tempest/src/generator/JaniNextStateGenerator.cpp

#include "src/generator/JaniNextStateGenerator.h"

#include "src/models/sparse/StateLabeling.h"

#include "src/storage/expressions/SimpleValuation.h"

#include "src/solver/SmtSolver.h"

#include "src/utility/constants.h"
#include "src/utility/macros.h"
#include "src/utility/solver.h"
#include "src/exceptions/InvalidSettingsException.h"
#include "src/exceptions/WrongFormatException.h"

namespace storm {
    namespace generator {
        
        template<typename ValueType, typename StateType>
        JaniNextStateGenerator<ValueType, StateType>::JaniNextStateGenerator(storm::jani::Model const& model, NextStateGeneratorOptions const& options) : JaniNextStateGenerator(model.substituteConstants(), options, false) {
            // Intentionally left empty.
        }
        
        template<typename ValueType, typename StateType>
        JaniNextStateGenerator<ValueType, StateType>::JaniNextStateGenerator(storm::jani::Model const& model, NextStateGeneratorOptions const& options, bool flag) : NextStateGenerator<ValueType, StateType>(model.getExpressionManager(), VariableInformation(model), options), model(model) {
            STORM_LOG_THROW(model.hasDefaultComposition(), storm::exceptions::WrongFormatException, "The explicit next-state generator currently does not support custom system compositions.");
            STORM_LOG_THROW(!this->options.isBuildAllRewardModelsSet() && this->options.getRewardModelNames().empty(), storm::exceptions::InvalidSettingsException, "The explicit next-state generator currently does not support building reward models.");
            STORM_LOG_THROW(!this->options.isBuildChoiceLabelsSet(), storm::exceptions::InvalidSettingsException, "JANI next-state generator cannot generate choice labels.");
            
            // If there are terminal states we need to handle, we now need to translate all labels to expressions.
            if (this->options.hasTerminalStates()) {
                for (auto const& expressionOrLabelAndBool : this->options.getTerminalStates()) {
                    if (expressionOrLabelAndBool.first.isExpression()) {
                        this->terminalStates.push_back(std::make_pair(expressionOrLabelAndBool.first.getExpression(), expressionOrLabelAndBool.second));
                    } else {
                        STORM_LOG_THROW(expressionOrLabelAndBool.first.getLabel() == "init" || expressionOrLabelAndBool.first.getLabel() == "deadlock", storm::exceptions::InvalidSettingsException, "Terminal states refer to illegal label '" << expressionOrLabelAndBool.first.getLabel() << "'.");
                    }
                }
            }
        }
        
        template<typename ValueType, typename StateType>
        ModelType JaniNextStateGenerator<ValueType, StateType>::getModelType() const {
            switch (model.getModelType()) {
                case storm::jani::ModelType::DTMC: return ModelType::DTMC;
                case storm::jani::ModelType::CTMC: return ModelType::CTMC;
                case storm::jani::ModelType::MDP: return ModelType::MDP;
                case storm::jani::ModelType::MA: return ModelType::MA;
                default:
                    STORM_LOG_THROW(false, storm::exceptions::WrongFormatException, "Invalid model type.");
            }
        }
        
        template<typename ValueType, typename StateType>
        bool JaniNextStateGenerator<ValueType, StateType>::isDeterministicModel() const {
            return model.isDeterministicModel();
        }
        
        template<typename ValueType, typename StateType>
        bool JaniNextStateGenerator<ValueType, StateType>::isDiscreteTimeModel() const {
            return model.isDiscreteTimeModel();
        }
        
        template<typename ValueType, typename StateType>
        uint64_t JaniNextStateGenerator<ValueType, StateType>::getLocation(CompressedState const& state, LocationVariableInformation const& locationVariable) const {
            if (locationVariable.bitWidth == 0) {
                return 0;
            } else {
                return state.getAsInt(locationVariable.bitOffset, locationVariable.bitWidth);
            }
        }
        
        template<typename ValueType, typename StateType>
        void JaniNextStateGenerator<ValueType, StateType>::setLocation(CompressedState& state, LocationVariableInformation const& locationVariable, uint64_t locationIndex) const {
            if (locationVariable.bitWidth != 0) {
                state.setFromInt(locationVariable.bitOffset, locationVariable.bitWidth, locationIndex);
            }
        }
        
        template<typename ValueType, typename StateType>
        std::vector<uint64_t> JaniNextStateGenerator<ValueType, StateType>::getLocations(CompressedState const& state) const {
            std::vector<uint64_t> result(this->variableInformation.locationVariables.size());
            
            auto resultIt = result.begin();
            for (auto it = this->variableInformation.locationVariables.begin(), ite = this->variableInformation.locationVariables.end(); it != ite; ++it, ++resultIt) {
                *resultIt = getLocation(state, *it);
            }
            
            return result;
        }
        
        template<typename ValueType, typename StateType>
        std::vector<StateType> JaniNextStateGenerator<ValueType, StateType>::getInitialStates(StateToIdCallback const& stateToIdCallback) {
            // Prepare an SMT solver to enumerate all initial states.
            storm::utility::solver::SmtSolverFactory factory;
            std::unique_ptr<storm::solver::SmtSolver> solver = factory.create(model.getExpressionManager());
            
            std::vector<storm::expressions::Expression> rangeExpressions = model.getAllRangeExpressions();
            for (auto const& expression : rangeExpressions) {
                solver->add(expression);
            }
            solver->add(model.getInitialStatesExpression(true));
            
            // Proceed as long as the solver can still enumerate initial states.
            std::vector<StateType> initialStateIndices;
            while (solver->check() == storm::solver::SmtSolver::CheckResult::Sat) {
                // Create fresh state.
                CompressedState initialState(this->variableInformation.getTotalBitOffset());
                
                // Read variable assignment from the solution of the solver. Also, create an expression we can use to
                // prevent the variable assignment from being enumerated again.
                storm::expressions::Expression blockingExpression;
                std::shared_ptr<storm::solver::SmtSolver::ModelReference> model = solver->getModel();
                for (auto const& booleanVariable : this->variableInformation.booleanVariables) {
                    bool variableValue = model->getBooleanValue(booleanVariable.variable);
                    storm::expressions::Expression localBlockingExpression = variableValue ? !booleanVariable.variable : booleanVariable.variable;
                    blockingExpression = blockingExpression.isInitialized() ? blockingExpression || localBlockingExpression : localBlockingExpression;
                    initialState.set(booleanVariable.bitOffset, variableValue);
                }
                for (auto const& integerVariable : this->variableInformation.integerVariables) {
                    int_fast64_t variableValue = model->getIntegerValue(integerVariable.variable);
                    storm::expressions::Expression localBlockingExpression = integerVariable.variable != model->getManager().integer(variableValue);
                    blockingExpression = blockingExpression.isInitialized() ? blockingExpression || localBlockingExpression : localBlockingExpression;
                    initialState.setFromInt(integerVariable.bitOffset, integerVariable.bitWidth, static_cast<uint_fast64_t>(variableValue - integerVariable.lowerBound));
                }
                
                // Gather iterators to the initial locations of all the automata.
                std::vector<std::set<uint64_t>::const_iterator> initialLocationsIterators;
                uint64_t currentLocationVariable = 0;
                for (auto const& automaton : this->model.getAutomata()) {
                    initialLocationsIterators.push_back(automaton.getInitialLocationIndices().cbegin());
                    
                    // Initialize the locations to the first possible combination.
                    setLocation(initialState, this->variableInformation.locationVariables[currentLocationVariable], *initialLocationsIterators.back());
                    ++currentLocationVariable;
                }
                
                // Now iterate through all combinations of initial locations.
                while (true) {
                    // Register initial state.
                    StateType id = stateToIdCallback(initialState);
                    initialStateIndices.push_back(id);
                    
                    uint64_t index = 0;
                    for (; index < initialLocationsIterators.size(); ++index) {
                        ++initialLocationsIterators[index];
                        if (initialLocationsIterators[index] == this->model.getAutomata()[index].getInitialLocationIndices().cend()) {
                            initialLocationsIterators[index] = this->model.getAutomata()[index].getInitialLocationIndices().cbegin();
                        } else {
                            break;
                        }
                    }
                    
                    // If we are at the end, leave the loop. Otherwise, create the next initial state.
                    if (index == initialLocationsIterators.size()) {
                        break;
                    } else {
                        for (uint64_t j = 0; j <= index; ++j) {
                            setLocation(initialState, this->variableInformation.locationVariables[j], *initialLocationsIterators[j]);
                        }
                    }
                }
                
                // Block the current initial state to search for the next one.
                solver->add(blockingExpression);
            }
            
            return initialStateIndices;
        }
        
        template<typename ValueType, typename StateType>
        CompressedState JaniNextStateGenerator<ValueType, StateType>::applyUpdate(CompressedState const& state, storm::jani::EdgeDestination const& destination) {
            CompressedState newState(state);
            
            // NOTE: the following process assumes that the assignments of the destination are ordered in such a way
            // that the assignments to boolean variables precede the assignments to all integer variables and that
            // within the types, the assignments to variables are ordered (in ascending order) by the expression variables.
            // This is guaranteed for JANI models, by sorting the assignments as soon as an edge destination is created.
            
            auto assignmentIt = destination.getAssignments().begin();
            auto assignmentIte = destination.getAssignments().end();
            
            // Iterate over all boolean assignments and carry them out.
            auto boolIt = this->variableInformation.booleanVariables.begin();
            for (; assignmentIt != assignmentIte && assignmentIt->getAssignedExpression().hasBooleanType(); ++assignmentIt) {
                while (assignmentIt->getExpressionVariable() != boolIt->variable) {
                    ++boolIt;
                }
                newState.set(boolIt->bitOffset, this->evaluator.asBool(assignmentIt->getAssignedExpression()));
            }
            
            // Iterate over all integer assignments and carry them out.
            auto integerIt = this->variableInformation.integerVariables.begin();
            for (; assignmentIt != assignmentIte && assignmentIt->getAssignedExpression().hasIntegerType(); ++assignmentIt) {
                while (assignmentIt->getExpressionVariable() != integerIt->variable) {
                    ++integerIt;
                }
                int_fast64_t assignedValue = this->evaluator.asInt(assignmentIt->getAssignedExpression());
                STORM_LOG_THROW(assignedValue <= integerIt->upperBound, storm::exceptions::WrongFormatException, "The update " << assignmentIt->getExpressionVariable().getName() << " := " << assignmentIt->getAssignedExpression() << " leads to an out-of-bounds value (" << assignedValue << ") for the variable '" << assignmentIt->getExpressionVariable().getName() << "'.");
                newState.setFromInt(integerIt->bitOffset, integerIt->bitWidth, assignedValue - integerIt->lowerBound);
                STORM_LOG_ASSERT(static_cast<int_fast64_t>(newState.getAsInt(integerIt->bitOffset, integerIt->bitWidth)) + integerIt->lowerBound == assignedValue, "Writing to the bit vector bucket failed (read " << newState.getAsInt(integerIt->bitOffset, integerIt->bitWidth) << " but wrote " << assignedValue << ").");
            }
            
            // Check that we processed all assignments.
            STORM_LOG_ASSERT(assignmentIt == assignmentIte, "Not all assignments were consumed.");
            
            return newState;
        }
        
        template<typename ValueType, typename StateType>
        StateBehavior<ValueType, StateType> JaniNextStateGenerator<ValueType, StateType>::expand(StateToIdCallback const& stateToIdCallback) {
            // Prepare the result, in case we return early.
            StateBehavior<ValueType, StateType> result;
            
            // If a terminal expression was set and we must not expand this state, return now.
            if (!this->terminalStates.empty()) {
                for (auto const& expressionBool : this->terminalStates) {
                    if (this->evaluator.asBool(expressionBool.first) == expressionBool.second) {
                        return result;
                    }
                }
            }
            
            // Retrieve the locations from the state.
            std::vector<uint64_t> locations = getLocations(*this->state);
            
            // Get all choices for the state.
            std::vector<Choice<ValueType>> allChoices = getSilentActionChoices(locations, *this->state, stateToIdCallback);
            std::vector<Choice<ValueType>> allLabeledChoices = getNonsilentActionChoices(locations, *this->state, stateToIdCallback);
            for (auto& choice : allLabeledChoices) {
                allChoices.push_back(std::move(choice));
            }
            
            std::size_t totalNumberOfChoices = allChoices.size();
            
            // If there is not a single choice, we return immediately, because the state has no behavior (other than
            // the state reward).
            if (totalNumberOfChoices == 0) {
                return result;
            }
            
            // If the model is a deterministic model, we need to fuse the choices into one.
            if (this->isDeterministicModel() && totalNumberOfChoices > 1) {
                Choice<ValueType> globalChoice;
                
                // Iterate over all choices and combine the probabilities/rates into one choice.
                for (auto const& choice : allChoices) {
                    for (auto const& stateProbabilityPair : choice) {
                        if (this->isDiscreteTimeModel()) {
                            globalChoice.addProbability(stateProbabilityPair.first, stateProbabilityPair.second / totalNumberOfChoices);
                        } else {
                            globalChoice.addProbability(stateProbabilityPair.first, stateProbabilityPair.second);
                        }
                    }
                    
                    if (this->options.isBuildChoiceLabelsSet()) {
                        globalChoice.addChoiceLabels(choice.getChoiceLabels());
                    }
                }
                
                // Move the newly fused choice in place.
                allChoices.clear();
                allChoices.push_back(std::move(globalChoice));
            }
            
            // Move all remaining choices in place.
            for (auto& choice : allChoices) {
                result.addChoice(std::move(choice));
            }
            
            result.setExpanded();
            return result;
        }
        
        template<typename ValueType, typename StateType>
        std::vector<Choice<ValueType>> JaniNextStateGenerator<ValueType, StateType>::getSilentActionChoices(std::vector<uint64_t> const& locations, CompressedState const& state, StateToIdCallback stateToIdCallback) {
            std::vector<Choice<ValueType>> result;
            
            // Iterate over all automata.
            uint64_t automatonIndex = 0;
            for (auto const& automaton : model.getAutomata()) {
                uint64_t location = locations[automatonIndex];
                
                // Iterate over all edges from the source location.
                for (auto const& edge : automaton.getEdgesFromLocation(location)) {
                    // Skip the edge if it is labeled with a non-silent action.
                    if (edge.getActionIndex() != model.getSilentActionIndex()) {
                        continue;
                    }
                    
                    // Skip the command, if it is not enabled.
                    if (!this->evaluator.asBool(edge.getGuard())) {
                        continue;
                    }
                    
                    result.push_back(Choice<ValueType>(edge.getActionIndex()));
                    Choice<ValueType>& choice = result.back();
                    
                    // Iterate over all updates of the current command.
                    ValueType probabilitySum = storm::utility::zero<ValueType>();
                    for (auto const& destination : edge.getDestinations()) {
                        // Obtain target state index and add it to the list of known states. If it has not yet been
                        // seen, we also add it to the set of states that have yet to be explored.
                        StateType stateIndex = stateToIdCallback(applyUpdate(state, destination));
                        
                        // Update the choice by adding the probability/target state to it.
                        ValueType probability = this->evaluator.asRational(destination.getProbability());
                        choice.addProbability(stateIndex, probability);
                        probabilitySum += probability;
                    }
                    
                    // Check that the resulting distribution is in fact a distribution.
                    STORM_LOG_THROW(!this->isDiscreteTimeModel() || this->comparator.isOne(probabilitySum), storm::exceptions::WrongFormatException, "Probabilities do not sum to one for edge (actually sum to " << probabilitySum << ").");
                }
                
                ++automatonIndex;
            }
            
            return result;
        }
        
        template<typename ValueType, typename StateType>
        std::vector<Choice<ValueType>> JaniNextStateGenerator<ValueType, StateType>::getNonsilentActionChoices(std::vector<uint64_t> const& locations, CompressedState const& state, StateToIdCallback stateToIdCallback) {
            std::vector<Choice<ValueType>> result;
            
            for (uint64_t actionIndex : model.getNonsilentActionIndices()) {
                std::vector<std::vector<storm::jani::Edge const*>> enabledEdges = getEnabledEdges(locations, actionIndex);
                
                // Only process this action, if there is at least one feasible solution.
                if (!enabledEdges.empty()) {
                    // Check whether a global variable is written multiple times in any combination.
                    checkGlobalVariableWritesValid(enabledEdges);
                    
                    std::vector<std::vector<storm::jani::Edge const*>::const_iterator> iteratorList(enabledEdges.size());
                    
                    // Initialize the list of iterators.
                    for (size_t i = 0; i < enabledEdges.size(); ++i) {
                        iteratorList[i] = enabledEdges[i].cbegin();
                    }
                    
                    // As long as there is one feasible combination of commands, keep on expanding it.
                    bool done = false;
                    while (!done) {
                        boost::container::flat_map<CompressedState, ValueType>* currentTargetStates = new boost::container::flat_map<CompressedState, ValueType>();
                        boost::container::flat_map<CompressedState, ValueType>* newTargetStates = new boost::container::flat_map<CompressedState, ValueType>();
                        
                        currentTargetStates->emplace(state, storm::utility::one<ValueType>());
                        
                        for (uint_fast64_t i = 0; i < iteratorList.size(); ++i) {
                            storm::jani::Edge const& edge = **iteratorList[i];
                            
                            for (auto const& destination : edge.getDestinations()) {
                                for (auto const& stateProbabilityPair : *currentTargetStates) {
                                    // Compute the new state under the current update and add it to the set of new target states.
                                    CompressedState newTargetState = applyUpdate(stateProbabilityPair.first, destination);
                                    
                                    // If the new state was already found as a successor state, update the probability
                                    // and otherwise insert it.
                                    auto targetStateIt = newTargetStates->find(newTargetState);
                                    if (targetStateIt != newTargetStates->end()) {
                                        targetStateIt->second += stateProbabilityPair.second * this->evaluator.asRational(destination.getProbability());
                                    } else {
                                        newTargetStates->emplace(newTargetState, stateProbabilityPair.second * this->evaluator.asRational(destination.getProbability()));
                                    }
                                }
                            }
                            
                            // If there is one more command to come, shift the target states one time step back.
                            if (i < iteratorList.size() - 1) {
                                delete currentTargetStates;
                                currentTargetStates = newTargetStates;
                                newTargetStates = new boost::container::flat_map<CompressedState, ValueType>();
                            }
                        }
                        
                        // At this point, we applied all commands of the current command combination and newTargetStates
                        // contains all target states and their respective probabilities. That means we are now ready to
                        // add the choice to the list of transitions.
                        result.push_back(Choice<ValueType>(actionIndex));
                        
                        // Now create the actual distribution.
                        Choice<ValueType>& choice = result.back();
                        
                        // Add the probabilities/rates to the newly created choice.
                        ValueType probabilitySum = storm::utility::zero<ValueType>();
                        for (auto const& stateProbabilityPair : *newTargetStates) {
                            StateType actualIndex = stateToIdCallback(stateProbabilityPair.first);
                            choice.addProbability(actualIndex, stateProbabilityPair.second);
                            probabilitySum += stateProbabilityPair.second;
                        }
                        
                        // Check that the resulting distribution is in fact a distribution.
                        STORM_LOG_THROW(!this->isDiscreteTimeModel() || !this->comparator.isConstant(probabilitySum) || this->comparator.isOne(probabilitySum), storm::exceptions::WrongFormatException, "Sum of update probabilities do not some to one for some command (actually sum to " << probabilitySum << ").");
                        
                        // Dispose of the temporary maps.
                        delete currentTargetStates;
                        delete newTargetStates;
                        
                        // Now, check whether there is one more command combination to consider.
                        bool movedIterator = false;
                        for (uint64_t j = 0; !movedIterator && j < iteratorList.size(); ++j) {
                            ++iteratorList[j];
                            if (iteratorList[j] != enabledEdges[j].end()) {
                                movedIterator = true;
                            } else {
                                // Reset the iterator to the beginning of the list.
                                iteratorList[j] = enabledEdges[j].begin();
                            }
                        }
                        
                        done = !movedIterator;
                    }
                }
            }
            
            return result;
        }
        
        template<typename ValueType, typename StateType>
        std::vector<std::vector<storm::jani::Edge const*>> JaniNextStateGenerator<ValueType, StateType>::getEnabledEdges(std::vector<uint64_t> const& locationIndices, uint64_t actionIndex) {
            std::vector<std::vector<storm::jani::Edge const*>> result;
            
            // Iterate over all automata.
            uint64_t automatonIndex = 0;
            for (auto const& automaton : model.getAutomata()) {
                
                // If the automaton has no edge labeled with the given action, we can skip it.
                if (!automaton.hasEdgeLabeledWithActionIndex(actionIndex)) {
                    continue;
                }
                
                auto edges = automaton.getEdgesFromLocation(locationIndices[automatonIndex], actionIndex);
                
                // If the automaton contains the action, but there is no edge available labeled with
                // this action, we don't have any feasible command combinations.
                if (edges.empty()) {
                    return std::vector<std::vector<storm::jani::Edge const*>>();
                }
                
                std::vector<storm::jani::Edge const*> edgePointers;
                for (auto const& edge : edges) {
                    if (this->evaluator.asBool(edge.getGuard())) {
                        edgePointers.push_back(&edge);
                    }
                }
                
                // If there was no enabled edge although the automaton has some edge with the required action, we must
                // not return anything.
                if (edgePointers.empty()) {
                    return std::vector<std::vector<storm::jani::Edge const*>>();
                }
                
                result.emplace_back(std::move(edgePointers));
                ++automatonIndex;
            }
            
            return result;
        }
        
        template<typename ValueType, typename StateType>
        void JaniNextStateGenerator<ValueType, StateType>::checkGlobalVariableWritesValid(std::vector<std::vector<storm::jani::Edge const*>> const& enabledEdges) const {
            std::map<storm::expressions::Variable, uint64_t> writtenGlobalVariables;
            for (auto edgeSetIt = enabledEdges.begin(), edgeSetIte = enabledEdges.end(); edgeSetIt != edgeSetIte; ++edgeSetIt) {
                for (auto const& edge : *edgeSetIt) {
                    for (auto const& globalVariable : edge->getWrittenGlobalVariables()) {
                        auto it = writtenGlobalVariables.find(globalVariable);
                        
                        auto index = std::distance(enabledEdges.begin(), edgeSetIt);
                        if (it != writtenGlobalVariables.end()) {
                            STORM_LOG_THROW(it->second == index, storm::exceptions::WrongFormatException, "Multiple writes to global variable '" << globalVariable.getName() << "' in synchronizing edges.");
                        } else {
                            writtenGlobalVariables.emplace(globalVariable, index);
                        }
                    }
                }
            }
        }
        
        template<typename ValueType, typename StateType>
        std::size_t JaniNextStateGenerator<ValueType, StateType>::getNumberOfRewardModels() const {
            return 0;
        }
        
        template<typename ValueType, typename StateType>
        RewardModelInformation JaniNextStateGenerator<ValueType, StateType>::getRewardModelInformation(uint64_t const& index) const {
            STORM_LOG_THROW(false, storm::exceptions::InvalidSettingsException, "Cannot retrieve reward model information.");
            return RewardModelInformation("", false, false, false);
        }
        
        template<typename ValueType, typename StateType>
        storm::models::sparse::StateLabeling JaniNextStateGenerator<ValueType, StateType>::label(storm::storage::BitVectorHashMap<StateType> const& states, std::vector<StateType> const& initialStateIndices, std::vector<StateType> const& deadlockStateIndices) {
            return NextStateGenerator<ValueType, StateType>::label(states, initialStateIndices, deadlockStateIndices, {});
        }
        
        template class JaniNextStateGenerator<double>;
        template class JaniNextStateGenerator<storm::RationalNumber>;
        template class JaniNextStateGenerator<storm::RationalFunction>;
        
    }
}