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.FileWriter;
32 import java.io.PrintWriter;
34 import java.util.logging.Logger;
35 import java.io.IOException;
38 * This a DPOR implementation for event-driven applications with loops that create cycles of state matching
39 * In this new DPOR algorithm/implementation, each run is terminated iff:
40 * - we find a state that matches a state in a previous run, or
41 * - we have a matched state in the current run that consists of cycles that contain all choices/events.
43 public class DPORStateReducer extends ListenerAdapter {
45 // Information printout fields for verbose mode
46 private boolean verboseMode;
47 private boolean stateReductionMode;
48 private final PrintWriter out;
49 private PrintWriter fileWriter;
50 private String detail;
53 private Transition transition;
55 // DPOR-related fields
57 private Integer[] choices;
58 private Integer[] refChoices; // Second reference to a copy of choices (choices may be modified for fair scheduling)
59 private int choiceCounter;
60 private int maxEventChoice;
61 // Data structure to track the events seen by each state to track cycles (containing all events) for termination
62 private HashSet<Integer> currVisitedStates; // States being visited in the current execution
63 private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
64 private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
65 private HashMap<Integer, HashSet<Integer>> stateToEventMap;
66 // Data structure to analyze field Read/Write accesses and conflicts
67 private HashMap<Integer, LinkedList<BacktrackExecution>> backtrackMap; // Track created backtracking points
68 private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
69 private Execution currentExecution; // Holds the information about the current execution
70 private HashSet<String> doneBacktrackSet; // Record state ID and trace already constructed
71 private HashMap<Integer, RestorableVMState> restorableStateMap; // Maps state IDs to the restorable state object
72 private HashMap<Integer, Integer> stateToChoiceCounterMap; // Maps state IDs to the choice counter
73 private HashMap<Integer, HashSet<TransitionEvent>> rGraph; // Reachability graph for past executions
76 private boolean isBooleanCGFlipped;
77 private boolean isEndOfExecution;
80 private int numOfConflicts;
81 private int numOfTransitions;
83 public DPORStateReducer(Config config, JPF jpf) {
84 verboseMode = config.getBoolean("printout_state_transition", false);
85 stateReductionMode = config.getBoolean("activate_state_reduction", true);
87 out = new PrintWriter(System.out, true);
91 String outputFile = config.getString("file_output");
92 if (!outputFile.isEmpty()) {
94 fileWriter = new PrintWriter(new FileWriter(outputFile, true), true);
95 } catch (IOException e) {
98 isBooleanCGFlipped = false;
100 numOfTransitions = 0;
101 restorableStateMap = new HashMap<>();
102 initializeStatesVariables();
106 public void stateRestored(Search search) {
108 id = search.getStateId();
109 depth = search.getDepth();
110 transition = search.getTransition();
112 out.println("\n==> DEBUG: The state is restored to state with id: " + id + " -- Transition: " + transition +
113 " and depth: " + depth + "\n");
118 public void searchStarted(Search search) {
120 out.println("\n==> DEBUG: ----------------------------------- search started" + "\n");
125 public void stateAdvanced(Search search) {
127 id = search.getStateId();
128 depth = search.getDepth();
129 transition = search.getTransition();
130 if (search.isNewState()) {
136 if (search.isEndState()) {
137 out.println("\n==> DEBUG: This is the last state!\n");
140 out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
141 " which is " + detail + " Transition: " + transition + "\n");
143 if (stateReductionMode) {
144 // Only add a transition into R-Graph when it advances the state
145 addTransitionToRGRaph();
146 updateStateInfo(search);
151 public void stateBacktracked(Search search) {
153 id = search.getStateId();
154 depth = search.getDepth();
155 transition = search.getTransition();
158 out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
159 " and depth: " + depth + "\n");
161 if (stateReductionMode) {
162 updateStateInfo(search);
166 static Logger log = JPF.getLogger("report");
169 public void searchFinished(Search search) {
170 if (stateReductionMode) {
171 // Number of conflicts = first trace + subsequent backtrack points
172 numOfConflicts += 1 + doneBacktrackSet.size();
175 out.println("\n==> DEBUG: ----------------------------------- search finished");
176 out.println("\n==> DEBUG: State reduction mode : " + stateReductionMode);
177 out.println("\n==> DEBUG: Number of conflicts : " + numOfConflicts);
178 out.println("\n==> DEBUG: Number of transitions : " + numOfTransitions);
179 out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
181 fileWriter.println("==> DEBUG: State reduction mode : " + stateReductionMode);
182 fileWriter.println("==> DEBUG: Number of conflicts : " + numOfConflicts);
183 fileWriter.println("==> DEBUG: Number of transitions : " + numOfTransitions);
184 fileWriter.println();
190 public void choiceGeneratorRegistered(VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
191 if (stateReductionMode) {
192 // Initialize with necessary information from the CG
193 if (nextCG instanceof IntChoiceFromSet) {
194 IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
195 if (!isEndOfExecution) {
196 // Check if CG has been initialized, otherwise initialize it
197 Integer[] cgChoices = icsCG.getAllChoices();
198 // Record the events (from choices)
199 if (choices == null) {
201 // Make a copy of choices as reference
202 refChoices = copyChoices(choices);
203 // Record the max event choice (the last element of the choice array)
204 maxEventChoice = choices[choices.length - 1];
206 icsCG.setNewValues(choices);
208 // Use a modulo since choiceCounter is going to keep increasing
209 int choiceIndex = choiceCounter % choices.length;
210 icsCG.advance(choices[choiceIndex]);
212 // Set done all CGs while transitioning to a new execution
220 public void choiceGeneratorAdvanced(VM vm, ChoiceGenerator<?> currentCG) {
222 if (stateReductionMode) {
223 // Check the boolean CG and if it is flipped, we are resetting the analysis
224 if (currentCG instanceof BooleanChoiceGenerator) {
225 if (!isBooleanCGFlipped) {
226 isBooleanCGFlipped = true;
228 // Number of conflicts = first trace + subsequent backtrack points
229 numOfConflicts = 1 + doneBacktrackSet.size();
230 // Allocate new objects for data structure when the boolean is flipped from "false" to "true"
231 initializeStatesVariables();
234 // Check every choice generated and ensure fair scheduling!
235 if (currentCG instanceof IntChoiceFromSet) {
236 IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
237 // If this is a new CG then we need to update data structures
238 resetStatesForNewExecution(icsCG, vm);
239 // If we don't see a fair scheduling of events/choices then we have to enforce it
240 fairSchedulingAndTransition(icsCG, vm);
241 // Update backtrack set of an executed event (transition): one transition before this one
242 updateBacktrackSet(currentExecution, choiceCounter - 1);
243 // Explore the next backtrack point:
244 // 1) if we have seen this state or this state contains cycles that involve all events, and
245 // 2) after the current CG is advanced at least once
246 if (terminateCurrentExecution() && choiceCounter > 0) {
247 exploreNextBacktrackPoints(vm, icsCG);
251 // Map state to event
252 mapStateToEvent(icsCG.getNextChoice());
253 justVisitedStates.clear();
262 public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
263 if (stateReductionMode) {
264 if (!isEndOfExecution) {
265 // Has to be initialized and a integer CG
266 ChoiceGenerator<?> cg = vm.getChoiceGenerator();
267 if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
268 int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
269 if (currentChoice < 0) { // If choice is -1 then skip
272 currentChoice = checkAndAdjustChoice(currentChoice, vm);
273 // Record accesses from executed instructions
274 if (executedInsn instanceof JVMFieldInstruction) {
275 // Analyze only after being initialized
276 String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
277 // We don't care about libraries
278 if (!isFieldExcluded(fieldClass)) {
279 analyzeReadWriteAccesses(executedInsn, fieldClass, currentChoice);
281 } else if (executedInsn instanceof INVOKEINTERFACE) {
282 // Handle the read/write accesses that occur through iterators
283 analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
295 // This class compactly stores backtrack execution:
296 // 1) backtrack choice list, and
297 // 2) first backtrack point (linking with predecessor execution)
298 private class BacktrackExecution {
299 private Integer[] choiceList;
300 private TransitionEvent firstTransition;
302 public BacktrackExecution(Integer[] choList, TransitionEvent fTransition) {
303 choiceList = choList;
304 firstTransition = fTransition;
307 public Integer[] getChoiceList() {
311 public TransitionEvent getFirstTransition() {
312 return firstTransition;
316 // This class stores a representation of the execution graph node
317 // TODO: We can modify this class to implement some optimization (e.g., clock-vector)
318 // TODO: We basically need to keep track of:
319 // TODO: (1) last read/write access to each memory location
320 // TODO: (2) last state with two or more incoming events (transitions)
321 private class Execution {
322 private HashMap<IntChoiceFromSet, Integer> cgToChoiceMap; // Map between CG to choice numbers for O(1) access
323 private ArrayList<TransitionEvent> executionTrace; // The BacktrackPoint objects of this execution
324 private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
325 private HashMap<Integer, TransitionEvent> stateToTransitionMap; // For O(1) access to backtrack point
328 cgToChoiceMap = new HashMap<>();
329 executionTrace = new ArrayList<>();
330 readWriteFieldsMap = new HashMap<>();
331 stateToTransitionMap = new HashMap<>();
334 public void addTransition(TransitionEvent newBacktrackPoint) {
335 executionTrace.add(newBacktrackPoint);
338 public void clearCGToChoiceMap() {
339 cgToChoiceMap = null;
342 public TransitionEvent getTransitionFromState(int stateId) {
343 if (stateToTransitionMap.containsKey(stateId)) {
344 return stateToTransitionMap.get(stateId);
349 public int getChoiceFromCG(IntChoiceFromSet icsCG) {
350 return cgToChoiceMap.get(icsCG);
353 public ArrayList<TransitionEvent> getExecutionTrace() {
354 return executionTrace;
357 public HashMap<Integer, ReadWriteSet> getReadWriteFieldsMap() {
358 return readWriteFieldsMap;
361 public TransitionEvent getFirstTransition() {
362 return executionTrace.get(0);
365 public TransitionEvent getLastTransition() {
366 return executionTrace.get(executionTrace.size() - 1);
369 public boolean isNew() {
370 return executionTrace.size() == 1;
373 public void mapCGToChoice(IntChoiceFromSet icsCG, int choice) {
374 cgToChoiceMap.put(icsCG, choice);
377 public void mapStateToTransition(int stateId, TransitionEvent backtrackPoint) {
378 stateToTransitionMap.put(stateId, backtrackPoint);
382 // This class compactly stores a predecessor
383 // 1) a predecessor execution
384 // 2) the predecessor choice in that predecessor execution
385 private class Predecessor {
386 private int predecessorChoice; // Predecessor choice
387 private Execution predecessorExecution; // Predecessor execution
389 public Predecessor(int predChoice, Execution predExec) {
390 predecessorChoice = predChoice;
391 predecessorExecution = predExec;
394 public int getPredecessorChoice() {
395 return predecessorChoice;
398 public Execution getPredecessorExecution() {
399 return predecessorExecution;
403 // This class compactly stores backtrack points:
407 // 4) predecessors (for backward DFS).
408 private class TransitionEvent {
409 private IntChoiceFromSet transitionCG; // CG at this transition
410 private int stateId; // State at this transition
411 private int choice; // Choice chosen at this transition
412 private Execution execution; // The execution where this transition belongs
413 private int choiceCounter; // Choice counter at this transition
414 private HashSet<Predecessor> predecessors; // Maps incoming events/transitions (execution and choice)
416 public TransitionEvent() {
422 predecessors = new HashSet<>();
425 public void setTransitionCG(IntChoiceFromSet cg) {
429 public void setStateId(int stId) {
433 public void setChoice(int cho) {
437 public void setChoiceCounter(int choCounter) {
438 choiceCounter = choCounter;
441 public IntChoiceFromSet getTransitionCG() { return transitionCG; }
443 public int getStateId() {
447 public int getChoice() {
451 public int getChoiceCounter() {
452 return choiceCounter;
455 public void setExecution(Execution exec) {
459 public Execution getExecution() {
463 public HashSet<Predecessor> getPredecessors() {
467 public void recordPredecessor(Execution execution, int choice) {
468 predecessors.add(new Predecessor(choice, execution));
472 // This class compactly stores Read and Write field sets
473 // We store the field name and its object ID
474 // Sharing the same field means the same field name and object ID
475 private class ReadWriteSet {
476 private HashMap<String, Integer> readMap;
477 private HashMap<String, Integer> writeMap;
479 public ReadWriteSet() {
480 readMap = new HashMap<>();
481 writeMap = new HashMap<>();
484 public void addReadField(String field, int objectId) {
485 readMap.put(field, objectId);
488 public void addWriteField(String field, int objectId) {
489 writeMap.put(field, objectId);
492 public void removeReadField(String field) {
493 readMap.remove(field);
496 public void removeWriteField(String field) {
497 writeMap.remove(field);
500 public boolean isEmpty() {
501 return readMap.isEmpty() && writeMap.isEmpty();
504 public ReadWriteSet getCopy() {
505 ReadWriteSet copyRWSet = new ReadWriteSet();
506 // Copy the maps in the set into the new object copy
507 copyRWSet.setReadMap(new HashMap<>(this.getReadMap()));
508 copyRWSet.setWriteMap(new HashMap<>(this.getWriteMap()));
512 public Set<String> getReadSet() {
513 return readMap.keySet();
516 public Set<String> getWriteSet() {
517 return writeMap.keySet();
520 public boolean readFieldExists(String field) {
521 return readMap.containsKey(field);
524 public boolean writeFieldExists(String field) {
525 return writeMap.containsKey(field);
528 public int readFieldObjectId(String field) {
529 return readMap.get(field);
532 public int writeFieldObjectId(String field) {
533 return writeMap.get(field);
536 private HashMap<String, Integer> getReadMap() {
540 private HashMap<String, Integer> getWriteMap() {
544 private void setReadMap(HashMap<String, Integer> rMap) {
548 private void setWriteMap(HashMap<String, Integer> wMap) {
554 private final static String DO_CALL_METHOD = "doCall";
555 // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
556 private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
557 private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST =
558 // Groovy library created fields
559 {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__",
561 "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList",
562 "eventList", "valueList", "settings", "printToConsole", "app1", "app2"};
563 private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST =
564 // Java and Groovy libraries
565 { "java", "org", "sun", "com", "gov", "groovy"};
566 private final static String[] EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
567 private final static String GET_PROPERTY_METHOD =
568 "invokeinterface org.codehaus.groovy.runtime.callsite.CallSite.callGetProperty";
569 private final static String GROOVY_CALLSITE_LIB = "org.codehaus.groovy.runtime.callsite";
570 private final static String JAVA_INTEGER = "int";
571 private final static String JAVA_STRING_LIB = "java.lang.String";
574 private void fairSchedulingAndTransition(IntChoiceFromSet icsCG, VM vm) {
575 // Check the next choice and if the value is not the same as the expected then force the expected value
576 int choiceIndex = choiceCounter % refChoices.length;
577 int nextChoice = icsCG.getNextChoice();
578 if (refChoices[choiceIndex] != nextChoice) {
579 int expectedChoice = refChoices[choiceIndex];
580 int currCGIndex = icsCG.getNextChoiceIndex();
581 if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
582 icsCG.setChoice(currCGIndex, expectedChoice);
585 // Get state ID and associate it with this transition
586 int stateId = vm.getStateId();
587 // Get a new transition
588 TransitionEvent transition;
589 if (currentExecution.isNew()) {
590 // We need to handle the first transition differently because this has a predecessor execution
591 transition = currentExecution.getFirstTransition();
593 transition = new TransitionEvent();
594 transition.recordPredecessor(currentExecution, choiceCounter - 1);
596 transition.setExecution(currentExecution);
597 transition.setTransitionCG(icsCG);
598 transition.setStateId(stateId);
599 transition.setChoice(refChoices[choiceIndex]);
600 transition.setChoiceCounter(choiceCounter);
601 // Add new transition to the current execution
602 currentExecution.mapStateToTransition(stateId, transition);
603 currentExecution.addTransition(transition);
604 currentExecution.mapCGToChoice(icsCG, choiceCounter);
605 // Store restorable state object for this state (always store the latest)
606 RestorableVMState restorableState = vm.getRestorableState();
607 restorableStateMap.put(stateId, restorableState);
610 private Integer[] copyChoices(Integer[] choicesToCopy) {
612 Integer[] copyOfChoices = new Integer[choicesToCopy.length];
613 System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
614 return copyOfChoices;
617 // --- Functions related to cycle detection and reachability graph
619 // Detect cycles in the current execution/trace
620 // We terminate the execution iff:
621 // (1) the state has been visited in the current execution
622 // (2) the state has one or more cycles that involve all the events
623 // With simple approach we only need to check for a re-visited state.
624 // Basically, we have to check that we have executed all events between two occurrences of such state.
625 private boolean completeFullCycle(int stId) {
627 // False if the state ID hasn't been recorded
628 if (!stateToEventMap.containsKey(stId)) {
631 HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
632 // Check if this set contains all the event choices
633 // If not then this is not the terminating condition
634 for(int i=0; i<=maxEventChoice; i++) {
635 if (!visitedEvents.contains(i)) {
642 private void initializeStatesVariables() {
649 currVisitedStates = new HashSet<>();
650 justVisitedStates = new HashSet<>();
651 prevVisitedStates = new HashSet<>();
652 stateToEventMap = new HashMap<>();
654 backtrackMap = new HashMap<>();
655 backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
656 currentExecution = new Execution();
657 currentExecution.addTransition(new TransitionEvent()); // Always start with 1 backtrack point
658 doneBacktrackSet = new HashSet<>();
659 stateToChoiceCounterMap = new HashMap<>();
660 rGraph = new HashMap<>();
662 isEndOfExecution = false;
665 private void mapStateToEvent(int nextChoiceValue) {
666 // Update all states with this event/choice
667 // This means that all past states now see this transition
668 Set<Integer> stateSet = stateToEventMap.keySet();
669 for(Integer stateId : stateSet) {
670 HashSet<Integer> eventSet = stateToEventMap.get(stateId);
671 eventSet.add(nextChoiceValue);
675 // Save the current transition into R-Graph
676 // Basically the current transition is reachable from the final state of the previous transition in this execution
677 private void addTransitionToRGRaph() {
678 // Get the current transition
679 TransitionEvent currTrans = currentExecution.getLastTransition();
680 // This transition is reachable from this source state when it has advanced the state
681 int stateId = currTrans.getStateId();
682 // Add transition into R-Graph
683 HashSet<TransitionEvent> transitionSet;
684 if (rGraph.containsKey(stateId)) {
685 transitionSet = rGraph.get(stateId);
687 transitionSet = new HashSet<>();
689 // Insert into the set if it does not contain it yet
690 if (!transitionSet.contains(currTrans)) {
691 transitionSet.add(currTrans);
695 private boolean terminateCurrentExecution() {
696 // We need to check all the states that have just been visited
697 // Often a transition (choice/event) can result into forwarding/backtracking to a number of states
698 for(Integer stateId : justVisitedStates) {
699 if (prevVisitedStates.contains(stateId) || completeFullCycle(stateId)) {
706 private void updateStateInfo(Search search) {
707 // Update the state variables
708 // Line 19 in the paper page 11 (see the heading note above)
709 int stateId = search.getStateId();
710 // Insert state ID into the map if it is new
711 if (!stateToEventMap.containsKey(stateId)) {
712 HashSet<Integer> eventSet = new HashSet<>();
713 stateToEventMap.put(stateId, eventSet);
715 analyzeReachabilityAndCreateBacktrackPoints(search.getVM(), stateId);
716 stateToChoiceCounterMap.put(stateId, choiceCounter);
717 justVisitedStates.add(stateId);
718 currVisitedStates.add(stateId);
721 // --- Functions related to Read/Write access analysis on shared fields
723 private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList, Execution parentExecution, int parentChoice) {
724 // Insert backtrack point to the right state ID
725 LinkedList<BacktrackExecution> backtrackExecList;
726 if (backtrackMap.containsKey(stateId)) {
727 backtrackExecList = backtrackMap.get(stateId);
729 backtrackExecList = new LinkedList<>();
730 backtrackMap.put(stateId, backtrackExecList);
732 // Add the new backtrack execution object
733 TransitionEvent backtrackTransition = new TransitionEvent();
734 backtrackTransition.recordPredecessor(parentExecution, parentChoice);
735 backtrackExecList.addFirst(new BacktrackExecution(newChoiceList, backtrackTransition));
736 // Add to priority queue
737 if (!backtrackStateQ.contains(stateId)) {
738 backtrackStateQ.add(stateId);
742 // Analyze Read/Write accesses that are directly invoked on fields
743 private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
744 // Do the analysis to get Read and Write accesses to fields
745 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
746 int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().getClassInfo().getClassObjectRef();
747 // Record the field in the map
748 if (executedInsn instanceof WriteInstruction) {
749 // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
750 for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
751 if (fieldClass.startsWith(str)) {
755 rwSet.addWriteField(fieldClass, objectId);
756 } else if (executedInsn instanceof ReadInstruction) {
757 rwSet.addReadField(fieldClass, objectId);
761 // Analyze Read accesses that are indirect (performed through iterators)
762 // These accesses are marked by certain bytecode instructions, e.g., INVOKEINTERFACE
763 private void analyzeReadWriteAccesses(Instruction instruction, ThreadInfo ti, int currentChoice) {
765 INVOKEINTERFACE insn = (INVOKEINTERFACE) instruction;
766 if (insn.toString().startsWith(GET_PROPERTY_METHOD) &&
767 insn.getMethodInfo().getName().equals(DO_CALL_METHOD)) {
768 // Extract info from the stack frame
769 StackFrame frame = ti.getTopFrame();
770 int[] frameSlots = frame.getSlots();
771 // Get the Groovy callsite library at index 0
772 ElementInfo eiCallsite = VM.getVM().getHeap().get(frameSlots[0]);
773 if (!eiCallsite.getClassInfo().getName().startsWith(GROOVY_CALLSITE_LIB)) {
776 // Get the iterated object whose property is accessed
777 ElementInfo eiAccessObj = VM.getVM().getHeap().get(frameSlots[1]);
778 if (eiAccessObj == null) {
781 // We exclude library classes (they start with java, org, etc.) and some more
782 String objClassName = eiAccessObj.getClassInfo().getName();
783 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName) ||
784 excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName)) {
787 // Extract fields from this object and put them into the read write
788 int numOfFields = eiAccessObj.getNumberOfFields();
789 for(int i=0; i<numOfFields; i++) {
790 FieldInfo fieldInfo = eiAccessObj.getFieldInfo(i);
791 if (fieldInfo.getType().equals(JAVA_STRING_LIB) || fieldInfo.getType().equals(JAVA_INTEGER)) {
792 String fieldClass = fieldInfo.getFullName();
793 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
794 int objectId = fieldInfo.getClassInfo().getClassObjectRef();
795 // Record the field in the map
796 rwSet.addReadField(fieldClass, objectId);
802 private int checkAndAdjustChoice(int currentChoice, VM vm) {
803 // If current choice is not the same, then this is caused by the firing of IntIntervalGenerator
804 // for certain method calls in the infrastructure, e.g., eventSince()
805 ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
806 // This is the main event CG
807 if (currentCG instanceof IntIntervalGenerator) {
808 // This is the interval CG used in device handlers
809 ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
810 // Iterate until we find the IntChoiceFromSet CG
811 while (!(parentCG instanceof IntChoiceFromSet)) {
812 parentCG = ((IntIntervalGenerator) parentCG).getPreviousChoiceGenerator();
814 // Find the choice related to the IntIntervalGenerator CG from the map
815 currentChoice = currentExecution.getChoiceFromCG((IntChoiceFromSet) parentCG);
817 return currentChoice;
820 private void createBacktrackingPoint(Execution execution, int currentChoice, int conflictChoice) {
822 // Create a new list of choices for backtrack based on the current choice and conflicting event number
823 // E.g. if we have a conflict between 1 and 3, then we create the list {3, 1, 0, 2}
824 // for the original set {0, 1, 2, 3}
825 Integer[] newChoiceList = new Integer[refChoices.length];
826 //int firstChoice = choices[actualChoice];
827 ArrayList<TransitionEvent> pastTrace = execution.getExecutionTrace();
828 ArrayList<TransitionEvent> currTrace = currentExecution.getExecutionTrace();
829 int currChoice = currTrace.get(currentChoice).getChoice();
830 int stateId = pastTrace.get(conflictChoice).getStateId();
831 // Check if this trace has been done from this state
832 if (isTraceAlreadyConstructed(currChoice, stateId)) {
835 // Put the conflicting event numbers first and reverse the order
836 newChoiceList[0] = currChoice;
837 // Put the rest of the event numbers into the array starting from the minimum to the upper bound
838 for (int i = 0, j = 1; i < refChoices.length; i++) {
839 if (refChoices[i] != newChoiceList[0]) {
840 newChoiceList[j] = refChoices[i];
844 // Parent choice is conflict choice - 1
845 addNewBacktrackPoint(stateId, newChoiceList, execution, conflictChoice - 1);
848 private boolean excludeThisForItContains(String[] excludedStrings, String className) {
849 for (String excludedField : excludedStrings) {
850 if (className.contains(excludedField)) {
857 private boolean excludeThisForItEndsWith(String[] excludedStrings, String className) {
858 for (String excludedField : excludedStrings) {
859 if (className.endsWith(excludedField)) {
866 private boolean excludeThisForItStartsWith(String[] excludedStrings, String className) {
867 for (String excludedField : excludedStrings) {
868 if (className.startsWith(excludedField)) {
875 private void exploreNextBacktrackPoints(VM vm, IntChoiceFromSet icsCG) {
877 // Check if we are reaching the end of our execution: no more backtracking points to explore
878 // cgMap, backtrackMap, backtrackStateQ are updated simultaneously (checking backtrackStateQ is enough)
879 if (!backtrackStateQ.isEmpty()) {
880 // Set done all the other backtrack points
881 for (TransitionEvent backtrackTransition : currentExecution.getExecutionTrace()) {
882 backtrackTransition.getTransitionCG().setDone();
884 // Reset the next backtrack point with the latest state
885 int hiStateId = backtrackStateQ.peek();
886 // Restore the state first if necessary
887 if (vm.getStateId() != hiStateId) {
888 RestorableVMState restorableState = restorableStateMap.get(hiStateId);
889 vm.restoreState(restorableState);
891 // Set the backtrack CG
892 IntChoiceFromSet backtrackCG = (IntChoiceFromSet) vm.getChoiceGenerator();
893 setBacktrackCG(hiStateId, backtrackCG);
895 // Set done this last CG (we save a few rounds)
898 // Save all the visited states when starting a new execution of trace
899 prevVisitedStates.addAll(currVisitedStates);
900 // This marks a transitional period to the new CG
901 isEndOfExecution = true;
904 private boolean isConflictFound(Execution execution, int reachableChoice, int conflictChoice,
905 ReadWriteSet currRWSet) {
907 ArrayList<TransitionEvent> executionTrace = execution.getExecutionTrace();
908 HashMap<Integer, ReadWriteSet> execRWFieldsMap = execution.getReadWriteFieldsMap();
909 // Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
910 if (!execRWFieldsMap.containsKey(conflictChoice) ||
911 executionTrace.get(reachableChoice).getChoice() == executionTrace.get(conflictChoice).getChoice()) {
914 // R/W set of choice/event that may have a potential conflict
915 ReadWriteSet evtRWSet = execRWFieldsMap.get(conflictChoice);
916 // Check for conflicts with Read and Write fields for Write instructions
917 Set<String> currWriteSet = currRWSet.getWriteSet();
918 for(String writeField : currWriteSet) {
919 int currObjId = currRWSet.writeFieldObjectId(writeField);
920 if (evtRWSet.readFieldExists(writeField) && evtRWSet.readFieldObjectId(writeField) == currObjId) {
921 // Remove this from the read set as we are tracking per memory location
922 evtRWSet.removeWriteField(writeField);
924 } else if (evtRWSet.writeFieldExists(writeField) && evtRWSet.writeFieldObjectId(writeField) == currObjId) {
925 // Remove this from the write set as we are tracking per memory location
926 evtRWSet.removeReadField(writeField);
930 // Check for conflicts with Write fields for Read instructions
931 Set<String> currReadSet = currRWSet.getReadSet();
932 for(String readField : currReadSet) {
933 int currObjId = currRWSet.readFieldObjectId(readField);
934 if (evtRWSet.writeFieldExists(readField) && evtRWSet.writeFieldObjectId(readField) == currObjId) {
935 // Remove this from the write set as we are tracking per memory location
936 evtRWSet.removeWriteField(readField);
940 // Return false if no conflict is found
944 private boolean isConflictFound(Execution execution, int reachableChoice, int conflictChoice) {
946 ArrayList<TransitionEvent> executionTrace = execution.getExecutionTrace();
947 HashMap<Integer, ReadWriteSet> execRWFieldsMap = execution.getReadWriteFieldsMap();
948 // Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
949 if (!execRWFieldsMap.containsKey(conflictChoice) ||
950 executionTrace.get(reachableChoice).getChoice() == executionTrace.get(conflictChoice).getChoice()) {
954 ReadWriteSet currRWSet = execRWFieldsMap.get(reachableChoice);
955 // R/W set of choice/event that may have a potential conflict
956 ReadWriteSet evtRWSet = execRWFieldsMap.get(conflictChoice);
957 // Check for conflicts with Read and Write fields for Write instructions
958 Set<String> currWriteSet = currRWSet.getWriteSet();
959 for(String writeField : currWriteSet) {
960 int currObjId = currRWSet.writeFieldObjectId(writeField);
961 if ((evtRWSet.readFieldExists(writeField) && evtRWSet.readFieldObjectId(writeField) == currObjId) ||
962 (evtRWSet.writeFieldExists(writeField) && evtRWSet.writeFieldObjectId(writeField) == currObjId)) {
966 // Check for conflicts with Write fields for Read instructions
967 Set<String> currReadSet = currRWSet.getReadSet();
968 for(String readField : currReadSet) {
969 int currObjId = currRWSet.readFieldObjectId(readField);
970 if (evtRWSet.writeFieldExists(readField) && evtRWSet.writeFieldObjectId(readField) == currObjId) {
974 // Return false if no conflict is found
978 private ReadWriteSet getReadWriteSet(int currentChoice) {
979 // Do the analysis to get Read and Write accesses to fields
981 // We already have an entry
982 HashMap<Integer, ReadWriteSet> currReadWriteFieldsMap = currentExecution.getReadWriteFieldsMap();
983 if (currReadWriteFieldsMap.containsKey(currentChoice)) {
984 rwSet = currReadWriteFieldsMap.get(currentChoice);
985 } else { // We need to create a new entry
986 rwSet = new ReadWriteSet();
987 currReadWriteFieldsMap.put(currentChoice, rwSet);
992 private boolean isFieldExcluded(String field) {
993 // Check against "starts-with", "ends-with", and "contains" list
994 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, field) ||
995 excludeThisForItEndsWith(EXCLUDED_FIELDS_ENDS_WITH_LIST, field) ||
996 excludeThisForItContains(EXCLUDED_FIELDS_CONTAINS_LIST, field)) {
1003 // Check if this trace is already constructed
1004 private boolean isTraceAlreadyConstructed(int firstChoice, int stateId) {
1005 // Concatenate state ID and only the first event in the string, e.g., "1:1 for the trace 10234 at state 1"
1006 // TODO: THIS IS AN OPTIMIZATION!
1007 // This is the optimized version because after we execute, e.g., the trace 1:10234, we don't need to try
1008 // another trace that starts with event 1 at state 1, e.g., the trace 1:13024
1009 // The second time this event 1 is explored, it will generate the same state as the first one
1010 StringBuilder sb = new StringBuilder();
1013 sb.append(firstChoice);
1014 // Check if the trace has been constructed as a backtrack point for this state
1015 if (doneBacktrackSet.contains(sb.toString())) {
1018 doneBacktrackSet.add(sb.toString());
1022 // Reset data structure for each new execution
1023 private void resetStatesForNewExecution(IntChoiceFromSet icsCG, VM vm) {
1024 if (choices == null || choices != icsCG.getAllChoices()) {
1025 // Reset state variables
1027 choices = icsCG.getAllChoices();
1028 refChoices = copyChoices(choices);
1029 // Clear data structures
1030 currVisitedStates = new HashSet<>();
1031 stateToChoiceCounterMap = new HashMap<>();
1032 stateToEventMap = new HashMap<>();
1033 isEndOfExecution = false;
1037 // Set a backtrack point for a particular state
1038 private void setBacktrackCG(int stateId, IntChoiceFromSet backtrackCG) {
1039 // Set a backtrack CG based on a state ID
1040 LinkedList<BacktrackExecution> backtrackExecutions = backtrackMap.get(stateId);
1041 BacktrackExecution backtrackExecution = backtrackExecutions.removeLast();
1042 backtrackCG.setNewValues(backtrackExecution.getChoiceList()); // Get the last from the queue
1043 backtrackCG.setStateId(stateId);
1044 backtrackCG.reset();
1045 // Update current execution with this new execution
1046 Execution newExecution = new Execution();
1047 TransitionEvent firstTransition = backtrackExecution.getFirstTransition();
1048 newExecution.addTransition(firstTransition);
1049 // Try to free some memory since this map is only used for the current execution
1050 currentExecution.clearCGToChoiceMap();
1051 currentExecution = newExecution;
1052 // Remove from the queue if we don't have more backtrack points for that state
1053 if (backtrackExecutions.isEmpty()) {
1054 backtrackMap.remove(stateId);
1055 backtrackStateQ.remove(stateId);
1059 // Update backtrack sets
1060 // 1) recursively, and
1061 // 2) track accesses per memory location (per shared variable/field)
1062 private void updateBacktrackSet(Execution execution, int currentChoice) {
1063 // Choice/event we want to check for conflict against (start from actual choice)
1064 int conflictChoice = currentChoice;
1065 // Copy ReadWriteSet object
1066 HashMap<Integer, ReadWriteSet> currRWFieldsMap = execution.getReadWriteFieldsMap();
1067 ReadWriteSet currRWSet = currRWFieldsMap.get(currentChoice).getCopy();
1068 // Memorize visited TransitionEvent object while performing backward DFS to avoid getting caught up in a cycle
1069 HashSet<TransitionEvent> visited = new HashSet<>();
1070 // Update backtrack set recursively
1071 updateBacktrackSetRecursive(execution, currentChoice, conflictChoice, currRWSet, visited);
1074 private void updateBacktrackSetRecursive(Execution execution, int currentChoice, int conflictChoice,
1075 ReadWriteSet currRWSet, HashSet<TransitionEvent> visited) {
1076 // Halt when we have found the first read/write conflicts for all memory locations
1077 if (currRWSet.isEmpty()) {
1080 TransitionEvent confTrans = execution.getExecutionTrace().get(conflictChoice);
1081 // Halt when we have visited this transition (in a cycle)
1082 if (visited.contains(confTrans)) {
1085 visited.add(confTrans);
1086 // Explore all predecessors
1087 for (Predecessor predecessor : confTrans.getPredecessors()) {
1088 // Get the predecessor (previous conflict choice)
1089 conflictChoice = predecessor.getPredecessorChoice();
1090 execution = predecessor.getPredecessorExecution();
1091 // Check if a conflict is found
1092 if (isConflictFound(execution, currentChoice, conflictChoice, currRWSet)) {
1093 createBacktrackingPoint(execution, currentChoice, conflictChoice);
1095 // Continue performing DFS if conflict is not found
1096 updateBacktrackSetRecursive(execution, currentChoice, conflictChoice, currRWSet, visited);
1100 // --- Functions related to the reachability analysis when there is a state match
1102 private void analyzeReachabilityAndCreateBacktrackPoints(VM vm, int stateId) {
1103 // Perform this analysis only when:
1104 // 1) there is a state match,
1105 // 2) this is not during a switch to a new execution,
1106 // 3) at least 2 choices/events have been explored (choiceCounter > 1),
1107 // 4) state > 0 (state 0 is for boolean CG)
1108 if (!vm.isNewState() && !isEndOfExecution && choiceCounter > 1 && (stateId > 0)) {
1109 if (currVisitedStates.contains(stateId)) {
1110 // Get the backtrack point from the current execution
1111 TransitionEvent transition = currentExecution.getTransitionFromState(stateId);
1112 transition.recordPredecessor(currentExecution, choiceCounter - 1);
1113 updateBacktrackSetsFromPreviousExecution(stateId);
1114 } else if (prevVisitedStates.contains(stateId)) { // We visit a state in a previous execution
1115 // Update past executions with a predecessor
1116 HashSet<TransitionEvent> reachableTransitions = rGraph.get(stateId);
1117 for(TransitionEvent transition : reachableTransitions) {
1118 Execution execution = transition.getExecution();
1119 transition.recordPredecessor(execution, choiceCounter - 1);
1121 updateBacktrackSetsFromPreviousExecution(stateId);
1126 // Update the backtrack sets from previous executions
1127 private void updateBacktrackSetsFromPreviousExecution(int stateId) {
1128 // Collect all the reachable transitions from R-Graph
1129 HashSet<TransitionEvent> reachableTransitions = rGraph.get(stateId);
1130 for(TransitionEvent transition : reachableTransitions) {
1131 Execution execution = transition.getExecution();
1132 int currentChoice = transition.getChoiceCounter();
1133 updateBacktrackSet(execution, currentChoice);