1 /* Copyright (c) 2016-2021. 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. */
14 #include <xbt/sysdep.h>
16 #include "src/mc/Transition.hpp"
17 #include "src/mc/VisitedState.hpp"
18 #include "src/mc/checker/SafetyChecker.hpp"
19 #include "src/mc/mc_config.hpp"
20 #include "src/mc/mc_exit.hpp"
21 #include "src/mc/mc_private.hpp"
22 #include "src/mc/mc_record.hpp"
23 #include "src/mc/mc_request.hpp"
24 #include "src/mc/mc_smx.hpp"
26 #include "src/xbt/mmalloc/mmprivate.h"
28 using api = simgrid::mc::Api;
30 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_safety, mc, "Logging specific to MC safety verification ");
35 void SafetyChecker::check_non_termination(const State* current_state)
37 for (auto state = stack_.rbegin(); state != stack_.rend(); ++state)
38 if (api::get().snapshot_equal((*state)->system_state_.get(), current_state->system_state_.get())) {
39 XBT_INFO("Non-progressive cycle: state %d -> state %d", (*state)->num_, current_state->num_);
40 XBT_INFO("******************************************");
41 XBT_INFO("*** NON-PROGRESSIVE CYCLE DETECTED ***");
42 XBT_INFO("******************************************");
43 XBT_INFO("Counter-example execution trace:");
44 auto checker = api::get().mc_get_checker();
45 for (auto const& s : checker->get_textual_trace())
46 XBT_INFO(" %s", s.c_str());
47 api::get().dump_record_path();
48 api::get().log_state();
50 throw TerminationError();
54 RecordTrace SafetyChecker::get_record_trace() // override
57 for (auto const& state : stack_)
58 res.push_back(state->get_transition());
62 std::vector<std::string> SafetyChecker::get_textual_trace() // override
64 std::vector<std::string> trace;
65 for (auto const& state : stack_) {
66 int value = state->transition_.argument_;
67 smx_simcall_t req = &state->executed_req_;
68 trace.push_back(api::get().request_to_string(req, value, RequestType::executed));
73 void SafetyChecker::log_state() // override
75 XBT_INFO("Expanded states = %lu", expanded_states_count_);
76 XBT_INFO("Visited states = %lu", api::get().mc_get_visited_states());
77 XBT_INFO("Executed transitions = %lu", api::get().mc_get_executed_trans());
80 void SafetyChecker::run()
82 /* This function runs the DFS algorithm the state space.
83 * We do so iteratively instead of recursively, dealing with the call stack manually.
84 * This allows one to explore the call stack at will. */
86 while (not stack_.empty()) {
87 /* Get current state */
88 State* state = stack_.back().get();
90 XBT_DEBUG("**************************************************");
91 XBT_VERB("Exploration depth=%zu (state=%p, num %d)(%zu interleave)", stack_.size(), state, state->num_,
92 state->interleave_size());
94 api::get().mc_inc_visited_states();
96 // Backtrack if we reached the maximum depth
97 if (stack_.size() > (std::size_t)_sg_mc_max_depth) {
98 XBT_WARN("/!\\ Max depth reached ! /!\\ ");
103 // Backtrack if we are revisiting a state we saw previously
104 if (visited_state_ != nullptr) {
105 XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
106 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num);
108 visited_state_ = nullptr;
113 // Search an enabled transition in the current state; backtrack if the interleave set is empty
114 // get_request also sets state.transition to be the one corresponding to the returned req
115 smx_simcall_t req = api::get().mc_state_choose_request(state);
116 // req is now the transition of the process that was selected to be executed
118 if (req == nullptr) {
119 XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size() + 1);
125 // If there are processes to interleave and the maximum depth has not been
126 // reached then perform one step of the exploration algorithm.
127 XBT_DEBUG("Execute: %s", api::get().request_to_string(req, state->transition_.argument_, RequestType::simix).c_str());
130 if (dot_output != nullptr)
131 req_str = api::get().request_get_dot_output(req, state->transition_.argument_);
133 api::get().mc_inc_executed_trans();
135 /* Actually answer the request: let execute the selected request (MCed does one step) */
136 api::get().execute(state->transition_);
138 /* Create the new expanded state (copy the state of MCed into our MCer data) */
139 ++expanded_states_count_;
140 auto next_state = std::make_unique<State>(expanded_states_count_);
142 if (_sg_mc_termination)
143 this->check_non_termination(next_state.get());
145 /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */
146 if (_sg_mc_max_visited_states > 0)
147 visited_state_ = visited_states_.addVisitedState(expanded_states_count_, next_state.get(), true);
149 /* If this is a new state (or if we don't care about state-equality reduction) */
150 if (visited_state_ == nullptr) {
151 /* Get an enabled process and insert it in the interleave set of the next state */
152 auto actors = api::get().get_actors();
153 for (auto& remoteActor : actors) {
154 auto actor = remoteActor.copy.get_buffer();
155 if (api::get().actor_is_enabled(actor->get_pid())) {
156 next_state->add_interleaving_set(actor);
157 if (reductionMode_ == ReductionMode::dpor)
158 break; // With DPOR, we take the first enabled transition
162 if (dot_output != nullptr)
163 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_, next_state->num_, req_str.c_str());
165 } else if (dot_output != nullptr)
166 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_,
167 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num,
170 stack_.push_back(std::move(next_state));
173 XBT_INFO("No property violation found.");
174 api::get().log_state();
177 void SafetyChecker::backtrack()
181 /* Check for deadlocks */
182 if (api::get().mc_check_deadlock()) {
183 api::get().mc_show_deadlock();
184 throw DeadlockError();
187 /* Traverse the stack backwards until a state with a non empty interleave set is found, deleting all the states that
188 * have it empty in the way. For each deleted state, check if the request that has generated it (from its
189 * predecessor state), depends on any other previous request executed before it. If it does then add it to the
190 * interleave set of the state that executed that previous request. */
192 while (not stack_.empty()) {
193 std::unique_ptr<State> state = std::move(stack_.back());
195 if (reductionMode_ == ReductionMode::dpor) {
196 smx_simcall_t req = &state->internal_req_;
197 if (req->call_ == simix::Simcall::MUTEX_LOCK || req->call_ == simix::Simcall::MUTEX_TRYLOCK)
198 xbt_die("Mutex is currently not supported with DPOR, use --cfg=model-check/reduction:none");
200 const kernel::actor::ActorImpl* issuer = api::get().simcall_get_issuer(req);
201 for (auto i = stack_.rbegin(); i != stack_.rend(); ++i) {
202 State* prev_state = i->get();
203 if (api::get().simcall_check_dependency(req, &prev_state->internal_req_)) {
204 if (XBT_LOG_ISENABLED(mc_safety, xbt_log_priority_debug)) {
205 XBT_DEBUG("Dependent Transitions:");
206 int value = prev_state->transition_.argument_;
207 smx_simcall_t prev_req = &prev_state->executed_req_;
208 XBT_DEBUG("%s (state=%d)", api::get().request_to_string(prev_req, value, RequestType::internal).c_str(),
210 value = state->transition_.argument_;
211 prev_req = &state->executed_req_;
212 XBT_DEBUG("%s (state=%d)", api::get().request_to_string(prev_req, value, RequestType::executed).c_str(),
216 if (not prev_state->actor_states_[issuer->get_pid()].is_done())
217 prev_state->add_interleaving_set(issuer);
219 XBT_DEBUG("Process %p is in done set", req->issuer_);
221 } else if (req->issuer_ == prev_state->internal_req_.issuer_) {
222 XBT_DEBUG("Simcall %s and %s with same issuer", api::get().simcall_get_name(req->call_),
223 api::get().simcall_get_name(prev_state->internal_req_.call_));
226 const kernel::actor::ActorImpl* previous_issuer = api::get().simcall_get_issuer(&prev_state->internal_req_);
227 XBT_DEBUG("Simcall %s, process %ld (state %d) and simcall %s, process %ld (state %d) are independent",
228 api::get().simcall_get_name(req->call_), issuer->get_pid(), state->num_,
229 api::get().simcall_get_name(prev_state->internal_req_.call_), previous_issuer->get_pid(), prev_state->num_);
234 if (state->interleave_size() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
235 /* We found a back-tracking point, let's loop */
236 XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num_, stack_.size() + 1);
237 stack_.push_back(std::move(state));
238 this->restore_state();
239 XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num_, stack_.size());
242 XBT_DEBUG("Delete state %d at depth %zu", state->num_, stack_.size() + 1);
247 void SafetyChecker::restore_state()
249 /* Intermediate backtracking */
250 const State* last_state = stack_.back().get();
251 if (last_state->system_state_) {
252 Api::get().restore_state(last_state->system_state_);
256 /* Restore the initial state */
257 api::get().restore_initial_state();
259 /* Traverse the stack from the state at position start and re-execute the transitions */
260 for (std::unique_ptr<State> const& state : stack_) {
261 if (state == stack_.back())
263 api::get().execute(state->transition_);
264 /* Update statistics */
265 api::get().mc_inc_visited_states();
266 api::get().mc_inc_executed_trans();
270 SafetyChecker::SafetyChecker() : Checker()
272 reductionMode_ = reduction_mode;
273 if (_sg_mc_termination)
274 reductionMode_ = ReductionMode::none;
275 else if (reductionMode_ == ReductionMode::unset)
276 reductionMode_ = ReductionMode::dpor;
278 if (_sg_mc_termination)
279 XBT_INFO("Check non progressive cycles");
281 XBT_INFO("Check a safety property. Reduction is: %s.",
282 (reductionMode_ == ReductionMode::none ? "none"
283 : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown")));
285 api::get().session_initialize();
287 XBT_DEBUG("Starting the safety algorithm");
289 ++expanded_states_count_;
290 auto initial_state = std::make_unique<State>(expanded_states_count_);
292 XBT_DEBUG("**************************************************");
293 XBT_DEBUG("Initial state");
295 /* Get an enabled actor and insert it in the interleave set of the initial state */
296 auto actors = api::get().get_actors();
297 for (auto& actor : actors)
298 if (api::get().actor_is_enabled(actor.copy.get_buffer()->get_pid())) {
299 initial_state->add_interleaving_set(actor.copy.get_buffer());
300 if (reductionMode_ != ReductionMode::none)
304 stack_.push_back(std::move(initial_state));
307 Checker* createSafetyChecker()
309 return new SafetyChecker();
313 } // namespace simgrid