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.search.Search;
24 import gov.nasa.jpf.jvm.bytecode.*;
25 import gov.nasa.jpf.vm.*;
26 import gov.nasa.jpf.vm.bytecode.ReadInstruction;
27 import gov.nasa.jpf.vm.bytecode.WriteInstruction;
28 import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
29 import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
31 import java.io.PrintWriter;
34 // TODO: Fix for Groovy's model-checking
35 // TODO: This is a setter to change the values of the ChoiceGenerator to implement POR
37 * Simple tool to log state changes.
39 * This DPOR implementation is augmented by the algorithm presented in this SPIN paper:
40 * http://spinroot.com/spin/symposia/ws08/spin2008_submission_33.pdf
42 * The algorithm is presented on page 11 of the paper. Basically, we create a graph G
43 * (i.e., visible operation dependency graph)
44 * that maps inter-related threads/sub-programs that trigger state changes.
45 * The key to this approach is that we evaluate graph G in every iteration/recursion to
46 * only update the backtrack sets of the threads/sub-programs that are reachable in graph G
47 * from the currently running thread/sub-program.
49 public class DPORStateReducer extends ListenerAdapter {
51 // Information printout fields for verbose mode
52 private boolean verboseMode;
53 private boolean stateReductionMode;
54 private final PrintWriter out;
55 private String detail;
58 private Transition transition;
60 // DPOR-related fields
62 private Integer[] choices;
63 private Integer[] refChoices; // Second reference to a copy of choices (choices may be modified for fair scheduling)
64 private int choiceCounter;
65 private int lastCGStateId; // Record the state of the currently active CG
66 private int maxEventChoice;
67 // Data structure to track the events seen by each state to track cycles (containing all events) for termination
68 private HashSet<Integer> currVisitedStates; // States being visited in the current execution
69 private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
70 private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
71 private HashMap<Integer, HashSet<Integer>> stateToEventMap;
72 // Data structure to analyze field Read/Write accesses and conflicts
73 private HashMap<Integer, LinkedList<Integer[]>> backtrackMap; // Track created backtracking points
74 private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
75 private ArrayList<BacktrackPoint> backtrackPointList; // Record backtrack points (CG and choice)
76 private HashMap<Integer, IntChoiceFromSet> cgMap; // Maps state IDs to CGs
77 private HashMap<Integer, HashSet<Integer>> conflictPairMap; // Record conflicting events
78 private HashSet<String> doneBacktrackSet; // Record state ID and trace that are done
79 private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
81 // Visible operation dependency graph implementation (SPIN paper) related fields
82 private int prevChoiceValue;
83 private HashMap<Integer, HashSet<Integer>> vodGraphMap; // Visible operation dependency graph (VOD graph)
86 private boolean isBooleanCGFlipped;
87 private boolean isFirstResetDone;
88 private boolean isEndOfExecution;
90 public DPORStateReducer(Config config, JPF jpf) {
91 verboseMode = config.getBoolean("printout_state_transition", false);
92 stateReductionMode = config.getBoolean("activate_state_reduction", true);
94 out = new PrintWriter(System.out, true);
98 isBooleanCGFlipped = false;
99 initializeStatesVariables();
103 public void stateRestored(Search search) {
105 id = search.getStateId();
106 depth = search.getDepth();
107 transition = search.getTransition();
109 out.println("\n==> DEBUG: The state is restored to state with id: " + id + " -- Transition: " + transition +
110 " and depth: " + depth + "\n");
115 public void searchStarted(Search search) {
117 out.println("\n==> DEBUG: ----------------------------------- search started" + "\n");
122 public void stateAdvanced(Search search) {
124 id = search.getStateId();
125 depth = search.getDepth();
126 transition = search.getTransition();
127 if (search.isNewState()) {
133 if (search.isEndState()) {
134 out.println("\n==> DEBUG: This is the last state!\n");
137 out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
138 " which is " + detail + " Transition: " + transition + "\n");
140 if (stateReductionMode) {
141 updateStateInfo(search);
146 public void stateBacktracked(Search search) {
148 id = search.getStateId();
149 depth = search.getDepth();
150 transition = search.getTransition();
153 out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
154 " and depth: " + depth + "\n");
156 if (stateReductionMode) {
157 updateStateInfo(search);
162 public void searchFinished(Search search) {
164 out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
169 public void choiceGeneratorRegistered(VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
170 if (stateReductionMode) {
171 // Initialize with necessary information from the CG
172 if (nextCG instanceof IntChoiceFromSet) {
173 IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
174 if (!isEndOfExecution) {
175 // Check if CG has been initialized, otherwise initialize it
176 Integer[] cgChoices = icsCG.getAllChoices();
177 // Record the events (from choices)
178 if (choices == null) {
180 // Make a copy of choices as reference
181 refChoices = copyChoices(choices);
182 // Record the max event choice (the last element of the choice array)
183 maxEventChoice = choices[choices.length - 1];
185 icsCG.setNewValues(choices);
187 // Use a modulo since choiceCounter is going to keep increasing
188 int choiceIndex = choiceCounter % choices.length;
189 icsCG.advance(choices[choiceIndex]);
190 // Index the ChoiceGenerator to set backtracking points
191 BacktrackPoint backtrackPoint = new BacktrackPoint(icsCG, choices[choiceIndex]);
192 backtrackPointList.add(backtrackPoint);
194 // Set done all CGs while transitioning to a new execution
202 public void choiceGeneratorAdvanced(VM vm, ChoiceGenerator<?> currentCG) {
204 if (stateReductionMode) {
205 // Check the boolean CG and if it is flipped, we are resetting the analysis
206 if (currentCG instanceof BooleanChoiceGenerator) {
207 if (!isBooleanCGFlipped) {
208 isBooleanCGFlipped = true;
210 // Allocate new objects for data structure when the boolean is flipped from "false" to "true"
211 initializeStatesVariables();
214 // Check every choice generated and ensure fair scheduling!
215 if (currentCG instanceof IntChoiceFromSet) {
216 IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
217 // If this is a new CG then we need to update data structures
218 resetStatesForNewExecution(icsCG);
219 // If we don't see a fair scheduling of events/choices then we have to enforce it
220 checkAndEnforceFairScheduling(icsCG);
221 // Map state to event
222 mapStateToEvent(icsCG.getNextChoice());
223 // Update the VOD graph always with the latest
224 updateVODGraph(icsCG.getNextChoice());
225 // Check if we have seen this state or this state contains cycles that involve all events
226 if (terminateCurrentExecution()) {
227 exploreNextBacktrackPoints(icsCG, vm);
229 justVisitedStates.clear();
236 public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
237 if (stateReductionMode) {
238 if (!isEndOfExecution) {
239 // Has to be initialized and a integer CG
240 ChoiceGenerator<?> cg = vm.getChoiceGenerator();
241 if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
242 int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
243 if (currentChoice < 0) { // If choice is -1 then skip
246 currentChoice = checkAndAdjustChoice(currentChoice, vm);
247 // Record accesses from executed instructions
248 if (executedInsn instanceof JVMFieldInstruction) {
249 // Analyze only after being initialized
250 String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
251 // We don't care about libraries
252 if (!isFieldExcluded(fieldClass)) {
253 analyzeReadWriteAccesses(executedInsn, fieldClass, currentChoice);
255 } else if (executedInsn instanceof INVOKEINTERFACE) {
256 // Handle the read/write accesses that occur through iterators
257 analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
259 // Analyze conflicts from next instructions
260 if (nextInsn instanceof JVMFieldInstruction) {
261 // Skip the constructor because it is called once and does not have shared access with other objects
262 if (!nextInsn.getMethodInfo().getName().equals("<init>")) {
263 String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
264 if (!isFieldExcluded(fieldClass)) {
265 // Check for conflict (go backward from current choice and get the first conflict)
266 for (int eventCounter = currentChoice - 1; eventCounter >= 0; eventCounter--) {
267 // Check for conflicts with Write fields for both Read and Write instructions
268 // Check and record a backtrack set for just once!
269 if (isConflictFound(nextInsn, eventCounter, currentChoice, fieldClass) &&
270 isNewConflict(currentChoice, eventCounter)) {
271 // Lines 4-8 of the algorithm in the paper page 11 (see the heading note above)
272 if (vm.isNewState() || isReachableInVODGraph(currentChoice)) {
273 createBacktrackingPoint(currentChoice, eventCounter);
290 // This class compactly stores Read and Write field sets
291 // We store the field name and its object ID
292 // Sharing the same field means the same field name and object ID
293 private class ReadWriteSet {
294 private HashMap<String, Integer> readSet;
295 private HashMap<String, Integer> writeSet;
297 public ReadWriteSet() {
298 readSet = new HashMap<>();
299 writeSet = new HashMap<>();
302 public void addReadField(String field, int objectId) {
303 readSet.put(field, objectId);
306 public void addWriteField(String field, int objectId) {
307 writeSet.put(field, objectId);
310 public boolean readFieldExists(String field) {
311 return readSet.containsKey(field);
314 public boolean writeFieldExists(String field) {
315 return writeSet.containsKey(field);
318 public int readFieldObjectId(String field) {
319 return readSet.get(field);
322 public int writeFieldObjectId(String field) {
323 return writeSet.get(field);
327 // This class compactly stores backtracking points: 1) backtracking ChoiceGenerator, and 2) backtracking choices
328 private class BacktrackPoint {
329 private IntChoiceFromSet backtrackCG; // CG to backtrack from
330 private int choice; // Choice chosen at this backtrack point
332 public BacktrackPoint(IntChoiceFromSet cg, int cho) {
337 public IntChoiceFromSet getBacktrackCG() {
341 public int getChoice() {
347 private final static String DO_CALL_METHOD = "doCall";
348 // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
349 private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
350 private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST =
351 // Groovy library created fields
352 {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__",
354 "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList",
355 "eventList", "valueList", "settings", "printToConsole", "app1", "app2"};
356 private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST =
357 // Java and Groovy libraries
358 { "java", "org", "sun", "com", "gov", "groovy"};
359 private final static String[] EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
360 private final static String GET_PROPERTY_METHOD =
361 "invokeinterface org.codehaus.groovy.runtime.callsite.CallSite.callGetProperty";
362 private final static String GROOVY_CALLSITE_LIB = "org.codehaus.groovy.runtime.callsite";
363 private final static String JAVA_INTEGER = "int";
364 private final static String JAVA_STRING_LIB = "java.lang.String";
367 private void checkAndEnforceFairScheduling(IntChoiceFromSet icsCG) {
368 // Check the next choice and if the value is not the same as the expected then force the expected value
369 int choiceIndex = choiceCounter % refChoices.length;
370 int nextChoice = icsCG.getNextChoice();
371 if (refChoices[choiceIndex] != nextChoice) {
372 int expectedChoice = refChoices[choiceIndex];
373 int currCGIndex = icsCG.getNextChoiceIndex();
374 if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
375 icsCG.setChoice(currCGIndex, expectedChoice);
380 private Integer[] copyChoices(Integer[] choicesToCopy) {
382 Integer[] copyOfChoices = new Integer[choicesToCopy.length];
383 System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
384 return copyOfChoices;
387 // --- Functions related to cycle detection
389 // Detect cycles in the current execution/trace
390 // We terminate the execution iff:
391 // (1) the state has been visited in the current execution
392 // (2) the state has one or more cycles that involve all the events
393 // With simple approach we only need to check for a re-visited state.
394 // Basically, we have to check that we have executed all events between two occurrences of such state.
395 private boolean containsCyclesWithAllEvents(int stId) {
397 // False if the state ID hasn't been recorded
398 if (!stateToEventMap.containsKey(stId)) {
401 HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
402 // Check if this set contains all the event choices
403 // If not then this is not the terminating condition
404 for(int i=0; i<=maxEventChoice; i++) {
405 if (!visitedEvents.contains(i)) {
412 private void initializeStatesVariables() {
420 currVisitedStates = new HashSet<>();
421 justVisitedStates = new HashSet<>();
422 prevVisitedStates = new HashSet<>();
423 stateToEventMap = new HashMap<>();
425 backtrackMap = new HashMap<>();
426 backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
427 backtrackPointList = new ArrayList<>();
428 cgMap = new HashMap<>();
429 conflictPairMap = new HashMap<>();
430 doneBacktrackSet = new HashSet<>();
431 readWriteFieldsMap = new HashMap<>();
433 prevChoiceValue = -1;
434 vodGraphMap = new HashMap<>();
436 isEndOfExecution = false;
437 isFirstResetDone = false;
440 private void mapStateToEvent(int nextChoiceValue) {
441 // Update all states with this event/choice
442 // This means that all past states now see this transition
443 Set<Integer> stateSet = stateToEventMap.keySet();
444 for(Integer stateId : stateSet) {
445 HashSet<Integer> eventSet = stateToEventMap.get(stateId);
446 eventSet.add(nextChoiceValue);
450 private boolean terminateCurrentExecution() {
451 // We need to check all the states that have just been visited
452 // Often a transition (choice/event) can result into forwarding/backtracking to a number of states
453 for(Integer stateId : justVisitedStates) {
454 if (prevVisitedStates.contains(stateId) || containsCyclesWithAllEvents(stateId)) {
461 private void updateStateInfo(Search search) {
462 // Update the state variables
463 // Line 19 in the paper page 11 (see the heading note above)
464 int stateId = search.getStateId();
465 currVisitedStates.add(stateId);
466 // Insert state ID into the map if it is new
467 if (!stateToEventMap.containsKey(stateId)) {
468 HashSet<Integer> eventSet = new HashSet<>();
469 stateToEventMap.put(stateId, eventSet);
471 justVisitedStates.add(stateId);
474 // --- Functions related to Read/Write access analysis on shared fields
476 private void addNewBacktrackPoint(IntChoiceFromSet backtrackCG, Integer[] newChoiceList) {
477 int stateId = backtrackCG.getStateId();
478 // Insert backtrack point to the right state ID
479 LinkedList<Integer[]> backtrackList;
480 if (backtrackMap.containsKey(stateId)) {
481 backtrackList = backtrackMap.get(stateId);
483 backtrackList = new LinkedList<>();
484 backtrackMap.put(stateId, backtrackList);
486 backtrackList.addFirst(newChoiceList);
487 // Add CG for this state ID if there isn't one yet
488 if (!cgMap.containsKey(stateId)) {
489 cgMap.put(stateId, backtrackCG);
491 // Add to priority queue
492 if (!backtrackStateQ.contains(stateId)) {
493 backtrackStateQ.add(stateId);
497 // Analyze Read/Write accesses that are directly invoked on fields
498 private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
499 // Do the analysis to get Read and Write accesses to fields
500 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
501 int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().getClassInfo().getClassObjectRef();
502 // Record the field in the map
503 if (executedInsn instanceof WriteInstruction) {
504 // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
505 for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
506 if (fieldClass.startsWith(str)) {
510 rwSet.addWriteField(fieldClass, objectId);
511 } else if (executedInsn instanceof ReadInstruction) {
512 rwSet.addReadField(fieldClass, objectId);
516 // Analyze Read accesses that are indirect (performed through iterators)
517 // These accesses are marked by certain bytecode instructions, e.g., INVOKEINTERFACE
518 private void analyzeReadWriteAccesses(Instruction instruction, ThreadInfo ti, int currentChoice) {
520 INVOKEINTERFACE insn = (INVOKEINTERFACE) instruction;
521 if (insn.toString().startsWith(GET_PROPERTY_METHOD) &&
522 insn.getMethodInfo().getName().equals(DO_CALL_METHOD)) {
523 // Extract info from the stack frame
524 StackFrame frame = ti.getTopFrame();
525 int[] frameSlots = frame.getSlots();
526 // Get the Groovy callsite library at index 0
527 ElementInfo eiCallsite = VM.getVM().getHeap().get(frameSlots[0]);
528 if (!eiCallsite.getClassInfo().getName().startsWith(GROOVY_CALLSITE_LIB)) {
531 // Get the iterated object whose property is accessed
532 ElementInfo eiAccessObj = VM.getVM().getHeap().get(frameSlots[1]);
533 if (eiAccessObj == null) {
536 // We exclude library classes (they start with java, org, etc.) and some more
537 String objClassName = eiAccessObj.getClassInfo().getName();
538 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName) ||
539 excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName)) {
542 // Extract fields from this object and put them into the read write
543 int numOfFields = eiAccessObj.getNumberOfFields();
544 for(int i=0; i<numOfFields; i++) {
545 FieldInfo fieldInfo = eiAccessObj.getFieldInfo(i);
546 if (fieldInfo.getType().equals(JAVA_STRING_LIB) || fieldInfo.getType().equals(JAVA_INTEGER)) {
547 String fieldClass = fieldInfo.getFullName();
548 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
549 int objectId = fieldInfo.getClassInfo().getClassObjectRef();
550 // Record the field in the map
551 rwSet.addReadField(fieldClass, objectId);
557 private int checkAndAdjustChoice(int currentChoice, VM vm) {
558 // If current choice is not the same, then this is caused by the firing of IntIntervalGenerator
559 // for certain method calls in the infrastructure, e.g., eventSince()
560 int currChoiceInd = currentChoice % refChoices.length;
561 int currChoiceFromCG = getCurrentChoice(vm);
562 if (currChoiceInd != currChoiceFromCG) {
563 currentChoice = (currentChoice - currChoiceInd) + currChoiceFromCG;
565 return currentChoice;
568 private void createBacktrackingPoint(int currentChoice, int confEvtNum) {
570 // Create a new list of choices for backtrack based on the current choice and conflicting event number
571 // E.g. if we have a conflict between 1 and 3, then we create the list {3, 1, 0, 2}
572 // for the original set {0, 1, 2, 3}
573 Integer[] newChoiceList = new Integer[refChoices.length];
574 // Put the conflicting event numbers first and reverse the order
575 int actualCurrCho = currentChoice % refChoices.length;
576 // We use the actual choices here in case they have been modified/adjusted by the fair scheduling method
577 newChoiceList[0] = choices[actualCurrCho];
578 newChoiceList[1] = backtrackPointList.get(confEvtNum).getChoice();
579 // Put the rest of the event numbers into the array starting from the minimum to the upper bound
580 for (int i = 0, j = 2; i < refChoices.length; i++) {
581 if (refChoices[i] != newChoiceList[0] && refChoices[i] != newChoiceList[1]) {
582 newChoiceList[j] = refChoices[i];
586 // Get the backtrack CG for this backtrack point
587 IntChoiceFromSet backtrackCG = backtrackPointList.get(confEvtNum).getBacktrackCG();
588 // Check if this trace has been done starting from this state
589 if (isTraceConstructed(newChoiceList, backtrackCG)) {
592 //BacktrackPoint backtrackPoint = new BacktrackPoint(backtrackCG, newChoiceList);
593 addNewBacktrackPoint(backtrackCG, newChoiceList);
596 private boolean excludeThisForItContains(String[] excludedStrings, String className) {
597 for (String excludedField : excludedStrings) {
598 if (className.contains(excludedField)) {
605 private boolean excludeThisForItEndsWith(String[] excludedStrings, String className) {
606 for (String excludedField : excludedStrings) {
607 if (className.endsWith(excludedField)) {
614 private boolean excludeThisForItStartsWith(String[] excludedStrings, String className) {
615 for (String excludedField : excludedStrings) {
616 if (className.startsWith(excludedField)) {
623 private void exploreNextBacktrackPoints(IntChoiceFromSet icsCG, VM vm) {
624 // We can start exploring the next backtrack point after the current CG is advanced at least once
625 if (icsCG.getNextChoiceIndex() > 0) {
626 // Check if we are reaching the end of our execution: no more backtracking points to explore
627 if (!backtrackMap.isEmpty()) {
628 setNextBacktrackPoint(icsCG);
630 // Save all the visited states when starting a new execution of trace
631 prevVisitedStates.addAll(currVisitedStates);
632 currVisitedStates.clear();
633 // This marks a transitional period to the new CG
634 isEndOfExecution = true;
638 private int getCurrentChoice(VM vm) {
639 ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
640 // This is the main event CG
641 if (currentCG instanceof IntChoiceFromSet) {
642 return ((IntChoiceFromSet) currentCG).getNextChoiceIndex();
644 // This is the interval CG used in device handlers
645 ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
646 return ((IntChoiceFromSet) parentCG).getNextChoiceIndex();
650 private ReadWriteSet getReadWriteSet(int currentChoice) {
651 // Do the analysis to get Read and Write accesses to fields
653 // We already have an entry
654 if (readWriteFieldsMap.containsKey(currentChoice)) {
655 rwSet = readWriteFieldsMap.get(currentChoice);
656 } else { // We need to create a new entry
657 rwSet = new ReadWriteSet();
658 readWriteFieldsMap.put(currentChoice, rwSet);
663 private boolean isConflictFound(Instruction nextInsn, int eventCounter, int currentChoice, String fieldClass) {
664 int actualEvtCntr = eventCounter % refChoices.length;
665 int actualCurrCho = currentChoice % refChoices.length;
666 // Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
667 if (!readWriteFieldsMap.containsKey(eventCounter) || choices[actualCurrCho] == choices[actualEvtCntr]) {
670 ReadWriteSet rwSet = readWriteFieldsMap.get(eventCounter);
671 int currObjId = ((JVMFieldInstruction) nextInsn).getFieldInfo().getClassInfo().getClassObjectRef();
672 // Check for conflicts with Write fields for both Read and Write instructions
673 if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) &&
674 rwSet.writeFieldExists(fieldClass) && rwSet.writeFieldObjectId(fieldClass) == currObjId) ||
675 (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass) &&
676 rwSet.readFieldObjectId(fieldClass) == currObjId)) {
682 private boolean isFieldExcluded(String field) {
683 // Check against "starts-with", "ends-with", and "contains" list
684 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, field) ||
685 excludeThisForItEndsWith(EXCLUDED_FIELDS_ENDS_WITH_LIST, field) ||
686 excludeThisForItContains(EXCLUDED_FIELDS_CONTAINS_LIST, field)) {
693 private boolean isNewConflict(int currentEvent, int eventNumber) {
694 HashSet<Integer> conflictSet;
695 if (!conflictPairMap.containsKey(currentEvent)) {
696 conflictSet = new HashSet<>();
697 conflictPairMap.put(currentEvent, conflictSet);
699 conflictSet = conflictPairMap.get(currentEvent);
701 // If this conflict has been recorded before, we return false because
702 // we don't want to save this backtrack point twice
703 if (conflictSet.contains(eventNumber)) {
706 // If it hasn't been recorded, then do otherwise
707 conflictSet.add(eventNumber);
711 private boolean isTraceConstructed(Integer[] choiceList, IntChoiceFromSet backtrackCG) {
712 // Concatenate state ID and trace in a string, e.g., "1:10234"
713 int stateId = backtrackCG.getStateId();
714 StringBuilder sb = new StringBuilder();
717 for(Integer choice : choiceList) {
720 // Check if the trace has been constructed as a backtrack point for this state
721 if (doneBacktrackSet.contains(sb.toString())) {
724 doneBacktrackSet.add(sb.toString());
728 private void resetStatesForNewExecution(IntChoiceFromSet icsCG) {
729 if (choices == null || choices != icsCG.getAllChoices()) {
730 // Reset state variables
732 choices = icsCG.getAllChoices();
733 refChoices = copyChoices(choices);
734 lastCGStateId = icsCG.getStateId();
735 // Clearing data structures
736 conflictPairMap.clear();
737 readWriteFieldsMap.clear();
738 stateToEventMap.clear();
739 isEndOfExecution = false;
740 // Adding this CG as the first backtrack point for this execution
741 backtrackPointList.add(new BacktrackPoint(icsCG, choices[0]));
745 private void setBacktrackCG(int stateId) {
746 // Set a backtrack CG based on a state ID
747 IntChoiceFromSet backtrackCG = cgMap.get(stateId);
748 LinkedList<Integer[]> backtrackChoices = backtrackMap.get(stateId);
749 backtrackCG.setNewValues(backtrackChoices.removeLast()); // Get the last from the queue
751 // Remove from the queue if we don't have more backtrack points for that state
752 if (backtrackChoices.isEmpty()) {
753 cgMap.remove(stateId);
754 backtrackMap.remove(stateId);
755 backtrackStateQ.remove(stateId);
759 private void setNextBacktrackPoint(IntChoiceFromSet icsCG) {
761 HashSet<IntChoiceFromSet> backtrackCGs = new HashSet<>(cgMap.values());
762 if (!isFirstResetDone) {
763 // Reset the last CG of every LinkedList in the map and set done everything else
764 for (Integer stateId : cgMap.keySet()) {
765 setBacktrackCG(stateId);
767 isFirstResetDone = true;
769 // Check if we still have backtrack points for the last state after the last backtrack
770 if (backtrackMap.containsKey(lastCGStateId)) {
771 setBacktrackCG(lastCGStateId);
773 // We try to reset new CGs (if we do have) when we are running out of active CGs
774 if (!backtrackStateQ.isEmpty()) {
775 // Reset the next CG with the latest state
776 int hiStateId = backtrackStateQ.peek();
777 setBacktrackCG(hiStateId);
782 for(BacktrackPoint backtrackPoint : backtrackPointList) {
783 IntChoiceFromSet cg = backtrackPoint.getBacktrackCG();
784 if (!backtrackCGs.contains(cg)) {
788 backtrackPointList.clear();
791 // --- Functions related to the visible operation dependency graph implementation discussed in the SPIN paper
793 // This method checks whether a choice is reachable in the VOD graph from a reference choice (BFS algorithm)
794 //private boolean isReachableInVODGraph(int checkedChoice, int referenceChoice) {
795 private boolean isReachableInVODGraph(int currentChoice) {
796 // Extract previous and current events
797 int choiceIndex = currentChoice % refChoices.length;
798 int currEvent = refChoices[choiceIndex];
799 int prevEvent = refChoices[choiceIndex - 1];
800 // Record visited choices as we search in the graph
801 HashSet<Integer> visitedChoice = new HashSet<>();
802 visitedChoice.add(prevEvent);
803 LinkedList<Integer> nodesToVisit = new LinkedList<>();
804 // If the state doesn't advance as the threads/sub-programs are executed (basically there is no new state),
805 // there is a chance that the graph doesn't have new nodes---thus this check will return a null.
806 if (vodGraphMap.containsKey(prevEvent)) {
807 nodesToVisit.addAll(vodGraphMap.get(prevEvent));
808 while(!nodesToVisit.isEmpty()) {
809 int choice = nodesToVisit.getFirst();
810 if (choice == currEvent) {
813 if (visitedChoice.contains(choice)) { // If there is a loop then we don't find it
816 // Continue searching
817 visitedChoice.add(choice);
818 HashSet<Integer> choiceNextNodes = vodGraphMap.get(choice);
819 if (choiceNextNodes != null) {
820 // Add only if there is a mapping for next nodes
821 for (Integer nextNode : choiceNextNodes) {
823 if (nextNode == choice) {
826 nodesToVisit.addLast(nextNode);
834 private void updateVODGraph(int currChoiceValue) {
835 // Update the graph when we have the current choice value
836 HashSet<Integer> choiceSet;
837 if (vodGraphMap.containsKey(prevChoiceValue)) {
838 // If the key already exists, just retrieve it
839 choiceSet = vodGraphMap.get(prevChoiceValue);
841 // Create a new entry
842 choiceSet = new HashSet<>();
843 vodGraphMap.put(prevChoiceValue, choiceSet);
845 choiceSet.add(currChoiceValue);
846 prevChoiceValue = currChoiceValue;