import gov.nasa.jpf.search.Search;
import gov.nasa.jpf.jvm.bytecode.*;
import gov.nasa.jpf.vm.*;
-import gov.nasa.jpf.vm.bytecode.LocalVariableInstruction;
import gov.nasa.jpf.vm.bytecode.ReadInstruction;
-import gov.nasa.jpf.vm.bytecode.StoreInstruction;
import gov.nasa.jpf.vm.bytecode.WriteInstruction;
-import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
+import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
import java.io.PrintWriter;
import java.util.*;
+// TODO: Fix for Groovy's model-checking
+// TODO: This is a setter to change the values of the ChoiceGenerator to implement POR
/**
- * simple tool to log state changes
+ * Simple tool to log state changes.
+ *
+ * This DPOR implementation is augmented by the algorithm presented in this SPIN paper:
+ * http://spinroot.com/spin/symposia/ws08/spin2008_submission_33.pdf
+ *
+ * The algorithm is presented on page 11 of the paper. Basically, we create a graph G
+ * (i.e., visible operation dependency graph)
+ * that maps inter-related threads/sub-programs that trigger state changes.
+ * The key to this approach is that we evaluate graph G in every iteration/recursion to
+ * only update the backtrack sets of the threads/sub-programs that are reachable in graph G
+ * from the currently running thread/sub-program.
*/
public class StateReducer extends ListenerAdapter {
+ // Debug info fields
+ private boolean debugMode;
+ private boolean stateReductionMode;
private final PrintWriter out;
- volatile private String valueVarLock = "";
- volatile private String valueVarContact = "";
- volatile private String operation;
volatile private String detail;
volatile private int depth;
volatile private int id;
Transition transition;
- Object annotation;
- String label;
- String output;
- int stateId;
+ // State reduction fields
+ private Integer[] choices;
+ private IntChoiceFromSet currCG;
+ private int choiceCounter;
+ private Integer choiceUpperBound;
+ private Integer maxUpperBound;
+ private boolean isInitialized;
+ private boolean isResetAfterAnalysis;
+ private boolean isBooleanCGFlipped;
+ private HashMap<IntChoiceFromSet, Integer> cgMap;
+ // Record the mapping between event number and field accesses (Read and Write)
+ private HashMap<Integer, ReadWriteSet> readWriteFieldsMap;
+ // The following is the backtrack map (set) that stores all the backtrack information
+ // e.g., event number 1 can have two backtrack sequences: {3,1,2,4,...} and {2,1,3,4,...}
+ private HashMap<Integer, LinkedList<Integer[]>> backtrackMap;
+ // Stores explored backtrack lists in the form of HashSet of Strings
+ private HashSet<String> backtrackSet;
+ private HashMap<Integer, HashSet<Integer>> conflictPairMap;
+ // Map choicelist with start index
+ // private HashMap<Integer[],Integer> choiceListStartIndexMap;
+
+ // Map that represents graph G
+ // (i.e., visible operation dependency graph (VOD Graph)
+ private HashMap<Integer, HashSet<Integer>> vodGraphMap;
+ // Set that represents hash table H
+ // (i.e., hash table that records encountered states)
+ // VOD graph is updated when the state has not yet been seen
+ // Current state
+ private int stateId;
+ // Previous state
+ private int prevStateId;
+ // Previous choice number
+ private int prevChoiceValue;
+ // Counter for a visited state
+ private HashMap<Integer, Integer> visitedStateCounter;
+ // HashSet that stores references to unused CGs
+ private HashSet<IntChoiceFromSet> unusedCG;
+
+ public StateReducer(Config config, JPF jpf) {
+ debugMode = config.getBoolean("debug_state_transition", false);
+ stateReductionMode = config.getBoolean("activate_state_reduction", true);
+ if (debugMode) {
+ out = new PrintWriter(System.out, true);
+ } else {
+ out = null;
+ }
+ detail = null;
+ depth = 0;
+ id = 0;
+ transition = null;
+ isBooleanCGFlipped = false;
+ vodGraphMap = new HashMap<>();
+ stateId = -1;
+ prevStateId = -1;
+ prevChoiceValue = -1;
+ cgMap = new HashMap<>();
+ readWriteFieldsMap = new HashMap<>();
+ backtrackMap = new HashMap<>();
+ backtrackSet = new HashSet<>();
+ conflictPairMap = new HashMap<>();
+ unusedCG = new HashSet<>();
+ visitedStateCounter = new HashMap<>();
+ initializeStateReduction();
+ }
- public StateReducer (Config conf, JPF jpf) {
- out = new PrintWriter(System.out, true);
+ private void initializeStateReduction() {
+ if (stateReductionMode) {
+ choices = null;
+ currCG = null;
+ choiceCounter = 0;
+ choiceUpperBound = 0;
+ maxUpperBound = 0;
+ isInitialized = false;
+ isResetAfterAnalysis = false;
+ cgMap.clear();
+ readWriteFieldsMap.clear();
+ backtrackMap.clear();
+ backtrackSet.clear();
+ conflictPairMap.clear();
+ }
}
@Override
public void stateRestored(Search search) {
- id = search.getStateId();
- depth = search.getDepth();
- operation = "restored";
- transition = search.getTransition();
- if (transition != null) {
- annotation = transition.getAnnotation();
- label = transition.getLabel();
- output = transition.getOutput();
- stateId = transition.getStateId();
+ if (debugMode) {
+ id = search.getStateId();
+ depth = search.getDepth();
+ transition = search.getTransition();
+ detail = null;
+ out.println("\n==> DEBUG: The state is restored to state with id: " + id + " -- Transition: " + transition +
+ " and depth: " + depth + "\n");
}
- detail = null;
-
- out.println("\nThe state is restored to state with id: "+id+" Transition: "+transition+", with depth: "+depth+"##LockValue: "+valueVarLock+", ##ContactValue: "+valueVarContact +"\n");
}
//--- the ones we are interested in
@Override
public void searchStarted(Search search) {
- out.println("----------------------------------- search started");
+ if (debugMode) {
+ out.println("\n==> DEBUG: ----------------------------------- search started" + "\n");
+ }
}
- // Holds values that have appeared during CG advances
- private HashSet<Integer> cgChoiceSet = new HashSet<>();
- private Integer choiceUpperBound = 0;
- private boolean isInitialized = false;
-
@Override
- public void choiceGeneratorSet (VM vm, ChoiceGenerator<?> newCG) {
-
- // Initialize with necessary information from the CG
- if (newCG instanceof IntIntervalGenerator) {
- IntIntervalGenerator iigCG = (IntIntervalGenerator) newCG;
- // Check if CG has been initialized, otherwise initialize it
- if (!isInitialized) {
- Integer[] choices = iigCG.getChoices();
- // Get the upper bound from the last element of the choices
- choiceUpperBound = choices[choices.length - 1];
- isInitialized = true;
+ public void choiceGeneratorRegistered(VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
+ if (stateReductionMode) {
+ // Initialize with necessary information from the CG
+ if (nextCG instanceof IntChoiceFromSet) {
+ IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
+ // Check if CG has been initialized, otherwise initialize it
+ Integer[] cgChoices = icsCG.getAllChoices();
+ if (!isInitialized) {
+ // Get the upper bound from the last element of the choices
+ choiceUpperBound = cgChoices[cgChoices.length - 1];
+ isInitialized = true;
+ }
+ // Record the subsequent Integer CGs only until we hit the upper bound
+ if (!isResetAfterAnalysis) {
+ if (choiceCounter <= choiceUpperBound && !cgMap.containsValue(choiceCounter)) {
+ // Update the choices of the first CG and add '-1'
+ if (choices == null) {
+ // Initialize backtrack set that stores all the explored backtrack lists
+ maxUpperBound = cgChoices.length;
+ // All the choices are always the same so we only need to update it once
+ choices = new Integer[cgChoices.length + 1];
+ System.arraycopy(cgChoices, 0, choices, 0, cgChoices.length);
+ choices[choices.length - 1] = -1;
+ String firstChoiceListString = buildStringFromChoiceList(choices);
+ backtrackSet.add(firstChoiceListString);
+ }
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // Advance the current Integer CG
+ // This way we explore all the event numbers in the first pass
+ icsCG.advance(choices[choiceCounter]);
+ cgMap.put(icsCG, choices[choiceCounter]);
+ } else {
+ // We repeat the same trace if a state match is not found yet
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // Use a modulo since choiceCounter is going to keep increasing
+ int choiceIndex = choiceCounter % (choices.length - 1);
+ icsCG.advance(choices[choiceIndex]);
+ unusedCG.add(icsCG);
+ }
+ choiceCounter++;
+ } else {
+ // Set new CGs to done so that the search algorithm explores the existing CGs
+ icsCG.setDone();
+ }
+ }
+ }
+ }
+
+ private void resetAllCGs() {
+ // Extract the event numbers that have backtrack lists
+ Set<Integer> eventSet = backtrackMap.keySet();
+ // Return if there is no conflict at all (highly unlikely)
+ if (eventSet.isEmpty()) {
+ // Set every CG to done!
+ for (IntChoiceFromSet cg : cgMap.keySet()) {
+ cg.setDone();
+ }
+ return;
+ }
+ // Reset every CG with the first backtrack lists
+ for (IntChoiceFromSet cg : cgMap.keySet()) {
+ int event = cgMap.get(cg);
+ LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
+ if (choiceLists != null && choiceLists.peekFirst() != null) {
+ Integer[] choiceList = choiceLists.removeFirst();
+ // Deploy the new choice list for this CG
+ cg.setNewValues(choiceList);
+ cg.reset();
} else {
- newCG.setDone();
+ cg.setDone();
}
}
+ // Set done every CG in the unused CG set
+ for (IntChoiceFromSet cg : unusedCG) {
+ cg.setDone();
+ }
+ unusedCG.clear();
+ }
+
+ private void incrementVisitedStateCounter(int stId) {
+ // Increment counter for this state ID
+ if (visitedStateCounter.containsKey(stId)) {
+ int stateCount = visitedStateCounter.get(stId);
+ visitedStateCounter.put(stId, stateCount + 1);
+ } else {
+ // If we have seen it then the frequency is 2
+ visitedStateCounter.put(stId, 2);
+ }
+ }
+
+ private boolean isVisitedMultipleTimes(int stId) {
+ // Return true if the state has been visited more than once
+ if (visitedStateCounter.containsKey(stId) &&
+ visitedStateCounter.get(stId) > 1) {
+ return true;
+ }
+ return false;
}
@Override
- public void choiceGeneratorAdvanced (VM vm, ChoiceGenerator<?> currentCG) {
- // Check every choice generated and make sure that all the available choices
- // are chosen first before repeating the same choice of value twice!
- if (currentCG instanceof IntIntervalGenerator) {
- IntIntervalGenerator iigCG = (IntIntervalGenerator) currentCG;
- Integer nextChoice = iigCG.getNextChoice();
- if (!cgChoiceSet.contains(nextChoice)) {
- cgChoiceSet.add(nextChoice);
+ public void choiceGeneratorAdvanced(VM vm, ChoiceGenerator<?> currentCG) {
+
+ if (stateReductionMode) {
+ // Check the boolean CG and if it is flipped, we are resetting the analysis
+ if (currentCG instanceof BooleanChoiceGenerator) {
+ if (!isBooleanCGFlipped) {
+ isBooleanCGFlipped = true;
+ } else {
+ initializeStateReduction();
+ }
}
- // Allow reinitialization after an upper bound is hit
- // This means all available choices have been explored once during this iteration
- if (cgChoiceSet.contains(choiceUpperBound)) {
- isInitialized = false;
- cgChoiceSet.clear();
+ // Check every choice generated and make sure that all the available choices
+ // are chosen first before repeating the same choice of value twice!
+ if (currentCG instanceof IntChoiceFromSet) {
+ IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
+ // Update the current pointer to the current set of choices
+ if (choices == null || choices != icsCG.getAllChoices()) {
+ currCG = icsCG;
+ choices = icsCG.getAllChoices();
+ // Reset a few things for the sub-graph
+ conflictPairMap.clear();
+ readWriteFieldsMap.clear();
+ choiceCounter = 0;
+ }
+ if (!vm.isNewState()) {
+ incrementVisitedStateCounter(stateId);
+ }
+ // Check if we have seen this state and it's not looping back to itself
+ if (prevStateId != -1 && stateId != prevStateId && isVisitedMultipleTimes(stateId)) {
+ // Traverse the sub-graphs
+ if (isResetAfterAnalysis) {
+ // Advance choice counter for sub-graphs
+ choiceCounter++;
+ // Do this for every CG after finishing each backtrack list
+ // We try to update the CG with a backtrack list if the state has been visited multiple times
+ if ((icsCG.getNextChoice() == -1 || choiceCounter > 1) && cgMap.containsKey(icsCG)) {
+ int event = cgMap.get(icsCG);
+ LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
+ if (choiceLists != null && choiceLists.peekFirst() != null) {
+ Integer[] choiceList = choiceLists.removeFirst();
+ // Deploy the new choice list for this CG
+ icsCG.setNewValues(choiceList);
+ icsCG.reset();
+ } else {
+ // Set done if this was the last backtrack list
+ icsCG.setDone();
+ }
+ }
+ } else {
+ // Update and reset the CG if needed (do this for the first time after the analysis)
+ // Start backtracking if this is a visited state and it is not a repeating state
+ resetAllCGs();
+ isResetAfterAnalysis = true;
+ }
+ }
}
}
}
+ public void updateVODGraph(int prevChoice, int currChoice) {
+
+ HashSet<Integer> choiceSet;
+ if (vodGraphMap.containsKey(prevChoice)) {
+ // If the key already exists, just retrieve it
+ choiceSet = vodGraphMap.get(prevChoice);
+ } else {
+ // Create a new entry
+ choiceSet = new HashSet<>();
+ vodGraphMap.put(prevChoice, choiceSet);
+ }
+ choiceSet.add(currChoice);
+ }
+
+ private void updateStateId(Search search) {
+ // Saving the previous state
+ prevStateId = stateId;
+ // Line 19 in the paper page 11 (see the heading note above)
+ stateId = search.getStateId();
+ }
+
@Override
public void stateAdvanced(Search search) {
- String theEnd = null;
- id = search.getStateId();
- depth = search.getDepth();
- operation = "forward";
- transition = search.getTransition();
- if (transition != null) {
- annotation = transition.getAnnotation();
- label = transition.getLabel();
- output = transition.getOutput();
- stateId = transition.getStateId();
- }
- if (search.isNewState()) {
- detail = "new";
+ if (debugMode) {
+ id = search.getStateId();
+ depth = search.getDepth();
+ transition = search.getTransition();
+ if (search.isNewState()) {
+ detail = "new";
+ } else {
+ detail = "visited";
+ }
+
+ if (search.isEndState()) {
+ out.println("\n==> DEBUG: This is the last state!\n");
+ detail += " end";
+ }
+ out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
+ " which is " + detail + " Transition: " + transition + "\n");
+ }
+ if (stateReductionMode) {
+ // Update vodGraph
+ int currChoice = choiceCounter - 1;
+ // Adjust currChoice with modulo
+ currChoice = currChoice >= 0 ? currChoice % (choices.length -1) : currChoice;
+ if (currChoice < 0 || choices[currChoice] == -1 ||
+ prevChoiceValue == choices[currChoice]) {
+// || currChoice > choices.length - 1 || choices[currChoice] == -1 ||
+// prevChoiceValue == choices[currChoice]) {
+// // When current choice is 0, previous choice could be -1
+// updateVODGraph(prevChoiceValue, choices[currChoice]);
+// // Current choice becomes previous choice in the next iteration
+// prevChoiceValue = choices[currChoice];
+ // Update the state ID variables
+ updateStateId(search);
+ // Handle all corner cases (e.g., out of bound values)
+ return;
+ }
+ // When current choice is 0, previous choice could be -1
+ updateVODGraph(prevChoiceValue, choices[currChoice]);
+ // Current choice becomes previous choice in the next iteration
+ prevChoiceValue = choices[currChoice];
+ // Update the state ID variables
+ updateStateId(search);
+ }
+ }
+
+ @Override
+ public void stateBacktracked(Search search) {
+ if (debugMode) {
+ id = search.getStateId();
+ depth = search.getDepth();
+ transition = search.getTransition();
+ detail = null;
+
+ // Update the state variables
+ // Saving the previous state
+ prevStateId = stateId;
+ // Line 19 in the paper page 11 (see the heading note above)
+ stateId = search.getStateId();
+
+ out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
+ " and depth: " + depth + "\n");
+ }
+ }
+
+ @Override
+ public void searchFinished(Search search) {
+ if (debugMode) {
+ out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
+ }
+ }
+
+ // This class compactly stores Read and Write field sets
+ // We store the field name and its object ID
+ // Sharing the same field means the same field name and object ID
+ private class ReadWriteSet {
+ private HashMap<String, Integer> readSet;
+ private HashMap<String, Integer> writeSet;
+
+ public ReadWriteSet() {
+ readSet = new HashMap<>();
+ writeSet = new HashMap<>();
+ }
+
+ public void addReadField(String field, int objectId) {
+ readSet.put(field, objectId);
+ }
+
+ public void addWriteField(String field, int objectId) {
+ writeSet.put(field, objectId);
+ }
+
+ public boolean readFieldExists(String field) {
+ return readSet.containsKey(field);
+ }
+
+ public boolean writeFieldExists(String field) {
+ return writeSet.containsKey(field);
+ }
+
+ public int readFieldObjectId(String field) {
+ return readSet.get(field);
+ }
+
+ public int writeFieldObjectId(String field) {
+ return writeSet.get(field);
+ }
+ }
+
+ private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
+ // Do the analysis to get Read and Write accesses to fields
+ ReadWriteSet rwSet;
+ // We already have an entry
+ if (readWriteFieldsMap.containsKey(choices[currentChoice])) {
+ rwSet = readWriteFieldsMap.get(choices[currentChoice]);
+ } else { // We need to create a new entry
+ rwSet = new ReadWriteSet();
+ readWriteFieldsMap.put(choices[currentChoice], rwSet);
+ }
+ int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().getClassInfo().getClassObjectRef();
+ // Record the field in the map
+ if (executedInsn instanceof WriteInstruction) {
+ // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
+ for (String str : EXCLUDED_FIELDS_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
+ if (fieldClass.startsWith(str)) {
+ return;
+ }
+ }
+ rwSet.addWriteField(fieldClass, objectId);
+ } else if (executedInsn instanceof ReadInstruction) {
+ rwSet.addReadField(fieldClass, objectId);
+ }
+ }
+
+ private boolean recordConflictPair(int currentEvent, int eventNumber) {
+ HashSet<Integer> conflictSet;
+ if (!conflictPairMap.containsKey(currentEvent)) {
+ conflictSet = new HashSet<>();
+ conflictPairMap.put(currentEvent, conflictSet);
} else {
- detail = "visited";
+ conflictSet = conflictPairMap.get(currentEvent);
}
+ // If this conflict has been recorded before, we return false because
+ // we don't want to service this backtrack point twice
+ if (conflictSet.contains(eventNumber)) {
+ return false;
+ }
+ // If it hasn't been recorded, then do otherwise
+ conflictSet.add(eventNumber);
+ return true;
+ }
+
+ private String buildStringFromChoiceList(Integer[] newChoiceList) {
- if (search.isEndState()) {
- out.println("This is the last state!");
- theEnd = "end";
+ // When we see a choice list shorter than the upper bound, e.g., [3,2] for choices 0,1,2, and 3,
+ // then we have to pad the beginning before we store it, because [3,2] actually means [0,1,3,2]
+ // First, calculate the difference between this choice list and the upper bound
+ // The actual list doesn't include '-1' at the end
+ int actualListLength = newChoiceList.length - 1;
+ int diff = maxUpperBound - actualListLength;
+ StringBuilder sb = new StringBuilder();
+ // Pad the beginning if necessary
+ for (int i = 0; i < diff; i++) {
+ sb.append(i);
}
+ // Then continue with the actual choice list
+ // We don't include the '-1' at the end
+ for (int i = 0; i < newChoiceList.length - 1; i++) {
+ sb.append(newChoiceList[i]);
+ }
+ return sb.toString();
+ }
- //out.println("stateId: "+stateId+", output: "+output+", label: "+label);
- out.println("\nThe state is forwarded to state with id: "+id+", with depth: "+depth+" which is "+detail+" Transition: "+transition+" state: "+"% "+theEnd+"##LockValue: "+valueVarLock+", ##ContactValue: "+valueVarContact +"\n");
+ private void checkAndAddBacktrackList(LinkedList<Integer[]> backtrackChoiceLists, Integer[] newChoiceList) {
- if (search.isEndState()) {
- detail += " end";
+ String newChoiceListString = buildStringFromChoiceList(newChoiceList);
+ // Add only if we haven't seen this combination before
+ if (!backtrackSet.contains(newChoiceListString)) {
+ backtrackSet.add(newChoiceListString);
+ backtrackChoiceLists.addLast(newChoiceList);
}
}
- @Override
- public void stateBacktracked(Search search) {
- id = search.getStateId();
- depth = search.getDepth();
- operation = "backtrack";
- transition = search.getTransition();
- if (transition != null) {
- annotation = transition.getAnnotation();
- label = transition.getLabel();
- output = transition.getOutput();
- stateId = transition.getStateId();
+ private void createBacktrackChoiceList(int currentChoice, int conflictEventNumber) {
+
+ LinkedList<Integer[]> backtrackChoiceLists;
+ // Create a new list of choices for backtrack based on the current choice and conflicting event number
+ // If we have a conflict between 1 and 3, then we create the list {3, 1, 2, 4, 5} for backtrack
+ // The backtrack point is the CG for event number 1 and the list length is one less than the original list
+ // (originally of length 6) since we don't start from event number 0
+ if (!isResetAfterAnalysis) {
+ // Check if we have a list for this choice number
+ // If not we create a new one for it
+ if (!backtrackMap.containsKey(conflictEventNumber)) {
+ backtrackChoiceLists = new LinkedList<>();
+ backtrackMap.put(conflictEventNumber, backtrackChoiceLists);
+ } else {
+ backtrackChoiceLists = backtrackMap.get(conflictEventNumber);
+ }
+ int maxListLength = choiceUpperBound + 1;
+ int listLength = maxListLength - conflictEventNumber;
+ Integer[] newChoiceList = new Integer[listLength + 1];
+ // Put the conflicting event numbers first and reverse the order
+ newChoiceList[0] = choices[currentChoice];
+ newChoiceList[1] = choices[conflictEventNumber];
+ // Put the rest of the event numbers into the array starting from the minimum to the upper bound
+ for (int i = conflictEventNumber + 1, j = 2; j < listLength; i++) {
+ if (choices[i] != choices[currentChoice]) {
+ newChoiceList[j] = choices[i];
+ j++;
+ }
+ }
+ // Set the last element to '-1' as the end of the sequence
+ newChoiceList[newChoiceList.length - 1] = -1;
+ checkAndAddBacktrackList(backtrackChoiceLists, newChoiceList);
+ // The start index for the recursion is always 1 (from the main branch)
+ } else { // This is a sub-graph
+ // There is a case/bug that after a re-initialization, currCG is not yet initialized
+ if (currCG != null && cgMap.containsKey(currCG)) {
+ int backtrackListIndex = cgMap.get(currCG);
+ backtrackChoiceLists = backtrackMap.get(backtrackListIndex);
+ int listLength = choices.length;
+ Integer[] newChoiceList = new Integer[listLength];
+ // Copy everything before the conflict number
+ for (int i = 0; i < conflictEventNumber; i++) {
+ newChoiceList[i] = choices[i];
+ }
+ // Put the conflicting events
+ newChoiceList[conflictEventNumber] = choices[currentChoice];
+ newChoiceList[conflictEventNumber + 1] = choices[conflictEventNumber];
+ // Copy the rest
+ for (int i = conflictEventNumber + 1, j = conflictEventNumber + 2; j < listLength - 1; i++) {
+ if (choices[i] != choices[currentChoice]) {
+ newChoiceList[j] = choices[i];
+ j++;
+ }
+ }
+ // Set the last element to '-1' as the end of the sequence
+ newChoiceList[newChoiceList.length - 1] = -1;
+ checkAndAddBacktrackList(backtrackChoiceLists, newChoiceList);
+ }
+ }
+ }
+
+ // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
+ private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST =
+ // Java and Groovy libraries
+ { "java", "org", "sun", "com", "gov", "groovy"};
+ private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST =
+ // Groovy library created fields
+ {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__",
+ // Infrastructure
+ "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList",
+ "eventList", "valueList", "settings", "printToConsole", "app1", "app2"};
+ private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
+ private final static String[] EXCLUDED_FIELDS_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
+
+ private boolean isFieldExcluded(String field) {
+ // Check against "starts-with" list
+ for(String str : EXCLUDED_FIELDS_STARTS_WITH_LIST) {
+ if (field.startsWith(str)) {
+ return true;
+ }
+ }
+ // Check against "ends-with" list
+ for(String str : EXCLUDED_FIELDS_ENDS_WITH_LIST) {
+ if (field.endsWith(str)) {
+ return true;
+ }
+ }
+ // Check against "contains" list
+ for(String str : EXCLUDED_FIELDS_CONTAINS_LIST) {
+ if (field.contains(str)) {
+ return true;
+ }
}
- detail = null;
- out.println("\nThe state is backtracked to state with id: "+id+" Transition: "+ transition+", with depth: "+depth+"##LockValue: "+valueVarLock+", ##ContactValue: "+valueVarContact +"\n");
+ return false;
+ }
+
+ // This method checks whether a choice is reachable in the VOD graph from a reference choice
+ // This is a BFS search
+ private boolean isReachableInVODGraph(int checkedChoice, int referenceChoice) {
+ // Record visited choices as we search in the graph
+ HashSet<Integer> visitedChoice = new HashSet<>();
+ visitedChoice.add(referenceChoice);
+ LinkedList<Integer> nodesToVisit = new LinkedList<>();
+ // If the state doesn't advance as the threads/sub-programs are executed (basically there is no new state),
+ // there is a chance that the graph doesn't have new nodes---thus this check will return a null.
+ if (vodGraphMap.containsKey(referenceChoice)) {
+ nodesToVisit.addAll(vodGraphMap.get(referenceChoice));
+ while(!nodesToVisit.isEmpty()) {
+ int currChoice = nodesToVisit.getFirst();
+ if (currChoice == checkedChoice) {
+ return true;
+ }
+ if (visitedChoice.contains(currChoice)) {
+ // If there is a loop then we don't find it
+ return false;
+ }
+ // Continue searching
+ visitedChoice.add(currChoice);
+ HashSet<Integer> currChoiceNextNodes = vodGraphMap.get(currChoice);
+ if (currChoiceNextNodes != null) {
+ // Add only if there is a mapping for next nodes
+ for (Integer nextNode : currChoiceNextNodes) {
+ nodesToVisit.addLast(nextNode);
+ }
+ }
+ }
+ }
+ return false;
}
@Override
- public void searchFinished(Search search) {
- out.println("----------------------------------- search finished");
+ public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
+ if (stateReductionMode) {
+ if (isInitialized) {
+ if (choiceCounter <= 0 || choiceCounter > choices.length - 1) {
+ // We do not compute the conflicts for the choice '-1'
+ return;
+ }
+ int currentChoice = choiceCounter - 1;
+ // Record accesses from executed instructions
+ if (executedInsn instanceof JVMFieldInstruction) {
+ // Analyze only after being initialized
+ String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
+ // We don't care about libraries
+ if (!isFieldExcluded(fieldClass)) {
+ analyzeReadWriteAccesses(executedInsn, fieldClass, currentChoice);
+ }
+ }
+ // Analyze conflicts from next instructions
+ if (nextInsn instanceof JVMFieldInstruction) {
+ // The constructor is only called once when the object is initialized
+ // It does not have shared access with other objects
+ MethodInfo mi = nextInsn.getMethodInfo();
+ if (!mi.getName().equals("<init>")) {
+ String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
+ // We don't care about libraries
+ if (!isFieldExcluded(fieldClass)) {
+ // Check for conflict (go backward from currentChoice and get the first conflict)
+ // If the current event has conflicts with multiple events, then these will be detected
+ // one by one as this recursively checks backward when backtrack set is revisited and executed.
+ for (int eventNumber = currentChoice - 1; eventNumber >= 0; eventNumber--) {
+ // Skip if this event number does not have any Read/Write set
+ if (!readWriteFieldsMap.containsKey(choices[eventNumber])) {
+ continue;
+ }
+ ReadWriteSet rwSet = readWriteFieldsMap.get(choices[eventNumber]);
+ int currObjId = ((JVMFieldInstruction) nextInsn).getFieldInfo().getClassInfo().getClassObjectRef();
+ // 1) Check for conflicts with Write fields for both Read and Write instructions
+ if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) &&
+ rwSet.writeFieldExists(fieldClass) && rwSet.writeFieldObjectId(fieldClass) == currObjId) ||
+ (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass) &&
+ rwSet.readFieldObjectId(fieldClass) == currObjId)) {
+ // We do not record and service the same backtrack pair/point twice!
+ // If it has been serviced before, we just skip this
+ if (recordConflictPair(currentChoice, eventNumber)) {
+ // Lines 4-8 of the algorithm in the paper page 11 (see the heading note above)
+ if (vm.isNewState() ||
+ (!vm.isNewState() && isReachableInVODGraph(choices[currentChoice], choices[currentChoice-1]))) {
+ createBacktrackChoiceList(currentChoice, eventNumber);
+ // Break if a conflict is found!
+ break;
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
}
-}
\ No newline at end of file
+}
projects / jpf-core.git / blobdiff