X-Git-Url: http://bilbo.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/96d605fde63f72480bf570f7bc7609e2954cb2d7..0f0aacb167ddc9427ea1da1c8f1b66ef2d6f532e:/src/mc/explo/DFSExplorer.cpp diff --git a/src/mc/explo/DFSExplorer.cpp b/src/mc/explo/DFSExplorer.cpp index 1d429a2f24..180fe70b16 100644 --- a/src/mc/explo/DFSExplorer.cpp +++ b/src/mc/explo/DFSExplorer.cpp @@ -1,313 +1,479 @@ -/* Copyright (c) 2016-2022. The SimGrid Team. All rights reserved. */ +/* Copyright (c) 2016-2023. The SimGrid Team. All rights reserved. */ /* This program is free software; you can redistribute it and/or modify it * under the terms of the license (GNU LGPL) which comes with this package. */ #include "src/mc/explo/DFSExplorer.hpp" -#include "src/mc/VisitedState.hpp" #include "src/mc/mc_config.hpp" #include "src/mc/mc_exit.hpp" #include "src/mc/mc_private.hpp" #include "src/mc/mc_record.hpp" +#include "src/mc/remote/mc_protocol.h" #include "src/mc/transition/Transition.hpp" -#include "src/xbt/mmalloc/mmprivate.h" +#include "xbt/asserts.h" #include "xbt/log.h" +#include "xbt/string.hpp" #include "xbt/sysdep.h" #include #include +#include #include #include +#include #include XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dfs, mc, "DFS exploration algorithm of the model-checker"); namespace simgrid::mc { -xbt::signal DFSExplorer::on_exploration_start_signal; -xbt::signal DFSExplorer::on_backtracking_signal; +xbt::signal DFSExplorer::on_exploration_start_signal; +xbt::signal DFSExplorer::on_backtracking_signal; -xbt::signal DFSExplorer::on_state_creation_signal; +xbt::signal DFSExplorer::on_state_creation_signal; -xbt::signal DFSExplorer::on_restore_system_state_signal; -xbt::signal DFSExplorer::on_restore_initial_state_signal; -xbt::signal DFSExplorer::on_transition_replay_signal; -xbt::signal DFSExplorer::on_transition_execute_signal; +xbt::signal DFSExplorer::on_restore_system_state_signal; +xbt::signal DFSExplorer::on_restore_initial_state_signal; +xbt::signal DFSExplorer::on_transition_replay_signal; +xbt::signal DFSExplorer::on_transition_execute_signal; -xbt::signal DFSExplorer::on_log_state_signal; - -void DFSExplorer::check_non_termination(const State* current_state) -{ - for (auto state = stack_.rbegin(); state != stack_.rend(); ++state) - if (Api::get().snapshot_equal((*state)->get_system_state(), current_state->get_system_state())) { - XBT_INFO("Non-progressive cycle: state %ld -> state %ld", (*state)->get_num(), current_state->get_num()); - XBT_INFO("******************************************"); - XBT_INFO("*** NON-PROGRESSIVE CYCLE DETECTED ***"); - XBT_INFO("******************************************"); - XBT_INFO("Counter-example execution trace:"); - for (auto const& s : get_textual_trace()) - XBT_INFO(" %s", s.c_str()); - XBT_INFO("Path = %s", get_record_trace().to_string().c_str()); - log_state(); - - throw TerminationError(); - } -} +xbt::signal DFSExplorer::on_log_state_signal; RecordTrace DFSExplorer::get_record_trace() // override { RecordTrace res; - for (auto const& state : stack_) - res.push_back(state->get_transition()); + + if (const auto trans = stack_.back()->get_transition_out(); trans != nullptr) + res.push_back(trans.get()); + for (const auto* state = stack_.back().get(); state != nullptr; state = state->get_parent_state().get()) + if (state->get_transition_in() != nullptr) + res.push_front(state->get_transition_in().get()); + return res; } -std::vector DFSExplorer::get_textual_trace() // override +void DFSExplorer::restore_stack(std::shared_ptr state) { - std::vector trace; - for (auto const& state : stack_) { - const auto* t = state->get_transition(); - trace.push_back(xbt::string_printf("%ld: %s", t->aid_, t->to_string().c_str())); + stack_.clear(); + execution_seq_ = odpor::Execution(); + auto current_state = state; + stack_.emplace_front(current_state); + // condition corresponds to reaching initial state + while (current_state->get_parent_state() != nullptr) { + current_state = current_state->get_parent_state(); + stack_.emplace_front(current_state); + } + XBT_DEBUG("Replaced stack by %s", get_record_trace().to_string().c_str()); + if (reduction_mode_ == ReductionMode::sdpor || reduction_mode_ == ReductionMode::odpor) { + // NOTE: The outgoing transition for the top-most state of the stack refers to that which was taken + // as part of the last trace explored by the algorithm. Thus, only the sequence of transitions leading up to, + // but not including, the last state must be included when reconstructing the Exploration for SDPOR. + for (auto iter = std::next(stack_.begin()); iter != stack_.end(); ++iter) { + execution_seq_.push_transition((*iter)->get_transition_in()); + } + XBT_DEBUG("Replaced SDPOR/ODPOR execution to reflect the new stack"); } - return trace; } void DFSExplorer::log_state() // override { - on_log_state_signal(); - XBT_INFO("DFS exploration ended. %ld unique states visited; %ld backtracks (%lu transition replays, %lu states " + on_log_state_signal(get_remote_app()); + XBT_INFO("DFS exploration ended. %ld unique states visited; %lu backtracks (%lu transition replays, %lu states " "visited overall)", - State::get_expanded_states(), backtrack_count_, Api::get().mc_get_visited_states(), - Transition::get_replayed_transitions()); + State::get_expanded_states(), backtrack_count_, Transition::get_replayed_transitions(), + visited_states_count_); + Exploration::log_state(); } void DFSExplorer::run() { - on_exploration_start_signal(); + on_exploration_start_signal(get_remote_app()); /* This function runs the DFS algorithm the state space. * We do so iteratively instead of recursively, dealing with the call stack manually. * This allows one to explore the call stack at will. */ while (not stack_.empty()) { /* Get current state */ - State* state = stack_.back().get(); + auto state = stack_.back(); XBT_DEBUG("**************************************************"); - XBT_DEBUG("Exploration depth=%zu (state:%ld; %zu interleaves)", stack_.size(), state->get_num(), + XBT_DEBUG("Exploration depth=%zu (state:#%ld; %zu interleaves todo)", stack_.size(), state->get_num(), state->count_todo()); - Api::get().mc_inc_visited_states(); + visited_states_count_++; // Backtrack if we reached the maximum depth if (stack_.size() > (std::size_t)_sg_mc_max_depth) { - if (reductionMode_ == ReductionMode::dpor) { + if (reduction_mode_ == ReductionMode::dpor) { XBT_ERROR("/!\\ Max depth of %d reached! THIS WILL PROBABLY BREAK the dpor reduction /!\\", _sg_mc_max_depth.get()); XBT_ERROR("/!\\ If bad things happen, disable dpor with --cfg=model-check/reduction:none /!\\"); - } else + } else if (reduction_mode_ == ReductionMode::sdpor || reduction_mode_ == ReductionMode::odpor) { + XBT_ERROR("/!\\ Max depth of %d reached! THIS **WILL** BREAK the reduction, which is not sound " + "when stopping at a fixed depth /!\\", + _sg_mc_max_depth.get()); + XBT_ERROR("/!\\ If bad things happen, disable the reduction with --cfg=model-check/reduction:none /!\\"); + } else { XBT_WARN("/!\\ Max depth reached ! /!\\ "); + } this->backtrack(); continue; } - // Backtrack if we are revisiting a state we saw previously - if (visited_state_ != nullptr) { - XBT_DEBUG("State already visited (equal to state %ld), exploration stopped on this path.", - visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num); - - visited_state_ = nullptr; - this->backtrack(); - continue; + if (reduction_mode_ == ReductionMode::odpor) { + // In the case of ODPOR, the wakeup tree for this state may be empty if we're exploring new territory + // (rather than following the partial execution of a wakeup tree). This corresponds to lines 9 to 13 of + // the ODPOR pseudocode + // + // INVARIANT: The execution sequence should be consistent with the state when seeding the tree. If the sequence + // gets out of sync with the state, selection will not work as we intend + state->seed_wakeup_tree_if_needed(execution_seq_); } // Search for the next transition - int next = state->next_transition(); - - if (next < 0) { // If there is no more transition in the current state, backtrack. - XBT_DEBUG("There remains %d actors, but none to interleave (depth %zu).", state->get_actor_count(), - stack_.size() + 1); + // next_transition returns a pair + // in case we want to consider multiple states (eg. during backtrack) + const aid_t next = reduction_mode_ == ReductionMode::odpor ? state->next_odpor_transition() + : std::get<0>(state->next_transition_guided()); + + if (next < 0 || not state->is_actor_enabled(next)) { + if (next >= 0) { // Actor is not enabled, then + XBT_INFO("Reduction %s wants to execute a disabled transition %s. If it's ODPOR, ReversibleRace is suboptimal.", + to_c_str(reduction_mode_), + state->get_actors_list().at(next).get_transition()->to_string(true).c_str()); + if (reduction_mode_ == ReductionMode::odpor) { + XBT_INFO("Current trace:"); + for (auto elm : get_textual_trace()) + XBT_ERROR("%s", elm.c_str()); + // Remove the disabled transition from the wakeup tree so that ODPOR doesn't try it again + state->remove_subtree_at_aid(next); + state->add_sleep_set(state->get_actors_list().at(next).get_transition()); + } + } + // If there is no more transition in the current state (or if ODPOR picked an actor that is not enabled -- + // ReversibleRace is an overapproximation), backtrace + XBT_VERB("%lu actors remain, but none of them need to be interleaved (depth %zu).", state->get_actor_count(), + stack_.size() + 1); if (state->get_actor_count() == 0) { - mc_model_checker->finalize_app(); + get_remote_app().finalize_app(); XBT_VERB("Execution came to an end at %s (state: %ld, depth: %zu)", get_record_trace().to_string().c_str(), state->get_num(), stack_.size()); } + this->backtrack(); continue; } + if (XBT_LOG_ISENABLED(mc_dfs, xbt_log_priority_verbose)) { + XBT_VERB("Sleep set actually containing:"); + for (const auto& [aid, transition] : state->get_sleep_set()) + XBT_VERB(" <%ld,%s>", aid, transition->to_string().c_str()); + } + + auto todo = state->get_actors_list().at(next).get_transition(); + XBT_DEBUG("wanna execute %ld: %.60s", next, todo->to_string().c_str()); + /* Actually answer the request: let's execute the selected request (MCed does one step) */ - state->execute_next(next); - on_transition_execute_signal(state->get_transition()); + auto executed_transition = state->execute_next(next, get_remote_app()); + on_transition_execute_signal(state->get_transition_out().get(), get_remote_app()); // If there are processes to interleave and the maximum depth has not been // reached then perform one step of the exploration algorithm. - XBT_VERB("Execute %ld: %.60s (stack depth: %zu, state: %ld, %zu interleaves)", state->get_transition()->aid_, - state->get_transition()->to_string().c_str(), stack_.size(), state->get_num(), state->count_todo()); + XBT_VERB("Executed %ld: %.60s (stack depth: %zu, state: %ld, %zu interleaves)", state->get_transition_out()->aid_, + state->get_transition_out()->to_string().c_str(), stack_.size(), state->get_num(), state->count_todo()); /* Create the new expanded state (copy the state of MCed into our MCer data) */ - auto next_state = std::make_unique(get_remote_app()); - on_state_creation_signal(next_state.get()); - - if (_sg_mc_termination) - this->check_non_termination(next_state.get()); - - /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */ - if (_sg_mc_max_visited_states > 0) - visited_state_ = visited_states_.addVisitedState(next_state->get_num(), next_state.get(), true); + auto next_state = std::make_shared(get_remote_app(), state); + on_state_creation_signal(next_state.get(), get_remote_app()); + + if (reduction_mode_ == ReductionMode::odpor) { + // With ODPOR, after taking a step forward, we must assign a copy of that subtree to the next state. + // + // NOTE: We only add actions to the sleep set AFTER we've regenerated states. We must perform the search + // fully down a single path before we consider adding any elements to the sleep set according to the pseudocode + next_state->sprout_tree_from_parent_state(); + } else { + /* Sleep set procedure: + * adding the taken transition to the sleep set of the original state. + * Since the parent sleep set is used to compute the child sleep set, this need to be + * done after next_state creation */ + XBT_DEBUG("Marking Transition >>%s<< of process %ld done and adding it to the sleep set", + state->get_transition_out()->to_string().c_str(), state->get_transition_out()->aid_); + state->add_sleep_set( + state->get_transition_out()); // Actors are marked done when they are considered in ActorState + } - /* If this is a new state (or if we don't care about state-equality reduction) */ - if (visited_state_ == nullptr) { - /* Get an enabled process and insert it in the interleave set of the next state */ - for (auto const& [aid, _] : next_state->get_actors_list()) { - if (next_state->is_actor_enabled(aid)) { - next_state->mark_todo(aid); - if (reductionMode_ == ReductionMode::dpor) - break; // With DPOR, we take the first enabled transition + /* DPOR persistent set procedure: + * for each new transition considered, check if it depends on any other previous transition executed before it + * on another process. If there exists one, find the more recent, and add its process to the interleave set. + * If the process is not enabled at this point, then add every enabled process to the interleave */ + if (reduction_mode_ == ReductionMode::dpor) { + aid_t issuer_id = state->get_transition_out()->aid_; + stack_t tmp_stack = stack_; + while (not tmp_stack.empty()) { + if (const State* prev_state = tmp_stack.back().get(); + state->get_transition_out()->aid_ == prev_state->get_transition_out()->aid_) { + XBT_DEBUG("Simcall >>%s<< and >>%s<< with same issuer %ld", state->get_transition_out()->to_string().c_str(), + prev_state->get_transition_out()->to_string().c_str(), issuer_id); + tmp_stack.pop_back(); + continue; + } else if (prev_state->get_transition_out()->depends(state->get_transition_out().get())) { + XBT_VERB("Dependent Transitions:"); + XBT_VERB(" #%ld %s (state=%ld)", prev_state->get_transition_out()->aid_, + prev_state->get_transition_out()->to_string().c_str(), prev_state->get_num()); + XBT_VERB(" #%ld %s (state=%ld)", state->get_transition_out()->aid_, + state->get_transition_out()->to_string().c_str(), state->get_num()); + + if (prev_state->is_actor_enabled(issuer_id)) { + if (not prev_state->is_actor_done(issuer_id)) { + prev_state->consider_one(issuer_id); + opened_states_.emplace_back(tmp_stack.back()); + } else + XBT_DEBUG("Actor %ld is already in done set: no need to explore it again", issuer_id); + } else { + XBT_DEBUG("Actor %ld is not enabled: DPOR may be failing. To stay sound, we are marking every enabled " + "transition as todo", + issuer_id); + // If we ended up marking at least a transition, explore it at some point + if (prev_state->consider_all() > 0) + opened_states_.emplace_back(tmp_stack.back()); + } + break; + } else { + XBT_VERB("INDEPENDENT Transitions:"); + XBT_VERB(" #%ld %s (state=%ld)", prev_state->get_transition_out()->aid_, + prev_state->get_transition_out()->to_string().c_str(), prev_state->get_num()); + XBT_VERB(" #%ld %s (state=%ld)", state->get_transition_out()->aid_, + state->get_transition_out()->to_string().c_str(), state->get_num()); } + tmp_stack.pop_back(); } + } else if (reduction_mode_ == ReductionMode::sdpor) { + /** + * SDPOR Source Set Procedure: + * + * Find "reversible races" in the current execution `E` with respect to the latest action `p`. For each such race, + * determine one thread not contained in the backtrack set at the "race point" `r` which "represents" the trace + * formed by first executing everything after `r` that doesn't depend on it (`v := notdep(r, E)`) and then `p` to + * flip the race. + * + * The intuition is that some subsequence of `v` may enable `p`, so we want to be sure that search "in that + * direction" + */ + execution_seq_.push_transition(std::move(executed_transition)); + xbt_assert(execution_seq_.get_latest_event_handle().has_value(), "No events are contained in the SDPOR execution " + "even though one was just added"); + + const auto next_E_p = execution_seq_.get_latest_event_handle().value(); + for (const auto e_race : execution_seq_.get_reversible_races_of(next_E_p)) { + State* prev_state = stack_[e_race].get(); + const auto choices = execution_seq_.get_missing_source_set_actors_from(e_race, prev_state->get_backtrack_set()); + if (not choices.empty()) { + // NOTE: To incorporate the idea of attempting to select the "best" backtrack point into SDPOR, instead of + // selecting the `first` initial, we should instead compute all choices and decide which is best + // + // Here, we choose the actor with the lowest ID to ensure we get deterministic results + const auto q = + std::min_element(choices.begin(), choices.end(), [](const aid_t a1, const aid_t a2) { return a1 < a2; }); + prev_state->consider_one(*q); + opened_states_.emplace_back(std::move(prev_state)); + } + } + } else if (reduction_mode_ == ReductionMode::odpor) { + // In the case of ODPOR, we simply observe the transition that was executed until we've reached a maximal trace + execution_seq_.push_transition(std::move(executed_transition)); + } - if (dot_output != nullptr) - std::fprintf(dot_output, "\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), next_state->get_num(), - state->get_transition()->dot_string().c_str()); + // Before leaving that state, if the transition we just took can be taken multiple times, we + // need to give it to the opened states + if (stack_.back()->count_todo_multiples() > 0) + opened_states_.emplace_back(stack_.back()); - } else if (dot_output != nullptr) - std::fprintf(dot_output, "\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), - visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num, - state->get_transition()->dot_string().c_str()); + stack_.emplace_back(std::move(next_state)); - stack_.push_back(std::move(next_state)); - } + /* If this is a new state (or if we don't care about state-equality reduction) */ + /* Get an enabled process and insert it in the interleave set of the next state */ + if (reduction_mode_ == ReductionMode::dpor) + stack_.back()->consider_best(); // Take only one transition if DPOR: others may be considered later if required + else { + stack_.back()->consider_all(); + } + dot_output("\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), stack_.back()->get_num(), + state->get_transition_out()->dot_string().c_str()); + } log_state(); } -void DFSExplorer::backtrack() +std::shared_ptr DFSExplorer::best_opened_state() { - backtrack_count_++; - XBT_VERB("Backtracking from %s", get_record_trace().to_string().c_str()); - on_backtracking_signal(); - stack_.pop_back(); + int best_prio = 0; // cache the value for the best priority found so far (initialized to silence gcc) + auto best = end(opened_states_); // iterator to the state to explore having the best priority + auto valid = begin(opened_states_); // iterator marking the limit between states still to explore, and already + // explored ones + + // Keep only still non-explored states (aid != -1), and record the one with the best (greater) priority. + for (auto current = begin(opened_states_); current != end(opened_states_); ++current) { + auto [aid, prio] = (*current)->next_transition_guided(); + if (aid == -1) + continue; + if (valid != current) + *valid = std::move(*current); + if (best == end(opened_states_) || prio < best_prio) { + best_prio = prio; + best = valid; + } + ++valid; + } - get_remote_app().check_deadlock(); + std::shared_ptr best_state; + if (best < valid) { + // There are non-explored states, and one of them has the best priority. Remove it from opened_states_ before + // returning. + best_state = std::move(*best); + --valid; + if (best != valid) + *best = std::move(*valid); + } + opened_states_.erase(valid, end(opened_states_)); - /* Traverse the stack backwards until a state with a non empty interleave set is found, deleting all the states that - * have it empty in the way. For each deleted state, check if the request that has generated it (from its - * predecessor state), depends on any other previous request executed before it. If it does then add it to the - * interleave set of the state that executed that previous request. */ + return best_state; +} - while (not stack_.empty()) { - std::unique_ptr state = std::move(stack_.back()); - stack_.pop_back(); - if (reductionMode_ == ReductionMode::dpor) { - aid_t issuer_id = state->get_transition()->aid_; - for (auto i = stack_.rbegin(); i != stack_.rend(); ++i) { - State* prev_state = i->get(); - if (state->get_transition()->aid_ == prev_state->get_transition()->aid_) { - XBT_DEBUG("Simcall >>%s<< and >>%s<< with same issuer %ld", state->get_transition()->to_string().c_str(), - prev_state->get_transition()->to_string().c_str(), issuer_id); - break; - } else if (prev_state->get_transition()->depends(state->get_transition())) { - XBT_VERB("Dependent Transitions:"); - XBT_VERB(" %s (state=%ld)", prev_state->get_transition()->to_string().c_str(), prev_state->get_num()); - XBT_VERB(" %s (state=%ld)", state->get_transition()->to_string().c_str(), state->get_num()); +std::shared_ptr DFSExplorer::next_odpor_state() +{ + for (auto iter = stack_.rbegin(); iter != stack_.rend(); ++iter) { + const auto& state = *iter; + state->do_odpor_unwind(); + XBT_DEBUG("\tPerformed ODPOR 'clean-up'. Sleep set has:"); + for (const auto& [aid, transition] : state->get_sleep_set()) + XBT_DEBUG("\t <%ld,%s>", aid, transition->to_string().c_str()); + } + return nullptr; +} - if (not prev_state->is_done(issuer_id)) - prev_state->mark_todo(issuer_id); - else - XBT_DEBUG("Actor %ld is in done set", issuer_id); - break; +void DFSExplorer::backtrack() +{ + if (const auto last_event = execution_seq_.get_latest_event_handle(); + reduction_mode_ == ReductionMode::odpor and last_event.has_value()) { + /** + * ODPOR Race Detection Procedure: + * + * For each reversible race in the current execution, we note if there are any continuations `C` equivalent to that + * which would reverse the race that have already either a) been searched by ODPOR or b) been *noted* to be searched + * by the wakeup tree at the appropriate reversal point, either as `C` directly or an as equivalent to `C` + * ("eventually looks like C", viz. the `~_E` relation) + */ + for (auto e_prime = static_cast(0); e_prime <= last_event.value(); ++e_prime) { + XBT_DEBUG("ODPOR: Now considering all possible race with `%u`", e_prime); + for (const auto e : execution_seq_.get_reversible_races_of(e_prime)) { + XBT_DEBUG("ODPOR: Reversible race detected between events `%u` and `%u`", e, e_prime); + State& prev_state = *stack_[e]; + if (const auto v = execution_seq_.get_odpor_extension_from(e, e_prime, prev_state); v.has_value()) { + switch (prev_state.insert_into_wakeup_tree(v.value(), execution_seq_.get_prefix_before(e))) { + case odpor::WakeupTree::InsertionResult::root: { + XBT_DEBUG("ODPOR: Reversible race with `%u`(%ld: %.20s) unaccounted for in the wakeup tree for " + "the execution prior to event `%u`(%ld: %.20s):", + e_prime, stack_[e_prime]->get_transition_out()->aid_, + stack_[e_prime]->get_transition_out()->to_string(true).c_str(), e, + prev_state.get_transition_out()->aid_, + prev_state.get_transition_out()->to_string(true).c_str()); + break; + } + case odpor::WakeupTree::InsertionResult::interior_node: { + XBT_DEBUG("ODPOR: Reversible race with `%u` partially accounted for in the wakeup tree for " + "the execution prior to event `%u`:", + e_prime, e); + break; + } + case odpor::WakeupTree::InsertionResult::leaf: { + XBT_DEBUG("ODPOR: Reversible race with `%u` accounted for in the wakeup tree for " + "the execution prior to event `%u`:", + e_prime, e); + break; + } + } + for (const auto& seq : simgrid::mc::odpor::get_textual_trace(v.value())) { + XBT_DEBUG(" %s", seq.c_str()); + } } else { - XBT_VERB("INDEPENDENT Transitions:"); - XBT_VERB(" %s (state=%ld)", prev_state->get_transition()->to_string().c_str(), prev_state->get_num()); - XBT_VERB(" %s (state=%ld)", state->get_transition()->to_string().c_str(), state->get_num()); + XBT_DEBUG("ODPOR: Ignoring race: `sleep(E')` intersects `WI_[E'](v := notdep(%u, E))`", e); + XBT_DEBUG("Sleep set contains:"); + for (const auto& [aid, transition] : prev_state.get_sleep_set()) + XBT_DEBUG(" <%ld,%s>", aid, transition->to_string().c_str()); } } } - - if (state->count_todo() && stack_.size() < (std::size_t)_sg_mc_max_depth) { - /* We found a back-tracking point, let's loop */ - XBT_DEBUG("Back-tracking to state %ld at depth %zu", state->get_num(), stack_.size() + 1); - stack_.push_back( - std::move(state)); // Put it back on the stack from which it was removed earlier in this while loop - this->restore_state(); - XBT_DEBUG("Back-tracking to state %ld at depth %zu done", stack_.back()->get_num(), stack_.size()); - break; - } else { - XBT_DEBUG("Delete state %ld at depth %zu", state->get_num(), stack_.size() + 1); - } } -} -void DFSExplorer::restore_state() -{ - /* If asked to rollback on a state that has a snapshot, restore it */ - State* last_state = stack_.back().get(); - if (const auto* system_state = last_state->get_system_state()) { - Api::get().restore_state(system_state); - on_restore_system_state_signal(last_state); + XBT_VERB("Backtracking from %s", get_record_trace().to_string().c_str()); + XBT_DEBUG("%lu alternatives are yet to be explored:", opened_states_.size()); + + on_backtracking_signal(get_remote_app()); + get_remote_app().check_deadlock(); + + // Take the point with smallest distance + auto backtracking_point = reduction_mode_ == ReductionMode::odpor ? next_odpor_state() : best_opened_state(); + + // if no backtracking point, then set the stack_ to empty so we can end the exploration + if (not backtracking_point) { + XBT_DEBUG("No more opened point of exploration, the search will end"); + stack_.clear(); return; } - /* if no snapshot, we need to restore the initial state and replay the transitions */ + // We found a backtracking point, let's go to it + backtrack_count_++; + XBT_DEBUG("Backtracking to state#%ld", backtracking_point->get_num()); + + // Search how to restore the backtracking point + std::deque replay_recipe; + for (auto* s = backtracking_point.get(); s != nullptr; s = s->get_parent_state().get()) { + if (s->get_transition_in() != nullptr) // The root has no transition_in + replay_recipe.push_front(s->get_transition_in().get()); + } + + // Restore the initial state if no intermediate state was found get_remote_app().restore_initial_state(); - on_restore_initial_state_signal(); + on_restore_initial_state_signal(get_remote_app()); + /* if no snapshot, we need to restore the initial state and replay the transitions */ /* Traverse the stack from the state at position start and re-execute the transitions */ - for (std::unique_ptr const& state : stack_) { - if (state == stack_.back()) /* If we are arrived on the target state, don't replay the outgoing transition */ - break; - state->get_transition()->replay(); - on_transition_replay_signal(state->get_transition()); - /* Update statistics */ - Api::get().mc_inc_visited_states(); + for (auto& transition : replay_recipe) { + transition->replay(get_remote_app()); + on_transition_replay_signal(transition, get_remote_app()); + visited_states_count_++; } + this->restore_stack(backtracking_point); } -DFSExplorer::DFSExplorer(RemoteApp* remote_app) : Exploration(remote_app) +DFSExplorer::DFSExplorer(const std::vector& args, ReductionMode mode) : Exploration(args), reduction_mode_(mode) { - reductionMode_ = reduction_mode; - if (_sg_mc_termination) - reductionMode_ = ReductionMode::none; - else if (reductionMode_ == ReductionMode::unset) - reductionMode_ = ReductionMode::dpor; - - if (_sg_mc_termination) - XBT_INFO("Check non progressive cycles"); - else - XBT_INFO("Start a DFS exploration. Reduction is: %s.", - (reductionMode_ == ReductionMode::none ? "none" - : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown"))); - - get_remote_app().take_initial_snapshot(); - - XBT_DEBUG("Starting the DFS exploration"); + XBT_INFO("Start a DFS exploration. Reduction is: %s.", to_c_str(reduction_mode_)); - auto initial_state = std::make_unique(get_remote_app()); + auto initial_state = std::make_shared(get_remote_app()); XBT_DEBUG("**************************************************"); + stack_.emplace_back(std::move(initial_state)); + /* Get an enabled actor and insert it in the interleave set of the initial state */ - XBT_DEBUG("Initial state. %d actors to consider", initial_state->get_actor_count()); - for (auto const& [aid, _] : initial_state->get_actors_list()) { - if (initial_state->is_actor_enabled(aid)) { - initial_state->mark_todo(aid); - if (reductionMode_ == ReductionMode::dpor) { - XBT_DEBUG("Actor %ld is TODO, DPOR is ON so let's go for this one.", aid); - break; - } - XBT_DEBUG("Actor %ld is TODO", aid); - } + XBT_DEBUG("Initial state. %lu actors to consider", stack_.back()->get_actor_count()); + if (reduction_mode_ == ReductionMode::dpor) + stack_.back()->consider_best(); + else { + stack_.back()->consider_all(); } - - stack_.push_back(std::move(initial_state)); + if (stack_.back()->count_todo_multiples() > 1) + opened_states_.emplace_back(stack_.back()); } -Exploration* create_dfs_exploration(RemoteApp* remote_app) +Exploration* create_dfs_exploration(const std::vector& args, ReductionMode mode) { - return new DFSExplorer(remote_app); + return new DFSExplorer(args, mode); } } // namespace simgrid::mc