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 trace.push_back(state->transition_.textual);
70 void SafetyChecker::log_state() // override
72 XBT_INFO("Expanded states = %lu", expanded_states_count_);
73 XBT_INFO("Visited states = %lu", api::get().mc_get_visited_states());
74 XBT_INFO("Executed transitions = %lu", api::get().mc_get_executed_trans());
77 void SafetyChecker::run()
79 /* This function runs the DFS algorithm the state space.
80 * We do so iteratively instead of recursively, dealing with the call stack manually.
81 * This allows one to explore the call stack at will. */
83 while (not stack_.empty()) {
84 /* Get current state */
85 State* state = stack_.back().get();
87 XBT_DEBUG("**************************************************");
88 XBT_VERB("Exploration depth=%zu (state=%p, num %d)(%zu interleave)", stack_.size(), state, state->num_,
91 api::get().mc_inc_visited_states();
93 // Backtrack if we reached the maximum depth
94 if (stack_.size() > (std::size_t)_sg_mc_max_depth) {
95 XBT_WARN("/!\\ Max depth reached ! /!\\ ");
100 // Backtrack if we are revisiting a state we saw previously
101 if (visited_state_ != nullptr) {
102 XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
103 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num);
105 visited_state_ = nullptr;
110 // Search an enabled transition in the current state; backtrack if the interleave set is empty
111 // get_request also sets state.transition to be the one corresponding to the returned req
112 smx_simcall_t req = api::get().mc_state_choose_request(state);
113 // req is now the transition of the process that was selected to be executed
115 if (req == nullptr) {
116 XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size() + 1);
122 // If there are processes to interleave and the maximum depth has not been
123 // reached then perform one step of the exploration algorithm.
124 XBT_DEBUG("Execute: %s",
125 api::get().request_to_string(req, state->transition_.times_considered_, RequestType::simix).c_str());
128 if (dot_output != nullptr)
129 req_str = api::get().request_get_dot_output(req, state->transition_.times_considered_);
131 api::get().mc_inc_executed_trans();
133 /* Actually answer the request: let execute the selected request (MCed does one step) */
134 api::get().execute(state->transition_, &state->executed_req_);
136 /* Create the new expanded state (copy the state of MCed into our MCer data) */
137 ++expanded_states_count_;
138 auto next_state = std::make_unique<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 auto actors = api::get().get_actors();
151 for (auto& remoteActor : actors) {
152 auto actor = remoteActor.copy.get_buffer();
153 if (api::get().actor_is_enabled(actor->get_pid())) {
154 next_state->mark_todo(actor);
155 if (reductionMode_ == ReductionMode::dpor)
156 break; // With DPOR, we take the first enabled transition
160 if (dot_output != nullptr)
161 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_, next_state->num_, req_str.c_str());
163 } else if (dot_output != nullptr)
164 std::fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num_,
165 visited_state_->original_num == -1 ? visited_state_->num : visited_state_->original_num,
168 stack_.push_back(std::move(next_state));
171 XBT_INFO("No property violation found.");
172 api::get().log_state();
175 void SafetyChecker::backtrack()
179 api::get().mc_check_deadlock();
181 /* Traverse the stack backwards until a state with a non empty interleave set is found, deleting all the states that
182 * have it empty in the way. For each deleted state, check if the request that has generated it (from its
183 * predecessor state), depends on any other previous request executed before it. If it does then add it to the
184 * interleave set of the state that executed that previous request. */
186 while (not stack_.empty()) {
187 std::unique_ptr<State> state = std::move(stack_.back());
189 if (reductionMode_ == ReductionMode::dpor) {
190 smx_simcall_t req = &state->internal_req_;
191 if (req->call_ == simix::Simcall::MUTEX_LOCK || req->call_ == simix::Simcall::MUTEX_TRYLOCK)
192 xbt_die("Mutex is currently not supported with DPOR, use --cfg=model-check/reduction:none");
194 const kernel::actor::ActorImpl* issuer = api::get().simcall_get_issuer(req);
195 for (auto i = stack_.rbegin(); i != stack_.rend(); ++i) {
196 State* prev_state = i->get();
197 if (api::get().simcall_check_dependency(req, &prev_state->internal_req_)) {
198 if (XBT_LOG_ISENABLED(mc_safety, xbt_log_priority_debug)) {
199 XBT_DEBUG("Dependent Transitions:");
200 int value = prev_state->transition_.times_considered_;
201 smx_simcall_t prev_req = &prev_state->executed_req_;
202 XBT_DEBUG("%s (state=%d)", api::get().request_to_string(prev_req, value, RequestType::internal).c_str(),
204 value = state->transition_.times_considered_;
205 prev_req = &state->executed_req_;
206 XBT_DEBUG("%s (state=%d)", api::get().request_to_string(prev_req, value, RequestType::executed).c_str(),
210 if (not prev_state->actor_states_[issuer->get_pid()].is_done())
211 prev_state->mark_todo(issuer);
213 XBT_DEBUG("Process %p is in done set", req->issuer_);
215 } else if (req->issuer_ == prev_state->internal_req_.issuer_) {
216 XBT_DEBUG("Simcall %s and %s with same issuer", SIMIX_simcall_name(req->call_),
217 SIMIX_simcall_name(prev_state->internal_req_.call_));
220 const kernel::actor::ActorImpl* previous_issuer = api::get().simcall_get_issuer(&prev_state->internal_req_);
221 XBT_DEBUG("Simcall %s, process %ld (state %d) and simcall %s, process %ld (state %d) are independent",
222 SIMIX_simcall_name(req->call_), issuer->get_pid(), state->num_,
223 SIMIX_simcall_name(prev_state->internal_req_.call_), previous_issuer->get_pid(), prev_state->num_);
228 if (state->count_todo() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
229 /* We found a back-tracking point, let's loop */
230 XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num_, stack_.size() + 1);
231 stack_.push_back(std::move(state));
232 this->restore_state();
233 XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num_, stack_.size());
236 XBT_DEBUG("Delete state %d at depth %zu", state->num_, stack_.size() + 1);
241 void SafetyChecker::restore_state()
243 /* Intermediate backtracking */
244 const State* last_state = stack_.back().get();
245 if (last_state->system_state_) {
246 api::get().restore_state(last_state->system_state_);
250 /* Restore the initial state */
251 api::get().restore_initial_state();
253 /* Traverse the stack from the state at position start and re-execute the transitions */
254 for (std::unique_ptr<State> const& state : stack_) {
255 if (state == stack_.back())
257 api::get().execute(state->transition_, &state->executed_req_);
258 /* Update statistics */
259 api::get().mc_inc_visited_states();
260 api::get().mc_inc_executed_trans();
264 SafetyChecker::SafetyChecker() : Checker()
266 reductionMode_ = reduction_mode;
267 if (_sg_mc_termination)
268 reductionMode_ = ReductionMode::none;
269 else if (reductionMode_ == ReductionMode::unset)
270 reductionMode_ = ReductionMode::dpor;
272 if (_sg_mc_termination)
273 XBT_INFO("Check non progressive cycles");
275 XBT_INFO("Check a safety property. Reduction is: %s.",
276 (reductionMode_ == ReductionMode::none ? "none"
277 : (reductionMode_ == ReductionMode::dpor ? "dpor" : "unknown")));
279 api::get().session_initialize();
281 XBT_DEBUG("Starting the safety algorithm");
283 ++expanded_states_count_;
284 auto initial_state = std::make_unique<State>(expanded_states_count_);
286 XBT_DEBUG("**************************************************");
287 XBT_DEBUG("Initial state");
289 /* Get an enabled actor and insert it in the interleave set of the initial state */
290 auto actors = api::get().get_actors();
291 for (auto& actor : actors)
292 if (api::get().actor_is_enabled(actor.copy.get_buffer()->get_pid())) {
293 initial_state->mark_todo(actor.copy.get_buffer());
294 if (reductionMode_ != ReductionMode::none)
298 stack_.push_back(std::move(initial_state));
301 Checker* createSafetyChecker()
303 return new SafetyChecker();
307 } // namespace simgrid