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"
26 #include "src/mc/mc_api.hpp"
28 #include "src/xbt/mmalloc/mmprivate.h"
30 using mcapi = simgrid::mc::mc_api;
32 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_safety, mc, "Logging specific to MC safety verification ");
37 void SafetyChecker::check_non_termination(const State* current_state)
39 for (auto state = stack_.rbegin(); state != stack_.rend(); ++state)
40 if (snapshot_equal((*state)->system_state_.get(), current_state->system_state_.get())) {
41 XBT_INFO("Non-progressive cycle: state %d -> state %d", (*state)->num_, current_state->num_);
42 XBT_INFO("******************************************");
43 XBT_INFO("*** NON-PROGRESSIVE CYCLE DETECTED ***");
44 XBT_INFO("******************************************");
45 XBT_INFO("Counter-example execution trace:");
46 for (auto const& s : mc_model_checker->getChecker()->get_textual_trace())
47 XBT_INFO(" %s", s.c_str());
51 throw TerminationError();
55 RecordTrace SafetyChecker::get_record_trace() // override
58 for (auto const& state : stack_)
59 res.push_back(state->get_transition());
63 std::vector<std::string> SafetyChecker::get_textual_trace() // override
65 std::vector<std::string> trace;
66 for (auto const& state : stack_) {
67 int value = state->transition_.argument_;
68 smx_simcall_t req = &state->executed_req_;
70 trace.push_back(request_to_string(req, value, RequestType::executed));
75 void SafetyChecker::log_state() // override
77 XBT_INFO("Expanded states = %lu", expanded_states_count_);
78 XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
79 XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
82 void SafetyChecker::run()
84 /* This function runs the DFS algorithm the state space.
85 * We do so iteratively instead of recursively, dealing with the call stack manually.
86 * This allows one to explore the call stack at will. */
88 while (not stack_.empty()) {
89 /* Get current state */
90 State* state = stack_.back().get();
92 XBT_DEBUG("**************************************************");
93 XBT_VERB("Exploration depth=%zu (state=%p, num %d)(%zu interleave)", stack_.size(), state, state->num_,
94 state->interleave_size());
96 mc_model_checker->visited_states++;
98 // Backtrack if we reached the maximum depth
99 if (stack_.size() > (std::size_t)_sg_mc_max_depth) {
100 XBT_WARN("/!\\ Max depth reached ! /!\\ ");
105 // Backtrack if we are revisiting a state we saw previously
106 if (visited_state_ != nullptr) {
107 XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
108 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num);
110 visited_state_ = nullptr;
115 // Search an enabled transition in the current state; backtrack if the interleave set is empty
116 // get_request also sets state.transition to be the one corresponding to the returned req
117 smx_simcall_t req = MC_state_choose_request(state);
118 // req is now the transition of the process that was selected to be executed
120 if (req == nullptr) {
121 XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size() + 1);
127 // If there are processes to interleave and the maximum depth has not been
128 // reached then perform one step of the exploration algorithm.
129 XBT_DEBUG("Execute: %s", request_to_string(req, state->transition_.argument_, RequestType::simix).c_str());
132 if (dot_output != nullptr)
133 req_str = request_get_dot_output(req, state->transition_.argument_);
135 mc_model_checker->executed_transitions++;
137 /* Actually answer the request: let execute the selected request (MCed does one step) */
138 this->get_session().execute(state->transition_);
140 /* Create the new expanded state (copy the state of MCed into our MCer data) */
141 ++expanded_states_count_;
142 auto next_state = std::make_unique<State>(expanded_states_count_);
144 if (_sg_mc_termination)
145 this->check_non_termination(next_state.get());
147 /* Check whether we already explored next_state in the past (but only if interested in state-equality reduction) */
148 if (_sg_mc_max_visited_states > 0)
149 visited_state_ = visited_states_.addVisitedState(expanded_states_count_, next_state.get(), true);
151 /* If this is a new state (or if we don't care about state-equality reduction) */
152 if (visited_state_ == nullptr) {
153 /* Get an enabled process and insert it in the interleave set of the next state */
154 for (auto& remoteActor : mc_model_checker->get_remote_simulation().actors()) {
155 auto actor = remoteActor.copy.get_buffer();
156 if (actor_is_enabled(actor)) {
157 next_state->add_interleaving_set(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 session->log_state();
178 void SafetyChecker::backtrack()
182 /* Check for deadlocks */
183 if (mc_model_checker->checkDeadlock()) {
185 throw DeadlockError();
188 /* Traverse the stack backwards until a state with a non empty interleave set is found, deleting all the states that
189 * have it empty in the way. For each deleted state, check if the request that has generated it (from its
190 * predecessor state), depends on any other previous request executed before it. If it does then add it to the
191 * interleave set of the state that executed that previous request. */
193 while (not stack_.empty()) {
194 std::unique_ptr<State> state = std::move(stack_.back());
196 if (reductionMode_ == ReductionMode::dpor) {
197 smx_simcall_t req = &state->internal_req_;
198 if (req->call_ == SIMCALL_MUTEX_LOCK || req->call_ == SIMCALL_MUTEX_TRYLOCK)
199 xbt_die("Mutex is currently not supported with DPOR, use --cfg=model-check/reduction:none");
201 const kernel::actor::ActorImpl* issuer = MC_smx_simcall_get_issuer(req);
202 for (auto i = stack_.rbegin(); i != stack_.rend(); ++i) {
203 State* prev_state = i->get();
204 if (request_depend(req, &prev_state->internal_req_)) {
205 if (XBT_LOG_ISENABLED(mc_safety, xbt_log_priority_debug)) {
206 XBT_DEBUG("Dependent Transitions:");
207 int value = prev_state->transition_.argument_;
208 smx_simcall_t prev_req = &prev_state->executed_req_;
209 XBT_DEBUG("%s (state=%d)", simgrid::mc::request_to_string(prev_req, value, RequestType::internal).c_str(),
211 value = state->transition_.argument_;
212 prev_req = &state->executed_req_;
213 XBT_DEBUG("%s (state=%d)", simgrid::mc::request_to_string(prev_req, value, RequestType::executed).c_str(),
217 if (not prev_state->actor_states_[issuer->get_pid()].is_done())
218 prev_state->add_interleaving_set(issuer);
220 XBT_DEBUG("Process %p is in done set", req->issuer_);
222 } else if (req->issuer_ == prev_state->internal_req_.issuer_) {
223 XBT_DEBUG("Simcall %s and %s with same issuer", SIMIX_simcall_name(req->call_),
224 SIMIX_simcall_name(prev_state->internal_req_.call_));
227 const kernel::actor::ActorImpl* previous_issuer = MC_smx_simcall_get_issuer(&prev_state->internal_req_);
228 XBT_DEBUG("Simcall %s, process %ld (state %d) and simcall %s, process %ld (state %d) are independent",
229 SIMIX_simcall_name(req->call_), issuer->get_pid(), state->num_,
230 SIMIX_simcall_name(prev_state->internal_req_.call_), previous_issuer->get_pid(), prev_state->num_);
235 if (state->interleave_size() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
236 /* We found a back-tracking point, let's loop */
237 XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num_, stack_.size() + 1);
238 stack_.push_back(std::move(state));
239 this->restore_state();
240 XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num_, stack_.size());
243 XBT_DEBUG("Delete state %d at depth %zu", state->num_, stack_.size() + 1);
248 void SafetyChecker::restore_state()
250 /* Intermediate backtracking */
251 const State* last_state = stack_.back().get();
252 if (last_state->system_state_) {
253 last_state->system_state_->restore(&mcapi::get().mc_get_remote_simulation());
257 /* Restore the initial state */
258 mcapi::get().s_restore_initial_state();
260 /* Traverse the stack from the state at position start and re-execute the transitions */
261 for (std::unique_ptr<State> const& state : stack_) {
262 if (state == stack_.back())
264 mcapi::get().execute(state->transition_);
265 /* Update statistics */
266 mcapi::get().mc_inc_visited_states();
267 mcapi::get().mc_inc_executed_trans();
271 SafetyChecker::SafetyChecker(Session& s) : Checker(s)
273 reductionMode_ = reduction_mode;
274 if (_sg_mc_termination)
275 reductionMode_ = ReductionMode::none;
276 else if (reductionMode_ == ReductionMode::unset)
277 reductionMode_ = ReductionMode::dpor;
279 if (_sg_mc_termination)
280 XBT_INFO("Check non progressive cycles");
282 XBT_INFO("Check a safety property. Reduction is: %s.",
283 (reductionMode_ == ReductionMode::none ? "none"
284 : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown")));
286 mcapi::get().s_initialize();
288 XBT_DEBUG("Starting the safety algorithm");
290 ++expanded_states_count_;
291 auto initial_state = std::make_unique<State>(expanded_states_count_);
293 XBT_DEBUG("**************************************************");
294 XBT_DEBUG("Initial state");
296 /* Get an enabled actor and insert it in the interleave set of the initial state */
297 auto actors = mcapi::get().get_actors();
298 for (auto& actor : actors)
299 if (mcapi::get().actor_is_enabled(actor.copy.get_buffer()->get_pid())) {
300 initial_state->add_interleaving_set(actor.copy.get_buffer());
301 if (reductionMode_ != ReductionMode::none)
305 stack_.push_back(std::move(initial_state));
308 Checker* createSafetyChecker(Session& s)
310 return new SafetyChecker(s);
314 } // namespace simgrid