1 /* Copyright (c) 2016-2020. 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/Session.hpp"
17 #include "src/mc/Transition.hpp"
18 #include "src/mc/VisitedState.hpp"
19 #include "src/mc/checker/SafetyChecker.hpp"
20 #include "src/mc/mc_config.hpp"
21 #include "src/mc/mc_exit.hpp"
22 #include "src/mc/mc_private.hpp"
23 #include "src/mc/mc_record.hpp"
24 #include "src/mc/mc_request.hpp"
25 #include "src/mc/mc_smx.hpp"
27 #include "src/xbt/mmalloc/mmprivate.h"
29 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_safety, mc, "Logging specific to MC safety verification ");
34 void SafetyChecker::check_non_termination(const State* current_state)
36 for (auto state = stack_.rbegin(); state != stack_.rend(); ++state)
37 if (snapshot_equal((*state)->system_state_.get(), current_state->system_state_.get())) {
38 XBT_INFO("Non-progressive cycle: state %d -> state %d", (*state)->num_, current_state->num_);
39 XBT_INFO("******************************************");
40 XBT_INFO("*** NON-PROGRESSIVE CYCLE DETECTED ***");
41 XBT_INFO("******************************************");
42 XBT_INFO("Counter-example execution trace:");
43 for (auto const& s : mc_model_checker->getChecker()->get_textual_trace())
44 XBT_INFO(" %s", s.c_str());
48 throw TerminationError();
52 RecordTrace SafetyChecker::get_record_trace() // override
55 for (auto const& state : stack_)
56 res.push_back(state->get_transition());
60 std::vector<std::string> SafetyChecker::get_textual_trace() // override
62 std::vector<std::string> trace;
63 for (auto const& state : stack_) {
64 int value = state->transition_.argument_;
65 smx_simcall_t req = &state->executed_req_;
67 trace.push_back(request_to_string(req, value, RequestType::executed));
72 void SafetyChecker::log_state() // override
74 XBT_INFO("Expanded states = %lu", expanded_states_count_);
75 XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
76 XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
79 void SafetyChecker::run()
81 /* This function runs the DFS algorithm the state space.
82 * We do so iteratively instead of recursively, dealing with the call stack manually.
83 * This allows one to explore the call stack at will. */
85 while (not stack_.empty()) {
86 /* Get current state */
87 State* state = stack_.back().get();
89 XBT_DEBUG("**************************************************");
90 XBT_VERB("Exploration depth=%zu (state=%p, num %d)(%zu interleave)", stack_.size(), state, state->num_,
91 state->interleave_size());
93 mc_model_checker->visited_states++;
95 // Backtrack if we reached the maximum depth
96 if (stack_.size() > (std::size_t)_sg_mc_max_depth) {
97 XBT_WARN("/!\\ Max depth reached ! /!\\ ");
102 // Backtrack if we are revisiting a state we saw previously
103 if (visited_state_ != nullptr) {
104 XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
105 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num);
107 visited_state_ = nullptr;
112 // Search an enabled transition in the current state; backtrack if the interleave set is empty
113 // get_request also sets state.transition to be the one corresponding to the returned req
114 smx_simcall_t req = MC_state_choose_request(state);
115 // req is now the transition of the process that was selected to be executed
117 if (req == nullptr) {
118 XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size() + 1);
124 // If there are processes to interleave and the maximum depth has not been
125 // reached then perform one step of the exploration algorithm.
126 XBT_DEBUG("Execute: %s", request_to_string(req, state->transition_.argument_, RequestType::simix).c_str());
129 if (dot_output != nullptr)
130 req_str = request_get_dot_output(req, state->transition_.argument_);
132 mc_model_checker->executed_transitions++;
134 /* Actually answer the request: let execute the selected request (MCed does one step) */
135 this->get_session().execute(state->transition_);
137 /* Create the new expanded state (copy the state of MCed into our MCer data) */
138 std::unique_ptr<State> next_state = std::unique_ptr<State>(new State(++expanded_states_count_));
140 if (_sg_mc_termination)
141 this->check_non_termination(next_state.get());
143 /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */
144 if (_sg_mc_max_visited_states > 0)
145 visited_state_ = visited_states_.addVisitedState(expanded_states_count_, next_state.get(), true);
147 /* If this is a new state (or if we don't care about state-equality reduction) */
148 if (visited_state_ == nullptr) {
149 /* Get an enabled process and insert it in the interleave set of the next state */
150 for (auto& remoteActor : mc_model_checker->process().actors()) {
151 auto actor = remoteActor.copy.get_buffer();
152 if (actor_is_enabled(actor)) {
153 next_state->add_interleaving_set(actor);
154 if (reductionMode_ == ReductionMode::dpor)
155 break; // With DPOR, we take the first enabled transition
159 if (dot_output != nullptr)
160 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_, next_state->num_, req_str.c_str());
162 } else if (dot_output != nullptr)
163 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_,
164 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num,
167 stack_.push_back(std::move(next_state));
170 XBT_INFO("No property violation found.");
171 session->log_state();
174 void SafetyChecker::backtrack()
178 /* Check for deadlocks */
179 if (mc_model_checker->checkDeadlock()) {
181 throw DeadlockError();
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 smx_simcall_t req = &state->internal_req_;
194 if (req->call_ == SIMCALL_MUTEX_LOCK || req->call_ == SIMCALL_MUTEX_TRYLOCK)
195 xbt_die("Mutex is currently not supported with DPOR, use --cfg=model-check/reduction:none");
197 const kernel::actor::ActorImpl* issuer = MC_smx_simcall_get_issuer(req);
198 for (auto i = stack_.rbegin(); i != stack_.rend(); ++i) {
199 State* prev_state = i->get();
200 if (request_depend(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_.argument_;
204 smx_simcall_t prev_req = &prev_state->executed_req_;
205 XBT_DEBUG("%s (state=%d)", simgrid::mc::request_to_string(prev_req, value, RequestType::internal).c_str(),
207 value = state->transition_.argument_;
208 prev_req = &state->executed_req_;
209 XBT_DEBUG("%s (state=%d)", simgrid::mc::request_to_string(prev_req, value, RequestType::executed).c_str(),
213 if (not prev_state->actor_states_[issuer->get_pid()].is_done())
214 prev_state->add_interleaving_set(issuer);
216 XBT_DEBUG("Process %p is in done set", req->issuer_);
218 } else if (req->issuer_ == prev_state->internal_req_.issuer_) {
219 XBT_DEBUG("Simcall %s and %s with same issuer", SIMIX_simcall_name(req->call_),
220 SIMIX_simcall_name(prev_state->internal_req_.call_));
223 const kernel::actor::ActorImpl* previous_issuer = MC_smx_simcall_get_issuer(&prev_state->internal_req_);
224 XBT_DEBUG("Simcall %s, process %ld (state %d) and simcall %s, process %ld (state %d) are independent",
225 SIMIX_simcall_name(req->call_), issuer->get_pid(), state->num_,
226 SIMIX_simcall_name(prev_state->internal_req_.call_), previous_issuer->get_pid(), prev_state->num_);
231 if (state->interleave_size() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
232 /* We found a back-tracking point, let's loop */
233 XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num_, stack_.size() + 1);
234 stack_.push_back(std::move(state));
235 this->restore_state();
236 XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num_, stack_.size());
239 XBT_DEBUG("Delete state %d at depth %zu", state->num_, stack_.size() + 1);
244 void SafetyChecker::restore_state()
246 /* Intermediate backtracking */
247 const State* last_state = stack_.back().get();
248 if (last_state->system_state_) {
249 last_state->system_state_->restore(&mc_model_checker->process());
253 /* Restore the initial state */
254 session->restore_initial_state();
256 /* Traverse the stack from the state at position start and re-execute the transitions */
257 for (std::unique_ptr<State> const& state : stack_) {
258 if (state == stack_.back())
260 session->execute(state->transition_);
261 /* Update statistics */
262 mc_model_checker->visited_states++;
263 mc_model_checker->executed_transitions++;
267 SafetyChecker::SafetyChecker(Session& s) : Checker(s)
269 reductionMode_ = reduction_mode;
270 if (_sg_mc_termination)
271 reductionMode_ = ReductionMode::none;
272 else if (reductionMode_ == ReductionMode::unset)
273 reductionMode_ = ReductionMode::dpor;
275 if (_sg_mc_termination)
276 XBT_INFO("Check non progressive cycles");
278 XBT_INFO("Check a safety property. Reduction is: %s.",
279 (reductionMode_ == ReductionMode::none ? "none"
280 : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown")));
281 session->initialize();
283 XBT_DEBUG("Starting the safety algorithm");
285 std::unique_ptr<State> initial_state = std::unique_ptr<State>(new State(++expanded_states_count_));
287 XBT_DEBUG("**************************************************");
288 XBT_DEBUG("Initial state");
290 /* Get an enabled actor and insert it in the interleave set of the initial state */
291 for (auto& actor : mc_model_checker->process().actors())
292 if (actor_is_enabled(actor.copy.get_buffer())) {
293 initial_state->add_interleaving_set(actor.copy.get_buffer());
294 if (reductionMode_ != ReductionMode::none)
298 stack_.push_back(std::move(initial_state));
301 Checker* createSafetyChecker(Session& s)
303 return new SafetyChecker(s);
307 } // namespace simgrid