*/
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 int id;
private Transition transition;
+ // DPOR-related fields
+ private Integer[] choices;
+ private Integer[] refChoices;
+ private int choiceCounter;
+ private int maxEventChoice;
+ // Record CGs for backtracking points
+ private List<IntChoiceFromSet> cgList;
+ // Data structure to track the events seen by each state to track cycles (containing all events) for termination
+ private HashMap<Integer, HashSet<Integer>> stateToEventMap;
+ private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
+ private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
+ private HashSet<Integer> currVisitedStates; // States being visited in the current execution
+ // Data structure to analyze field Read/Write accesses
+ private HashMap<Integer, ReadWriteSet> readWriteFieldsMap;
+ private HashMap<Integer, HashSet<Integer>> conflictPairMap;
+
+ // Boolean states
+ private boolean isBooleanCGFlipped;
+
public DPORStateReducer(Config config, JPF jpf) {
verboseMode = config.getBoolean("printout_state_transition", false);
stateReductionMode = config.getBoolean("activate_state_reduction", true);
} else {
out = null;
}
+ // DPOR-related
+ choices = null;
+ refChoices = null;
+ choiceCounter = 0;
+ maxEventChoice = 0;
+ cgList = new ArrayList<>();
+ stateToEventMap = new HashMap<>();
+ justVisitedStates = new HashSet<>();
+ prevVisitedStates = new HashSet<>();
+ currVisitedStates = new HashSet<>();
+ readWriteFieldsMap = new HashMap<>();
+ conflictPairMap = new HashMap<>();
+ // Booleans
+ isBooleanCGFlipped = false;
}
@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);
+ }
}
@Override
out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
}
}
+
+ @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;
+ // 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];
+ }
+ // Use a modulo since choiceCounter is going to keep increasing
+ int choiceIndex = choiceCounter % choices.length;
+ icsCG.advance(choices[choiceIndex]);
+ // Index the ChoiceGenerator to set backtracking points
+ cgList.add(icsCG);
+ }
+ }
+ }
+
+ @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 {
+// initializeStateReduction();
+// }
+// }
+ // Check every choice generated and ensure fair scheduling!
+ if (currentCG instanceof IntChoiceFromSet) {
+ IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
+ // If we don't see a fair scheduling of events/choices then we have to enforce it
+ checkAndEnforceFairScheduling(icsCG);
+ // Map state to event
+ mapStateToEvent(icsCG.getNextChoice());
+ // Check if we have seen this state or this state contains cycles that involve all events
+ if (terminateCurrentExecution()) {
+ exploreNextBacktrackSets(icsCG);
+ }
+ justVisitedStates.clear();
+ choiceCounter++;
+ }
+ }
+ }
+
+ @Override
+ public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
+ if (stateReductionMode) {
+ // 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 (getCurrentChoice(vm) < 0) { // If choice is -1 then skip
+ if (currentChoice < 0) { // If choice is -1 then skip
+ return;
+ }
+ // 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);
+ }
+ } else if (executedInsn instanceof INVOKEINTERFACE) {
+ // Handle the read/write accesses that occur through iterators
+ analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
+ }
+ // Analyze conflicts from next instructions
+ if (nextInsn instanceof JVMFieldInstruction) {
+ // Skip the constructor because it is called once and does not have shared access with other objects
+ if (!nextInsn.getMethodInfo().getName().equals("<init>")) {
+ String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
+ if (!isFieldExcluded(fieldClass)) {
+ // Check for conflict (go backward from current choice and get the first conflict)
+ for (int evtCntr = currentChoice - 1; evtCntr >= 0; evtCntr--) {
+ if (!readWriteFieldsMap.containsKey(evtCntr)) { // Skip if this event does not have any Read/Write set
+ continue;
+ }
+ ReadWriteSet rwSet = readWriteFieldsMap.get(evtCntr);
+ int currObjId = ((JVMFieldInstruction) nextInsn).getFieldInfo().getClassInfo().getClassObjectRef();
+ // 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)) {
+ // Check and record a backtrack set for just once!
+ if (successfullyRecordConflictPair(currentChoice, evtCntr)) {
+ // 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);
+// }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+
+
+ // == HELPERS
+ // -- INNER CLASS
+ // 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);
+ }
+ }
+
+ // -- 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 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 % 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);
+ }
+ }
+ }
+
+ private Integer[] copyChoices(Integer[] choicesToCopy) {
+
+ Integer[] copyOfChoices = new Integer[choicesToCopy.length];
+ System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
+ return copyOfChoices;
+ }
+
+ // --- Functions related to cycle detection
+
+ // 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) {
+
+ // 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 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) || containsCyclesWithAllEvents(stateId)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private void updateStateInfo(Search search) {
+ // Update the state variables
+ // Line 19 in the paper page 11 (see the heading note above)
+ int stateId = search.getStateId();
+ currVisitedStates.add(stateId);
+ // Insert state ID into the map if it is new
+ if (!stateToEventMap.containsKey(stateId)) {
+ HashSet<Integer> eventSet = new HashSet<>();
+ stateToEventMap.put(stateId, eventSet);
+ }
+ justVisitedStates.add(stateId);
+ }
+
+ // --- Functions related to Read/Write access analysis on shared fields
+
+ // Analyze Read/Write accesses that are directly invoked on fields
+ private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
+ // Do the analysis to get Read and Write accesses to fields
+ ReadWriteSet rwSet = getReadWriteSet(currentChoice);
+ 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_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
+ if (fieldClass.startsWith(str)) {
+ 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]);
+ // We exclude library classes (they start with java, org, etc.) and some more
+ String objClassName = eiAccessObj.getClassInfo().getName();
+ if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName) ||
+ excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName)) {
+ 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 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 exploreNextBacktrackSets(IntChoiceFromSet icsCG) {
+ // Save all the visited states when starting a new execution of trace
+ prevVisitedStates.addAll(currVisitedStates);
+ currVisitedStates.clear();
+
+ }
+
+ private int getCurrentChoice(VM vm) {
+ ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
+ // This is the main event CG
+ if (currentCG instanceof IntChoiceFromSet) {
+ return ((IntChoiceFromSet) currentCG).getNextChoiceIndex();
+ } else {
+ // This is the interval CG used in device handlers
+ ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
+ return ((IntChoiceFromSet) parentCG).getNextChoiceIndex();
+ }
+ }
+
+ private ReadWriteSet getReadWriteSet(int currentChoice) {
+ // Do the analysis to get Read and Write accesses to fields
+ ReadWriteSet rwSet;
+ // We already have an entry
+ if (readWriteFieldsMap.containsKey(currentChoice)) {
+ rwSet = readWriteFieldsMap.get(currentChoice);
+ } else { // We need to create a new entry
+ rwSet = new ReadWriteSet();
+ readWriteFieldsMap.put(currentChoice, rwSet);
+ }
+ return rwSet;
+ }
+
+ private boolean isFieldExcluded(String field) {
+ // 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)) {
+ return true;
+ }
+
+ return false;
+ }
+
+ private boolean successfullyRecordConflictPair(int currentEvent, int eventNumber) {
+ HashSet<Integer> conflictSet;
+ if (!conflictPairMap.containsKey(currentEvent)) {
+ conflictSet = new HashSet<>();
+ conflictPairMap.put(currentEvent, conflictSet);
+ } else {
+ 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;
+ }
}
projects / jpf-core.git / commitdiff