*/
package gov.nasa.jpf.listener;
-import com.sun.org.apache.xpath.internal.operations.Bool;
import gov.nasa.jpf.Config;
import gov.nasa.jpf.JPF;
import gov.nasa.jpf.ListenerAdapter;
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.IntChoiceFromSet;
-import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
-import java.awt.*;
import java.io.PrintWriter;
import java.util.*;
-import java.util.List;
// 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 {
private boolean debugMode;
private boolean stateReductionMode;
private final PrintWriter out;
- volatile private String detail;
- volatile private int depth;
- volatile private int id;
- Transition transition;
+ private String detail;
+ private int depth;
+ private int id;
+ private Transition transition;
// State reduction fields
+ private Integer[] choices;
+ private Integer[] refChoices;
+ 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;
+ private HashMap<IntChoiceFromSet, Integer> cgMap;
// Record the mapping between event number and field accesses (Read and Write)
- private HashMap<Integer,ReadWriteSet> readWriteFieldsMap;
+ 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;
- private HashMap<Integer,HashSet<Integer>> conflictPairMap;
+ 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 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 HashSet<Integer> justVisitedStates;
+ // Previous choice number
+ private int prevChoiceValue;
+ // HashSet that stores references to unused CGs
+ private HashSet<IntChoiceFromSet> unusedCG;
- public StateReducer (Config config, JPF jpf) {
+ //private HashMap<Integer, ConflictTracker.Node> stateGraph;
+ private HashMap<Integer, HashSet<Integer>> stateToEventMap;
+ // Map state to event
+ // Visited states in the previous and current executions/traces for terminating condition
+ private HashSet<Integer> prevVisitedStates;
+ private HashSet<Integer> currVisitedStates;
+
+ public StateReducer(Config config, JPF jpf) {
debugMode = config.getBoolean("debug_state_transition", false);
stateReductionMode = config.getBoolean("activate_state_reduction", true);
if (debugMode) {
id = 0;
transition = null;
isBooleanCGFlipped = false;
+ vodGraphMap = new HashMap<>();
+ justVisitedStates = new HashSet<>();
+ prevChoiceValue = -1;
+ cgMap = new HashMap<>();
+ readWriteFieldsMap = new HashMap<>();
+ backtrackMap = new HashMap<>();
+ backtrackSet = new HashSet<>();
+ conflictPairMap = new HashMap<>();
+ unusedCG = new HashSet<>();
+ stateToEventMap = new HashMap<>();
+ prevVisitedStates = new HashSet<>();
+ currVisitedStates = new HashSet<>();
initializeStateReduction();
}
private void initializeStateReduction() {
if (stateReductionMode) {
+ choices = null;
+ refChoices = null;
+ currCG = null;
choiceCounter = 0;
choiceUpperBound = 0;
+ maxUpperBound = 0;
isInitialized = false;
isResetAfterAnalysis = false;
- cgMap = new HashMap<>();
- readWriteFieldsMap = new HashMap<>();
- backtrackMap = new HashMap<>();
- conflictPairMap = new HashMap<>();
+ cgMap.clear();
+ resetReadWriteAnalysis();
+ backtrackMap.clear();
+ backtrackSet.clear();
}
}
}
}
+ private void resetReadWriteAnalysis() {
+ // Reset the following data structure when the choice counter reaches 0 again
+ conflictPairMap.clear();
+ readWriteFieldsMap.clear();
+ }
+
+ private IntChoiceFromSet setNewCG(IntChoiceFromSet icsCG) {
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // Use a modulo since choiceCounter is going to keep increasing
+ int choiceIndex = choiceCounter % choices.length;
+ icsCG.advance(choices[choiceIndex]);
+ if (choiceIndex == 0) {
+ resetReadWriteAnalysis();
+ }
+ return icsCG;
+ }
+
+ private Integer[] copyChoices(Integer[] choicesToCopy) {
+
+ Integer[] copyOfChoices = new Integer[choicesToCopy.length];
+ System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
+ return copyOfChoices;
+ }
+
+ private void continueExecutingThisTrace(IntChoiceFromSet icsCG) {
+ // We repeat the same trace if a state match is not found yet
+ IntChoiceFromSet setCG = setNewCG(icsCG);
+ unusedCG.add(setCG);
+ }
+
+ private void initializeChoiceGenerators(IntChoiceFromSet icsCG, Integer[] cgChoices) {
+ 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
+ // Get the choice array and final choice in the array
+ choices = cgChoices;
+ // Make a copy of choices as reference
+ refChoices = copyChoices(choices);
+ String firstChoiceListString = buildStringFromChoiceList(choices);
+ backtrackSet.add(firstChoiceListString);
+ }
+ IntChoiceFromSet setCG = setNewCG(icsCG);
+ cgMap.put(setCG, refChoices[choiceCounter]);
+ } else {
+ continueExecutingThisTrace(icsCG);
+ }
+ }
+
+ private void manageChoiceGeneratorsInSubsequentTraces(IntChoiceFromSet icsCG) {
+ // If this is the first iteration of the trace then set other CGs done
+ if (choiceCounter <= choiceUpperBound) {
+ icsCG.setDone();
+ } else {
+ // If this is the subsequent iterations of the trace then set up new CGs to continue the execution
+ continueExecutingThisTrace(icsCG);
+ }
+ }
+
@Override
- public void choiceGeneratorRegistered (VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
+ 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
- Object[] choices = icsCG.getAllChoices();
+ Integer[] cgChoices = icsCG.getAllChoices();
if (!isInitialized) {
// Get the upper bound from the last element of the choices
- choiceUpperBound = (Integer) choices[choices.length - 1];
+ choiceUpperBound = cgChoices[cgChoices.length - 1];
isInitialized = true;
}
// Record the subsequent Integer CGs only until we hit the upper bound
- if (choiceCounter < choiceUpperBound && !cgMap.containsValue(choiceCounter)) {
- // Update the choices of the first CG and add '-1'
- Integer[] newChoices = new Integer[choices.length + 1];
- System.arraycopy(choices, 0, newChoices, 0, choices.length);
- newChoices[newChoices.length - 1] = -1;
- icsCG.setNewValues(newChoices);
- icsCG.reset();
- // Advance the current Integer CG
- // This way we explore all the event numbers in the first pass
- icsCG.advance(choiceCounter);
- cgMap.put(icsCG, choiceCounter);
- choiceCounter++;
+ if (!isResetAfterAnalysis) {
+ initializeChoiceGenerators(icsCG, cgChoices);
} else {
- // Set done the subsequent CGs
- // We only need n CGs (n is event numbers)
- icsCG.setDone();
+ // Set new CGs to done so that the search algorithm explores the existing CGs
+ //icsCG.setDone();
+ manageChoiceGeneratorsInSubsequentTraces(icsCG);
}
+ choiceCounter++;
}
}
}
+ private void setDoneUnusedCG() {
+ // Set done every CG in the unused CG set
+ for (IntChoiceFromSet cg : unusedCG) {
+ cg.setDone();
+ }
+ unusedCG.clear();
+ }
+
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()) {
+ for (IntChoiceFromSet cg : cgMap.keySet()) {
int event = cgMap.get(cg);
LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
if (choiceLists != null && choiceLists.peekFirst() != null) {
// Deploy the new choice list for this CG
cg.setNewValues(choiceList);
cg.reset();
+ } else {
+ cg.setDone();
}
}
+ setDoneUnusedCG();
+ saveVisitedStates();
+ }
+
+ // Detect cycles in the current execution/trace
+ // We terminate the execution iff:
+ // (1) the state has been visited in the current execution
+ // (2) the state has one or more cycles that involve all the events
+ // With simple approach we only need to check for a re-visited state.
+ // Basically, we have to check that we have executed all events between two occurrences of such state.
+ private boolean containsCyclesWithAllEvents(int stId) {
+
+ HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
+ boolean containsCyclesWithAllEvts = false;
+ if (checkIfAllEventsInvolved(visitedEvents)) {
+ containsCyclesWithAllEvts = true;
+ }
+
+ return containsCyclesWithAllEvts;
+ }
+
+ private boolean checkIfAllEventsInvolved(HashSet<Integer> visitedEvents) {
+
+ // Check if this set contains all the event choices
+ // If not then this is not the terminating condition
+ for(int i=0; i<=choiceUpperBound; i++) {
+ if (!visitedEvents.contains(i)) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ private void saveVisitedStates() {
+ // CG is being reset
+ // Save all the visited states
+ prevVisitedStates.addAll(currVisitedStates);
+ currVisitedStates.clear();
+ }
+
+ private void updateChoicesForNewExecution(IntChoiceFromSet icsCG) {
+ if (choices == null || choices != icsCG.getAllChoices()) {
+ currCG = icsCG;
+ choices = icsCG.getAllChoices();
+ refChoices = copyChoices(choices);
+ // Reset a few things for the sub-graph
+ resetReadWriteAnalysis();
+ choiceCounter = 0;
+ }
+ }
+
+ private void exploreNextBacktrackSets(IntChoiceFromSet icsCG) {
+ // Traverse the sub-graphs
+ if (isResetAfterAnalysis) {
+ // 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)) {
+ //if ((!icsCG.hasMoreChoices() || choiceCounter > 1) && cgMap.containsKey(icsCG)) {
+ if (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();
+ }
+ setDoneUnusedCG();
+ saveVisitedStates();
+ }
+ } 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;
+ }
+ }
+
+ private void checkAndEnforceFairScheduling(IntChoiceFromSet icsCG) {
+ // Check the next choice and if the value is not the same as the expected then force the expected value
+ int choiceIndex = (choiceCounter - 1) % refChoices.length;
+ if (choices[choiceIndex] != icsCG.getNextChoiceIndex()) {
+ int expectedChoice = refChoices[choiceIndex];
+ int currCGIndex = icsCG.getNextChoiceIndex();
+ if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
+ icsCG.setChoice(currCGIndex, expectedChoice);
+ }
+ }
+ }
+
+ private boolean terminateCurrentExecution() {
+ // We need to check all the states that have just been visited
+ // Often a transition (choice/event) can result into forwarding/backtracking to a number of states
+ for(Integer stateId : justVisitedStates) {
+ if (prevVisitedStates.contains(stateId) || containsCyclesWithAllEvents(stateId)) {
+ return true;
+ }
+ }
+ return false;
}
@Override
- public void choiceGeneratorAdvanced (VM vm, ChoiceGenerator<?> currentCG) {
-
- if(stateReductionMode) {
+ 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) {
// are chosen first before repeating the same choice of value twice!
if (currentCG instanceof IntChoiceFromSet) {
IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
- // Update and reset the CG if needed (do this for the first time after the analysis)
- if (!isResetAfterAnalysis && icsCG.getNextChoice() == -1) {
- resetAllCGs();
- isResetAfterAnalysis = true;
- }
- // Do this for every CG after finishing each backtrack list
- if (isResetAfterAnalysis && icsCG.getNextChoice() == -1) {
- int event = cgMap.get(icsCG);
- LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
- if (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();
- }
+ // Update the current pointer to the current set of choices
+ updateChoicesForNewExecution(icsCG);
+ // Check if we have seen this state or this state contains cycles that involve all events
+ if (terminateCurrentExecution()) {
+ exploreNextBacktrackSets(icsCG);
}
+ justVisitedStates.clear();
+ // If we don't see a fair scheduling of events/choices then we have to enforce it
+ checkAndEnforceFairScheduling(icsCG);
+ // Update the VOD graph always with the latest
+ updateVODGraph(icsCG.getNextChoice());
}
}
}
+ private void updateVODGraph(int currChoiceValue) {
+ // Update the graph when we have the current choice value
+ HashSet<Integer> choiceSet;
+ if (vodGraphMap.containsKey(prevChoiceValue)) {
+ // If the key already exists, just retrieve it
+ choiceSet = vodGraphMap.get(prevChoiceValue);
+ } else {
+ // Create a new entry
+ choiceSet = new HashSet<>();
+ vodGraphMap.put(prevChoiceValue, choiceSet);
+ }
+ choiceSet.add(currChoiceValue);
+ prevChoiceValue = currChoiceValue;
+ }
+
+ private void mapStateToEvent(Search search, int stateId) {
+ // Insert state ID and event choice into the map
+ HashSet<Integer> eventSet;
+ if (stateToEventMap.containsKey(stateId)) {
+ eventSet = stateToEventMap.get(stateId);
+ } else {
+ eventSet = new HashSet<>();
+ stateToEventMap.put(stateId, eventSet);
+ }
+ eventSet.add(prevChoiceValue);
+ }
+
+ private void updateStateInfo(Search search) {
+ if (stateReductionMode) {
+ // Update the state variables
+ // Line 19 in the paper page 11 (see the heading note above)
+ int stateId = search.getStateId();
+ currVisitedStates.add(stateId);
+ mapStateToEvent(search, stateId);
+ justVisitedStates.add(stateId);
+ }
+ }
+
@Override
public void stateAdvanced(Search search) {
if (debugMode) {
out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
" which is " + detail + " Transition: " + transition + "\n");
}
+ updateStateInfo(search);
}
@Override
out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
" and depth: " + depth + "\n");
}
+ updateStateInfo(search);
}
@Override
}
// 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 HashSet<String> readSet;
- private HashSet<String> writeSet;
+ private HashMap<String, Integer> readSet;
+ private HashMap<String, Integer> writeSet;
public ReadWriteSet() {
- readSet = new HashSet<>();
- writeSet = new HashSet<>();
+ readSet = new HashMap<>();
+ writeSet = new HashMap<>();
}
- public void addReadField(String field) {
- readSet.add(field);
+ public void addReadField(String field, int objectId) {
+ readSet.put(field, objectId);
}
- public void addWriteField(String field) {
- writeSet.add(field);
+ public void addWriteField(String field, int objectId) {
+ writeSet.put(field, objectId);
}
public boolean readFieldExists(String field) {
- return readSet.contains(field);
+ return readSet.containsKey(field);
}
public boolean writeFieldExists(String field) {
- return writeSet.contains(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) {
+ 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(choiceCounter)) {
- rwSet = readWriteFieldsMap.get(choiceCounter);
+ if (readWriteFieldsMap.containsKey(refChoices[currentChoice])) {
+ rwSet = readWriteFieldsMap.get(refChoices[currentChoice]);
} else { // We need to create a new entry
rwSet = new ReadWriteSet();
- readWriteFieldsMap.put(choiceCounter, rwSet);
+ readWriteFieldsMap.put(refChoices[currentChoice], rwSet);
}
+ int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().getClassInfo().getClassObjectRef();
// Record the field in the map
if (executedInsn instanceof WriteInstruction) {
- rwSet.addWriteField(fieldClass);
- }
- if (executedInsn instanceof ReadInstruction) {
- rwSet.addReadField(fieldClass);
+ // 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);
}
}
return true;
}
+ private String buildStringFromChoiceList(Integer[] newChoiceList) {
+
+ // 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();
+ }
+
+ private void checkAndAddBacktrackList(LinkedList<Integer[]> backtrackChoiceLists, Integer[] newChoiceList) {
+
+ String newChoiceListString = buildStringFromChoiceList(newChoiceList);
+ // Add only if we haven't seen this combination before
+ if (!backtrackSet.contains(newChoiceListString)) {
+ backtrackSet.add(newChoiceListString);
+ backtrackChoiceLists.addLast(newChoiceList);
+ }
+ }
+
private void createBacktrackChoiceList(int currentChoice, int conflictEventNumber) {
- int minChoice = Math.min(currentChoice, conflictEventNumber);
- int maxChoice = Math.max(currentChoice, conflictEventNumber);
LinkedList<Integer[]> backtrackChoiceLists;
- // Check if we have a list for this choice number
- // If not we create a new one for it
- if (!backtrackMap.containsKey(minChoice)) {
- backtrackChoiceLists = new LinkedList<>();
- backtrackMap.put(minChoice, backtrackChoiceLists);
- } else {
- backtrackChoiceLists = backtrackMap.get(minChoice);
- }
- // TODO: The following might change depending on the POR implementation detail
// 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
- int maxListLength = choiceUpperBound + 1;
- int listLength = maxListLength - minChoice;
- Integer[] choiceList = new Integer[listLength+1];
- // Put the conflicting event numbers first and reverse the order
- choiceList[0] = maxChoice;
- choiceList[1] = minChoice;
- // Put the rest of the event numbers into the array starting from the minimum to the upper bound
- for(int i = minChoice + 1, j = 2; j < listLength; i++) {
- if (i != maxChoice) {
- choiceList[j] = i;
- j++;
+ 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];
+ // Put the conflicting event numbers first and reverse the order
+ newChoiceList[0] = refChoices[currentChoice];
+ newChoiceList[1] = refChoices[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 (refChoices[i] != refChoices[currentChoice]) {
+ newChoiceList[j] = refChoices[i];
+ j++;
+ }
+ }
+ 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 = refChoices.length;
+ Integer[] newChoiceList = new Integer[listLength];
+ // Copy everything before the conflict number
+ for (int i = 0; i < conflictEventNumber; i++) {
+ newChoiceList[i] = refChoices[i];
+ }
+ // Put the conflicting events
+ newChoiceList[conflictEventNumber] = refChoices[currentChoice];
+ newChoiceList[conflictEventNumber + 1] = refChoices[conflictEventNumber];
+ // Copy the rest
+ for (int i = conflictEventNumber + 1, j = conflictEventNumber + 2; j < listLength - 1; i++) {
+ if (refChoices[i] != refChoices[currentChoice]) {
+ newChoiceList[j] = refChoices[i];
+ j++;
+ }
+ }
+ 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;
+ }
+ }
+
+ 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) {
+ // Skip cycles
+ if (nextNode == currChoice) {
+ continue;
+ }
+ nodesToVisit.addLast(nextNode);
+ }
+ }
}
}
- // Set the last element to '-1' as the end of the sequence
- choiceList[choiceList.length - 1] = -1;
- backtrackChoiceLists.addLast(choiceList);
+ return false;
}
@Override
public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
if (stateReductionMode) {
- // Record accesses from executed instructions
- if (executedInsn instanceof JVMFieldInstruction) {
- String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
- // We don't care about libraries
- if (!fieldClass.startsWith("java") &&
- !fieldClass.startsWith("org") &&
- !fieldClass.startsWith("sun") &&
- !fieldClass.startsWith("com") &&
- !fieldClass.startsWith("gov") &&
- !fieldClass.startsWith("groovy") &&
- // and fields generated for the Groovy library
- !fieldClass.endsWith("stMC") &&
- !fieldClass.endsWith("callSiteArray") &&
- !fieldClass.endsWith("metaClass") &&
- !fieldClass.endsWith("staticClassInfo") &&
- !fieldClass.endsWith("__constructor__")) {
+ if (isInitialized) {
+ int currentChoice = (choiceCounter % refChoices.length) - 1;
+ if (currentChoice < 0) {
+ // We do not compute the conflicts for the choice '-1'
+ return;
+ }
+ // Record accesses from executed instructions
+ if (executedInsn instanceof JVMFieldInstruction) {
// Analyze only after being initialized
- if (isInitialized) {
- analyzeReadWriteAccesses(executedInsn, fieldClass);
+ 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) {
- String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
- // We don't care about libraries
- if (!fieldClass.startsWith("java") &&
- !fieldClass.startsWith("org") &&
- !fieldClass.startsWith("sun") &&
- !fieldClass.startsWith("com") &&
- !fieldClass.startsWith("gov") &&
- !fieldClass.startsWith("groovy") &&
- // and fields generated for the Groovy library
- !fieldClass.endsWith("stMC") &&
- !fieldClass.endsWith("callSiteArray") &&
- !fieldClass.endsWith("metaClass") &&
- !fieldClass.endsWith("staticClassInfo") &&
- !fieldClass.endsWith("__constructor__")) {
- // 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=choiceCounter-1; eventNumber>=0; eventNumber--) {
- // Skip if this event number does not have any Read/Write set
- if (!readWriteFieldsMap.containsKey(eventNumber)) {
- continue;
- }
- ReadWriteSet rwSet = readWriteFieldsMap.get(eventNumber);
- // 1) Check for conflicts with Write fields for both Read and Write instructions
- // 2) Check for conflicts with Read fields for Write instructions
- if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) &&
- rwSet.writeFieldExists(fieldClass)) ||
- (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass))) {
- // We do not record and service the same backtrack pair/point twice!
- // If it has been serviced before, we just skip this
- if (recordConflictPair(choiceCounter, eventNumber)) {
- createBacktrackChoiceList(choiceCounter, eventNumber);
- // Break if a conflict is found!
- break;
+ // 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(refChoices[eventNumber])) {
+ continue;
+ }
+ ReadWriteSet rwSet = readWriteFieldsMap.get(refChoices[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() || isReachableInVODGraph(refChoices[currentChoice], refChoices[currentChoice-1])) {
+ createBacktrackChoiceList(currentChoice, eventNumber);
+ // Break if a conflict is found!
+ break;
+ }
+ }
+ }
}
}
}
}
}
}
-}
\ No newline at end of file
+}
projects / jpf-core.git / blobdiff