-/* 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/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 "xbt/sysdep.h"
#include <cassert>
namespace simgrid::mc {
-xbt::signal<void()> DFSExplorer::on_exploration_start_signal;
-xbt::signal<void()> DFSExplorer::on_backtracking_signal;
+xbt::signal<void(RemoteApp&)> DFSExplorer::on_exploration_start_signal;
+xbt::signal<void(RemoteApp&)> DFSExplorer::on_backtracking_signal;
-xbt::signal<void(State*)> DFSExplorer::on_state_creation_signal;
+xbt::signal<void(State*, RemoteApp&)> DFSExplorer::on_state_creation_signal;
-xbt::signal<void(State*)> DFSExplorer::on_restore_system_state_signal;
-xbt::signal<void()> DFSExplorer::on_restore_initial_state_signal;
-xbt::signal<void(Transition*)> DFSExplorer::on_transition_replay_signal;
-xbt::signal<void(Transition*)> DFSExplorer::on_transition_execute_signal;
+xbt::signal<void(State*, RemoteApp&)> DFSExplorer::on_restore_system_state_signal;
+xbt::signal<void(RemoteApp&)> DFSExplorer::on_restore_initial_state_signal;
+xbt::signal<void(Transition*, RemoteApp&)> DFSExplorer::on_transition_replay_signal;
+xbt::signal<void(Transition*, RemoteApp&)> DFSExplorer::on_transition_execute_signal;
-xbt::signal<void()> DFSExplorer::on_log_state_signal;
+xbt::signal<void(RemoteApp&)> 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());
+#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())) {
+ 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());
+ XBT_INFO("You can debug the problem (and see the whole details) by rerunning out of simgrid-mc with "
+ "--cfg=model-check/replay:'%s'",
+ get_record_trace().to_string().c_str());
log_state();
throw TerminationError();
}
+ }
+#endif
}
RecordTrace DFSExplorer::get_record_trace() // override
{
RecordTrace res;
- for (auto const& state : stack_)
- res.push_back(state->get_transition());
+ 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& state : stack_) {
- const auto* t = state->get_transition();
- trace.push_back(xbt::string_printf("%ld: %s", t->aid_, t->to_string().c_str()));
+ 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;
}
+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));
+ // 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));
+ }
+ XBT_DEBUG("Replaced stack by %s", get_record_trace().to_string().c_str());
+}
+
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(),
+ State::get_expanded_states(), backtrack_count_, visited_states_count_,
Transition::get_replayed_transitions());
+ 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();
+ std::shared_ptr<State> 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 /!\\");
continue;
}
- // Backtrack if we are revisiting a state we saw previously
+#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.",
- 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();
continue;
}
+#endif
// Search for the next transition
- int 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 %zu actors, but none to interleave (depth %zu).",
- mc_model_checker->get_remote_process().actors().size(), stack_.size() + 1);
+ XBT_VERB("%lu actors remain, but none of them need to be interleaved (depth %zu).", state->get_actor_count(),
+ stack_.size() + 1);
- if (mc_model_checker->get_remote_process().actors().empty()) {
- mc_model_checker->finalize_app();
+ if (state->get_actor_count() == 0) {
+ 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);
- on_transition_execute_signal(state->get_transition());
+ 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
// 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());
- std::string req_str;
- if (dot_output != nullptr)
- req_str = state->get_transition()->dot_string();
-
/* Create the new expanded state (copy the state of MCed into our MCer data) */
- auto next_state = std::make_unique<State>();
- on_state_creation_signal(next_state.get());
+ std::shared_ptr<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);
+ opened_states_.push(std::shared_ptr<State>(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_.push(std::shared_ptr<State>(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());
+ }
+ 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)
+ opened_states_.push(std::shared_ptr<State>(stack_.back()));
if (_sg_mc_termination)
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) */
if (_sg_mc_max_visited_states > 0)
- visited_state_ = visited_states_.addVisitedState(next_state->get_num(), next_state.get(), true);
+ visited_state_ = visited_states_.addVisitedState(next_state->get_num(), next_state.get(), get_remote_app());
+#endif
+
+ 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 */
- auto actors = mc_model_checker->get_remote_process().actors();
- for (auto& remoteActor : actors) {
- auto actor = remoteActor.copy.get_buffer();
- if (get_session().actor_is_enabled(actor->get_pid())) {
- next_state->mark_todo(actor->get_pid());
- if (reductionMode_ == 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();
}
- if (dot_output != nullptr)
- std::fprintf(dot_output, "\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), next_state->get_num(),
- req_str.c_str());
-
- } 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,
- req_str.c_str());
-
- stack_.push_back(std::move(next_state));
+ dot_output("\"%ld\" -> \"%ld\" [%s];\n", state->get_num(), stack_.back()->get_num(),
+ state->get_transition()->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());
+#endif
+ }
}
-
log_state();
}
void DFSExplorer::backtrack()
{
- backtrack_count_++;
XBT_VERB("Backtracking from %s", get_record_trace().to_string().c_str());
- on_backtracking_signal();
- stack_.pop_back();
+ XBT_DEBUG("%lu alternatives are yet to be explored:", opened_states_.size());
- get_session().check_deadlock();
+ 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. */
+ // if no backtracking point, then set the stack_ to empty so we can end the exploration
+ if (opened_states_.empty()) {
+ XBT_DEBUG("No more opened point of exploration, the search will end");
+ stack_ = std::list<std::shared_ptr<State>>();
+ return;
+ }
- while (not stack_.empty()) {
- std::unique_ptr<State> 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<State> backtracking_point = opened_states_.top(); // Take the point with smallest distance
+ opened_states_.pop();
- 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());
- }
- }
- }
-
- 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);
- }
+ // 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();
+ return;
}
-}
-void DFSExplorer::restore_state()
-{
+ // We found a real backtracking point, let's go to it
+ backtrack_count_++;
+ XBT_DEBUG("Backtracking to state#%ld", backtracking_point->get_num());
+
+#if SIMGRID_HAVE_STATEFUL_MC
/* 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);
+ if (const auto* system_state = backtracking_point->get_system_state()) {
+ system_state->restore(*get_remote_app().get_remote_process_memory());
+ on_restore_system_state_signal(backtracking_point.get(), get_remote_app());
+ this->restore_stack(backtracking_point);
return;
}
+#endif
/* if no snapshot, we need to restore the initial state and replay the transitions */
- get_session().restore_initial_state();
- on_restore_initial_state_signal();
-
+ 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());
- /* Update statistics */
- Api::get().mc_inc_visited_states();
+ for (auto& state : backtracking_point->get_recipe()) {
+ state->replay(get_remote_app());
+ on_transition_replay_signal(state, get_remote_app());
+ visited_states_count_++;
}
+ this->restore_stack(backtracking_point);
}
-DFSExplorer::DFSExplorer(Session* session) : Exploration(session)
+DFSExplorer::DFSExplorer(const std::vector<char*>& args, bool with_dpor, bool need_memory_info)
+ : Exploration(args, need_memory_info || _sg_mc_termination)
{
- 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");
+ if (with_dpor)
+ reduction_mode_ = ReductionMode::dpor;
else
- XBT_INFO("Start a DFS exploration. Reduction is: %s.",
- (reductionMode_ == ReductionMode::none ? "none"
- : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown")));
+ reduction_mode_ = ReductionMode::none;
- get_session().take_initial_snapshot();
-
- XBT_DEBUG("Starting the DFS exploration");
+ if (_sg_mc_termination) {
+ if (with_dpor) {
+ XBT_INFO("Check non progressive cycles (turning DPOR off)");
+ reduction_mode_ = ReductionMode::none;
+ } else {
+ XBT_INFO("Check non progressive cycles");
+ }
+ } else
+ XBT_INFO("Start a DFS exploration. Reduction is: %s.", to_c_str(reduction_mode_));
- auto initial_state = std::make_unique<State>();
+ auto initial_state = std::make_shared<State>(get_remote_app());
XBT_DEBUG("**************************************************");
+ stack_.push_back(std::move(initial_state));
+
/* Get an enabled actor and insert it in the interleave set of the initial state */
- auto actors = mc_model_checker->get_remote_process().actors();
- XBT_DEBUG("Initial state. %zu actors to consider", actors.size());
- for (auto& actor : actors) {
- aid_t aid = actor.copy.get_buffer()->get_pid();
- if (get_session().actor_is_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_.push(std::shared_ptr<State>(stack_.back()));
}
-Exploration* create_dfs_exploration(Session* session)
+Exploration* create_dfs_exploration(const std::vector<char*>& args, bool with_dpor)
{
- return new DFSExplorer(session);
+ return new DFSExplorer(args, with_dpor);
}
} // namespace simgrid::mc
