-/* 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. */
void DFSExplorer::check_non_termination(const State* current_state)
{
- for (auto state = stack_.rbegin(); state != stack_.rend(); ++state)
- if (*(*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());
+ for (auto const& state : stack_) {
+ if (state->get_system_state()->equals_to(*current_state->get_system_state(),
+ *get_remote_app().get_remote_process_memory())) {
+ 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("******************************************");
throw TerminationError();
}
+ }
}
RecordTrace DFSExplorer::get_record_trace() // override
+{
+ return get_record_trace_of_stack(stack_);
+}
+
+/* Usefull to show debug information */
+RecordTrace DFSExplorer::get_record_trace_of_stack(stack_t stack)
{
RecordTrace res;
- for (auto const& state : stack_)
+ for (auto const& state : stack)
res.push_back(state->get_transition());
return res;
}
void DFSExplorer::log_state() // override
{
on_log_state_signal(get_remote_app());
- XBT_INFO("DFS exploration ended. %ld unique states visited; %ld backtracks (%lu transition replays, %lu states "
+ XBT_INFO("DFS exploration ended. %ld unique states visited; %lu backtracks (%lu transition replays, %lu states "
"visited overall)",
- State::get_expanded_states(), backtrack_count_, mc_model_checker->get_visited_states(),
+ State::get_expanded_states(), backtrack_count_, visited_states_count_,
Transition::get_replayed_transitions());
+ Exploration::log_state();
+}
+
+/* Copy a given stack by deep-copying it at the State level : this is required so we can backtrack at different
+ * points without interacting with the stacks in the opened_states_ waiting for their turn. On the other hand,
+ * the exploration of one stack in opened_states_ could only slightly modify the sleep set of another stack in
+ * opened_states_, so it is only a slight waste of performance in the exploration. */
+void DFSExplorer::add_to_opened_states(stack_t stack)
+{
+ stack_t tmp_stack;
+ for (auto& state : stack)
+ tmp_stack.push_back(std::make_shared<State>(State(*state)));
+ opened_states_.emplace(tmp_stack);
}
void DFSExplorer::run()
XBT_DEBUG("Exploration depth=%zu (state:#%ld; %zu interleaves todo)", stack_.size(), state->get_num(),
state->count_todo());
- mc_model_checker->inc_visited_states();
+ visited_states_count_++;
// Backtrack if we reached the maximum depth
if (stack_.size() > (std::size_t)_sg_mc_max_depth) {
continue;
}
- // Backtrack if we are revisiting a state we saw previously
+ // Backtrack if we are revisiting a state we saw previously while applying state-equality reduction
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_->original_num_ == -1 ? visited_state_->num_ : visited_state_->original_num_);
visited_state_ = nullptr;
this->backtrack();
}
// Search for the next transition
- aid_t next = state->next_transition();
+ // next_transition returns a pair<aid_t, double> in case we want to consider multiple state (eg. during backtrack)
+ auto [next, _] = state->next_transition_guided();
if (next < 0) { // If there is no more transition in the current state, backtrack.
- XBT_DEBUG("There remains %lu actors, but none to interleave (depth %zu).", state->get_actor_count(),
- stack_.size() + 1);
+ XBT_VERB("There remains %lu actors, but none to interleave (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 (_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());
+ }
+
/* Actually answer the request: let's execute the selected request (MCed does one step) */
- state->execute_next(next);
+ state->execute_next(next, get_remote_app());
on_transition_execute_signal(state->get_transition(), get_remote_app());
// If there are processes to interleave and the maximum depth has not been
state->get_transition()->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<State>(get_remote_app());
+ std::shared_ptr<State> next_state;
+ next_state = std::make_shared<State>(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
+
+ /* 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_;
+ stack_t tmp_stack = std::list(stack_);
+ while (not tmp_stack.empty()) {
+ State* prev_state = tmp_stack.back().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);
+ tmp_stack.pop_back();
+ continue;
+ } 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());
+
+ if (prev_state->is_actor_enabled(issuer_id)) {
+ if (not prev_state->is_actor_done(issuer_id)) {
+ prev_state->consider_one(issuer_id);
+ add_to_opened_states(tmp_stack);
+ } 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 (prev_state->consider_all() >
+ 0) // If we ended up marking at least a transition, explore it at some point
+ add_to_opened_states(tmp_stack);
+ }
+ 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());
+ }
+ tmp_stack.pop_back();
+ }
+ }
+
+ // 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)
+ add_to_opened_states(stack_);
+
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());
+ visited_state_ = visited_states_.addVisitedState(next_state->get_num(), next_state.get(), get_remote_app());
+
+ stack_.push_back(std::move(next_state));
/* 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 (reduction_mode_ == ReductionMode::dpor)
- break; // With DPOR, we take the first enabled transition
- }
+ 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();
}
- mc_model_checker->dot_output("\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), next_state->get_num(),
- state->get_transition()->dot_string().c_str());
+ dot_output("\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), stack_.back()->get_num(),
+ state->get_transition()->dot_string().c_str());
} else
- mc_model_checker->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_.push_back(std::move(next_state));
+ 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());
}
-
log_state();
}
void DFSExplorer::backtrack()
{
- backtrack_count_++;
XBT_VERB("Backtracking from %s", get_record_trace().to_string().c_str());
- on_backtracking_signal(get_remote_app());
- stack_.pop_back();
+ XBT_DEBUG("%lu alternatives are yet to be explored:", opened_states_.size());
+ on_backtracking_signal(get_remote_app());
get_remote_app().check_deadlock();
- /* 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. */
- bool found_backtracking_point = false;
- while (not stack_.empty() && not found_backtracking_point) {
- std::unique_ptr<State> state = std::move(stack_.back());
- stack_.pop_back();
- if (reduction_mode_ == 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());
+ // if no backtracking point, then set the stack_ to empty so we can end the exploration
+ if (opened_states_.empty()) {
+ stack_ = std::list<std::shared_ptr<State>>();
+ return;
+ }
- 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;
- } 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());
- }
- }
- }
+ stack_t backtrack = opened_states_.top(); // Take the point with smallest distance
+ opened_states_.pop();
- if (state->count_todo() == 0) { // Empty interleaving set
- XBT_DEBUG("Delete state %ld at depth %zu", state->get_num(), stack_.size() + 1);
+ // if the smallest distance corresponded to no enable actor, remove this and let the
+ // exploration ask again for a backtrack
+ if (backtrack.back()->next_transition_guided().first == -1)
+ return;
- } else {
- 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
- found_backtracking_point = true;
- }
- }
+ // We found a real backtracking point, let's go to it
+ backtrack_count_++;
- if (found_backtracking_point) {
- /* 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()) {
- system_state->restore(&get_remote_app().get_remote_process());
- on_restore_system_state_signal(last_state, get_remote_app());
- return;
- }
+ /* If asked to rollback on a state that has a snapshot, restore it */
+ State* last_state = backtrack.back().get();
+ if (const auto* system_state = last_state->get_system_state()) {
+ system_state->restore(*get_remote_app().get_remote_process_memory());
+ on_restore_system_state_signal(last_state, get_remote_app());
+ stack_ = backtrack;
+ return;
+ }
- /* 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 (std::unique_ptr<State> 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(), get_remote_app());
- /* Update statistics */
- mc_model_checker->inc_visited_states();
- }
- } // If no backtracing point, then the stack is empty and the exploration is over
+ /* 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 (std::shared_ptr<State> const& state : backtrack) {
+ if (state == backtrack.back()) /* If we are arrived on the target state, don't replay the outgoing transition */
+ break;
+ state->get_transition()->replay(get_remote_app());
+ on_transition_replay_signal(state->get_transition(), get_remote_app());
+ visited_states_count_++;
+ }
+ stack_ = backtrack;
+ XBT_DEBUG(">> Backtracked to %s", get_record_trace().to_string().c_str());
}
-DFSExplorer::DFSExplorer(const std::vector<char*>& args, bool with_dpor) : Exploration(args)
+DFSExplorer::DFSExplorer(const std::vector<char*>& args, bool with_dpor, bool need_memory_info)
+ : Exploration(args, need_memory_info || _sg_mc_termination)
{
if (with_dpor)
reduction_mode_ = ReductionMode::dpor;
XBT_DEBUG("**************************************************");
+ stack_.push_back(std::move(initial_state));
+
/* Get an enabled actor and insert it in the interleave set of the initial state */
XBT_DEBUG("Initial state. %lu 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 (reduction_mode_ == 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);
- }
+ 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)
+ add_to_opened_states(stack_);
}
Exploration* create_dfs_exploration(const std::vector<char*>& args, bool with_dpor)