1 /* Copyright (c) 2016-2022. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/mc/Session.hpp"
7 #include "src/mc/Transition.hpp"
8 #include "src/mc/VisitedState.hpp"
9 #include "src/mc/checker/SafetyChecker.hpp"
10 #include "src/mc/mc_config.hpp"
11 #include "src/mc/mc_exit.hpp"
12 #include "src/mc/mc_private.hpp"
13 #include "src/mc/mc_record.hpp"
15 #include "src/xbt/mmalloc/mmprivate.h"
17 #include "xbt/sysdep.h"
26 using api = simgrid::mc::Api;
28 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_safety, mc, "Logging specific to MC safety verification ");
33 void SafetyChecker::check_non_termination(const State* current_state)
35 for (auto state = stack_.rbegin(); state != stack_.rend(); ++state)
36 if (api::get().snapshot_equal((*state)->system_state_.get(), current_state->system_state_.get())) {
37 XBT_INFO("Non-progressive cycle: state %d -> state %d", (*state)->num_, current_state->num_);
38 XBT_INFO("******************************************");
39 XBT_INFO("*** NON-PROGRESSIVE CYCLE DETECTED ***");
40 XBT_INFO("******************************************");
41 XBT_INFO("Counter-example execution trace:");
42 for (auto const& s : get_textual_trace())
43 XBT_INFO(" %s", s.c_str());
44 api::get().dump_record_path();
45 api::get().log_state();
47 throw TerminationError();
51 RecordTrace SafetyChecker::get_record_trace() // override
54 for (auto const& state : stack_)
55 res.push_back(state->get_transition());
59 std::vector<std::string> SafetyChecker::get_textual_trace() // override
61 std::vector<std::string> trace;
62 for (auto const& state : stack_)
63 trace.push_back(state->transition_.textual);
67 void SafetyChecker::log_state() // override
69 XBT_INFO("Expanded states = %lu", expanded_states_count_);
70 XBT_INFO("Visited states = %lu", api::get().mc_get_visited_states());
71 XBT_INFO("Executed transitions = %lu", api::get().mc_get_executed_trans());
74 void SafetyChecker::run()
76 /* This function runs the DFS algorithm the state space.
77 * We do so iteratively instead of recursively, dealing with the call stack manually.
78 * This allows one to explore the call stack at will. */
80 while (not stack_.empty()) {
81 /* Get current state */
82 State* state = stack_.back().get();
84 XBT_DEBUG("**************************************************");
85 XBT_VERB("Exploration depth=%zu (state=%p, num %d)(%zu interleave)", stack_.size(), state, state->num_,
88 api::get().mc_inc_visited_states();
90 // Backtrack if we reached the maximum depth
91 if (stack_.size() > (std::size_t)_sg_mc_max_depth) {
92 if (reductionMode_ == ReductionMode::dpor) {
93 XBT_ERROR("/!\\ Max depth reached! THIS WILL PROBABLY BREAK the dpor reduction /!\\");
94 XBT_ERROR("/!\\ If bad things happen, disable dpor with --cfg=model-check/reduction:none /!\\");
96 XBT_WARN("/!\\ Max depth reached ! /!\\ ");
101 // Backtrack if we are revisiting a state we saw previously
102 if (visited_state_ != nullptr) {
103 XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
104 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num);
106 visited_state_ = nullptr;
111 // Search an enabled transition in the current state; backtrack if the interleave set is empty
112 // get_request also sets state.transition to be the one corresponding to the returned req
113 smx_simcall_t req = api::get().mc_state_choose_request(state);
114 // req is now the transition of the process that was selected to be executed
116 if (req == nullptr) {
117 XBT_DEBUG("There remains %zu actors, but no more processes to interleave. (depth %zu)",
118 mc_model_checker->get_remote_process().actors().size(), stack_.size() + 1);
120 if (mc_model_checker->get_remote_process().actors().empty())
121 mc_model_checker->finalize_app();
126 // If there are processes to interleave and the maximum depth has not been
127 // reached then perform one step of the exploration algorithm.
128 XBT_DEBUG("Execute: %s", api::get().request_to_string(req, state->transition_.times_considered_).c_str());
131 if (dot_output != nullptr)
132 req_str = api::get().request_get_dot_output(req, state->transition_.times_considered_);
134 api::get().mc_inc_executed_trans();
136 /* Actually answer the request: let execute the selected request (MCed does one step) */
137 api::get().execute(state->transition_, &state->executed_req_);
139 /* Create the new expanded state (copy the state of MCed into our MCer data) */
140 ++expanded_states_count_;
141 auto next_state = std::make_unique<State>(expanded_states_count_);
143 if (_sg_mc_termination)
144 this->check_non_termination(next_state.get());
146 /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */
147 if (_sg_mc_max_visited_states > 0)
148 visited_state_ = visited_states_.addVisitedState(expanded_states_count_, next_state.get(), true);
150 /* If this is a new state (or if we don't care about state-equality reduction) */
151 if (visited_state_ == nullptr) {
152 /* Get an enabled process and insert it in the interleave set of the next state */
153 auto actors = api::get().get_actors();
154 for (auto& remoteActor : actors) {
155 auto actor = remoteActor.copy.get_buffer();
156 if (get_session().actor_is_enabled(actor->get_pid())) {
157 next_state->mark_todo(actor);
158 if (reductionMode_ == ReductionMode::dpor)
159 break; // With DPOR, we take the first enabled transition
163 if (dot_output != nullptr)
164 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_, next_state->num_, req_str.c_str());
166 } else if (dot_output != nullptr)
167 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_,
168 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num,
171 stack_.push_back(std::move(next_state));
174 XBT_INFO("No property violation found.");
175 api::get().log_state();
178 void SafetyChecker::backtrack()
182 api::get().mc_check_deadlock();
184 /* Traverse the stack backwards until a state with a non empty interleave set is found, deleting all the states that
185 * have it empty in the way. For each deleted state, check if the request that has generated it (from its
186 * predecessor state), depends on any other previous request executed before it. If it does then add it to the
187 * interleave set of the state that executed that previous request. */
189 while (not stack_.empty()) {
190 std::unique_ptr<State> state = std::move(stack_.back());
192 if (reductionMode_ == ReductionMode::dpor) {
193 kernel::actor::ActorImpl* issuer = api::get().simcall_get_issuer(&state->executed_req_);
194 for (auto i = stack_.rbegin(); i != stack_.rend(); ++i) {
195 State* prev_state = i->get();
196 if (state->executed_req_.issuer_ == prev_state->executed_req_.issuer_) {
197 XBT_DEBUG("Simcall %s and %s with same issuer", SIMIX_simcall_name(state->executed_req_),
198 SIMIX_simcall_name(prev_state->executed_req_));
200 } else if (api::get().simcall_check_dependency(&state->internal_req_, &prev_state->internal_req_)) {
201 if (XBT_LOG_ISENABLED(mc_safety, xbt_log_priority_debug)) {
202 XBT_DEBUG("Dependent Transitions:");
203 int value = prev_state->transition_.times_considered_;
204 smx_simcall_t prev_req = &prev_state->executed_req_;
205 XBT_DEBUG("%s (state=%d)", api::get().request_to_string(prev_req, value).c_str(), prev_state->num_);
206 value = state->transition_.times_considered_;
207 prev_req = &state->executed_req_;
208 XBT_DEBUG("%s (state=%d)", api::get().request_to_string(prev_req, value).c_str(), state->num_);
211 if (not prev_state->actor_states_[issuer->get_pid()].is_done())
212 prev_state->mark_todo(issuer);
214 XBT_DEBUG("Actor %s %ld is in done set", api::get().get_actor_name(issuer).c_str(), issuer->get_pid());
217 const kernel::actor::ActorImpl* previous_issuer = api::get().simcall_get_issuer(&prev_state->executed_req_);
218 XBT_DEBUG("Simcall %s, process %ld (state %d) and simcall %s, process %ld (state %d) are independent",
219 SIMIX_simcall_name(state->executed_req_), issuer->get_pid(), state->num_,
220 SIMIX_simcall_name(prev_state->executed_req_), previous_issuer->get_pid(), prev_state->num_);
225 if (state->count_todo() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
226 /* We found a back-tracking point, let's loop */
227 XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num_, stack_.size() + 1);
228 stack_.push_back(std::move(state));
229 this->restore_state();
230 XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num_, stack_.size());
233 XBT_DEBUG("Delete state %d at depth %zu", state->num_, stack_.size() + 1);
238 void SafetyChecker::restore_state()
240 /* Intermediate backtracking */
241 const State* last_state = stack_.back().get();
242 if (last_state->system_state_) {
243 api::get().restore_state(last_state->system_state_);
247 get_session().restore_initial_state();
249 /* Traverse the stack from the state at position start and re-execute the transitions */
250 for (std::unique_ptr<State> const& state : stack_) {
251 if (state == stack_.back())
253 api::get().execute(state->transition_, &state->executed_req_);
254 /* Update statistics */
255 api::get().mc_inc_visited_states();
256 api::get().mc_inc_executed_trans();
260 SafetyChecker::SafetyChecker(Session* session) : Checker(session)
262 reductionMode_ = reduction_mode;
263 if (_sg_mc_termination)
264 reductionMode_ = ReductionMode::none;
265 else if (reductionMode_ == ReductionMode::unset)
266 reductionMode_ = ReductionMode::dpor;
268 if (_sg_mc_termination)
269 XBT_INFO("Check non progressive cycles");
271 XBT_INFO("Check a safety property. Reduction is: %s.",
272 (reductionMode_ == ReductionMode::none ? "none"
273 : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown")));
275 get_session().take_initial_snapshot();
277 XBT_DEBUG("Starting the safety algorithm");
279 ++expanded_states_count_;
280 auto initial_state = std::make_unique<State>(expanded_states_count_);
282 XBT_DEBUG("**************************************************");
283 XBT_DEBUG("Initial state");
285 /* Get an enabled actor and insert it in the interleave set of the initial state */
286 auto actors = api::get().get_actors();
287 for (auto& actor : actors)
288 if (get_session().actor_is_enabled(actor.copy.get_buffer()->get_pid())) {
289 initial_state->mark_todo(actor.copy.get_buffer());
290 if (reductionMode_ != ReductionMode::none)
294 stack_.push_back(std::move(initial_state));
297 Checker* create_safety_checker(Session* session)
299 return new SafetyChecker(session);
303 } // namespace simgrid