import gov.nasa.jpf.Config;
import gov.nasa.jpf.JPF;
import gov.nasa.jpf.ListenerAdapter;
+import gov.nasa.jpf.jvm.bytecode.INVOKEINTERFACE;
+import gov.nasa.jpf.jvm.bytecode.JVMFieldInstruction;
import gov.nasa.jpf.search.Search;
-import gov.nasa.jpf.jvm.bytecode.*;
import gov.nasa.jpf.vm.*;
import gov.nasa.jpf.vm.bytecode.ReadInstruction;
import gov.nasa.jpf.vm.bytecode.WriteInstruction;
import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
+import java.io.FileWriter;
+import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
+import java.util.logging.Logger;
-// 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.
- *
- * 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.
+ * This a DPOR implementation for event-driven applications with loops that create cycles of state matching
+ * In this new DPOR algorithm/implementation, each run is terminated iff:
+ * - we find a state that matches a state in a previous run, or
+ * - we have a matched state in the current run that consists of cycles that contain all choices/events.
*/
public class DPORStateReducer extends ListenerAdapter {
- // Debug info fields
+ // Information printout fields for verbose mode
private boolean verboseMode;
private boolean stateReductionMode;
private final PrintWriter out;
+ private PrintWriter fileWriter;
private String detail;
private int depth;
private int id;
private Transition transition;
+ // DPOR-related fields
+ // Basic information
+ private Integer[] choices;
+ private Integer[] refChoices; // Second reference to a copy of choices (choices may be modified for fair scheduling)
+ private int choiceCounter;
+ private int maxEventChoice;
+ // Data structure to track the events seen by each state to track cycles (containing all events) for termination
+ private HashSet<Integer> currVisitedStates; // States being visited in the current execution
+ private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
+ private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
+ private HashSet<ClassInfo> nonRelevantClasses;// Class info objects of non-relevant classes
+ private HashSet<FieldInfo> nonRelevantFields; // Field info objects of non-relevant fields
+ private HashSet<FieldInfo> relevantFields; // Field info objects of relevant fields
+ private HashMap<Integer, HashSet<Integer>> stateToEventMap;
+ // Data structure to analyze field Read/Write accesses and conflicts
+ private HashMap<Integer, LinkedList<BacktrackExecution>> backtrackMap; // Track created backtracking points
+ private PriorityQueue<Integer> backtrackStateQ; // Heap that returns the latest state
+ private Execution currentExecution; // Holds the information about the current execution
+ private HashMap<Integer, HashSet<Integer>> doneBacktrackMap; // Record state ID and trace already constructed
+ private HashMap<Integer, RestorableVMState> restorableStateMap; // Maps state IDs to the restorable state object
+ private RGraph rGraph; // R-Graph for past executions
+
+ // Boolean states
+ private boolean isBooleanCGFlipped;
+ private boolean isEndOfExecution;
+
+ // Statistics
+ private int numOfTransitions;
+
public DPORStateReducer(Config config, JPF jpf) {
verboseMode = config.getBoolean("printout_state_transition", false);
stateReductionMode = config.getBoolean("activate_state_reduction", true);
} else {
out = null;
}
+ String outputFile = config.getString("file_output");
+ if (!outputFile.isEmpty()) {
+ try {
+ fileWriter = new PrintWriter(new FileWriter(outputFile, true), true);
+ } catch (IOException e) {
+ }
+ }
+ isBooleanCGFlipped = false;
+ numOfTransitions = 0;
+ nonRelevantClasses = new HashSet<>();
+ nonRelevantFields = new HashSet<>();
+ relevantFields = new HashSet<>();
+ restorableStateMap = new HashMap<>();
+ initializeStatesVariables();
}
@Override
out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
" which is " + detail + " Transition: " + transition + "\n");
}
+ if (stateReductionMode) {
+ updateStateInfo(search);
+ }
}
@Override
out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
" and depth: " + depth + "\n");
}
+ if (stateReductionMode) {
+ updateStateInfo(search);
+ }
}
+ static Logger log = JPF.getLogger("report");
+
@Override
public void searchFinished(Search search) {
if (verboseMode) {
+ out.println("\n==> DEBUG: ----------------------------------- search finished");
+ out.println("\n==> DEBUG: State reduction mode : " + stateReductionMode);
+ out.println("\n==> DEBUG: Number of transitions : " + numOfTransitions);
out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
+
+ fileWriter.println("==> DEBUG: State reduction mode : " + stateReductionMode);
+ fileWriter.println("==> DEBUG: Number of transitions : " + numOfTransitions);
+ fileWriter.println();
+ fileWriter.close();
+ }
+ }
+
+ @Override
+ 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;
+ // Tell JPF that we are performing DPOR
+ icsCG.setDpor();
+ if (!isEndOfExecution) {
+ // Check if CG has been initialized, otherwise initialize it
+ Integer[] cgChoices = icsCG.getAllChoices();
+ // Record the events (from choices)
+ if (choices == null) {
+ choices = cgChoices;
+ // Make a copy of choices as reference
+ refChoices = copyChoices(choices);
+ // Record the max event choice (the last element of the choice array)
+ maxEventChoice = choices[choices.length - 1];
+ }
+ icsCG.setNewValues(choices);
+ icsCG.reset();
+ // Use a modulo since choiceCounter is going to keep increasing
+ int choiceIndex = choiceCounter % choices.length;
+ icsCG.advance(choices[choiceIndex]);
+ } else {
+ // Set done all CGs while transitioning to a new execution
+ icsCG.setDone();
+ }
+ }
+ }
+ }
+
+ @Override
+ 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 {
+ // Allocate new objects for data structure when the boolean is flipped from "false" to "true"
+ initializeStatesVariables();
+ }
+ }
+ // Check every choice generated and ensure fair scheduling!
+ if (currentCG instanceof IntChoiceFromSet) {
+ IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
+ // If this is a new CG then we need to update data structures
+ resetStatesForNewExecution(icsCG, vm);
+ // If we don't see a fair scheduling of events/choices then we have to enforce it
+ ensureFairSchedulingAndSetupTransition(icsCG, vm);
+ // Update backtrack set of an executed event (transition): one transition before this one
+ updateBacktrackSet(currentExecution, choiceCounter - 1);
+ // Explore the next backtrack point:
+ // 1) if we have seen this state or this state contains cycles that involve all events, and
+ // 2) after the current CG is advanced at least once
+ if (terminateCurrentExecution() && choiceCounter > 0) {
+ exploreNextBacktrackPoints(vm, icsCG);
+ } else {
+ numOfTransitions++;
+ }
+ // Map state to event
+ mapStateToEvent(icsCG.getNextChoice());
+ justVisitedStates.clear();
+ choiceCounter++;
+ }
+ } else {
+ numOfTransitions++;
+ }
+ }
+
+ @Override
+ public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
+ if (stateReductionMode) {
+ if (!isEndOfExecution) {
+ // Has to be initialized and a integer CG
+ ChoiceGenerator<?> cg = vm.getChoiceGenerator();
+ if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
+ int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
+ if (currentChoice < 0) { // If choice is -1 then skip
+ return;
+ }
+ currentChoice = checkAndAdjustChoice(currentChoice, vm);
+ // Record accesses from executed instructions
+ if (executedInsn instanceof JVMFieldInstruction) {
+ // We don't care about libraries
+ if (!isFieldExcluded(executedInsn)) {
+ analyzeReadWriteAccesses(executedInsn, currentChoice);
+ }
+ } else if (executedInsn instanceof INVOKEINTERFACE) {
+ // Handle the read/write accesses that occur through iterators
+ analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
+ }
+ }
+ }
+ }
+ }
+
+
+ // == HELPERS
+
+ // -- INNER CLASSES
+
+ // This class compactly stores backtrack execution:
+ // 1) backtrack choice list, and
+ // 2) first backtrack point (linking with predecessor execution)
+ private class BacktrackExecution {
+ private Integer[] choiceList;
+ private TransitionEvent firstTransition;
+
+ public BacktrackExecution(Integer[] choList, TransitionEvent fTransition) {
+ choiceList = choList;
+ firstTransition = fTransition;
+ }
+
+ public Integer[] getChoiceList() {
+ return choiceList;
+ }
+
+ public TransitionEvent getFirstTransition() {
+ return firstTransition;
+ }
+ }
+
+ // This class stores a representation of an execution
+ // TODO: We can modify this class to implement some optimization (e.g., clock-vector)
+ // TODO: We basically need to keep track of:
+ // TODO: (1) last read/write access to each memory location
+ // TODO: (2) last state with two or more incoming events/transitions
+ private class Execution {
+ private HashMap<IntChoiceFromSet, Integer> cgToChoiceMap; // Map between CG to choice numbers for O(1) access
+ private ArrayList<TransitionEvent> executionTrace; // The BacktrackPoint objects of this execution
+ private boolean isNew; // Track if this is the first time it is accessed
+ private HashMap<Integer, ReadWriteSet> readWriteFieldsMap; // Record fields that are accessed
+
+ public Execution() {
+ cgToChoiceMap = new HashMap<>();
+ executionTrace = new ArrayList<>();
+ isNew = true;
+ readWriteFieldsMap = new HashMap<>();
+ }
+
+ public void addTransition(TransitionEvent newBacktrackPoint) {
+ executionTrace.add(newBacktrackPoint);
+ }
+
+ public void clearCGToChoiceMap() {
+ cgToChoiceMap = null;
+ }
+
+ public int getChoiceFromCG(IntChoiceFromSet icsCG) {
+ return cgToChoiceMap.get(icsCG);
+ }
+
+ public ArrayList<TransitionEvent> getExecutionTrace() {
+ return executionTrace;
+ }
+
+ public TransitionEvent getFirstTransition() {
+ return executionTrace.get(0);
+ }
+
+ public TransitionEvent getLastTransition() {
+ return executionTrace.get(executionTrace.size() - 1);
+ }
+
+ public HashMap<Integer, ReadWriteSet> getReadWriteFieldsMap() {
+ return readWriteFieldsMap;
+ }
+
+ public boolean isNew() {
+ if (isNew) {
+ // Right after this is accessed, it is no longer new
+ isNew = false;
+ return true;
+ }
+ return false;
+ }
+
+ public void mapCGToChoice(IntChoiceFromSet icsCG, int choice) {
+ cgToChoiceMap.put(icsCG, choice);
+ }
+ }
+
+ // This class compactly stores a predecessor
+ // 1) a predecessor execution
+ // 2) the predecessor choice in that predecessor execution
+ private class Predecessor {
+ private int choice; // Predecessor choice
+ private Execution execution; // Predecessor execution
+
+ public Predecessor(int predChoice, Execution predExec) {
+ choice = predChoice;
+ execution = predExec;
+ }
+
+ public int getChoice() {
+ return choice;
+ }
+
+ public Execution getExecution() {
+ return execution;
+ }
+ }
+
+ // This class represents a R-Graph (in the paper it is a state transition graph R)
+ // This implementation stores reachable transitions from and connects with past executions
+ private class RGraph {
+ private int hiStateId; // Maximum state Id
+ private HashMap<Integer, HashSet<TransitionEvent>> graph; // Reachable transitions from past executions
+
+ public RGraph() {
+ hiStateId = 0;
+ graph = new HashMap<>();
+ }
+
+ public void addReachableTransition(int stateId, TransitionEvent transition) {
+ HashSet<TransitionEvent> transitionSet;
+ if (graph.containsKey(stateId)) {
+ transitionSet = graph.get(stateId);
+ } else {
+ transitionSet = new HashSet<>();
+ graph.put(stateId, transitionSet);
+ }
+ // Insert into the set if it does not contain it yet
+ if (!transitionSet.contains(transition)) {
+ transitionSet.add(transition);
+ }
+ // Update highest state ID
+ if (hiStateId < stateId) {
+ hiStateId = stateId;
+ }
+ }
+
+ public HashSet<TransitionEvent> getReachableTransitionsAtState(int stateId) {
+ if (!graph.containsKey(stateId)) {
+ // This is a loop from a transition to itself, so just return the current transition
+ HashSet<TransitionEvent> transitionSet = new HashSet<>();
+ transitionSet.add(currentExecution.getLastTransition());
+ return transitionSet;
+ }
+ return graph.get(stateId);
+ }
+
+ public HashSet<TransitionEvent> getReachableTransitions(int stateId) {
+ HashSet<TransitionEvent> reachableTransitions = new HashSet<>();
+ // All transitions from states higher than the given state ID (until the highest state ID) are reachable
+ for(int stId = stateId; stId <= hiStateId; stId++) {
+ // We might encounter state IDs from the first round of Boolean CG
+ // The second round of Boolean CG should consider these new states
+ if (graph.containsKey(stId)) {
+ reachableTransitions.addAll(graph.get(stId));
+ }
+ }
+ return reachableTransitions;
+ }
+ }
+
+ // 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> readMap;
+ private HashMap<String, Integer> writeMap;
+
+ public ReadWriteSet() {
+ readMap = new HashMap<>();
+ writeMap = new HashMap<>();
+ }
+
+ public void addReadField(String field, int objectId) {
+ readMap.put(field, objectId);
+ }
+
+ public void addWriteField(String field, int objectId) {
+ writeMap.put(field, objectId);
+ }
+
+ public void removeReadField(String field) {
+ readMap.remove(field);
+ }
+
+ public void removeWriteField(String field) {
+ writeMap.remove(field);
+ }
+
+ public boolean isEmpty() {
+ return readMap.isEmpty() && writeMap.isEmpty();
+ }
+
+ public ReadWriteSet getCopy() {
+ ReadWriteSet copyRWSet = new ReadWriteSet();
+ // Copy the maps in the set into the new object copy
+ copyRWSet.setReadMap(new HashMap<>(this.getReadMap()));
+ copyRWSet.setWriteMap(new HashMap<>(this.getWriteMap()));
+ return copyRWSet;
+ }
+
+ public Set<String> getReadSet() {
+ return readMap.keySet();
+ }
+
+ public Set<String> getWriteSet() {
+ return writeMap.keySet();
+ }
+
+ public boolean readFieldExists(String field) {
+ return readMap.containsKey(field);
+ }
+
+ public boolean writeFieldExists(String field) {
+ return writeMap.containsKey(field);
+ }
+
+ public int readFieldObjectId(String field) {
+ return readMap.get(field);
+ }
+
+ public int writeFieldObjectId(String field) {
+ return writeMap.get(field);
+ }
+
+ private HashMap<String, Integer> getReadMap() {
+ return readMap;
+ }
+
+ private HashMap<String, Integer> getWriteMap() {
+ return writeMap;
+ }
+
+ private void setReadMap(HashMap<String, Integer> rMap) {
+ readMap = rMap;
+ }
+
+ private void setWriteMap(HashMap<String, Integer> wMap) {
+ writeMap = wMap;
+ }
+ }
+
+ // This class compactly stores transitions:
+ // 1) CG,
+ // 2) state ID,
+ // 3) choice,
+ // 4) predecessors (for backward DFS).
+ private class TransitionEvent {
+ private int choice; // Choice chosen at this transition
+ private int choiceCounter; // Choice counter at this transition
+ private Execution execution; // The execution where this transition belongs
+ private HashSet<Predecessor> predecessors; // Maps incoming events/transitions (execution and choice)
+ private HashMap<Execution, HashSet<Integer>> recordedPredecessors;
+ // Memorize event and choice number to not record them twice
+ private int stateId; // State at this transition
+ private IntChoiceFromSet transitionCG; // CG at this transition
+
+ public TransitionEvent() {
+ choice = 0;
+ choiceCounter = 0;
+ execution = null;
+ predecessors = new HashSet<>();
+ recordedPredecessors = new HashMap<>();
+ stateId = 0;
+ transitionCG = null;
+ }
+
+ public int getChoice() {
+ return choice;
+ }
+
+ public int getChoiceCounter() {
+ return choiceCounter;
+ }
+
+ public Execution getExecution() {
+ return execution;
+ }
+
+ public HashSet<Predecessor> getPredecessors() {
+ return predecessors;
+ }
+
+ public int getStateId() {
+ return stateId;
+ }
+
+ public IntChoiceFromSet getTransitionCG() { return transitionCG; }
+
+ private boolean isRecordedPredecessor(Execution execution, int choice) {
+ // See if we have recorded this predecessor earlier
+ HashSet<Integer> recordedChoices;
+ if (recordedPredecessors.containsKey(execution)) {
+ recordedChoices = recordedPredecessors.get(execution);
+ if (recordedChoices.contains(choice)) {
+ return true;
+ }
+ } else {
+ recordedChoices = new HashSet<>();
+ recordedPredecessors.put(execution, recordedChoices);
+ }
+ // Record the choice if we haven't seen it
+ recordedChoices.add(choice);
+
+ return false;
+ }
+
+ public void recordPredecessor(Execution execution, int choice) {
+ if (!isRecordedPredecessor(execution, choice)) {
+ predecessors.add(new Predecessor(choice, execution));
+ }
+ }
+
+ public void setChoice(int cho) {
+ choice = cho;
+ }
+
+ public void setChoiceCounter(int choCounter) {
+ choiceCounter = choCounter;
+ }
+
+ public void setExecution(Execution exec) {
+ execution = exec;
+ }
+
+ public void setPredecessors(HashSet<Predecessor> preds) {
+ predecessors = new HashSet<>(preds);
+ }
+
+ public void setStateId(int stId) {
+ stateId = stId;
+ }
+
+ public void setTransitionCG(IntChoiceFromSet cg) {
+ transitionCG = cg;
+ }
+ }
+
+ // -- CONSTANTS
+ private final static String DO_CALL_METHOD = "doCall";
+ // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
+ private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
+ 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_STARTS_WITH_LIST =
+ // Java and Groovy libraries
+ { "java", "org", "sun", "com", "gov", "groovy"};
+ private final static String[] EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
+ private final static String GET_PROPERTY_METHOD =
+ "invokeinterface org.codehaus.groovy.runtime.callsite.CallSite.callGetProperty";
+ private final static String GROOVY_CALLSITE_LIB = "org.codehaus.groovy.runtime.callsite";
+ private final static String JAVA_INTEGER = "int";
+ private final static String JAVA_STRING_LIB = "java.lang.String";
+
+ // -- FUNCTIONS
+ private Integer[] copyChoices(Integer[] choicesToCopy) {
+
+ Integer[] copyOfChoices = new Integer[choicesToCopy.length];
+ System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
+ return copyOfChoices;
+ }
+
+ private void ensureFairSchedulingAndSetupTransition(IntChoiceFromSet icsCG, VM vm) {
+ // Check the next choice and if the value is not the same as the expected then force the expected value
+ int choiceIndex = choiceCounter % refChoices.length;
+ int nextChoice = icsCG.getNextChoice();
+ if (refChoices[choiceIndex] != nextChoice) {
+ int expectedChoice = refChoices[choiceIndex];
+ int currCGIndex = icsCG.getNextChoiceIndex();
+ if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
+ icsCG.setChoice(currCGIndex, expectedChoice);
+ }
+ }
+ // Get state ID and associate it with this transition
+ int stateId = vm.getStateId();
+ TransitionEvent transition = setupTransition(icsCG, stateId, choiceIndex);
+ // Add new transition to the current execution and map it in R-Graph
+ for (Integer stId : justVisitedStates) { // Map this transition to all the previously passed states
+ rGraph.addReachableTransition(stId, transition);
+ }
+ currentExecution.mapCGToChoice(icsCG, choiceCounter);
+ // Store restorable state object for this state (always store the latest)
+ if (!restorableStateMap.containsKey(stateId)) {
+ RestorableVMState restorableState = vm.getRestorableState();
+ restorableStateMap.put(stateId, restorableState);
+ }
+ }
+
+ private TransitionEvent setupTransition(IntChoiceFromSet icsCG, int stateId, int choiceIndex) {
+ // Get a new transition
+ TransitionEvent transition;
+ if (currentExecution.isNew()) {
+ // We need to handle the first transition differently because this has a predecessor execution
+ transition = currentExecution.getFirstTransition();
+ } else {
+ transition = new TransitionEvent();
+ currentExecution.addTransition(transition);
+ transition.recordPredecessor(currentExecution, choiceCounter - 1);
+ }
+ transition.setExecution(currentExecution);
+ transition.setTransitionCG(icsCG);
+ transition.setStateId(stateId);
+ transition.setChoice(refChoices[choiceIndex]);
+ transition.setChoiceCounter(choiceCounter);
+
+ return transition;
+ }
+
+ // --- Functions related to cycle detection and reachability graph
+
+ // 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 completeFullCycle(int stId) {
+ // False if the state ID hasn't been recorded
+ if (!stateToEventMap.containsKey(stId)) {
+ return false;
+ }
+ HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
+ // Check if this set contains all the event choices
+ // If not then this is not the terminating condition
+ for(int i=0; i<=maxEventChoice; i++) {
+ if (!visitedEvents.contains(i)) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ private void initializeStatesVariables() {
+ // DPOR-related
+ choices = null;
+ refChoices = null;
+ choiceCounter = 0;
+ maxEventChoice = 0;
+ // Cycle tracking
+ currVisitedStates = new HashSet<>();
+ justVisitedStates = new HashSet<>();
+ prevVisitedStates = new HashSet<>();
+ stateToEventMap = new HashMap<>();
+ // Backtracking
+ backtrackMap = new HashMap<>();
+ backtrackStateQ = new PriorityQueue<>(Collections.reverseOrder());
+ currentExecution = new Execution();
+ currentExecution.addTransition(new TransitionEvent()); // Always start with 1 backtrack point
+ doneBacktrackMap = new HashMap<>();
+ rGraph = new RGraph();
+ // Booleans
+ isEndOfExecution = false;
+ }
+
+ private void mapStateToEvent(int nextChoiceValue) {
+ // Update all states with this event/choice
+ // This means that all past states now see this transition
+ Set<Integer> stateSet = stateToEventMap.keySet();
+ for(Integer stateId : stateSet) {
+ HashSet<Integer> eventSet = stateToEventMap.get(stateId);
+ eventSet.add(nextChoiceValue);
+ }
+ }
+
+ 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) || completeFullCycle(stateId)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private void updateStateInfo(Search search) {
+ // Update the state variables
+ int stateId = search.getStateId();
+ // Insert state ID into the map if it is new
+ if (!stateToEventMap.containsKey(stateId)) {
+ HashSet<Integer> eventSet = new HashSet<>();
+ stateToEventMap.put(stateId, eventSet);
+ }
+ analyzeReachabilityAndCreateBacktrackPoints(search.getVM(), stateId);
+ justVisitedStates.add(stateId);
+ if (!prevVisitedStates.contains(stateId)) {
+ // It is a currently visited states if the state has not been seen in previous executions
+ currVisitedStates.add(stateId);
+ }
+ }
+
+ // --- Functions related to Read/Write access analysis on shared fields
+
+ private void addNewBacktrackPoint(int stateId, Integer[] newChoiceList, TransitionEvent conflictTransition) {
+ // Insert backtrack point to the right state ID
+ LinkedList<BacktrackExecution> backtrackExecList;
+ if (backtrackMap.containsKey(stateId)) {
+ backtrackExecList = backtrackMap.get(stateId);
+ } else {
+ backtrackExecList = new LinkedList<>();
+ backtrackMap.put(stateId, backtrackExecList);
+ }
+ // Add the new backtrack execution object
+ TransitionEvent backtrackTransition = new TransitionEvent();
+ backtrackTransition.setPredecessors(conflictTransition.getPredecessors());
+ backtrackExecList.addFirst(new BacktrackExecution(newChoiceList, backtrackTransition));
+ // Add to priority queue
+ if (!backtrackStateQ.contains(stateId)) {
+ backtrackStateQ.add(stateId);
+ }
+ }
+
+ // Analyze Read/Write accesses that are directly invoked on fields
+ private void analyzeReadWriteAccesses(Instruction executedInsn, int currentChoice) {
+ // Get the field info
+ FieldInfo fieldInfo = ((JVMFieldInstruction) executedInsn).getFieldInfo();
+ // Analyze only after being initialized
+ String fieldClass = fieldInfo.getFullName();
+ // Do the analysis to get Read and Write accesses to fields
+ ReadWriteSet rwSet = getReadWriteSet(currentChoice);
+ int objectId = fieldInfo.getClassInfo().getClassObjectRef();
+ // Record the field in the map
+ if (executedInsn instanceof WriteInstruction) {
+ // We first check the non-relevant fields set
+ if (!nonRelevantFields.contains(fieldInfo)) {
+ // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
+ for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
+ if (fieldClass.startsWith(str)) {
+ nonRelevantFields.add(fieldInfo);
+ return;
+ }
+ }
+ } else {
+ // If we have this field in the non-relevant fields set then we return right away
+ return;
+ }
+ rwSet.addWriteField(fieldClass, objectId);
+ } else if (executedInsn instanceof ReadInstruction) {
+ rwSet.addReadField(fieldClass, objectId);
+ }
+ }
+
+ // Analyze Read accesses that are indirect (performed through iterators)
+ // These accesses are marked by certain bytecode instructions, e.g., INVOKEINTERFACE
+ private void analyzeReadWriteAccesses(Instruction instruction, ThreadInfo ti, int currentChoice) {
+ // Get method name
+ INVOKEINTERFACE insn = (INVOKEINTERFACE) instruction;
+ if (insn.toString().startsWith(GET_PROPERTY_METHOD) &&
+ insn.getMethodInfo().getName().equals(DO_CALL_METHOD)) {
+ // Extract info from the stack frame
+ StackFrame frame = ti.getTopFrame();
+ int[] frameSlots = frame.getSlots();
+ // Get the Groovy callsite library at index 0
+ ElementInfo eiCallsite = VM.getVM().getHeap().get(frameSlots[0]);
+ if (!eiCallsite.getClassInfo().getName().startsWith(GROOVY_CALLSITE_LIB)) {
+ return;
+ }
+ // Get the iterated object whose property is accessed
+ ElementInfo eiAccessObj = VM.getVM().getHeap().get(frameSlots[1]);
+ if (eiAccessObj == null) {
+ return;
+ }
+ // We exclude library classes (they start with java, org, etc.) and some more
+ ClassInfo classInfo = eiAccessObj.getClassInfo();
+ String objClassName = classInfo.getName();
+ // Check if this class info is part of the non-relevant classes set already
+ if (!nonRelevantClasses.contains(classInfo)) {
+ if (excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName) ||
+ excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName)) {
+ nonRelevantClasses.add(classInfo);
+ return;
+ }
+ } else {
+ // If it is part of the non-relevant classes set then return immediately
+ return;
+ }
+ // Extract fields from this object and put them into the read write
+ int numOfFields = eiAccessObj.getNumberOfFields();
+ for(int i=0; i<numOfFields; i++) {
+ FieldInfo fieldInfo = eiAccessObj.getFieldInfo(i);
+ if (fieldInfo.getType().equals(JAVA_STRING_LIB) || fieldInfo.getType().equals(JAVA_INTEGER)) {
+ String fieldClass = fieldInfo.getFullName();
+ ReadWriteSet rwSet = getReadWriteSet(currentChoice);
+ int objectId = fieldInfo.getClassInfo().getClassObjectRef();
+ // Record the field in the map
+ rwSet.addReadField(fieldClass, objectId);
+ }
+ }
+ }
+ }
+
+ private int checkAndAdjustChoice(int currentChoice, VM vm) {
+ // If current choice is not the same, then this is caused by the firing of IntIntervalGenerator
+ // for certain method calls in the infrastructure, e.g., eventSince()
+ ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
+ // This is the main event CG
+ if (currentCG instanceof IntIntervalGenerator) {
+ // This is the interval CG used in device handlers
+ ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
+ // Iterate until we find the IntChoiceFromSet CG
+ while (!(parentCG instanceof IntChoiceFromSet)) {
+ parentCG = ((IntIntervalGenerator) parentCG).getPreviousChoiceGenerator();
+ }
+ // Find the choice related to the IntIntervalGenerator CG from the map
+ currentChoice = currentExecution.getChoiceFromCG((IntChoiceFromSet) parentCG);
+ }
+ return currentChoice;
+ }
+
+ private void createBacktrackingPoint(Execution execution, int currentChoice,
+ Execution conflictExecution, int conflictChoice) {
+ // Create a new list of choices for backtrack based on the current choice and conflicting event number
+ // E.g. if we have a conflict between 1 and 3, then we create the list {3, 1, 0, 2}
+ // for the original set {0, 1, 2, 3}
+
+ // execution/currentChoice represent the event/transaction that will be put into the backtracking set of
+ // conflictExecution/conflictChoice
+ Integer[] newChoiceList = new Integer[refChoices.length];
+ ArrayList<TransitionEvent> currentTrace = execution.getExecutionTrace();
+ ArrayList<TransitionEvent> conflictTrace = conflictExecution.getExecutionTrace();
+ int currChoice = currentTrace.get(currentChoice).getChoice();
+ int stateId = conflictTrace.get(conflictChoice).getStateId();
+ // Check if this trace has been done from this state
+ if (isTraceAlreadyConstructed(currChoice, stateId)) {
+ return;
+ }
+ // Put the conflicting event numbers first and reverse the order
+ newChoiceList[0] = currChoice;
+ // Put the rest of the event numbers into the array starting from the minimum to the upper bound
+ for (int i = 0, j = 1; i < refChoices.length; i++) {
+ if (refChoices[i] != newChoiceList[0]) {
+ newChoiceList[j] = refChoices[i];
+ j++;
+ }
+ }
+ // Predecessor of the new backtrack point is the same as the conflict point's
+ addNewBacktrackPoint(stateId, newChoiceList, conflictTrace.get(conflictChoice));
+ }
+
+ private boolean excludeThisForItContains(String[] excludedStrings, String className) {
+ for (String excludedField : excludedStrings) {
+ if (className.contains(excludedField)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private boolean excludeThisForItEndsWith(String[] excludedStrings, String className) {
+ for (String excludedField : excludedStrings) {
+ if (className.endsWith(excludedField)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private boolean excludeThisForItStartsWith(String[] excludedStrings, String className) {
+ for (String excludedField : excludedStrings) {
+ if (className.startsWith(excludedField)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private void exploreNextBacktrackPoints(VM vm, IntChoiceFromSet icsCG) {
+ // Check if we are reaching the end of our execution: no more backtracking points to explore
+ // cgMap, backtrackMap, backtrackStateQ are updated simultaneously (checking backtrackStateQ is enough)
+ if (!backtrackStateQ.isEmpty()) {
+ // Set done all the other backtrack points
+ for (TransitionEvent backtrackTransition : currentExecution.getExecutionTrace()) {
+ backtrackTransition.getTransitionCG().setDone();
+ }
+ // Reset the next backtrack point with the latest state
+ int hiStateId = backtrackStateQ.peek();
+ // Restore the state first if necessary
+ if (vm.getStateId() != hiStateId) {
+ RestorableVMState restorableState = restorableStateMap.get(hiStateId);
+ vm.restoreState(restorableState);
+ }
+ // Set the backtrack CG
+ IntChoiceFromSet backtrackCG = (IntChoiceFromSet) vm.getChoiceGenerator();
+ setBacktrackCG(hiStateId, backtrackCG);
+ } else {
+ // Set done this last CG (we save a few rounds)
+ icsCG.setDone();
+ }
+ // Save all the visited states when starting a new execution of trace
+ prevVisitedStates.addAll(currVisitedStates);
+ // This marks a transitional period to the new CG
+ isEndOfExecution = true;
+ }
+
+ private boolean isConflictFound(Execution execution, int reachableChoice, Execution conflictExecution, int conflictChoice,
+ ReadWriteSet currRWSet) {
+ // conflictExecution/conflictChoice represent a predecessor event/transaction that can potentially have a conflict
+ ArrayList<TransitionEvent> executionTrace = execution.getExecutionTrace();
+ ArrayList<TransitionEvent> conflictTrace = conflictExecution.getExecutionTrace();
+ HashMap<Integer, ReadWriteSet> confRWFieldsMap = conflictExecution.getReadWriteFieldsMap();
+ // Skip if this event does not have any Read/Write set or the two events are basically the same event (number)
+ if (!confRWFieldsMap.containsKey(conflictChoice) ||
+ executionTrace.get(reachableChoice).getChoice() == conflictTrace.get(conflictChoice).getChoice()) {
+ return false;
+ }
+ // R/W set of choice/event that may have a potential conflict
+ ReadWriteSet confRWSet = confRWFieldsMap.get(conflictChoice);
+ // Check for conflicts with Read and Write fields for Write instructions
+ Set<String> currWriteSet = currRWSet.getWriteSet();
+ for(String writeField : currWriteSet) {
+ int currObjId = currRWSet.writeFieldObjectId(writeField);
+ if ((confRWSet.readFieldExists(writeField) && confRWSet.readFieldObjectId(writeField) == currObjId) ||
+ (confRWSet.writeFieldExists(writeField) && confRWSet.writeFieldObjectId(writeField) == currObjId)) {
+ // Remove this from the write set as we are tracking per memory location
+ currRWSet.removeWriteField(writeField);
+ return true;
+ }
+ }
+ // Check for conflicts with Write fields for Read instructions
+ Set<String> currReadSet = currRWSet.getReadSet();
+ for(String readField : currReadSet) {
+ int currObjId = currRWSet.readFieldObjectId(readField);
+ if (confRWSet.writeFieldExists(readField) && confRWSet.writeFieldObjectId(readField) == currObjId) {
+ // Remove this from the read set as we are tracking per memory location
+ currRWSet.removeReadField(readField);
+ return true;
+ }
+ }
+ // Return false if no conflict is found
+ return false;
+ }
+
+ private ReadWriteSet getReadWriteSet(int currentChoice) {
+ // Do the analysis to get Read and Write accesses to fields
+ ReadWriteSet rwSet;
+ // We already have an entry
+ HashMap<Integer, ReadWriteSet> currReadWriteFieldsMap = currentExecution.getReadWriteFieldsMap();
+ if (currReadWriteFieldsMap.containsKey(currentChoice)) {
+ rwSet = currReadWriteFieldsMap.get(currentChoice);
+ } else { // We need to create a new entry
+ rwSet = new ReadWriteSet();
+ currReadWriteFieldsMap.put(currentChoice, rwSet);
+ }
+ return rwSet;
+ }
+
+ private boolean isFieldExcluded(Instruction executedInsn) {
+ // Get the field info
+ FieldInfo fieldInfo = ((JVMFieldInstruction) executedInsn).getFieldInfo();
+ // Check if the non-relevant fields set already has it
+ if (nonRelevantFields.contains(fieldInfo)) {
+ return true;
+ }
+ // Check if the relevant fields set already has it
+ if (relevantFields.contains(fieldInfo)) {
+ return false;
+ }
+ // Analyze only after being initialized
+ String field = fieldInfo.getFullName();
+ // Check against "starts-with", "ends-with", and "contains" list
+ if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, field) ||
+ excludeThisForItEndsWith(EXCLUDED_FIELDS_ENDS_WITH_LIST, field) ||
+ excludeThisForItContains(EXCLUDED_FIELDS_CONTAINS_LIST, field)) {
+ nonRelevantFields.add(fieldInfo);
+ return true;
+ }
+ relevantFields.add(fieldInfo);
+ return false;
+ }
+
+ // Check if this trace is already constructed
+ private boolean isTraceAlreadyConstructed(int firstChoice, int stateId) {
+ // Concatenate state ID and only the first event in the string, e.g., "1:1 for the trace 10234 at state 1"
+ // Check if the trace has been constructed as a backtrack point for this state
+ // TODO: THIS IS AN OPTIMIZATION!
+ HashSet<Integer> choiceSet;
+ if (doneBacktrackMap.containsKey(stateId)) {
+ choiceSet = doneBacktrackMap.get(stateId);
+ if (choiceSet.contains(firstChoice)) {
+ return true;
+ }
+ } else {
+ choiceSet = new HashSet<>();
+ doneBacktrackMap.put(stateId, choiceSet);
+ }
+ choiceSet.add(firstChoice);
+
+ return false;
+ }
+
+ // Reset data structure for each new execution
+ private void resetStatesForNewExecution(IntChoiceFromSet icsCG, VM vm) {
+ if (choices == null || choices != icsCG.getAllChoices()) {
+ // Reset state variables
+ choiceCounter = 0;
+ choices = icsCG.getAllChoices();
+ refChoices = copyChoices(choices);
+ // Clear data structures
+ currVisitedStates = new HashSet<>();
+ stateToEventMap = new HashMap<>();
+ isEndOfExecution = false;
+ }
+ }
+
+ // Set a backtrack point for a particular state
+ private void setBacktrackCG(int stateId, IntChoiceFromSet backtrackCG) {
+ // Set a backtrack CG based on a state ID
+ LinkedList<BacktrackExecution> backtrackExecutions = backtrackMap.get(stateId);
+ BacktrackExecution backtrackExecution = backtrackExecutions.removeLast();
+ backtrackCG.setNewValues(backtrackExecution.getChoiceList()); // Get the last from the queue
+ backtrackCG.setStateId(stateId);
+ backtrackCG.reset();
+ // Update current execution with this new execution
+ Execution newExecution = new Execution();
+ TransitionEvent firstTransition = backtrackExecution.getFirstTransition();
+ newExecution.addTransition(firstTransition);
+ // Try to free some memory since this map is only used for the current execution
+ currentExecution.clearCGToChoiceMap();
+ currentExecution = newExecution;
+ // Remove from the queue if we don't have more backtrack points for that state
+ if (backtrackExecutions.isEmpty()) {
+ backtrackMap.remove(stateId);
+ backtrackStateQ.remove(stateId);
+ }
+ }
+
+ // Update backtrack sets
+ // 1) recursively, and
+ // 2) track accesses per memory location (per shared variable/field)
+ private void updateBacktrackSet(Execution execution, int currentChoice) {
+ // Copy ReadWriteSet object
+ HashMap<Integer, ReadWriteSet> currRWFieldsMap = execution.getReadWriteFieldsMap();
+ ReadWriteSet currRWSet = currRWFieldsMap.get(currentChoice);
+ if (currRWSet == null) {
+ return;
+ }
+ currRWSet = currRWSet.getCopy();
+ // Memorize visited TransitionEvent object while performing backward DFS to avoid getting caught up in a cycle
+ HashSet<TransitionEvent> visited = new HashSet<>();
+ // Update backtrack set recursively
+ updateBacktrackSetRecursive(execution, currentChoice, execution, currentChoice, currRWSet, visited);
+ }
+
+ private void updateBacktrackSetRecursive(Execution execution, int currentChoice,
+ Execution conflictExecution, int conflictChoice,
+ ReadWriteSet currRWSet, HashSet<TransitionEvent> visited) {
+ // Halt when we have found the first read/write conflicts for all memory locations
+ if (currRWSet.isEmpty()) {
+ return;
+ }
+ TransitionEvent currTrans = execution.getExecutionTrace().get(currentChoice);
+ // Halt when we have visited this transition (in a cycle)
+ if (visited.contains(currTrans)) {
+ return;
+ }
+ visited.add(currTrans);
+ // Explore all predecessors
+ for (Predecessor predecessor : currTrans.getPredecessors()) {
+ // Get the predecessor (previous conflict choice)
+ int predecessorChoice = predecessor.getChoice();
+ Execution predecessorExecution = predecessor.getExecution();
+ // Push up one happens-before transition
+ int newConflictChoice = conflictChoice;
+ Execution newConflictExecution = conflictExecution;
+ // Check if a conflict is found
+ if (isConflictFound(conflictExecution, conflictChoice, predecessorExecution, predecessorChoice, currRWSet)) {
+ createBacktrackingPoint(conflictExecution, conflictChoice, predecessorExecution, predecessorChoice);
+ newConflictChoice = predecessorChoice;
+ newConflictExecution = predecessorExecution;
+ }
+ // Continue performing DFS if conflict is not found
+ updateBacktrackSetRecursive(predecessorExecution, predecessorChoice, newConflictExecution, newConflictChoice,
+ currRWSet, visited);
+ }
+ }
+
+ // --- Functions related to the reachability analysis when there is a state match
+
+ private void analyzeReachabilityAndCreateBacktrackPoints(VM vm, int stateId) {
+ // Perform this analysis only when:
+ // 1) this is not during a switch to a new execution,
+ // 2) at least 2 choices/events have been explored (choiceCounter > 1),
+ // 3) state > 0 (state 0 is for boolean CG)
+ if (!isEndOfExecution && choiceCounter > 1 && stateId > 0) {
+ if (currVisitedStates.contains(stateId) || prevVisitedStates.contains(stateId)) {
+ // Update reachable transitions in the graph with a predecessor
+ HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitionsAtState(stateId);
+ for(TransitionEvent transition : reachableTransitions) {
+ transition.recordPredecessor(currentExecution, choiceCounter - 1);
+ }
+ updateBacktrackSetsFromGraph(stateId);
+ }
+ }
+ }
+
+ // Update the backtrack sets from previous executions
+ private void updateBacktrackSetsFromGraph(int stateId) {
+ // Collect all the reachable transitions from R-Graph
+ HashSet<TransitionEvent> reachableTransitions = rGraph.getReachableTransitions(stateId);
+ for(TransitionEvent transition : reachableTransitions) {
+ Execution execution = transition.getExecution();
+ int currentChoice = transition.getChoiceCounter();
+ updateBacktrackSet(execution, currentChoice);
}
}
}
projects / jpf-core.git / blobdiff