2 * Copyright (C) 2014, United States Government, as represented by the
3 * Administrator of the National Aeronautics and Space Administration.
6 * The Java Pathfinder core (jpf-core) platform is licensed under the
7 * Apache License, Version 2.0 (the "License"); you may not use this file except
8 * in compliance with the License. You may obtain a copy of the License at
10 * http://www.apache.org/licenses/LICENSE-2.0.
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
18 package gov.nasa.jpf.listener;
20 import gov.nasa.jpf.Config;
21 import gov.nasa.jpf.JPF;
22 import gov.nasa.jpf.ListenerAdapter;
23 import gov.nasa.jpf.search.Search;
24 import gov.nasa.jpf.jvm.bytecode.*;
25 import gov.nasa.jpf.vm.*;
26 import gov.nasa.jpf.vm.bytecode.ReadInstruction;
27 import gov.nasa.jpf.vm.bytecode.WriteInstruction;
28 import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
29 import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
31 import java.io.PrintWriter;
34 // TODO: Fix for Groovy's model-checking
35 // TODO: This is a setter to change the values of the ChoiceGenerator to implement POR
37 * Simple tool to log state changes.
39 * This DPOR implementation is augmented by the algorithm presented in this SPIN paper:
40 * http://spinroot.com/spin/symposia/ws08/spin2008_submission_33.pdf
42 * The algorithm is presented on page 11 of the paper. Basically, we create a graph G
43 * (i.e., visible operation dependency graph)
44 * that maps inter-related threads/sub-programs that trigger state changes.
45 * The key to this approach is that we evaluate graph G in every iteration/recursion to
46 * only update the backtrack sets of the threads/sub-programs that are reachable in graph G
47 * from the currently running thread/sub-program.
49 public class DPORStateReducer extends ListenerAdapter {
51 // Information printout fields for verbose mode
52 private boolean verboseMode;
53 private boolean stateReductionMode;
54 private final PrintWriter out;
55 private String detail;
58 private Transition transition;
60 // DPOR-related fields
61 private Integer[] choices;
62 private Integer[] refChoices;
63 private int choiceCounter;
64 private int maxEventChoice;
65 // Record CGs for backtracking points
66 private List<IntChoiceFromSet> cgList;
67 // Data structure to track the events seen by each state to track cycles (containing all events) for termination
68 private HashMap<Integer, HashSet<Integer>> stateToEventMap;
69 private HashSet<Integer> justVisitedStates; // States just visited in the previous choice/event
70 private HashSet<Integer> prevVisitedStates; // States visited in the previous execution
71 private HashSet<Integer> currVisitedStates; // States being visited in the current execution
72 // Data structure to analyze field Read/Write accesses
73 private HashMap<Integer, ReadWriteSet> readWriteFieldsMap;
74 private HashMap<Integer, HashSet<Integer>> conflictPairMap;
77 private boolean isBooleanCGFlipped;
79 public DPORStateReducer(Config config, JPF jpf) {
80 verboseMode = config.getBoolean("printout_state_transition", false);
81 stateReductionMode = config.getBoolean("activate_state_reduction", true);
83 out = new PrintWriter(System.out, true);
92 cgList = new ArrayList<>();
93 stateToEventMap = new HashMap<>();
94 justVisitedStates = new HashSet<>();
95 prevVisitedStates = new HashSet<>();
96 currVisitedStates = new HashSet<>();
97 readWriteFieldsMap = new HashMap<>();
98 conflictPairMap = new HashMap<>();
100 isBooleanCGFlipped = false;
104 public void stateRestored(Search search) {
106 id = search.getStateId();
107 depth = search.getDepth();
108 transition = search.getTransition();
110 out.println("\n==> DEBUG: The state is restored to state with id: " + id + " -- Transition: " + transition +
111 " and depth: " + depth + "\n");
116 public void searchStarted(Search search) {
118 out.println("\n==> DEBUG: ----------------------------------- search started" + "\n");
123 public void stateAdvanced(Search search) {
125 id = search.getStateId();
126 depth = search.getDepth();
127 transition = search.getTransition();
128 if (search.isNewState()) {
134 if (search.isEndState()) {
135 out.println("\n==> DEBUG: This is the last state!\n");
138 out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
139 " which is " + detail + " Transition: " + transition + "\n");
141 if (stateReductionMode) {
142 updateStateInfo(search);
147 public void stateBacktracked(Search search) {
149 id = search.getStateId();
150 depth = search.getDepth();
151 transition = search.getTransition();
154 out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
155 " and depth: " + depth + "\n");
157 if (stateReductionMode) {
158 updateStateInfo(search);
163 public void searchFinished(Search search) {
165 out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
170 public void choiceGeneratorRegistered(VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
171 if (stateReductionMode) {
172 // Initialize with necessary information from the CG
173 if (nextCG instanceof IntChoiceFromSet) {
174 IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
175 // Check if CG has been initialized, otherwise initialize it
176 Integer[] cgChoices = icsCG.getAllChoices();
177 // Record the events (from choices)
178 if (choices == null) {
180 // Make a copy of choices as reference
181 refChoices = copyChoices(choices);
182 // Record the max event choice (the last element of the choice array)
183 maxEventChoice = choices[choices.length - 1];
185 // Use a modulo since choiceCounter is going to keep increasing
186 int choiceIndex = choiceCounter % choices.length;
187 icsCG.advance(choices[choiceIndex]);
188 // Index the ChoiceGenerator to set backtracking points
195 public void choiceGeneratorAdvanced(VM vm, ChoiceGenerator<?> currentCG) {
197 if (stateReductionMode) {
198 // Check the boolean CG and if it is flipped, we are resetting the analysis
199 // if (currentCG instanceof BooleanChoiceGenerator) {
200 // if (!isBooleanCGFlipped) {
201 // isBooleanCGFlipped = true;
203 // initializeStateReduction();
206 // Check every choice generated and ensure fair scheduling!
207 if (currentCG instanceof IntChoiceFromSet) {
208 IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
209 // If we don't see a fair scheduling of events/choices then we have to enforce it
210 checkAndEnforceFairScheduling(icsCG);
211 // Map state to event
212 mapStateToEvent(icsCG.getNextChoice());
213 // Check if we have seen this state or this state contains cycles that involve all events
214 if (terminateCurrentExecution()) {
215 exploreNextBacktrackSets(icsCG);
217 justVisitedStates.clear();
224 public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
225 if (stateReductionMode) {
226 // Has to be initialized and a integer CG
227 ChoiceGenerator<?> cg = vm.getChoiceGenerator();
228 if (cg instanceof IntChoiceFromSet || cg instanceof IntIntervalGenerator) {
229 int currentChoice = choiceCounter - 1; // Accumulative choice w.r.t the current trace
230 //if (getCurrentChoice(vm) < 0) { // If choice is -1 then skip
231 if (currentChoice < 0) { // If choice is -1 then skip
234 // Record accesses from executed instructions
235 if (executedInsn instanceof JVMFieldInstruction) {
236 // Analyze only after being initialized
237 String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
238 // We don't care about libraries
239 if (!isFieldExcluded(fieldClass)) {
240 analyzeReadWriteAccesses(executedInsn, fieldClass, currentChoice);
242 } else if (executedInsn instanceof INVOKEINTERFACE) {
243 // Handle the read/write accesses that occur through iterators
244 analyzeReadWriteAccesses(executedInsn, ti, currentChoice);
246 // Analyze conflicts from next instructions
247 if (nextInsn instanceof JVMFieldInstruction) {
248 // Skip the constructor because it is called once and does not have shared access with other objects
249 if (!nextInsn.getMethodInfo().getName().equals("<init>")) {
250 String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
251 if (!isFieldExcluded(fieldClass)) {
252 // Check for conflict (go backward from current choice and get the first conflict)
253 for (int evtCntr = currentChoice - 1; evtCntr >= 0; evtCntr--) {
254 if (!readWriteFieldsMap.containsKey(evtCntr)) { // Skip if this event does not have any Read/Write set
257 ReadWriteSet rwSet = readWriteFieldsMap.get(evtCntr);
258 int currObjId = ((JVMFieldInstruction) nextInsn).getFieldInfo().getClassInfo().getClassObjectRef();
259 // Check for conflicts with Write fields for both Read and Write instructions
260 if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) &&
261 rwSet.writeFieldExists(fieldClass) && rwSet.writeFieldObjectId(fieldClass) == currObjId) ||
262 (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass) &&
263 rwSet.readFieldObjectId(fieldClass) == currObjId)) {
264 // Check and record a backtrack set for just once!
265 if (successfullyRecordConflictPair(currentChoice, evtCntr)) {
266 // Lines 4-8 of the algorithm in the paper page 11 (see the heading note above)
267 // if (vm.isNewState() || isReachableInVODGraph(refChoices[currentChoice], refChoices[currentChoice-1])) {
268 // createBacktrackChoiceList(currentChoice, eventNumber);
283 // This class compactly stores Read and Write field sets
284 // We store the field name and its object ID
285 // Sharing the same field means the same field name and object ID
286 private class ReadWriteSet {
287 private HashMap<String, Integer> readSet;
288 private HashMap<String, Integer> writeSet;
290 public ReadWriteSet() {
291 readSet = new HashMap<>();
292 writeSet = new HashMap<>();
295 public void addReadField(String field, int objectId) {
296 readSet.put(field, objectId);
299 public void addWriteField(String field, int objectId) {
300 writeSet.put(field, objectId);
303 public boolean readFieldExists(String field) {
304 return readSet.containsKey(field);
307 public boolean writeFieldExists(String field) {
308 return writeSet.containsKey(field);
311 public int readFieldObjectId(String field) {
312 return readSet.get(field);
315 public int writeFieldObjectId(String field) {
316 return writeSet.get(field);
321 private final static String DO_CALL_METHOD = "doCall";
322 // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure
323 private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"};
324 private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST =
325 // Groovy library created fields
326 {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__",
328 "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList",
329 "eventList", "valueList", "settings", "printToConsole", "app1", "app2"};
330 private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST =
331 // Java and Groovy libraries
332 { "java", "org", "sun", "com", "gov", "groovy"};
333 private final static String[] EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"};
334 private final static String GET_PROPERTY_METHOD =
335 "invokeinterface org.codehaus.groovy.runtime.callsite.CallSite.callGetProperty";
336 private final static String GROOVY_CALLSITE_LIB = "org.codehaus.groovy.runtime.callsite";
337 private final static String JAVA_INTEGER = "int";
338 private final static String JAVA_STRING_LIB = "java.lang.String";
341 private void checkAndEnforceFairScheduling(IntChoiceFromSet icsCG) {
342 // Check the next choice and if the value is not the same as the expected then force the expected value
343 int choiceIndex = choiceCounter % refChoices.length;
344 int nextChoice = icsCG.getNextChoice();
345 if (refChoices[choiceIndex] != nextChoice) {
346 int expectedChoice = refChoices[choiceIndex];
347 int currCGIndex = icsCG.getNextChoiceIndex();
348 if ((currCGIndex >= 0) && (currCGIndex < refChoices.length)) {
349 icsCG.setChoice(currCGIndex, expectedChoice);
354 private Integer[] copyChoices(Integer[] choicesToCopy) {
356 Integer[] copyOfChoices = new Integer[choicesToCopy.length];
357 System.arraycopy(choicesToCopy, 0, copyOfChoices, 0, choicesToCopy.length);
358 return copyOfChoices;
361 // --- Functions related to cycle detection
363 // Detect cycles in the current execution/trace
364 // We terminate the execution iff:
365 // (1) the state has been visited in the current execution
366 // (2) the state has one or more cycles that involve all the events
367 // With simple approach we only need to check for a re-visited state.
368 // Basically, we have to check that we have executed all events between two occurrences of such state.
369 private boolean containsCyclesWithAllEvents(int stId) {
371 // False if the state ID hasn't been recorded
372 if (!stateToEventMap.containsKey(stId)) {
375 HashSet<Integer> visitedEvents = stateToEventMap.get(stId);
376 // Check if this set contains all the event choices
377 // If not then this is not the terminating condition
378 for(int i=0; i<=maxEventChoice; i++) {
379 if (!visitedEvents.contains(i)) {
386 private void mapStateToEvent(int nextChoiceValue) {
387 // Update all states with this event/choice
388 // This means that all past states now see this transition
389 Set<Integer> stateSet = stateToEventMap.keySet();
390 for(Integer stateId : stateSet) {
391 HashSet<Integer> eventSet = stateToEventMap.get(stateId);
392 eventSet.add(nextChoiceValue);
396 private boolean terminateCurrentExecution() {
397 // We need to check all the states that have just been visited
398 // Often a transition (choice/event) can result into forwarding/backtracking to a number of states
399 for(Integer stateId : justVisitedStates) {
400 if (prevVisitedStates.contains(stateId) || containsCyclesWithAllEvents(stateId)) {
407 private void updateStateInfo(Search search) {
408 // Update the state variables
409 // Line 19 in the paper page 11 (see the heading note above)
410 int stateId = search.getStateId();
411 currVisitedStates.add(stateId);
412 // Insert state ID into the map if it is new
413 if (!stateToEventMap.containsKey(stateId)) {
414 HashSet<Integer> eventSet = new HashSet<>();
415 stateToEventMap.put(stateId, eventSet);
417 justVisitedStates.add(stateId);
420 // --- Functions related to Read/Write access analysis on shared fields
422 // Analyze Read/Write accesses that are directly invoked on fields
423 private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) {
424 // Do the analysis to get Read and Write accesses to fields
425 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
426 int objectId = ((JVMFieldInstruction) executedInsn).getFieldInfo().getClassInfo().getClassObjectRef();
427 // Record the field in the map
428 if (executedInsn instanceof WriteInstruction) {
429 // Exclude certain field writes because of infrastructure needs, e.g., Event class field writes
430 for (String str : EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) {
431 if (fieldClass.startsWith(str)) {
435 rwSet.addWriteField(fieldClass, objectId);
436 } else if (executedInsn instanceof ReadInstruction) {
437 rwSet.addReadField(fieldClass, objectId);
441 // Analyze Read accesses that are indirect (performed through iterators)
442 // These accesses are marked by certain bytecode instructions, e.g., INVOKEINTERFACE
443 private void analyzeReadWriteAccesses(Instruction instruction, ThreadInfo ti, int currentChoice) {
445 INVOKEINTERFACE insn = (INVOKEINTERFACE) instruction;
446 if (insn.toString().startsWith(GET_PROPERTY_METHOD) &&
447 insn.getMethodInfo().getName().equals(DO_CALL_METHOD)) {
448 // Extract info from the stack frame
449 StackFrame frame = ti.getTopFrame();
450 int[] frameSlots = frame.getSlots();
451 // Get the Groovy callsite library at index 0
452 ElementInfo eiCallsite = VM.getVM().getHeap().get(frameSlots[0]);
453 if (!eiCallsite.getClassInfo().getName().startsWith(GROOVY_CALLSITE_LIB)) {
456 // Get the iterated object whose property is accessed
457 ElementInfo eiAccessObj = VM.getVM().getHeap().get(frameSlots[1]);
458 // We exclude library classes (they start with java, org, etc.) and some more
459 String objClassName = eiAccessObj.getClassInfo().getName();
460 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, objClassName) ||
461 excludeThisForItStartsWith(EXCLUDED_FIELDS_READ_WRITE_INSTRUCTIONS_STARTS_WITH_LIST, objClassName)) {
464 // Extract fields from this object and put them into the read write
465 int numOfFields = eiAccessObj.getNumberOfFields();
466 for(int i=0; i<numOfFields; i++) {
467 FieldInfo fieldInfo = eiAccessObj.getFieldInfo(i);
468 if (fieldInfo.getType().equals(JAVA_STRING_LIB) || fieldInfo.getType().equals(JAVA_INTEGER)) {
469 String fieldClass = fieldInfo.getFullName();
470 ReadWriteSet rwSet = getReadWriteSet(currentChoice);
471 int objectId = fieldInfo.getClassInfo().getClassObjectRef();
472 // Record the field in the map
473 rwSet.addReadField(fieldClass, objectId);
479 private boolean excludeThisForItContains(String[] excludedStrings, String className) {
480 for (String excludedField : excludedStrings) {
481 if (className.contains(excludedField)) {
488 private boolean excludeThisForItEndsWith(String[] excludedStrings, String className) {
489 for (String excludedField : excludedStrings) {
490 if (className.endsWith(excludedField)) {
497 private boolean excludeThisForItStartsWith(String[] excludedStrings, String className) {
498 for (String excludedField : excludedStrings) {
499 if (className.startsWith(excludedField)) {
506 private void exploreNextBacktrackSets(IntChoiceFromSet icsCG) {
507 // Save all the visited states when starting a new execution of trace
508 prevVisitedStates.addAll(currVisitedStates);
509 currVisitedStates.clear();
513 private int getCurrentChoice(VM vm) {
514 ChoiceGenerator<?> currentCG = vm.getChoiceGenerator();
515 // This is the main event CG
516 if (currentCG instanceof IntChoiceFromSet) {
517 return ((IntChoiceFromSet) currentCG).getNextChoiceIndex();
519 // This is the interval CG used in device handlers
520 ChoiceGenerator<?> parentCG = ((IntIntervalGenerator) currentCG).getPreviousChoiceGenerator();
521 return ((IntChoiceFromSet) parentCG).getNextChoiceIndex();
525 private ReadWriteSet getReadWriteSet(int currentChoice) {
526 // Do the analysis to get Read and Write accesses to fields
528 // We already have an entry
529 if (readWriteFieldsMap.containsKey(currentChoice)) {
530 rwSet = readWriteFieldsMap.get(currentChoice);
531 } else { // We need to create a new entry
532 rwSet = new ReadWriteSet();
533 readWriteFieldsMap.put(currentChoice, rwSet);
538 private boolean isFieldExcluded(String field) {
539 // Check against "starts-with", "ends-with", and "contains" list
540 if (excludeThisForItStartsWith(EXCLUDED_FIELDS_STARTS_WITH_LIST, field) ||
541 excludeThisForItEndsWith(EXCLUDED_FIELDS_ENDS_WITH_LIST, field) ||
542 excludeThisForItContains(EXCLUDED_FIELDS_CONTAINS_LIST, field)) {
549 private boolean successfullyRecordConflictPair(int currentEvent, int eventNumber) {
550 HashSet<Integer> conflictSet;
551 if (!conflictPairMap.containsKey(currentEvent)) {
552 conflictSet = new HashSet<>();
553 conflictPairMap.put(currentEvent, conflictSet);
555 conflictSet = conflictPairMap.get(currentEvent);
557 // If this conflict has been recorded before, we return false because
558 // we don't want to service this backtrack point twice
559 if (conflictSet.contains(eventNumber)) {
562 // If it hasn't been recorded, then do otherwise
563 conflictSet.add(eventNumber);