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/*
* PathBasedSubsystemGenerator.h
*
* Created on: 11.10.2013
* Author: Manuel Sascha Weiand
*/
#ifndef STORM_COUNTEREXAMPLES_PATHBASEDSUBSYSTEMGENERATOR_H_
#define STORM_COUNTEREXAMPLES_PATHBASEDSUBSYSTEMGENERATOR_H_
#include "src/models/Dtmc.h"
#include "src/models/AbstractModel.h"
#include "src/modelchecker/prctl/SparseDtmcPrctlModelChecker.h"
#include "src/solver/GmmxxLinearEquationSolver.h"
#include "src/storage/BitVector.h"
#include "src/storage/SparseMatrix.h"
#include "log4cplus/logger.h"
#include "log4cplus/loggingmacros.h"
extern log4cplus::Logger logger;
namespace storm {
namespace counterexamples {
template <class T>
class PathBasedSubsystemGenerator {
private:
template <class CompareType>
class CompareStates {
public:
bool operator()(const std::pair<uint_fast64_t, CompareType>& s1, const std::pair<uint_fast64_t, CompareType>& s2) {
return s1.second < s2.second;
}
};
public:
/*!
*
*/
static void computeShortestDistances(storm::storage::SparseMatrix<T> const& transMat, storm::storage::BitVector& subSysStates, storm::storage::BitVector& terminalStates, storm::storage::BitVector& allowedStates, std::vector<std::pair<uint_fast64_t, T>>& distances) {
std::multiset<std::pair<uint_fast64_t, T>, CompareStates<T> > activeSet;
//std::priority_queue<std::pair<uint_fast64_t, T*>, std::vector<std::pair<uint_fast64_t, T*>>, CompareStates<T> > queue;
// resize and init distances
const std::pair<uint_fast64_t, T> initDistances(0, (T) -1);
distances.resize(transMat.getColumnCount(), initDistances);
//since gcc 4.7.2 does not implement std::set::emplace(), insert is used.
std::pair<uint_fast64_t, T> state;
// First store all transitions from initial states
// Also save all found initial states in array of discovered states.
for(auto init : subSysStates) {
//use init state only if it is allowed
if(allowedStates.get(init)) {
if(terminalStates.get(init)) {
// it's an init -> target search
// save target state as discovered and get it's outgoing transitions
distances[init].first = init;
distances[init].second = (T) 1;
}
for(auto const& trans : transMat.getRow(init)) {
//save transition only if it's no 'virtual transition of prob 0 and it doesn't go from init state to init state.
if(trans.getValue() != (T) 0 && !subSysStates.get(trans.getColumn())) {
//new state?
if(distances[trans.getColumn()].second == (T) -1) {
distances[trans.getColumn()].first = init;
distances[trans.getColumn()].second = trans.getValue();
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), distances[trans.getColumn()].second));
}
else if(distances[trans.getColumn()].second < trans.getValue()){
//This state has already been discovered
//And the distance can be improved by using this transition.
//find state in set, remove it, reenter it with new and correct values.
auto range = activeSet.equal_range(std::pair<uint_fast64_t, T>(trans.getColumn(), distances[trans.getColumn()].second));
for(;range.first != range.second; range.first++) {
if(trans.getColumn() == range.first->first) {
activeSet.erase(range.first);
break;
}
}
distances[trans.getColumn()].first = init;
distances[trans.getColumn()].second = trans.getValue();
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), trans.getValue()));
}
}
}
}
}
LOG4CPLUS_DEBUG(logger, "Initialized.");
//Now find the shortest distances to all states
while(!activeSet.empty()) {
// copy here since using a reference leads to segfault
std::pair<uint_fast64_t, T> activeState = *(--activeSet.end());
activeSet.erase(--activeSet.end());
// If this is an initial state, do not consider its outgoing transitions, since all relevant ones have already been considered
// Same goes for forbidden states since they may not be used on a path, except as last node.
if(!subSysStates.get(activeState.first) && allowedStates.get(activeState.first)) {
// Look at all neighbors
for(auto const& trans : transMat.getRow(activeState.first)) {
// Only consider the transition if it's not virtual
if(trans.getValue() != (T) 0) {
T distance = activeState.second * trans.getValue();
//not discovered or initial terminal state
if(distances[trans.getColumn()].second == (T)-1) {
//New state discovered -> save it
distances[trans.getColumn()].first = activeState.first;
distances[trans.getColumn()].second = distance;
// push newly discovered state into activeSet
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), distance));
}
else if(distances[trans.getColumn()].second < distance) {
//This state has already been discovered
//And the distance can be improved by using this transition.
//find state in set, remove it, reenter it with new and correct values.
auto range = activeSet.equal_range(std::pair<uint_fast64_t, T>(trans.getColumn(), distances[trans.getColumn()].second));
for(;range.first != range.second; range.first++) {
if(trans.getColumn() == range.first->first) {
activeSet.erase(range.first);
break;
}
}
distances[trans.getColumn()].first = activeState.first;
distances[trans.getColumn()].second = distance;
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), distance));
}
}
}
}
}
LOG4CPLUS_DEBUG(logger, "Discovery done.");
}
/*!
*
*/
static void doDijkstraSearch(storm::storage::SparseMatrix<T> const& transMat, storm::storage::BitVector& subSysStates, storm::storage::BitVector& terminalStates, storm::storage::BitVector& allowedStates, std::vector<std::pair<uint_fast64_t, T>>& itDistances, std::vector<std::pair<uint_fast64_t, T>>& distances) {
std::multiset<std::pair<uint_fast64_t, T>, CompareStates<T> > activeSet;
// resize and init distances
const std::pair<uint_fast64_t, T> initDistances(0, (T) -1);
distances.resize(transMat.getColumnCount(), initDistances);
//since gcc 4.7.2 does not implement std::set::emplace(), insert is used.
std::pair<uint_fast64_t, T> state;
// First store all transitions from initial states
// Also save all found initial states in array of discovered states.
for(auto init : subSysStates) {
//use init state only if it is allowed
if(allowedStates.get(init)) {
if(terminalStates.get(init)) {
// it's a subsys -> subsys search
// ignore terminal state completely
// (since any target state that is only reached by a path going through this state should not be reached)
continue;
}
for(auto const& trans : transMat.getRow(init)) {
//save transition only if it's no 'virtual transition of prob 0 and it doesn't go from init state to init state.
if(trans.getValue() != (T) 0 && !subSysStates.get(trans.getColumn())) {
//new state?
if(distances[trans.getColumn()].second == (T) -1) {
//for initialization of subsys -> subsys search use prob (init -> subsys state -> found state) instead of prob(subsys state -> found state)
distances[trans.getColumn()].first = init;
distances[trans.getColumn()].second = trans.getValue() * (itDistances[init].second == -1 ? 1 : itDistances[init].second);
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), distances[trans.getColumn()].second));
}
else if(distances[trans.getColumn()].second < trans.getValue() * itDistances[init].second){
//This state has already been discovered
//And the distance can be improved by using this transition.
//find state in set, remove it, reenter it with new and correct values.
auto range = activeSet.equal_range(std::pair<uint_fast64_t, T>(trans.getColumn(), distances[trans.getColumn()].second));
for(;range.first != range.second; range.first++) {
if(trans.getColumn() == range.first->first) {
activeSet.erase(range.first);
break;
}
}
//for initialization of subsys -> subsys search use prob (init -> subsys state -> found state) instead of prob(subsys state -> found state)
distances[trans.getColumn()].first = init;
distances[trans.getColumn()].second = trans.getValue() * (itDistances[init].second == -1 ? 1 : itDistances[init].second);
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), trans.getValue()));
}
}
}
}
}
LOG4CPLUS_DEBUG(logger, "Initialized.");
//Now find the shortest distances to all states
while(!activeSet.empty()) {
// copy here since using a reference leads to segfault
std::pair<uint_fast64_t, T> activeState = *(--activeSet.end());
activeSet.erase(--activeSet.end());
// Always stop at first target/terminal state
//if(terminalStates.get(activeState.getColumn()) || subSysStates.get(activeState.getColumn())) break;
// If this is an initial state, do not consider its outgoing transitions, since all relevant ones have already been considered
// Same goes for forbidden states since they may not be used on a path, except as last node.
if(!subSysStates.get(activeState.first) && allowedStates.get(activeState.first)) {
// Look at all neighbors
for(auto const& trans : transMat.getRow(activeState.first)) {
// Only consider the transition if it's not virtual
if(trans.getValue() != (T) 0) {
T distance = activeState.second * trans.getValue();
//not discovered or initial terminal state
if(distances[trans.getColumn()].second == (T)-1) {
//New state discovered -> save it
distances[trans.getColumn()].first = activeState.first;
distances[trans.getColumn()].second = distance;
// push newly discovered state into activeSet
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), distance));
}
else if(distances[trans.getColumn()].second < distance) {
//This state has already been discovered
//And the distance can be improved by using this transition.
//find state in set, remove it, reenter it with new and correct values.
auto range = activeSet.equal_range(std::pair<uint_fast64_t, T>(trans.getColumn(), distances[trans.getColumn()].second));
for(;range.first != range.second; range.first++) {
if(trans.getColumn() == range.first->first) {
activeSet.erase(range.first);
break;
}
}
distances[trans.getColumn()].first = activeState.first;
distances[trans.getColumn()].second = distance;
activeSet.insert(std::pair<uint_fast64_t, T>(trans.getColumn(), distance));
}
}
}
}
}
LOG4CPLUS_DEBUG(logger, "Discovery done.");
}
/*!
*
*/
static void findShortestPath(storm::storage::SparseMatrix<T> const& transMat, storm::storage::BitVector& subSysStates, storm::storage::BitVector& terminalStates, storm::storage::BitVector& allowedStates, std::vector<std::pair<uint_fast64_t, T>>& itDistances, std::vector<uint_fast64_t>& shortestPath, T& probability) {
//Do Dijksta to find the shortest path from init states to all states
std::vector<std::pair<uint_fast64_t, T>> distances;
doDijkstraSearch(transMat, subSysStates, terminalStates, allowedStates, itDistances, distances);
// Then get the shortest of them
extractShortestPath(subSysStates, terminalStates, distances, itDistances, shortestPath, probability,false);
}
/*!
* Only initialized distances vector!
*/
static void extractShortestPath(storm::storage::BitVector& subSysStates, storm::storage::BitVector& terminalStates, std::vector<std::pair<uint_fast64_t, T>>& distances, std::vector<std::pair<uint_fast64_t, T>>& itDistances, std::vector<uint_fast64_t>& shortestPath, T& probability, bool stopAtFirstTarget = true, bool itSearch = false) {
//Find terminal state of best distance
uint_fast64_t bestIndex = 0;
T bestValue = (T) 0;
for(auto term : terminalStates) {
//the terminal state might not have been found if it is in a system of forbidden states
if(distances[term].second != -1 && distances[term].second > bestValue){
bestIndex = term;
bestValue = distances[term].second;
//if set, stop since the first target that is not null was the only one found
if(stopAtFirstTarget) break;
}
}
if(!itSearch) {
// it's a subSys->subSys search. So target states are terminals and subsys states
for(auto term : subSysStates) {
//the terminal state might not have been found if it is in a system of forbidden states
if(distances[term].second != -1 && distances[term].second > bestValue){
bestIndex = term;
bestValue = distances[term].second;
//if set, stop since the first target that is not null was the only one found
if(stopAtFirstTarget) break;
}
}
}
//safety test: is the best terminal state viable?
if(distances[bestIndex].second == (T) -1){
shortestPath.push_back(bestIndex);
probability = (T) 0;
LOG4CPLUS_DEBUG(logger, "Terminal state not viable!");
return;
}
// save the probability to reach the state via the shortest path
probability = distances[bestIndex].second;
//Reconstruct shortest path. Notice that the last state of the path might be an initState.
//There might be a chain of terminal states with 1.0 transitions at the end of the path
while(terminalStates.get(distances[bestIndex].first)) {
bestIndex = distances[bestIndex].first;
}
LOG4CPLUS_DEBUG(logger, "Found best state: " << bestIndex);
LOG4CPLUS_DEBUG(logger, "Value: " << bestValue);
shortestPath.push_back(bestIndex);
bestIndex = distances[bestIndex].first;
while(!subSysStates.get(bestIndex)) {
shortestPath.push_back(bestIndex);
bestIndex = distances[bestIndex].first;
}
shortestPath.push_back(bestIndex);
//At last compensate for the distance between init and source state
probability = itSearch ? probability : probability / itDistances[bestIndex].first;
}
private:
template <typename Type>
struct transition {
uint_fast64_t source;
Type prob;
uint_fast64_t target;
};
template <class CompareType>
class CompareTransitions {
public:
bool operator()(transition<CompareType>& t1, transition<CompareType>& t2) {
return t1.prob < t2.prob;
}
};
public:
/*!
*
*/
static storm::models::Dtmc<T> computeCriticalSubsystem(storm::models::Dtmc<T> & model, std::shared_ptr<storm::properties::prctl::AbstractStateFormula<T>> const & stateFormula) {
//-------------------------------------------------------------
// 1. Strip and handle formulas
//-------------------------------------------------------------
#ifdef BENCHMARK
LOG4CPLUS_INFO(logger, "Formula: " << stateFormula.toString());
#endif
LOG4CPLUS_INFO(logger, "Start finding critical subsystem.");
// make model checker
// TODO: Implement and use generic Model Checker factory.
storm::modelchecker::prctl::SparseDtmcPrctlModelChecker<T> modelCheck {model, new storm::solver::GmmxxLinearEquationSolver<T>()};
// init bit vector to contain the subsystem
storm::storage::BitVector subSys(model.getNumberOfStates());
// Strip bound operator
std::shared_ptr<storm::properties::prctl::ProbabilisticBoundOperator<T>> boundOperator = std::dynamic_pointer_cast<storm::properties::prctl::ProbabilisticBoundOperator<T>>(stateFormula);
if(boundOperator == nullptr){
LOG4CPLUS_ERROR(logger, "No path bound operator at formula root.");
return model.getSubDtmc(subSys);
}
T bound = boundOperator->getBound();
std::shared_ptr<storm::properties::prctl::AbstractPathFormula<T>> pathFormula = boundOperator->getChild();
// get "init" labeled states
storm::storage::BitVector initStates = model.getStates("init");
//get real prob for formula
logger.getAppender("mainFileAppender")->setThreshold(log4cplus::WARN_LOG_LEVEL);
std::vector<T> trueProbs = pathFormula->check(modelCheck, false);
logger.getAppender("mainFileAppender")->setThreshold(log4cplus::INFO_LOG_LEVEL);
T trueProb = 0;
for(auto index : initStates) {
trueProb += trueProbs[index];
}
trueProb /= initStates.getNumberOfSetBits();
//std::cout << "True Prob: " << trueProb << std::endl;
// get allowed and target states
storm::storage::BitVector allowedStates;
storm::storage::BitVector targetStates;
std::shared_ptr<storm::properties::prctl::Eventually<T>> eventually = std::dynamic_pointer_cast<storm::properties::prctl::Eventually<T>>(pathFormula);
std::shared_ptr<storm::properties::prctl::Globally<T>> globally = std::dynamic_pointer_cast<storm::properties::prctl::Globally<T>>(pathFormula);
std::shared_ptr<storm::properties::prctl::Until<T>> until = std::dynamic_pointer_cast<storm::properties::prctl::Until<T>>(pathFormula);
if(eventually.get() != nullptr) {
targetStates = eventually->getChild()->check(modelCheck);
allowedStates = storm::storage::BitVector(targetStates.size(), true);
}
else if(globally.get() != nullptr){
// eventually reaching a state without property visiting only states with property
allowedStates = globally->getChild()->check(modelCheck);
targetStates = storm::storage::BitVector(allowedStates);
targetStates.complement();
}
else if(until.get() != nullptr) {
allowedStates = until->getLeft()->check(modelCheck);
targetStates = until->getRight()->check(modelCheck);
}
else {
LOG4CPLUS_ERROR(logger, "Strange path formula. Can't decipher.");
return model.getSubDtmc(subSys);
}
//-------------------------------------------------------------
// 2. Precomputations for heuristics
//-------------------------------------------------------------
// estimate the path count using the models state count as well as the probability bound
uint_fast8_t const minPrec = 10;
uint_fast64_t const stateCount = model.getNumberOfStates();
uint_fast64_t const stateEstimate = static_cast<uint_fast64_t>((static_cast<T>(stateCount)) * bound);
// since this only has a good effect on big models -> use only if model has at least 10^5 states
uint_fast64_t precision = stateEstimate > 100000 ? stateEstimate/1000 : minPrec;
//-------------------------------------------------------------
// 3. Subsystem generation
//-------------------------------------------------------------
// Search from init to target states until the shortest path for each target state is reached.
std::vector<uint_fast64_t> shortestPath;
std::vector<T> subSysProbs;
T pathProb = 0;
T subSysProb = 0;
uint_fast64_t pathCount = 0;
uint_fast64_t mcCount = 0;
// First test if there are init states that are also target states.
// If so the init state represents a subsystem with probability mass 1.
// -> return it
if((initStates & targetStates).getNumberOfSetBits() != 0) {
subSys.set(*(initStates & targetStates).begin());
LOG4CPLUS_INFO(logger, "Critical subsystem found.");
LOG4CPLUS_INFO(logger, "Paths needed: " << pathCount);
LOG4CPLUS_INFO(logger, "State count of critical subsystem: " << subSys.getNumberOfSetBits());
LOG4CPLUS_INFO(logger, "Prob: " << 1);
LOG4CPLUS_INFO(logger, "Model checks: " << mcCount);
return model.getSubDtmc(subSys);
}
// Then compute the shortest paths from init states to all target states
std::vector<std::pair<uint_fast64_t, T>> initTargetDistances;
computeShortestDistances(model.getTransitionMatrix(), initStates, targetStates, allowedStates, initTargetDistances);
pathProb = 0;
extractShortestPath(initStates, targetStates, initTargetDistances, initTargetDistances, shortestPath, pathProb, false, true);
// push states of found path into subsystem
for(auto index : shortestPath) {
subSys.set(index, true);
}
pathCount++;
// Get estimate (upper bound) of new sub system probability
// That is: prob(target) * cost(path) * (mean(prob(inits))/prob(source))
subSysProb += trueProbs[shortestPath[0]] * pathProb * trueProb / trueProbs[shortestPath.back()];
//find new nodes until the system becomes critical.
while(true) {
shortestPath.clear();
pathProb = 0;
findShortestPath(model.getTransitionMatrix(), subSys, targetStates, allowedStates, initTargetDistances, shortestPath, pathProb);
//doBackwardsSearch(*model->getTransitionMatrix(), *initStates, subSys, targetStates, allowedStates, trueProbs, shortestPath, pathProb);
pathCount++;
// merge found states into subsystem
for(uint_fast32_t i = 0; i < shortestPath.size(); i++) {
subSys.set(shortestPath[i], true);
}
// Get estimate (upper bound) of new sub system probability
// That is: prob(target) * cost(path) * (mean(prob(inits))/prob(source))
//subSysProb += (trueProbs[shortestPath.back()] == 0 ? 0 : trueProbs[shortestPath[0]] * pathProb * trueProb / trueProbs[shortestPath.back()]);
subSysProb += 1*(trueProbs[shortestPath.back()] == 0 ? 1 : trueProbs[shortestPath[0]] * pathProb == 0 ? 1 : pathProb );
//std::cout << "Est. prob: " << subSysProb << std::endl;
// Do we want to model check?
if((pathCount % precision == 0) && subSysProb >= bound) {
//get probabilities
logger.getAppender("mainFileAppender")->setThreshold(log4cplus::WARN_LOG_LEVEL);
subSysProbs = modelCheck.checkUntil(allowedStates & subSys, targetStates & subSys, false);
logger.getAppender("mainFileAppender")->setThreshold(log4cplus::INFO_LOG_LEVEL);
//T diff = subSysProb;
//std::cout << "Est. prob: " << diff << std::endl;
// reset sub system prob to correct value
subSysProb = 0;
for(auto index : initStates) {
subSysProb += subSysProbs[index];
}
subSysProb /= initStates.getNumberOfSetBits();
mcCount++;
//diff -= subSysProb;
//std::cout << "Real prob: " << subSysProb << std::endl;
//std::cout << "Diff: " << diff << std::endl;
//std::cout << "Path count: " << pathCount << std::endl;
// Are we critical?
if(subSysProb >= bound){
break;
} else if (stateEstimate > 100000){
precision = static_cast<uint_fast64_t>((stateEstimate / 1000.0) - ((stateEstimate / 1000.0) - minPrec) * (subSysProb/bound));
}
}
}
LOG4CPLUS_INFO(logger, "Critical subsystem found.");
LOG4CPLUS_INFO(logger, "Paths needed: " << pathCount);
LOG4CPLUS_INFO(logger, "State count of critical subsystem: " << subSys.getNumberOfSetBits());
LOG4CPLUS_INFO(logger, "Prob: " << subSysProb);
LOG4CPLUS_INFO(logger, "Model checks: " << mcCount);
return model.getSubDtmc(subSys);
}
};
} // namespace counterexamples
} // namespace storm
#endif /* STORM_COUNTEREXAMPLES_PATHBASEDSUBSYSTEMGENERATOR_H_ */