accesses that are indirect (performed through iterators)
977 // These accesses are marked by certain bytecode instructions, e.g., INVOKEINTERFACE
978 private void analyzeReadWriteAccesses(Instruction instruction, ThreadInfo ti, int currentChoice) {
980 INVOKEINTERFACE insn = (INVOKEINTERFACE) instruction;
981 if (insn.toString().startsWith(GET_PROPERTY_METHOD) &&
982 insn.getMethodInfo().getName().equals(DO_CALL_METHOD)) {
983 // Extract info from the stack frame
984 StackFrame frame = ti.getTopFrame();
985 int[] frameSlots = frame.getSlots();
986 // Get the Groovy callsite library at index 0
987 ElementInfo eiCallsite = VM.getVM().getHeap().get(frameSlots[0]);
988 if (!eiCallsite.getClassInfo().getName().startsWith(GROOVY_CALLSITE_LIB)) {
991 // Get the iterated object whose property is accessed
992 ElementInfo eiAccessObj = VM.getVM().getHeap().get(frameSlots[1]);
993 if (eiAccessObj == null) {
996 // We exclude library classes (they start with java, org, etc.) and some more
997 ClassInfo classInfo = eiAccessObj.getClassInfo();
998 String objClassName = classInfo.getName();
999 // Check if this class info is part of the non-relevant classes set already
1000 if (!nonRelevantClasses.contains(classInfo)) {
1001 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName) ||
1002 excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName)) {
1003 nonRelevantClasses.add(classInfo);
1007 // If it is part of the non-relevant classes set then return immediately
1010 // Extract fields from this object and put them into the read write
1011 int numOfFields = eiAccessObj.getNumberOfFields();
1012 for(int i=0; i<numOfFields; i++) {
1013 FieldInfo fieldInfo = eiAccessObj.getFieldInfo(i);
1014 if (fieldInfo.getType().equals(JAVA_STRING_LIB) || fieldInfo.getType().equals(JAVA_INTEGER)) {
1015 String fieldClass = fieldInfo.getFullName();
1016 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
1017 int objectId = fieldInfo.getClassInfo().getClassObjectRef();
1018 // Record the field in the map
1019 rwSet.addReadField(fieldClass, objectId);
1025 private int checkAndAdjustChoice(int currentChoice, VM vm) {
1026 // If current choice is not the same, then this is caused by the firing of IntIntervalGenerator
1027 // for certain method calls in the infrastructure, e.g., eventSince()
1028 ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
1029 // This is the main event CG
1030 if (currentCG instanceof IntIntervalGenerator) {
1031 // This is the interval CG used in device handlers
1032 ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
1033 // Iterate until we find the IntChoiceFromSet CG
1034 while (!(parentCG instanceof IntChoiceFromSet)) {
1035 parentCG = ((IntIntervalGenerator) parentCG).getPreviousChoiceGenerator();
1037 // Find the choice related to the IntIntervalGenerator CG from the map
1038 currentChoice = currentExecution.getChoiceFromCG((IntChoiceFromSet) parentCG);
1040 return currentChoice;
1043 private void createBacktrackingPoint(Execution execution, int currentChoice,
1044 Execution conflictExecution, int conflictChoice) {
1045 // Create a new list of choices for backtrack based on the current choice and conflicting event number
1046 // E.g. if we have a conflict between 1 and 3, then we create the list {3, 1, 0, 2}
1047 // for the original set {0, 1, 2, 3}
1049 // execution/currentChoice represent the event/transaction that will be put into the backtracking set of
1050 // conflictExecution/conflictChoice
1051 Integer[] newChoiceList = new Integer[refChoices.length];
1052 ArrayList<TransitionEvent> currentTrace = execution.getExecutionTrace();
1053 ArrayList<TransitionEvent> conflictTrace = conflictExecution.getExecutionTrace();
1054 int currChoice = currentTrace.get(currentChoice).getChoice();
1055 int stateId = conflictTrace.get(conflictChoice).getStateId();
1056 // Check if this trace has been done from this state
1057 if (isTraceAlreadyConstructed(currChoice, stateId)) {
1060 // Put the conflicting event numbers first and reverse the order
1061 newChoiceList[0] = currChoice;
1062 // Put the rest of the event numbers into the array starting from the minimum to the upper bound
1063 for (int i = 0, j = 1; i < refChoices.length; i++) {
1064 if (refChoices[i] != newChoiceList[0]) {
1065 newChoiceList[j] = refChoices[i];
1069 // Predecessor of the new backtrack point is the same as the conflict point's
1070 addNewBacktrackPoint(stateId, newChoiceList, conflictTrace.get(conflictChoice));
1073 private boolean excludeThisForItContains(String[] excludedStrings, String className) {
1074 for (String excludedField : excludedStrings) {
1075 if (className.contains(excludedField)) {
1082 private boolean excludeThisForItEndsWith(String[] excludedStrings, String className) {
1083 for (String excludedField : excludedStrings) {
1084 if (className.endsWith(excludedField)) {
1091 private boolean excludeThisForItStartsWith(String[] excludedStrings, String className) {
1092 for (String excludedField : excludedStrings) {
1093 if (className.startsWith(excludedField)) {
1100 private void exploreNextBacktrackPoints(VM vm, IntChoiceFromSet icsCG) {
1101 // Check if we are reaching the end of our execution: no more backtracking points to explore
1102 // cgMap, backtrackMap, backtrackStateQ are updated simultaneously (checking backtrackStateQ is enough)
1103 if (!backtrackStateQ.isEmpty()) {
1104 // Set done all the other backtrack points
1105 for (TransitionEvent backtrackTransition : currentExecution.getExecutionTrace()) {
1106 backtrackTransition.getTransitionCG().setDone();
1108 // Reset the next backtrack point with the latest state
1109 int hiStateId = backtrackStateQ.peek();
1110 // Restore the state first if necessary
1111 if (vm.getStateId() != hiStateId) {
1112 RestorableVMState restorableState = restorableStateMap.get(hiStateId);
1113 vm.restoreState(restorableState);
1115 // Set the backtrack CG
1116 IntChoiceFromSet backtrackCG = (IntChoiceFromSet) vm.getChoiceGenerator();
1117 setBacktrackCG(hiStateId, backtrackCG);
1119 // Set done this last CG (we save a few rounds)
1122 // Save all the visited states when starting a new execution of trace
1123 prevVisitedStates.addAll(currVisitedStates);
1124 // This marks a transitional period to the new CG
1125 isEndOfExecution = true;
1128 private boolean isConflictFound(Execution execution, int reachableChoice, Execution conflictExecution, int conflictChoice,
1129 ReadWriteSet currRWSet) {
1130 // conflictExecution/conflictChoice represent a predecessor event/transaction that can potentially have a conflict
1131 ArrayList<TransitionEvent> executionTrace = execution.getExecutionTrace();
1132 ArrayList<TransitionEvent> conflictTrace = conflictExecution.getExecutionTrace();
1133 HashMap<Integer, ReadWriteSet> confRWFieldsMap = conflictExecution.getReadWriteFieldsMap();
1134 // Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
1135 if (!confRWFieldsMap.containsKey(conflictChoice) ||
1136 executionTrace.get(reachableChoice).getChoice() == conflictTrace.get(conflictChoice).getChoice()) {
1139 // R/W set of choice/event that may have a potential conflict
1140 ReadWriteSet confRWSet = confRWFieldsMap.get(conflictChoice);
1141 // Check for conflicts with Read and Write fields for Write instructions
1142 Set<String> currWriteSet = currRWSet.getWriteSet();
1143 for(String writeField : currWriteSet) {
1144 int currObjId = currRWSet.writeFieldObjectId(writeField);
1145 if ((confRWSet.readFieldExists(writeField) && confRWSet.readFieldObjectId(writeField) == currObjId) ||
1146 (confRWSet.writeFieldExists(writeField) && confRWSet.writeFieldObjectId(writeField) == currObjId)) {
1147 // Remove this from the write set as we are tracking per memory location
1148 currRWSet.removeWriteField(writeField);
1152 // Check for conflicts with Write fields for Read instructions
1153 Set<String> currReadSet = currRWSet.getReadSet();
1154 for(String readField : currReadSet) {
1155 int currObjId = currRWSet.readFieldObjectId(readField);
1156 if (confRWSet.writeFieldExists(readField) && confRWSet.writeFieldObjectId(readField) == currObjId) {
1157 // Remove this from the read set as we are tracking per memory location
1158 currRWSet.removeReadField(readField);
1162 // Return false if no conflict is found
1166 private ReadWriteSet getReadWriteSet(int currentChoice) {
1167 // Do the analysis to get Read and Write accesses to fields
1169 // We already have an entry
1170 HashMap<Integer, ReadWriteSet> currReadWriteFieldsMap = currentExecution.getReadWriteFieldsMap();
1171 if (currReadWriteFieldsMap.containsKey(currentChoice)) {
1172 rwSet = currReadWriteFieldsMap.get(currentChoice);
1173 } else { // We need to create a new entry
1174 rwSet = new ReadWriteSet();
1175 currReadWriteFieldsMap.put(currentChoice, rwSet);
1180 private boolean isFieldExcluded(Instruction executedInsn) {
1181 // Get the field info
1182 FieldInfo fieldInfo = ((JVMFieldInstruction) executedInsn).getFieldInfo();
1183 // Check if the non-relevant fields set already has it
1184 if (nonRelevantFields.contains(fieldInfo)) {
1187 // Check if the relevant fields set already has it
1188 if (relevantFields.contains(fieldInfo)) {
1191 // Analyze only after being initialized
1192 String field = fieldInfo.getFullName();
1193 // Check against "starts-with", "ends-with", and "contains" list
1194 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, field) ||
1195 excludeThisForItEndsWith(EXCLUDED_FIELDS_ENDS_WITH_LIST, field) ||
1196 excludeThisForItContains(EXCLUDED_FIELDS_CONTAINS_LIST, field)) {
1197 nonRelevantFields.add(fieldInfo);
1200 relevantFields.add(fieldInfo);
1204 // Check if this trace is already constructed
1205 private boolean isTraceAlreadyConstructed(int firstChoice, int stateId) {
1206 // Concatenate state ID and only the first event in the string, e.g., "1:1 for the trace 10234 at state 1"
1207 // Check if the trace has been constructed as a backtrack point for this state
1208 // TODO: THIS IS AN OPTIMIZATION!
1209 HashSet<Integer> choiceSet;
1210 if (doneBacktrackMap.containsKey(stateId)) {
1211 choiceSet = doneBacktrackMap.get(stateId);
1212 if (choiceSet.contains(firstChoice)) {
1216 choiceSet = new HashSet<>();
1217 doneBacktrackMap.put(stateId, choiceSet);
1219 choiceSet.add(firstChoice);
1224 // Reset data structure for each new execution
1225 private void resetStatesForNewExecution(IntChoiceFromSet icsCG, VM vm) {
1226 if (choices == null || choices != icsCG.getAllChoices()) {
1227 // Reset state variables
1229 choices = icsCG.getAllChoices();
1230 refChoices = copyChoices(choices);
1231 // Clear data structures
1232 currVisitedStates = new HashSet<>();
1233 stateToEventMap = new HashMap<>();
1234 isEndOfExecution = false;
1238 // Set a backtrack point for a particular state
1239 private void setBacktrackCG(int stateId, IntChoiceFromSet backtrackCG) {
1240 // Set a backtrack CG based on a state ID
1241 LinkedList<BacktrackExecution> backtrackExecutions = backtrackMap.get(stateId);
1242 BacktrackExecution backtrackExecution = backtrackExecutions.removeLast();
1243 backtrackCG.setNewValues(backtrackExecution.getChoiceList()); // Get the last from the queue
1244 backtrackCG.setStateId(stateId);
1245 backtrackCG.reset();
1246 // Update current execution with this new execution
1247 Execution newExecution = new Execution();
1248 TransitionEvent firstTransition = backtrackExecution.getFirstTransition();
1249 newExecution.addTransition(firstTransition);
1250 // Try to free some memory since this map is only used for the current execution
1251 currentExecution.clearCGToChoiceMap();
1252 currentExecution = newExecution;
1253 // Remove from the queue if we don't have more backtrack points for that state
1254 if (backtrackExecutions.isEmpty()) {
1255 backtrackMap.remove(stateId);
1256 backtrackStateQ.remove(stateId);
1260 // Update backtrack sets
1261 // 1) recursively, and
1262 // 2) track accesses per memory location (per shared variable/field)
1263 private void updateBacktrackSet(Execution execution, int currentChoice) {
1264 // Copy ReadWriteSet object
1265 HashMap<Integer, ReadWriteSet> currRWFieldsMap = execution.getReadWriteFieldsMap();
1266 ReadWriteSet currRWSet = currRWFieldsMap.get(currentChoice);
1267 if (currRWSet == null) {
1270 currRWSet = currRWSet.getCopy();
1271 // Memorize visited TransitionEvent object while performing backward DFS to avoid getting caught up in a cycle
1272 HashSet<TransitionEvent> visited = new HashSet<>();
1273 // Update backtrack set recursively
1274 // TODO: The following is the call to the original version of the method
1275 // updateBacktrackSetRecursive(execution, currentChoice, execution, currentChoice, currRWSet, visited);
1276 // TODO: The following is the call to the version of the method with pushing up happens-before transitions
1277 updateBacktrackSetRecursive(execution, currentChoice, execution, currentChoice, currRWSet, visited);
1280 // TODO: This is the original version of the recursive method
1281 // private void updateBacktrackSetRecursive(Execution execution, int currentChoice,
1282 // Execution conflictExecution, int conflictChoice,
1283 // ReadWriteSet currRWSet, HashSet<TransitionEvent> visited) {
1284 // // Halt when we have found the first read/write conflicts for all memory locations
1285 // if (currRWSet.isEmpty()) {
1288 // TransitionEvent confTrans = conflictExecution.getExecutionTrace().get(conflictChoice);
1289 // // Halt when we have visited this transition (in a cycle)
1290 // if (visited.contains(confTrans)) {
1293 // visited.add(confTrans);
1294 // // Explore all predecessors
1295 // for (Predecessor predecessor : confTrans.getPredecessors()) {
1296 // // Get the predecessor (previous conflict choice)
1297 // conflictChoice = predecessor.getChoice();
1298 // conflictExecution = predecessor.getExecution();
1299 // // Check if a conflict is found
1300 // if (isConflictFound(execution, currentChoice, conflictExecution, conflictChoice, currRWSet)) {
1301 // createBacktrackingPoint(execution, currentChoice, conflictExecution, conflictChoice);
1303 // // Continue performing DFS if conflict is not found
1304 // updateBacktrackSetRecursive(execution, currentChoice, conflictExecution, conflictChoice, currRWSet, visited);
1308 // TODO: This is the version of the method with pushing up happens-before transitions
1309 private void updateBacktrackSetRecursive(Execution execution, int currentChoice,
1310 Execution conflictExecution, int conflictChoice,
1311 ReadWriteSet currRWSet, HashSet<TransitionEvent> visited) {
1312 TransitionEvent currTrans = execution.getExecutionTrace().get(currentChoice);
1313 // TODO: THIS IS THE ACCESS SUMMARY
1314 TransitionEvent confTrans = conflictExecution.getExecutionTrace().get(conflictChoice);
1315 // Record this transition into rGraph summary
1316 //currRWSet = rGraph.recordTransitionSummary(currTrans.getStateId(), confTrans, currRWSet);
1317 currRWSet = currTrans.recordTransitionSummary(confTrans, currRWSet);
1318 rGraph.recordTransitionSummaryAtState(currTrans.getStateId(), currTrans.getTransitionSummary());
1319 // Halt when we have found the first read/write conflicts for all memory locations
1320 if (currRWSet.isEmpty()) {
1323 if (visited.contains(currTrans)) {
1326 visited.add(currTrans);
1327 // Explore all predecessors
1328 for (Predecessor predecessor : currTrans.getPredecessors()) {
1329 // Get the predecessor (previous conflict choice)
1330 int predecessorChoice = predecessor.getChoice();
1331 Execution predecessorExecution = predecessor.getExecution();
1332 // Push up one happens-before transition
1333 int newConflictChoice = conflictChoice;
1334 Execution newConflictExecution = conflictExecution;
1335 // Check if a conflict is found
1336 if (isConflictFound(conflictExecution, conflictChoice, predecessorExecution, predecessorChoice, currRWSet)) {
1337 createBacktrackingPoint(conflictExecution, conflictChoice, predecessorExecution, predecessorChoice);
1338 newConflictChoice = conflictChoice;
1339 newConflictExecution = conflictExecution;
1341 // Continue performing DFS if conflict is not found
1342 updateBacktrackSetRecursive(predecessorExecution, predecessorChoice, newConflictExecution, newConflictChoice,
1343 currRWSet, visited);
1345 // Remove the transition after being explored
1346 // TODO: Seems to cause a lot of loops---commented out for now
1347 //visited.remove(confTrans);
1350 // --- Functions related to the reachability analysis when there is a state match
1352 /*private void analyzeReachabilityAndCreateBacktrackPoints(VM vm, int stateId) {
1353 // Perform this analysis only when:
1354 // 1) this is not during a switch to a new execution,
1355 // 2) at least 2 choices/events have been explored (choiceCounter > 1),
1356 // 3) state > 0 (state 0 is for boolean CG)
1357 if (!isEndOfExecution && choiceCounter > 1 && stateId > 0) {
1358 if (currVisitedStates.contains(stateId) || prevVisitedStates.contains(stateId)) {
1359 // Update reachable transitions in the graph with a predecessor
1360 HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitionsAtState(stateId);
1361 for(TransitionEvent transition : reachableTransitions) {
1362 transition.recordPredecessor(currentExecution, choiceCounter - 1);
1364 updateBacktrackSetsFromPreviousExecution(stateId);
1369 // Update the backtrack sets from previous executions
1370 private void updateBacktrackSetsFromPreviousExecution(int stateId) {
1371 // Collect all the reachable transitions from R-Graph
1372 HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitions(stateId);
1373 for(TransitionEvent transition : reachableTransitions) {
1374 Execution execution = transition.getExecution();
1375 int currentChoice = transition.getChoiceCounter();
1376 updateBacktrackSet(execution, currentChoice);
1380 // TODO: THIS IS THE ACCESS SUMMARY
1381 private void analyzeReachabilityAndCreateBacktrackPoints(VM vm, int stateId) {
1382 // Perform this analysis only when:
1383 // 1) this is not during a switch to a new execution,
1384 // 2) at least 2 choices/events have been explored (choiceCounter > 1),
1385 // 3) state > 0 (state 0 is for boolean CG)
1386 if (!isEndOfExecution && choiceCounter > 1 && stateId > 0) {
1387 if (currVisitedStates.contains(stateId) || prevVisitedStates.contains(stateId)) {
1388 // Update reachable transitions in the graph with a predecessor
1389 HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitionsAtState(stateId);
1390 for(TransitionEvent transition : reachableTransitions) {
1391 transition.recordPredecessor(currentExecution, choiceCounter - 1);
1393 updateBacktrackSetsFromPreviousExecution(currentExecution, choiceCounter - 1, stateId);
1398 private void updateBacktrackSetsFromPreviousExecution(Execution execution, int currentChoice, int stateId) {
1399 // Collect all the reachable transitions from R-Graph
1400 HashMap<Integer, SummaryNode> reachableTransitions = rGraph.getReachableTransitionSummary(stateId);
1401 for(Map.Entry<Integer, SummaryNode> transition : reachableTransitions.entrySet()) {
1402 SummaryNode summaryNode = transition.getValue();
1403 TransitionEvent reachableTransition = summaryNode.getTransitionEvent();
1404 Execution conflictExecution = reachableTransition.getExecution();
1405 int conflictChoice = reachableTransition.getChoiceCounter();
1406 // Copy ReadWriteSet object
1407 ReadWriteSet currRWSet = summaryNode.getReadWriteSet();
1408 currRWSet = currRWSet.getCopy();
1409 // Memorize visited TransitionEvent object while performing backward DFS to avoid getting caught up in a cycle
1410 HashSet<TransitionEvent> visited = new HashSet<>();
1411 updateBacktrackSetRecursive(execution, currentChoice, conflictExecution, conflictChoice, currRWSet, visited);