* 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/transition/Transition.hpp"
+#if SIMGRID_HAVE_STATEFUL_MC
+#include "src/mc/VisitedState.hpp"
+#endif
+
#include "src/xbt/mmalloc/mmprivate.h"
#include "xbt/log.h"
#include "xbt/string.hpp"
#include <cassert>
#include <cstdio>
+#include <algorithm>
#include <memory>
#include <string>
+#include <unordered_set>
#include <vector>
XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dfs, mc, "DFS exploration algorithm of the model-checker");
void DFSExplorer::check_non_termination(const State* current_state)
{
-#if SIMGRID_HAVE_MC
+#if SIMGRID_HAVE_STATEFUL_MC
for (auto const& state : stack_) {
if (state->get_system_state()->equals_to(*current_state->get_system_state(),
*get_remote_app().get_remote_process_memory())) {
get_record_trace().to_string().c_str());
log_state();
- throw TerminationError();
+ throw McError(ExitStatus::NON_TERMINATION);
}
}
#endif
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<std::string> DFSExplorer::get_textual_trace() // override
-{
- std::vector<std::string> trace;
- for (auto const& transition : stack_.back()->get_recipe()) {
- trace.push_back(xbt::string_printf("%ld: %s", transition->aid_, transition->to_string().c_str()));
- }
- trace.push_back(xbt::string_printf("%ld: %s", stack_.back()->get_transition()->aid_,
- stack_.back()->get_transition()->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> state)
{
-
- stack_ = std::list<std::shared_ptr<State>>();
- std::shared_ptr<State> current_state(state);
- stack_.push_front(std::shared_ptr<State>(current_state));
+ stack_.clear();
+ 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_.push_front(std::shared_ptr<State>(current_state));
+ stack_.emplace_front(current_state);
}
XBT_DEBUG("Replaced stack by %s", get_record_trace().to_string().c_str());
+
+ // TODO: See if we can simply take a prefix of what
+ // currently exists instead of performing a recomputation.
+ // There seems to be a subtlety here that at the moment
+ // I can't figure out
+ if (reduction_mode_ == ReductionMode::sdpor) {
+ execution_seq_ = sdpor::Execution();
+ for (const auto& state : stack_) {
+ execution_seq_.push_transition(state->get_transition_out().get());
+ }
+ }
+ XBT_DEBUG("Additionally replaced corresponding SDPOR execution stack");
}
void DFSExplorer::log_state() // override
while (not stack_.empty()) {
/* Get current state */
- std::shared_ptr<State> state(stack_.back());
+ auto state = stack_.back();
XBT_DEBUG("**************************************************");
XBT_DEBUG("Exploration depth=%zu (state:#%ld; %zu interleaves todo)", stack_.size(), state->get_num(),
continue;
}
+#if SIMGRID_HAVE_STATEFUL_MC
// 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.",
this->backtrack();
continue;
}
+#endif
// Search for the next transition
- // next_transition returns a pair<aid_t, double> in case we want to consider multiple state (eg. during backtrack)
+ // next_transition returns a pair<aid_t, int> 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.
}
/* 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) */
- std::shared_ptr<State> next_state = std::make_shared<State>(get_remote_app(), state);
+ auto next_state = std::make_shared<State>(get_remote_app(), state);
on_state_creation_signal(next_state.get(), get_remote_app());
/* Sleep set procedure:
* <!> 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
+ 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 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_);
+ aid_t issuer_id = state->get_transition_out()->aid_;
+ stack_t tmp_stack = 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);
+ 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()->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)) {
prev_state->consider_one(issuer_id);
- opened_states_.push(std::shared_ptr<State>(tmp_stack.back()));
+ 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 {
issuer_id);
// If we ended up marking at least a transition, explore it at some point
if (prev_state->consider_all() > 0)
- opened_states_.push(std::shared_ptr<State>(tmp_stack.back()));
+ opened_states_.emplace_back(tmp_stack.back());
}
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 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` and then `p` to flip the race
+ */
+ execution_seq_.push_transition(executed_transition.get());
+
+ xbt_assert(execution_seq_.get_latest_event_handle().has_value(),
+ "No events are contained in the SDPOR/OPDPOR execution "
+ "even though one was just added");
+ const aid_t p = executed_transition->aid_;
+ const auto next_E_p = execution_seq_.get_latest_event_handle().value();
+
+ for (const auto racing_event_handle : execution_seq_.get_racing_events_of(next_E_p)) {
+ // To determine if the race is reversible, we have to ensure
+ // that actor `p` running `next_E_p` (viz. the event such that
+ // `racing_event -> (E_p) next_E_p` and no other event
+ // "happens-between" the two) is enabled in any equivalent
+ // execution where `racing_event` happens before `next_E_p`.
+ //
+ // Importantly, it is equivalent to checking if in ANY
+ // such equivalent execution sequence where `racing_event`
+ // happens-before `next_E_p` that `p` is enabled in `pre(racing_event, E.p)`.
+ // Thus it suffices to check THIS execution
+ //
+ // If the actor `p` is not enabled at s_[E'], it is not a *reversible* race
+ const std::shared_ptr<State> prev_state = stack_[racing_event_handle];
+ if (prev_state->is_actor_enabled(p)) {
+ // 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 bes
+ const std::optional<aid_t> q =
+ execution_seq_.get_first_ssdpor_initial_from(racing_event_handle, prev_state->get_backtrack_set());
+ if (q.has_value()) {
+ prev_state->consider_one(q.value());
+ opened_states_.emplace_back(std::move(prev_state));
+ }
+ }
+ }
}
// 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_.push(std::shared_ptr<State>(stack_.back()));
+ opened_states_.emplace_back(stack_.back());
if (_sg_mc_termination)
this->check_non_termination(next_state.get());
-#if SIMGRID_HAVE_MC
- /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */
+#if SIMGRID_HAVE_STATEFUL_MC
+ /* 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
- stack_.push_back(std::move(next_state));
+ stack_.emplace_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) {
}
dot_output("\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), stack_.back()->get_num(),
- state->get_transition()->dot_string().c_str());
- } else
+ 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
+ }
}
log_state();
}
+std::shared_ptr<State> DFSExplorer::best_opened_state()
+{
+ 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;
+ }
+
+ std::shared_ptr<State> 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_));
+
+ return best_state;
+}
+
void DFSExplorer::backtrack()
{
XBT_VERB("Backtracking from %s", get_record_trace().to_string().c_str());
on_backtracking_signal(get_remote_app());
get_remote_app().check_deadlock();
+ // Take the point with smallest distance
+ auto backtracking_point = best_opened_state();
+
// if no backtracking point, then set the stack_ to empty so we can end the exploration
- if (opened_states_.empty()) {
+ if (not backtracking_point) {
XBT_DEBUG("No more opened point of exploration, the search will end");
- stack_ = std::list<std::shared_ptr<State>>();
- return;
- }
-
- std::shared_ptr<State> backtracking_point = opened_states_.top(); // Take the point with smallest distance
- opened_states_.pop();
-
- // if the smallest distance corresponded to no enable actor, remove this and let the
- // exploration ask again for a backtrack
- if (backtracking_point->next_transition_guided().first == -1) {
- XBT_DEBUG("Best backtracking candidates has already been explored. Let's backtrack again");
- this->backtrack();
+ stack_.clear();
return;
}
- // We found a real backtracking point, let's go to it
+ // We found a backtracking point, let's go to it
backtrack_count_++;
XBT_DEBUG("Backtracking to state#%ld", backtracking_point->get_num());
-#if SIMGRID_HAVE_MC
+#if SIMGRID_HAVE_STATEFUL_MC
/* If asked to rollback on a state that has a snapshot, restore it */
if (const auto* system_state = backtracking_point->get_system_state()) {
system_state->restore(*get_remote_app().get_remote_process_memory());
}
#endif
+ // Search how to restore the backtracking point
+ State* init_state = nullptr;
+ std::deque<Transition*> 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<char*>& args, bool with_dpor, bool need_memory_info)
- : Exploration(args, need_memory_info || _sg_mc_termination)
+ : Exploration(args, need_memory_info || _sg_mc_termination
+#if SIMGRID_HAVE_STATEFUL_MC
+ || _sg_mc_checkpoint > 0
+#endif
+ )
{
if (with_dpor)
reduction_mode_ = ReductionMode::dpor;
XBT_DEBUG("**************************************************");
- stack_.push_back(std::move(initial_state));
+ 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. %lu actors to consider", stack_.back()->get_actor_count());
stack_.back()->consider_all();
}
if (stack_.back()->count_todo_multiples() > 1)
- opened_states_.push(std::shared_ptr<State>(stack_.back()));
+ opened_states_.emplace_back(stack_.back());
}
Exploration* create_dfs_exploration(const std::vector<char*>& args, bool with_dpor)
