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 com.sun.org.apache.xpath.internal.operations.Bool;
21 import gov.nasa.jpf.Config;
22 import gov.nasa.jpf.JPF;
23 import gov.nasa.jpf.ListenerAdapter;
24 import gov.nasa.jpf.search.Search;
25 import gov.nasa.jpf.jvm.bytecode.*;
26 import gov.nasa.jpf.vm.*;
27 import gov.nasa.jpf.vm.bytecode.LocalVariableInstruction;
28 import gov.nasa.jpf.vm.bytecode.ReadInstruction;
29 import gov.nasa.jpf.vm.bytecode.StoreInstruction;
30 import gov.nasa.jpf.vm.bytecode.WriteInstruction;
31 import gov.nasa.jpf.vm.choice.IntChoiceFromSet;
32 import gov.nasa.jpf.vm.choice.IntIntervalGenerator;
35 import java.io.PrintWriter;
38 import java.util.List;
40 // TODO: Fix for Groovy's model-checking
41 // TODO: This is a setter to change the values of the ChoiceGenerator to implement POR
43 * simple tool to log state changes
45 public class StateReducer extends ListenerAdapter {
48 private boolean debugMode;
49 private boolean stateReductionMode;
50 private final PrintWriter out;
51 volatile private String detail;
52 volatile private int depth;
53 volatile private int id;
54 Transition transition;
56 // State reduction fields
57 private int choiceCounter;
58 private Integer choiceUpperBound;
59 private boolean isInitialized;
60 private boolean isResetAfterAnalysis;
61 private boolean isBooleanCGFlipped;
62 private HashMap<IntChoiceFromSet,Integer> cgMap;
63 // Record the mapping between event number and field accesses (Read and Write)
64 private HashMap<Integer,ReadWriteSet> readWriteFieldsMap;
65 // The following is the backtrack map (set) that stores all the backtrack information
66 // e.g., event number 1 can have two backtrack sequences: {3,1,2,4,...} and {2,1,3,4,...}
67 private HashMap<Integer,LinkedList<Integer[]>> backtrackMap;
68 private HashMap<Integer,HashSet<Integer>> conflictPairMap;
70 public StateReducer (Config config, JPF jpf) {
71 debugMode = config.getBoolean("debug_state_transition", false);
72 stateReductionMode = config.getBoolean("activate_state_reduction", true);
74 out = new PrintWriter(System.out, true);
82 isBooleanCGFlipped = false;
83 initializeStateReduction();
86 private void initializeStateReduction() {
87 if (stateReductionMode) {
90 isInitialized = false;
91 isResetAfterAnalysis = false;
92 cgMap = new HashMap<>();
93 readWriteFieldsMap = new HashMap<>();
94 backtrackMap = new HashMap<>();
95 conflictPairMap = new HashMap<>();
100 public void stateRestored(Search search) {
102 id = search.getStateId();
103 depth = search.getDepth();
104 transition = search.getTransition();
106 out.println("\n==> DEBUG: The state is restored to state with id: " + id + " -- Transition: " + transition +
107 " and depth: " + depth + "\n");
111 //--- the ones we are interested in
113 public void searchStarted(Search search) {
115 out.println("\n==> DEBUG: ----------------------------------- search started" + "\n");
120 public void choiceGeneratorRegistered (VM vm, ChoiceGenerator<?> nextCG, ThreadInfo currentThread, Instruction executedInstruction) {
121 if (stateReductionMode) {
122 // Initialize with necessary information from the CG
123 if (nextCG instanceof IntChoiceFromSet) {
124 IntChoiceFromSet icsCG = (IntChoiceFromSet) nextCG;
125 // Check if CG has been initialized, otherwise initialize it
126 Object[] choices = icsCG.getAllChoices();
127 if (!isInitialized) {
128 // Get the upper bound from the last element of the choices
129 choiceUpperBound = (Integer) choices[choices.length - 1];
130 isInitialized = true;
132 // Record the subsequent Integer CGs only until we hit the upper bound
133 if (choiceCounter < choiceUpperBound && !cgMap.containsValue(choiceCounter)) {
134 // Update the choices of the first CG and add '-1'
135 Integer[] newChoices = new Integer[choices.length + 1];
136 System.arraycopy(choices, 0, newChoices, 0, choices.length);
137 newChoices[newChoices.length - 1] = -1;
138 icsCG.setNewValues(newChoices);
140 // Advance the current Integer CG
141 // This way we explore all the event numbers in the first pass
142 icsCG.advance(choiceCounter);
143 cgMap.put(icsCG, choiceCounter);
146 // Set done the subsequent CGs
147 // We only need n CGs (n is event numbers)
154 private void resetAllCGs() {
155 // Extract the event numbers that have backtrack lists
156 Set<Integer> eventSet = backtrackMap.keySet();
157 // Return if there is no conflict at all (highly unlikely)
158 if (eventSet.isEmpty()) {
161 // Reset every CG with the first backtrack lists
162 for(IntChoiceFromSet cg : cgMap.keySet()) {
163 int event = cgMap.get(cg);
164 LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
165 if (choiceLists != null && choiceLists.peekFirst() != null) {
166 Integer[] choiceList = choiceLists.removeFirst();
167 // Deploy the new choice list for this CG
168 cg.setNewValues(choiceList);
175 public void choiceGeneratorAdvanced (VM vm, ChoiceGenerator<?> currentCG) {
177 if(stateReductionMode) {
178 // Check the boolean CG and if it is flipped, we are resetting the analysis
179 if (currentCG instanceof BooleanChoiceGenerator) {
180 if (!isBooleanCGFlipped) {
181 isBooleanCGFlipped = true;
183 initializeStateReduction();
186 // Check every choice generated and make sure that all the available choices
187 // are chosen first before repeating the same choice of value twice!
188 if (currentCG instanceof IntChoiceFromSet) {
189 IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG;
190 // Update and reset the CG if needed (do this for the first time after the analysis)
191 if (!isResetAfterAnalysis && icsCG.getNextChoice() == -1) {
193 isResetAfterAnalysis = true;
195 // Do this for every CG after finishing each backtrack list
196 if (isResetAfterAnalysis && icsCG.getNextChoice() == -1) {
197 int event = cgMap.get(icsCG);
198 LinkedList<Integer[]> choiceLists = backtrackMap.get(event);
199 if (choiceLists.peekFirst() != null) {
200 Integer[] choiceList = choiceLists.removeFirst();
201 // Deploy the new choice list for this CG
202 icsCG.setNewValues(choiceList);
205 // Set done if this was the last backtrack list
214 public void stateAdvanced(Search search) {
216 id = search.getStateId();
217 depth = search.getDepth();
218 transition = search.getTransition();
219 if (search.isNewState()) {
225 if (search.isEndState()) {
226 out.println("\n==> DEBUG: This is the last state!\n");
229 out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth +
230 " which is " + detail + " Transition: " + transition + "\n");
235 public void stateBacktracked(Search search) {
237 id = search.getStateId();
238 depth = search.getDepth();
239 transition = search.getTransition();
242 out.println("\n==> DEBUG: The state is backtracked to state with id: " + id + " -- Transition: " + transition +
243 " and depth: " + depth + "\n");
248 public void searchFinished(Search search) {
250 out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n");
254 // This class compactly stores Read and Write field sets
255 private class ReadWriteSet {
256 private HashSet<String> readSet;
257 private HashSet<String> writeSet;
259 public ReadWriteSet() {
260 readSet = new HashSet<>();
261 writeSet = new HashSet<>();
264 public void addReadField(String field) {
268 public void addWriteField(String field) {
272 public boolean readFieldExists(String field) {
273 return readSet.contains(field);
276 public boolean writeFieldExists(String field) {
277 return writeSet.contains(field);
281 private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass) {
282 // Do the analysis to get Read and Write accesses to fields
284 // We already have an entry
285 if (readWriteFieldsMap.containsKey(choiceCounter)) {
286 rwSet = readWriteFieldsMap.get(choiceCounter);
287 } else { // We need to create a new entry
288 rwSet = new ReadWriteSet();
289 readWriteFieldsMap.put(choiceCounter, rwSet);
291 // Record the field in the map
292 if (executedInsn instanceof WriteInstruction) {
293 rwSet.addWriteField(fieldClass);
295 if (executedInsn instanceof ReadInstruction) {
296 rwSet.addReadField(fieldClass);
300 private boolean recordConflictPair(int currentEvent, int eventNumber) {
301 HashSet<Integer> conflictSet;
302 if (!conflictPairMap.containsKey(currentEvent)) {
303 conflictSet = new HashSet<>();
304 conflictPairMap.put(currentEvent, conflictSet);
306 conflictSet = conflictPairMap.get(currentEvent);
308 // If this conflict has been recorded before, we return false because
309 // we don't want to service this backtrack point twice
310 if (conflictSet.contains(eventNumber)) {
313 // If it hasn't been recorded, then do otherwise
314 conflictSet.add(eventNumber);
318 private void createBacktrackChoiceList(int currentChoice, int conflictEventNumber) {
320 int minChoice = Math.min(currentChoice, conflictEventNumber);
321 int maxChoice = Math.max(currentChoice, conflictEventNumber);
322 LinkedList<Integer[]> backtrackChoiceLists;
323 // Check if we have a list for this choice number
324 // If not we create a new one for it
325 if (!backtrackMap.containsKey(minChoice)) {
326 backtrackChoiceLists = new LinkedList<>();
327 backtrackMap.put(minChoice, backtrackChoiceLists);
329 backtrackChoiceLists = backtrackMap.get(minChoice);
331 // TODO: The following might change depending on the POR implementation detail
332 // Create a new list of choices for backtrack based on the current choice and conflicting event number
333 // If we have a conflict between 1 and 3, then we create the list {3, 1, 2, 4, 5} for backtrack
334 // The backtrack point is the CG for event number 1 and the list length is one less than the original list
335 // (originally of length 6) since we don't start from event number 0
336 int maxListLength = choiceUpperBound + 1;
337 int listLength = maxListLength - minChoice;
338 Integer[] choiceList = new Integer[listLength+1];
339 // Put the conflicting event numbers first and reverse the order
340 choiceList[0] = maxChoice;
341 choiceList[1] = minChoice;
342 // Put the rest of the event numbers into the array starting from the minimum to the upper bound
343 for(int i = minChoice + 1, j = 2; j < listLength; i++) {
344 if (i != maxChoice) {
349 // Set the last element to '-1' as the end of the sequence
350 choiceList[choiceList.length - 1] = -1;
351 backtrackChoiceLists.addLast(choiceList);
355 public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) {
356 if (stateReductionMode) {
357 // Record accesses from executed instructions
358 if (executedInsn instanceof JVMFieldInstruction) {
359 String fieldClass = ((JVMFieldInstruction) executedInsn).getFieldInfo().getFullName();
360 // We don't care about libraries
361 if (!fieldClass.startsWith("java") &&
362 !fieldClass.startsWith("org") &&
363 !fieldClass.startsWith("sun") &&
364 !fieldClass.startsWith("com") &&
365 !fieldClass.startsWith("gov") &&
366 !fieldClass.startsWith("groovy")) {
367 analyzeReadWriteAccesses(executedInsn, fieldClass);
370 // Analyze conflicts from next instructions
371 if (nextInsn instanceof JVMFieldInstruction) {
372 String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName();
373 // We don't care about libraries
374 if (!fieldClass.startsWith("java") &&
375 !fieldClass.startsWith("org") &&
376 !fieldClass.startsWith("sun") &&
377 !fieldClass.startsWith("com") &&
378 !fieldClass.startsWith("gov") &&
379 !fieldClass.startsWith("groovy")) {
380 // Check for conflict (go backward from currentChoice and get the first conflict)
381 // If the current event has conflicts with multiple events, then these will be detected
382 // one by one as this recursively checks backward when backtrack set is revisited and executed.
383 for(int eventNumber=choiceCounter-1; eventNumber>=0; eventNumber--) {
384 // Skip if this event number does not have any Read/Write set
385 if (!readWriteFieldsMap.containsKey(eventNumber)) {
388 ReadWriteSet rwSet = readWriteFieldsMap.get(eventNumber);
389 // 1) Check for conflicts with Write fields for both Read and Write instructions
390 // 2) Check for conflicts with Read fields for Write instructions
391 if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) &&
392 rwSet.writeFieldExists(fieldClass)) ||
393 (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass))) {
394 // We do not record and service the same backtrack pair/point twice!
395 // If it has been serviced before, we just skip this
396 if (recordConflictPair(choiceCounter, eventNumber)) {
397 createBacktrackChoiceList(choiceCounter, eventNumber);
398 // Break if a conflict is found!