X-Git-Url: http://bilbo.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/80b0dab1bd7ba4a54252a45cba41e33991e9f6ff..122a5a2813fd6d64d4db8ee7f1fdb5a62b7e0d6a:/src/mc/explo/DFSExplorer.cpp diff --git a/src/mc/explo/DFSExplorer.cpp b/src/mc/explo/DFSExplorer.cpp index cfacee45a3..aa7fbb023c 100644 --- a/src/mc/explo/DFSExplorer.cpp +++ b/src/mc/explo/DFSExplorer.cpp @@ -22,8 +22,10 @@ #include #include +#include #include #include +#include #include XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dfs, mc, "DFS exploration algorithm of the model-checker"); @@ -69,26 +71,20 @@ void DFSExplorer::check_non_termination(const State* current_state) RecordTrace DFSExplorer::get_record_trace() // override { RecordTrace res; - for (auto const& transition : stack_.back()->get_recipe()) - res.push_back(transition); - res.push_back(stack_.back()->get_transition()); - return res; -} -std::vector DFSExplorer::get_textual_trace() // override -{ - std::vector trace; - for (auto const& transition : stack_.back()->get_recipe()) { - trace.push_back(xbt::string_printf("%ld: %s", transition->aid_, transition->to_string().c_str())); - } - if (const auto* trans = stack_.back()->get_transition(); trans != nullptr) - trace.push_back(xbt::string_printf("%ld: %s", trans->aid_, trans->to_string().c_str())); - return trace; + 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; } void DFSExplorer::restore_stack(std::shared_ptr state) { stack_.clear(); + execution_seq_ = odpor::Execution(); auto current_state = state; stack_.emplace_front(current_state); // condition corresponds to reaching initial state @@ -97,6 +93,18 @@ void DFSExplorer::restore_stack(std::shared_ptr 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"); + } } void DFSExplorer::log_state() // override @@ -104,8 +112,8 @@ void DFSExplorer::log_state() // override 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_, visited_states_count_, - Transition::get_replayed_transitions()); + State::get_expanded_states(), backtrack_count_, Transition::get_replayed_transitions(), + visited_states_count_); Exploration::log_state(); } @@ -132,8 +140,14 @@ void DFSExplorer::run() 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; } @@ -150,9 +164,25 @@ void DFSExplorer::run() } #endif + 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 - // next_transition returns a pair in case we want to consider multiple state (eg. during backtrack) - auto [next, _] = state->next_transition_guided(); + // 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) { // If there is no more transition in the current state, backtrack. XBT_VERB("%lu actors remain, but none of them need to be interleaved (depth %zu).", state->get_actor_count(), @@ -170,49 +200,61 @@ void DFSExplorer::run() if (_sg_mc_sleep_set && XBT_LOG_ISENABLED(mc_dfs, xbt_log_priority_verbose)) { XBT_VERB("Sleep set actually containing:"); - for (auto& [aid, transition] : state->get_sleep_set()) - XBT_VERB(" <%ld,%s>", aid, transition.to_string().c_str()); + for (const auto& [aid, transition] : state->get_sleep_set()) + XBT_VERB(" <%ld,%s>", aid, transition->to_string().c_str()); } /* Actually answer the request: let's execute the selected request (MCed does one step) */ - state->execute_next(next, get_remote_app()); - on_transition_execute_signal(state->get_transition(), get_remote_app()); + const 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("Execute %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_shared(get_remote_app(), state); on_state_creation_signal(next_state.get(), get_remote_app()); - /* 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()->to_string().c_str(), state->get_transition()->aid_); - state->add_sleep_set(state->get_transition()); // Actors are marked done when they are considerd in ActorState + 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 + } /* 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()->aid_; + 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()->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); + 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()->depends(state->get_transition())) { + } else if (prev_state->get_transition_out()->depends(state->get_transition_out().get())) { 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()); + XBT_VERB(" %s (state=%ld)", prev_state->get_transition_out()->to_string().c_str(), prev_state->get_num()); + XBT_VERB(" %s (state=%ld)", 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)) { @@ -231,11 +273,50 @@ void DFSExplorer::run() break; } 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_VERB(" %s (state=%ld)", prev_state->get_transition_out()->to_string().c_str(), prev_state->get_num()); + XBT_VERB(" %s (state=%ld)", 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 (!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)); } // Before leaving that state, if the transition we just took can be taken multiple times, we @@ -247,7 +328,8 @@ void DFSExplorer::run() this->check_non_termination(next_state.get()); #if SIMGRID_HAVE_STATEFUL_MC - /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */ + /* 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(), get_remote_app()); #endif @@ -264,12 +346,12 @@ void DFSExplorer::run() } dot_output("\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), stack_.back()->get_num(), - state->get_transition()->dot_string().c_str()); + state->get_transition_out()->dot_string().c_str()); #if SIMGRID_HAVE_STATEFUL_MC } else { 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()); + state->get_transition_out()->dot_string().c_str()); #endif } } @@ -290,7 +372,7 @@ std::shared_ptr DFSExplorer::best_opened_state() continue; if (valid != current) *valid = std::move(*current); - if (best == end(opened_states_) || prio > best_prio) { + if (best == end(opened_states_) || prio < best_prio) { best_prio = prio; best = valid; } @@ -311,8 +393,75 @@ std::shared_ptr DFSExplorer::best_opened_state() return best_state; } +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()); + if (!state->has_empty_tree()) { + return state; + } + } + return nullptr; +} + 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) { + 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()) { + const auto result = prev_state.insert_into_wakeup_tree(v.value(), execution_seq_.get_prefix_before(e)); + switch (result) { + case odpor::WakeupTree::InsertionResult::root: { + XBT_DEBUG("ODPOR: Reversible race with `%u` unaccounted for in the wakeup tree for " + "the execution prior to event `%u`:", + e_prime, e); + 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_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()); + } + } + } + } + XBT_VERB("Backtracking from %s", get_record_trace().to_string().c_str()); XBT_DEBUG("%lu alternatives are yet to be explored:", opened_states_.size()); @@ -320,7 +469,7 @@ void DFSExplorer::backtrack() get_remote_app().check_deadlock(); // Take the point with smallest distance - auto backtracking_point = best_opened_state(); + 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) { @@ -343,28 +492,52 @@ void DFSExplorer::backtrack() } #endif + // Search how to restore the backtracking point + State* init_state = nullptr; + std::deque replay_recipe; + for (auto* s = backtracking_point.get(); s != nullptr; s = s->get_parent_state().get()) { +#if SIMGRID_HAVE_STATEFUL_MC + if (s->get_system_state() != nullptr) { // Found a state that I can restore + init_state = s; + break; + } +#endif + if (s->get_transition_in() != nullptr) // The root has no transition_in + replay_recipe.push_front(s->get_transition_in().get()); + } + + // Restore the init_state, if any + if (init_state != nullptr) { +#if SIMGRID_HAVE_STATEFUL_MC + const auto* system_state = init_state->get_system_state(); + system_state->restore(*get_remote_app().get_remote_process_memory()); + on_restore_system_state_signal(init_state, get_remote_app()); +#endif + } else { // Restore the initial state if no intermediate state was found + get_remote_app().restore_initial_state(); + on_restore_initial_state_signal(get_remote_app()); + } + /* if no snapshot, we need to restore the initial state and replay the transitions */ - get_remote_app().restore_initial_state(); - on_restore_initial_state_signal(get_remote_app()); /* Traverse the stack from the state at position start and re-execute the transitions */ - for (auto& state : backtracking_point->get_recipe()) { - state->replay(get_remote_app()); - on_transition_replay_signal(state, get_remote_app()); + 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(const std::vector& args, bool with_dpor, bool need_memory_info) - : Exploration(args, need_memory_info || _sg_mc_termination) +DFSExplorer::DFSExplorer(const std::vector& args, ReductionMode mode, bool need_memory_info) + : Exploration(args, need_memory_info || _sg_mc_termination +#if SIMGRID_HAVE_STATEFUL_MC + || _sg_mc_checkpoint > 0 +#endif + ) + , reduction_mode_(mode) { - if (with_dpor) - reduction_mode_ = ReductionMode::dpor; - else - reduction_mode_ = ReductionMode::none; - if (_sg_mc_termination) { - if (with_dpor) { + if (mode != ReductionMode::none) { XBT_INFO("Check non progressive cycles (turning DPOR off)"); reduction_mode_ = ReductionMode::none; } else { @@ -388,11 +561,19 @@ DFSExplorer::DFSExplorer(const std::vector& args, bool with_dpor, bool ne } if (stack_.back()->count_todo_multiples() > 1) opened_states_.emplace_back(stack_.back()); + + if (mode == ReductionMode::odpor && !_sg_mc_sleep_set) { + // ODPOR requires the use of sleep sets; SDPOR + // "likes" using sleep sets but it is not strictly + // required + XBT_INFO("Forcing the use of sleep sets for use with ODPOR"); + _sg_mc_sleep_set = true; + } } -Exploration* create_dfs_exploration(const std::vector& args, bool with_dpor) +Exploration* create_dfs_exploration(const std::vector& args, ReductionMode mode) { - return new DFSExplorer(args, with_dpor); + return new DFSExplorer(args, mode); } } // namespace simgrid::mc