X-Git-Url: http://plrg.eecs.uci.edu/git/?p=jpf-core.git;a=blobdiff_plain;f=src%2Fmain%2Fgov%2Fnasa%2Fjpf%2Flistener%2FStateReducer.java;h=474058355c1f7f82f00403cf67705e4d406fd8a5;hp=60782a98e9b73615789c937a80326eaee3fbbfdd;hb=8fb77ba10fd95f3f2f5707b1b69e30c4dbb7a04a;hpb=75c00d3f11e45587f0919d4c7de84a2249d1567e diff --git a/src/main/gov/nasa/jpf/listener/StateReducer.java b/src/main/gov/nasa/jpf/listener/StateReducer.java index 60782a9..4740583 100644 --- a/src/main/gov/nasa/jpf/listener/StateReducer.java +++ b/src/main/gov/nasa/jpf/listener/StateReducer.java @@ -23,39 +23,76 @@ import gov.nasa.jpf.ListenerAdapter; import gov.nasa.jpf.search.Search; import gov.nasa.jpf.jvm.bytecode.*; import gov.nasa.jpf.vm.*; -import gov.nasa.jpf.vm.bytecode.LocalVariableInstruction; import gov.nasa.jpf.vm.bytecode.ReadInstruction; -import gov.nasa.jpf.vm.bytecode.StoreInstruction; import gov.nasa.jpf.vm.bytecode.WriteInstruction; -import gov.nasa.jpf.vm.choice.IntIntervalGenerator; +import gov.nasa.jpf.vm.choice.IntChoiceFromSet; import java.io.PrintWriter; import java.util.*; // TODO: Fix for Groovy's model-checking -// TODO: This is a listener created to detect device conflicts and global variable conflicts +// TODO: This is a setter to change the values of the ChoiceGenerator to implement POR /** - * Simple listener tool to track remove unwanted ChoiceGenerators that are registered - * while an existing ChoiceGenerator is being explored. Multiple ChoiceGenerators of the same - * type could be registered spuriously during a while(true) loop. + * Simple tool to log state changes. + * + * This DPOR implementation is augmented by the algorithm presented in this SPIN paper: + * http://spinroot.com/spin/symposia/ws08/spin2008_submission_33.pdf + * + * The algorithm is presented on page 11 of the paper. Basically, we create a graph G + * (i.e., visible operation dependency graph) + * that maps inter-related threads/sub-programs that trigger state changes. + * The key to this approach is that we evaluate graph G in every iteration/recursion to + * only update the backtrack sets of the threads/sub-programs that are reachable in graph G + * from the currently running thread/sub-program. */ public class StateReducer extends ListenerAdapter { + // Debug info fields private boolean debugMode; + private boolean stateReductionMode; private final PrintWriter out; - private String detail; - private int depth; - private int id; - private Transition transition; + volatile private String detail; + volatile private int depth; + volatile private int id; + Transition transition; - // Holds values that have appeared during CG advances - private HashSet cgChoiceSet; + // State reduction fields + private Integer[] choices; + private IntChoiceFromSet currCG; + private int choiceCounter; private Integer choiceUpperBound; + private Integer maxUpperBound; private boolean isInitialized; + private boolean isResetAfterAnalysis; + private boolean isBooleanCGFlipped; + private HashMap cgMap; + // Record the mapping between event number and field accesses (Read and Write) + private HashMap readWriteFieldsMap; + // The following is the backtrack map (set) that stores all the backtrack information + // e.g., event number 1 can have two backtrack sequences: {3,1,2,4,...} and {2,1,3,4,...} + private HashMap> backtrackMap; + // Stores explored backtrack lists in the form of HashSet of Strings + private HashSet backtrackSet; + private HashMap> conflictPairMap; + // Map choicelist with start index + // private HashMap choiceListStartIndexMap; + + // Map that represents graph G + // (i.e., visible operation dependency graph (VOD Graph) + private HashMap> vodGraphMap; + // Set that represents hash table H + // (i.e., hash table that records encountered states) + // VOD graph is updated when the state has not yet been seen + private HashSet visitedStateSet; + // Current state + private int stateId; + // Previous choice number + private int prevChoiceValue; - public StateReducer (Config config, JPF jpf) { + public StateReducer(Config config, JPF jpf) { debugMode = config.getBoolean("debug_state_transition", false); + stateReductionMode = config.getBoolean("activate_state_reduction", true); if (debugMode) { out = new PrintWriter(System.out, true); } else { @@ -65,9 +102,29 @@ public class StateReducer extends ListenerAdapter { depth = 0; id = 0; transition = null; - cgChoiceSet = new HashSet<>(); - choiceUpperBound = 0; - isInitialized = false; + isBooleanCGFlipped = false; + vodGraphMap = new HashMap<>(); + visitedStateSet = new HashSet<>(); + stateId = -1; + prevChoiceValue = -1; + initializeStateReduction(); + } + + private void initializeStateReduction() { + if (stateReductionMode) { + choices = null; + currCG = null; + choiceCounter = 0; + choiceUpperBound = 0; + maxUpperBound = 0; + isInitialized = false; + isResetAfterAnalysis = false; + cgMap = new HashMap<>(); + readWriteFieldsMap = new HashMap<>(); + backtrackMap = new HashMap<>(); + backtrackSet = new HashSet<>(); + conflictPairMap = new HashMap<>(); + } } @Override @@ -91,41 +148,136 @@ public class StateReducer extends ListenerAdapter { } @Override - public void choiceGeneratorSet (VM vm, ChoiceGenerator newCG) { - // Initialize with necessary information from the CG - if (newCG instanceof IntIntervalGenerator) { - IntIntervalGenerator iigCG = (IntIntervalGenerator) newCG; - // Check if CG has been initialized, otherwise initialize it - if (!isInitialized) { - Integer[] choices = iigCG.getChoices(); - // Get the upper bound from the last element of the choices - choiceUpperBound = choices[choices.length - 1]; - isInitialized = true; + 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(); + if (!isInitialized) { + // Get the upper bound from the last element of the choices + choiceUpperBound = cgChoices[cgChoices.length - 1]; + isInitialized = true; + } + // Record the subsequent Integer CGs only until we hit the upper bound + if (!isResetAfterAnalysis && choiceCounter <= choiceUpperBound && !cgMap.containsValue(choiceCounter)) { + // Update the choices of the first CG and add '-1' + if (choices == null) { + // Initialize backtrack set that stores all the explored backtrack lists + maxUpperBound = cgChoices.length; + // All the choices are always the same so we only need to update it once + choices = new Integer[cgChoices.length + 1]; + System.arraycopy(cgChoices, 0, choices, 0, cgChoices.length); + choices[choices.length - 1] = -1; + String firstChoiceListString = buildStringFromChoiceList(choices); + backtrackSet.add(firstChoiceListString); + } + icsCG.setNewValues(choices); + icsCG.reset(); + // Advance the current Integer CG + // This way we explore all the event numbers in the first pass + icsCG.advance(choices[choiceCounter]); + cgMap.put(icsCG, choices[choiceCounter]); + choiceCounter++; + } else { + // Set done the subsequent CGs + // We only need n CGs (n is event numbers) + icsCG.setDone(); + } + } + } + } + + private void resetAllCGs() { + // Extract the event numbers that have backtrack lists + Set eventSet = backtrackMap.keySet(); + // Return if there is no conflict at all (highly unlikely) + if (eventSet.isEmpty()) { + return; + } + // Reset every CG with the first backtrack lists + for (IntChoiceFromSet cg : cgMap.keySet()) { + int event = cgMap.get(cg); + LinkedList choiceLists = backtrackMap.get(event); + if (choiceLists != null && choiceLists.peekFirst() != null) { + Integer[] choiceList = choiceLists.removeFirst(); + // Deploy the new choice list for this CG + cg.setNewValues(choiceList); + cg.reset(); } else { - newCG.setDone(); + cg.setDone(); } } } @Override - public void choiceGeneratorAdvanced (VM vm, ChoiceGenerator currentCG) { - // Check every choice generated and make sure that all the available choices - // are chosen first before repeating the same choice of value twice! - if (currentCG instanceof IntIntervalGenerator) { - IntIntervalGenerator iigCG = (IntIntervalGenerator) currentCG; - Integer nextChoice = iigCG.getNextChoice(); - if (!cgChoiceSet.contains(nextChoice)) { - cgChoiceSet.add(nextChoice); + 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(); + } } - // Allow reinitialization after an upper bound is hit - // This means all available choices have been explored once during this iteration - if (cgChoiceSet.contains(choiceUpperBound)) { - isInitialized = false; - cgChoiceSet.clear(); + // Check every choice generated and make sure that all the available choices + // are chosen first before repeating the same choice of value twice! + if (currentCG instanceof IntChoiceFromSet) { + IntChoiceFromSet icsCG = (IntChoiceFromSet) currentCG; + // Update the current pointer to the current set of choices + if (choices == null || choices != icsCG.getAllChoices()) { + currCG = icsCG; + choices = icsCG.getAllChoices(); + // Reset a few things for the sub-graph + conflictPairMap.clear(); + readWriteFieldsMap.clear(); + choiceCounter = 0; + } + // Traverse the sub-graphs + if (isResetAfterAnalysis) { + // Advance choice counter for sub-graphs + choiceCounter++; + // Do this for every CG after finishing each backtrack list + if (icsCG.getNextChoice() == -1 || visitedStateSet.contains(stateId)) { + int event = cgMap.get(icsCG); + LinkedList choiceLists = backtrackMap.get(event); + if (choiceLists != null && choiceLists.peekFirst() != null) { + Integer[] choiceList = choiceLists.removeFirst(); + // Deploy the new choice list for this CG + icsCG.setNewValues(choiceList); + icsCG.reset(); + } else { + // Set done if this was the last backtrack list + icsCG.setDone(); + } + } + } + // Update and reset the CG if needed (do this for the first time after the analysis) + if (!isResetAfterAnalysis && icsCG.getNextChoice() == -1) { + resetAllCGs(); + isResetAfterAnalysis = true; + } } } } + public void updateVODGraph(int prevChoice, int currChoice) { + + HashSet choiceSet; + if (vodGraphMap.containsKey(prevChoice)) { + // If the key already exists, just retrieve it + choiceSet = vodGraphMap.get(prevChoice); + } else { + // Create a new entry + choiceSet = new HashSet<>(); + vodGraphMap.put(prevChoice, choiceSet); + } + choiceSet.add(currChoice); + } + @Override public void stateAdvanced(Search search) { if (debugMode) { @@ -145,6 +297,22 @@ public class StateReducer extends ListenerAdapter { out.println("\n==> DEBUG: The state is forwarded to state with id: " + id + " with depth: " + depth + " which is " + detail + " Transition: " + transition + "\n"); } + if (stateReductionMode) { + // Update vodGraph + int currChoice = choiceCounter - 1; + if (currChoice < 0 || choices[currChoice] == -1 || prevChoiceValue == choices[currChoice]) { + // Current choice has to be at least 0 (initial case can be -1) + return; + } + // When current choice is 0, previous choice could be -1 + updateVODGraph(prevChoiceValue, choices[currChoice]); + // Current choice becomes previous choice in the next iteration + prevChoiceValue = choices[currChoice]; + // Line 19 in the paper page 11 (see the heading note above) + stateId = search.getStateId(); + // Add state ID into the visited state set + visitedStateSet.add(stateId); + } } @Override @@ -166,4 +334,308 @@ public class StateReducer extends ListenerAdapter { out.println("\n==> DEBUG: ----------------------------------- search finished" + "\n"); } } -} \ No newline at end of file + + // 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 readSet; + private HashMap 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); + } + } + + private void analyzeReadWriteAccesses(Instruction executedInsn, String fieldClass, int currentChoice) { + // Do the analysis to get Read and Write accesses to fields + ReadWriteSet rwSet; + // We already have an entry + if (readWriteFieldsMap.containsKey(choices[currentChoice])) { + rwSet = readWriteFieldsMap.get(choices[currentChoice]); + } else { // We need to create a new entry + rwSet = new ReadWriteSet(); + readWriteFieldsMap.put(choices[currentChoice], rwSet); + } + 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_WRITE_INSTRUCTIONS_STARTS_WITH_LIST) { + if (fieldClass.startsWith(str)) { + return; + } + } + rwSet.addWriteField(fieldClass, objectId); + } else if (executedInsn instanceof ReadInstruction) { + rwSet.addReadField(fieldClass, objectId); + } + } + + private boolean recordConflictPair(int currentEvent, int eventNumber) { + HashSet 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; + } + + private String buildStringFromChoiceList(Integer[] newChoiceList) { + + // When we see a choice list shorter than the upper bound, e.g., [3,2] for choices 0,1,2, and 3, + // then we have to pad the beginning before we store it, because [3,2] actually means [0,1,3,2] + // First, calculate the difference between this choice list and the upper bound + // The actual list doesn't include '-1' at the end + int actualListLength = newChoiceList.length - 1; + int diff = maxUpperBound - actualListLength; + StringBuilder sb = new StringBuilder(); + // Pad the beginning if necessary + for (int i = 0; i < diff; i++) { + sb.append(i); + } + // Then continue with the actual choice list + // We don't include the '-1' at the end + for (int i = 0; i < newChoiceList.length - 1; i++) { + sb.append(newChoiceList[i]); + } + return sb.toString(); + } + + private void checkAndAddBacktrackList(LinkedList backtrackChoiceLists, Integer[] newChoiceList) { + + String newChoiceListString = buildStringFromChoiceList(newChoiceList); + // Add only if we haven't seen this combination before + if (!backtrackSet.contains(newChoiceListString)) { + backtrackSet.add(newChoiceListString); + backtrackChoiceLists.addLast(newChoiceList); + } + } + + private void createBacktrackChoiceList(int currentChoice, int conflictEventNumber) { + + LinkedList backtrackChoiceLists; + // Create a new list of choices for backtrack based on the current choice and conflicting event number + // If we have a conflict between 1 and 3, then we create the list {3, 1, 2, 4, 5} for backtrack + // The backtrack point is the CG for event number 1 and the list length is one less than the original list + // (originally of length 6) since we don't start from event number 0 + if (!isResetAfterAnalysis) { + // Check if we have a list for this choice number + // If not we create a new one for it + if (!backtrackMap.containsKey(conflictEventNumber)) { + backtrackChoiceLists = new LinkedList<>(); + backtrackMap.put(conflictEventNumber, backtrackChoiceLists); + } else { + backtrackChoiceLists = backtrackMap.get(conflictEventNumber); + } + int maxListLength = choiceUpperBound + 1; + int listLength = maxListLength - conflictEventNumber; + Integer[] newChoiceList = new Integer[listLength + 1]; + // Put the conflicting event numbers first and reverse the order + newChoiceList[0] = choices[currentChoice]; + newChoiceList[1] = choices[conflictEventNumber]; + // Put the rest of the event numbers into the array starting from the minimum to the upper bound + for (int i = conflictEventNumber + 1, j = 2; j < listLength; i++) { + if (choices[i] != choices[currentChoice]) { + newChoiceList[j] = choices[i]; + j++; + } + } + // Set the last element to '-1' as the end of the sequence + newChoiceList[newChoiceList.length - 1] = -1; + checkAndAddBacktrackList(backtrackChoiceLists, newChoiceList); + // The start index for the recursion is always 1 (from the main branch) + } else { // This is a sub-graph + // There is a case/bug that after a re-initialization, currCG is not yet initialized + if (currCG != null) { + int backtrackListIndex = cgMap.get(currCG); + backtrackChoiceLists = backtrackMap.get(backtrackListIndex); + int listLength = choices.length; + Integer[] newChoiceList = new Integer[listLength]; + // Copy everything before the conflict number + for (int i = 0; i < conflictEventNumber; i++) { + newChoiceList[i] = choices[i]; + } + // Put the conflicting events + newChoiceList[conflictEventNumber] = choices[currentChoice]; + newChoiceList[conflictEventNumber + 1] = choices[conflictEventNumber]; + // Copy the rest + for (int i = conflictEventNumber + 1, j = conflictEventNumber + 2; j < listLength - 1; i++) { + if (choices[i] != choices[currentChoice]) { + newChoiceList[j] = choices[i]; + j++; + } + } + // Set the last element to '-1' as the end of the sequence + newChoiceList[newChoiceList.length - 1] = -1; + checkAndAddBacktrackList(backtrackChoiceLists, newChoiceList); + } + } + } + + // We exclude fields that come from libraries (Java and Groovy), and also the infrastructure + private final static String[] EXCLUDED_FIELDS_STARTS_WITH_LIST = + // Java and Groovy libraries + { "java", "org", "sun", "com", "gov", "groovy"}; + private final static String[] EXCLUDED_FIELDS_ENDS_WITH_LIST = + // Groovy library created fields + {"stMC", "callSiteArray", "metaClass", "staticClassInfo", "__constructor__", + // Infrastructure + "sendEvent", "Object", "reference", "location", "app", "state", "log", "functionList", "objectList", + "eventList", "valueList", "settings", "printToConsole", "app1", "app2"}; + private final static String[] EXCLUDED_FIELDS_CONTAINS_LIST = {"_closure"}; + private final static String[] EXCLUDED_FIELDS_WRITE_INSTRUCTIONS_STARTS_WITH_LIST = {"Event"}; + + private boolean isFieldExcluded(String field) { + // Check against "starts-with" list + for(String str : EXCLUDED_FIELDS_STARTS_WITH_LIST) { + if (field.startsWith(str)) { + return true; + } + } + // Check against "ends-with" list + for(String str : EXCLUDED_FIELDS_ENDS_WITH_LIST) { + if (field.endsWith(str)) { + return true; + } + } + // Check against "contains" list + for(String str : EXCLUDED_FIELDS_CONTAINS_LIST) { + if (field.contains(str)) { + return true; + } + } + + return false; + } + + // This method checks whether a choice is reachable in the VOD graph from a reference choice + // This is a BFS search + private boolean isReachableInVODGraph(int checkedChoice, int referenceChoice) { + // Record visited choices as we search in the graph + HashSet visitedChoice = new HashSet<>(); + visitedChoice.add(referenceChoice); + LinkedList nodesToVisit = new LinkedList<>(); + // If the state doesn't advance as the threads/sub-programs are executed (basically there is no new state), + // there is a chance that the graph doesn't have new nodes---thus this check will return a null. + if (vodGraphMap.containsKey(referenceChoice)) { + nodesToVisit.addAll(vodGraphMap.get(referenceChoice)); + while(!nodesToVisit.isEmpty()) { + int currChoice = nodesToVisit.getFirst(); + if (currChoice == checkedChoice) { + return true; + } + if (visitedChoice.contains(currChoice)) { + // If there is a loop then we don't find it + return false; + } + // Continue searching + visitedChoice.add(currChoice); + HashSet currChoiceNextNodes = vodGraphMap.get(currChoice); + if (currChoiceNextNodes != null) { + // Add only if there is a mapping for next nodes + for (Integer nextNode : currChoiceNextNodes) { + nodesToVisit.addLast(nextNode); + } + } + } + } + return false; + } + + @Override + public void instructionExecuted(VM vm, ThreadInfo ti, Instruction nextInsn, Instruction executedInsn) { + if (stateReductionMode) { + if (isInitialized) { + if (choiceCounter > choices.length - 1) { + // We do not compute the conflicts for the choice '-1' + return; + } + int currentChoice = choiceCounter - 1; + // 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); + } + } + // Analyze conflicts from next instructions + if (nextInsn instanceof JVMFieldInstruction) { + // The constructor is only called once when the object is initialized + // It does not have shared access with other objects + MethodInfo mi = nextInsn.getMethodInfo(); + if (!mi.getName().equals("")) { + String fieldClass = ((JVMFieldInstruction) nextInsn).getFieldInfo().getFullName(); + // We don't care about libraries + if (!isFieldExcluded(fieldClass)) { + // Check for conflict (go backward from currentChoice and get the first conflict) + // If the current event has conflicts with multiple events, then these will be detected + // one by one as this recursively checks backward when backtrack set is revisited and executed. + for (int eventNumber = currentChoice - 1; eventNumber >= 0; eventNumber--) { + // Skip if this event number does not have any Read/Write set + if (!readWriteFieldsMap.containsKey(choices[eventNumber])) { + continue; + } + ReadWriteSet rwSet = readWriteFieldsMap.get(choices[eventNumber]); + int currObjId = ((JVMFieldInstruction) nextInsn).getFieldInfo().getClassInfo().getClassObjectRef(); + // 1) Check for conflicts with Write fields for both Read and Write instructions + if (((nextInsn instanceof WriteInstruction || nextInsn instanceof ReadInstruction) && + rwSet.writeFieldExists(fieldClass) && rwSet.writeFieldObjectId(fieldClass) == currObjId) || + (nextInsn instanceof WriteInstruction && rwSet.readFieldExists(fieldClass) && + rwSet.readFieldObjectId(fieldClass) == currObjId)) { + // We do not record and service the same backtrack pair/point twice! + // If it has been serviced before, we just skip this + if (recordConflictPair(currentChoice, eventNumber)) { + // Lines 4-8 of the algorithm in the paper page 11 (see the heading note above) + if (!visitedStateSet.contains(stateId)|| + (visitedStateSet.contains(stateId) && isReachableInVODGraph(choices[currentChoice], choices[currentChoice-1]))) { + createBacktrackChoiceList(currentChoice, eventNumber); + // Break if a conflict is found! + break; + } + } + } + } + } + } + } + } + } + } +}