src/mc/checker/CommunicationDeterminismChecker.cpp

   1 /* Copyright (c) 2008-2019. The SimGrid Team. All rights reserved.          */
   2
   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. */
   5
   6 #include "src/mc/checker/CommunicationDeterminismChecker.hpp"
   7 #include "src/kernel/activity/MailboxImpl.hpp"
   8 #include "src/mc/VisitedState.hpp"
   9 #include "src/mc/mc_exit.hpp"
  10 #include "src/mc/mc_private.hpp"
  11 #include "src/mc/mc_record.hpp"
  12 #include "src/mc/mc_request.hpp"
  13 #include "src/mc/mc_smx.hpp"
  14 #include "src/mc/mc_state.hpp"
  15 #include "src/mc/remote/Client.hpp"
  16
  17 #if HAVE_SMPI
  18 #include "smpi_request.hpp"
  19 #endif
  20
  21 #include <cstdint>
  22
  23 using simgrid::mc::remote;
  24
  25 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_comm_determinism, mc, "Logging specific to MC communication determinism detection");
  26
  27 /********** Global variables **********/
  28
  29 std::vector<simgrid::mc::PatternCommunicationList> initial_communications_pattern;
  30 std::vector<std::vector<simgrid::mc::PatternCommunication*>> incomplete_communications_pattern;
  31
  32 /********** Static functions ***********/
  33
  34 static e_mc_comm_pattern_difference_t compare_comm_pattern(simgrid::mc::PatternCommunication* comm1,
  35                                                            simgrid::mc::PatternCommunication* comm2)
  36 {
  37   if(comm1->type != comm2->type)
  38     return TYPE_DIFF;
  39   if (comm1->rdv != comm2->rdv)
  40     return RDV_DIFF;
  41   if (comm1->src_proc != comm2->src_proc)
  42     return SRC_PROC_DIFF;
  43   if (comm1->dst_proc != comm2->dst_proc)
  44     return DST_PROC_DIFF;
  45   if (comm1->tag != comm2->tag)
  46     return TAG_DIFF;
  47   if (comm1->data.size() != comm2->data.size())
  48     return DATA_SIZE_DIFF;
  49   if (comm1->data != comm2->data)
  50     return DATA_DIFF;
  51   return NONE_DIFF;
  52 }
  53
  54 static char* print_determinism_result(e_mc_comm_pattern_difference_t diff, int process,
  55                                       simgrid::mc::PatternCommunication* comm, unsigned int cursor)
  56 {
  57   char* type;
  58   char* res;
  59
  60   if (comm->type == simgrid::mc::PatternCommunicationType::send)
  61     type = bprintf("The send communications pattern of the process %d is different!", process - 1);
  62   else
  63     type = bprintf("The recv communications pattern of the process %d is different!", process - 1);
  64
  65   switch(diff) {
  66   case TYPE_DIFF:
  67     res = bprintf("%s Different type for communication #%u", type, cursor);
  68     break;
  69   case RDV_DIFF:
  70     res = bprintf("%s Different rdv for communication #%u", type, cursor);
  71     break;
  72   case TAG_DIFF:
  73     res = bprintf("%s Different tag for communication #%u", type, cursor);
  74     break;
  75   case SRC_PROC_DIFF:
  76     res = bprintf("%s Different source for communication #%u", type, cursor);
  77     break;
  78   case DST_PROC_DIFF:
  79     res = bprintf("%s Different destination for communication #%u", type, cursor);
  80     break;
  81   case DATA_SIZE_DIFF:
  82     res = bprintf("%s\n Different data size for communication #%u", type, cursor);
  83     break;
  84   case DATA_DIFF:
  85     res = bprintf("%s\n Different data for communication #%u", type, cursor);
  86     break;
  87   default:
  88     res = nullptr;
  89     break;
  90   }
  91
  92   return res;
  93 }
  94
  95 static void update_comm_pattern(simgrid::mc::PatternCommunication* comm_pattern,
  96                                 simgrid::mc::RemotePtr<simgrid::kernel::activity::CommImpl> comm_addr)
  97 {
  98   // HACK, type punning
  99   simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 100   mc_model_checker->process().read(temp_comm, comm_addr);
 101   simgrid::kernel::activity::CommImpl* comm = temp_comm.getBuffer();
 102
 103   smx_actor_t src_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->src_actor_.get()));
 104   smx_actor_t dst_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_actor_.get()));
 105   comm_pattern->src_proc = src_proc->get_pid();
 106   comm_pattern->dst_proc = dst_proc->get_pid();
 107   comm_pattern->src_host = MC_smx_actor_get_host_name(src_proc);
 108   comm_pattern->dst_host = MC_smx_actor_get_host_name(dst_proc);
 109   if (comm_pattern->data.size() == 0 && comm->src_buff_ != nullptr) {
 110     size_t buff_size;
 111     mc_model_checker->process().read(&buff_size, remote(comm->dst_buff_size_));
 112     comm_pattern->data.resize(buff_size);
 113     mc_model_checker->process().read_bytes(comm_pattern->data.data(), comm_pattern->data.size(),
 114                                            remote(comm->src_buff_));
 115   }
 116 }
 117
 118 namespace simgrid {
 119 namespace mc {
 120
 121 void CommunicationDeterminismChecker::deterministic_comm_pattern(int process, simgrid::mc::PatternCommunication* comm,
 122                                                                  int backtracking)
 123 {
 124   simgrid::mc::PatternCommunicationList& list = initial_communications_pattern[process];
 125
 126   if (not backtracking) {
 127     e_mc_comm_pattern_difference_t diff = compare_comm_pattern(list.list[list.index_comm].get(), comm);
 128
 129     if (diff != NONE_DIFF) {
 130       if (comm->type == simgrid::mc::PatternCommunicationType::send) {
 131         this->send_deterministic = 0;
 132         if (this->send_diff != nullptr)
 133           xbt_free(this->send_diff);
 134         this->send_diff = print_determinism_result(diff, process, comm, list.index_comm + 1);
 135       } else {
 136         this->recv_deterministic = 0;
 137         if (this->recv_diff != nullptr)
 138           xbt_free(this->recv_diff);
 139         this->recv_diff = print_determinism_result(diff, process, comm, list.index_comm + 1);
 140       }
 141       if (_sg_mc_send_determinism && not this->send_deterministic) {
 142         XBT_INFO("*********************************************************");
 143         XBT_INFO("***** Non-send-deterministic communications pattern *****");
 144         XBT_INFO("*********************************************************");
 145         XBT_INFO("%s", this->send_diff);
 146         xbt_free(this->send_diff);
 147         this->send_diff = nullptr;
 148         simgrid::mc::session->logState();
 149         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 150       } else if (_sg_mc_comms_determinism && (not this->send_deterministic && not this->recv_deterministic)) {
 151         XBT_INFO("****************************************************");
 152         XBT_INFO("***** Non-deterministic communications pattern *****");
 153         XBT_INFO("****************************************************");
 154         XBT_INFO("%s", this->send_diff);
 155         XBT_INFO("%s", this->recv_diff);
 156         xbt_free(this->send_diff);
 157         this->send_diff = nullptr;
 158         xbt_free(this->recv_diff);
 159         this->recv_diff = nullptr;
 160         simgrid::mc::session->logState();
 161         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 162       }
 163     }
 164   }
 165 }
 166
 167 /********** Non Static functions ***********/
 168
 169 void CommunicationDeterminismChecker::get_comm_pattern(smx_simcall_t request, e_mc_call_type_t call_type,
 170                                                        int backtracking)
 171 {
 172   const smx_actor_t issuer = MC_smx_simcall_get_issuer(request);
 173   const simgrid::mc::PatternCommunicationList& initial_pattern = initial_communications_pattern[issuer->get_pid()];
 174   const std::vector<simgrid::mc::PatternCommunication*>& incomplete_pattern =
 175       incomplete_communications_pattern[issuer->get_pid()];
 176
 177   std::unique_ptr<simgrid::mc::PatternCommunication> pattern(new simgrid::mc::PatternCommunication());
 178   pattern->index = initial_pattern.index_comm + incomplete_pattern.size();
 179
 180   if (call_type == MC_CALL_TYPE_SEND) {
 181     /* Create comm pattern */
 182     pattern->type = simgrid::mc::PatternCommunicationType::send;
 183     pattern->comm_addr = static_cast<simgrid::kernel::activity::CommImpl*>(simcall_comm_isend__getraw__result(request));
 184
 185     simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_synchro;
 186     mc_model_checker->process().read(temp_synchro,
 187                                      remote(static_cast<simgrid::kernel::activity::CommImpl*>(pattern->comm_addr)));
 188     simgrid::kernel::activity::CommImpl* synchro =
 189         static_cast<simgrid::kernel::activity::CommImpl*>(temp_synchro.getBuffer());
 190
 191     char* remote_name = mc_model_checker->process().read<char*>(
 192         RemotePtr<char*>((uint64_t)(synchro->mbox ? &synchro->mbox->name_ : &synchro->mbox_cpy->name_)));
 193     pattern->rdv      = mc_model_checker->process().read_string(RemotePtr<char>(remote_name));
 194     pattern->src_proc =
 195         mc_model_checker->process().resolveActor(simgrid::mc::remote(synchro->src_actor_.get()))->get_pid();
 196     pattern->src_host = MC_smx_actor_get_host_name(issuer);
 197
 198 #if HAVE_SMPI
 199     simgrid::smpi::Request mpi_request;
 200     mc_model_checker->process().read(
 201         &mpi_request, remote(static_cast<simgrid::smpi::Request*>(simcall_comm_isend__get__data(request))));
 202     pattern->tag = mpi_request.tag();
 203 #endif
 204
 205     if (synchro->src_buff_ != nullptr) {
 206       pattern->data.resize(synchro->src_buff_size_);
 207       mc_model_checker->process().read_bytes(pattern->data.data(), pattern->data.size(), remote(synchro->src_buff_));
 208     }
 209 #if HAVE_SMPI
 210     if(mpi_request.detached()){
 211       if (not this->initial_communications_pattern_done) {
 212         /* Store comm pattern */
 213         initial_communications_pattern[pattern->src_proc].list.push_back(std::move(pattern));
 214       } else {
 215         /* Evaluate comm determinism */
 216         this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
 217         initial_communications_pattern[pattern->src_proc].index_comm++;
 218       }
 219       return;
 220     }
 221 #endif
 222   } else if (call_type == MC_CALL_TYPE_RECV) {
 223     pattern->type = simgrid::mc::PatternCommunicationType::receive;
 224     pattern->comm_addr = static_cast<simgrid::kernel::activity::CommImpl*>(simcall_comm_irecv__getraw__result(request));
 225
 226 #if HAVE_SMPI
 227     simgrid::smpi::Request mpi_request;
 228     mc_model_checker->process().read(
 229         &mpi_request, remote(static_cast<simgrid::smpi::Request*>(simcall_comm_irecv__get__data(request))));
 230     pattern->tag = mpi_request.tag();
 231 #endif
 232
 233     simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 234     mc_model_checker->process().read(temp_comm,
 235                                      remote(static_cast<simgrid::kernel::activity::CommImpl*>(pattern->comm_addr)));
 236     simgrid::kernel::activity::CommImpl* comm = temp_comm.getBuffer();
 237
 238     char* remote_name;
 239     mc_model_checker->process().read(
 240         &remote_name, remote(comm->mbox ? &simgrid::xbt::string::to_string_data(comm->mbox->name_).data
 241                                         : &simgrid::xbt::string::to_string_data(comm->mbox_cpy->name_).data));
 242     pattern->rdv      = mc_model_checker->process().read_string(RemotePtr<char>(remote_name));
 243     pattern->dst_proc =
 244         mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_actor_.get()))->get_pid();
 245     pattern->dst_host = MC_smx_actor_get_host_name(issuer);
 246   } else
 247     xbt_die("Unexpected call_type %i", (int) call_type);
 248
 249   XBT_DEBUG("Insert incomplete comm pattern %p for process %ld", pattern.get(), issuer->get_pid());
 250   incomplete_communications_pattern[issuer->get_pid()].push_back(pattern.release());
 251 }
 252
 253 void CommunicationDeterminismChecker::complete_comm_pattern(
 254     simgrid::mc::RemotePtr<simgrid::kernel::activity::CommImpl> comm_addr, unsigned int issuer, int backtracking)
 255 {
 256   /* Complete comm pattern */
 257   std::vector<simgrid::mc::PatternCommunication*>& incomplete_pattern = incomplete_communications_pattern[issuer];
 258   auto current_comm_pattern = std::find_if(
 259       begin(incomplete_pattern), end(incomplete_pattern),
 260       [&comm_addr](simgrid::mc::PatternCommunication* comm) { return remote(comm->comm_addr) == comm_addr; });
 261   if (current_comm_pattern == std::end(incomplete_pattern))
 262     xbt_die("Corresponding communication not found!");
 263
 264   update_comm_pattern(*current_comm_pattern, comm_addr);
 265   std::unique_ptr<simgrid::mc::PatternCommunication> comm_pattern(*current_comm_pattern);
 266   XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %zd", issuer,
 267             std::distance(begin(incomplete_pattern), current_comm_pattern));
 268   incomplete_pattern.erase(current_comm_pattern);
 269
 270   if (not this->initial_communications_pattern_done)
 271     /* Store comm pattern */
 272     initial_communications_pattern[issuer].list.push_back(std::move(comm_pattern));
 273   else {
 274     /* Evaluate comm determinism */
 275     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 276     initial_communications_pattern[issuer].index_comm++;
 277   }
 278 }
 279
 280 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& s) : Checker(s)
 281 {
 282 }
 283
 284 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 285
 286 RecordTrace CommunicationDeterminismChecker::getRecordTrace() // override
 287 {
 288   RecordTrace res;
 289   for (auto const& state : stack_)
 290     res.push_back(state->getTransition());
 291   return res;
 292 }
 293
 294 std::vector<std::string> CommunicationDeterminismChecker::getTextualTrace() // override
 295 {
 296   std::vector<std::string> trace;
 297   for (auto const& state : stack_) {
 298     smx_simcall_t req = &state->executed_req;
 299     if (req)
 300       trace.push_back(
 301           simgrid::mc::request_to_string(req, state->transition.argument, simgrid::mc::RequestType::executed));
 302   }
 303   return trace;
 304 }
 305
 306 void CommunicationDeterminismChecker::logState() // override
 307 {
 308   if (_sg_mc_comms_determinism && not this->recv_deterministic && this->send_deterministic) {
 309     XBT_INFO("******************************************************");
 310     XBT_INFO("**** Only-send-deterministic communication pattern ****");
 311     XBT_INFO("******************************************************");
 312     XBT_INFO("%s", this->recv_diff);
 313   } else if (_sg_mc_comms_determinism && not this->send_deterministic && this->recv_deterministic) {
 314     XBT_INFO("******************************************************");
 315     XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 316     XBT_INFO("******************************************************");
 317     XBT_INFO("%s", this->send_diff);
 318   }
 319   XBT_INFO("Expanded states = %lu", expandedStatesCount_);
 320   XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
 321   XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
 322   XBT_INFO("Send-deterministic : %s", not this->send_deterministic ? "No" : "Yes");
 323   if (_sg_mc_comms_determinism)
 324     XBT_INFO("Recv-deterministic : %s", not this->recv_deterministic ? "No" : "Yes");
 325 }
 326
 327 void CommunicationDeterminismChecker::prepare()
 328 {
 329   const int maxpid = MC_smx_get_maxpid();
 330
 331   initial_communications_pattern.resize(maxpid);
 332   incomplete_communications_pattern.resize(maxpid);
 333
 334   std::unique_ptr<simgrid::mc::State> initial_state =
 335       std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 336
 337   XBT_DEBUG("********* Start communication determinism verification *********");
 338
 339   /* Get an enabled actor and insert it in the interleave set of the initial state */
 340   for (auto& actor : mc_model_checker->process().actors())
 341     if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 342       initial_state->addInterleavingSet(actor.copy.getBuffer());
 343
 344   stack_.push_back(std::move(initial_state));
 345 }
 346
 347 static inline bool all_communications_are_finished()
 348 {
 349   for (size_t current_actor = 1; current_actor < MC_smx_get_maxpid(); current_actor++) {
 350     if (not incomplete_communications_pattern[current_actor].empty()) {
 351       XBT_DEBUG("Some communications are not finished, cannot stop the exploration! State not visited.");
 352       return false;
 353     }
 354   }
 355   return true;
 356 }
 357
 358 void CommunicationDeterminismChecker::restoreState()
 359 {
 360   /* Intermediate backtracking */
 361   simgrid::mc::State* last_state = stack_.back().get();
 362   if (last_state->system_state) {
 363     simgrid::mc::restore_snapshot(last_state->system_state);
 364     MC_restore_communications_pattern(last_state);
 365     return;
 366   }
 367
 368   /* Restore the initial state */
 369   simgrid::mc::session->restoreInitialState();
 370
 371   unsigned n = MC_smx_get_maxpid();
 372   assert(n == incomplete_communications_pattern.size());
 373   assert(n == initial_communications_pattern.size());
 374   for (unsigned j=0; j < n ; j++) {
 375     incomplete_communications_pattern[j].clear();
 376     initial_communications_pattern[j].index_comm = 0;
 377   }
 378
 379   /* Traverse the stack from the state at position start and re-execute the transitions */
 380   for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
 381     if (state == stack_.back())
 382       break;
 383
 384     int req_num = state->transition.argument;
 385     smx_simcall_t saved_req = &state->executed_req;
 386     xbt_assert(saved_req);
 387
 388     /* because we got a copy of the executed request, we have to fetch the
 389        real one, pointed by the request field of the issuer process */
 390
 391     const smx_actor_t issuer = MC_smx_simcall_get_issuer(saved_req);
 392     smx_simcall_t req = &issuer->simcall;
 393
 394     /* TODO : handle test and testany simcalls */
 395     e_mc_call_type_t call = MC_get_call_type(req);
 396     mc_model_checker->handle_simcall(state->transition);
 397     MC_handle_comm_pattern(call, req, req_num, 1);
 398     mc_model_checker->wait_for_requests();
 399
 400     /* Update statistics */
 401     mc_model_checker->visited_states++;
 402     mc_model_checker->executed_transitions++;
 403   }
 404 }
 405
 406 void CommunicationDeterminismChecker::real_run()
 407 {
 408   std::unique_ptr<simgrid::mc::VisitedState> visited_state = nullptr;
 409   smx_simcall_t req = nullptr;
 410
 411   while (not stack_.empty()) {
 412     /* Get current state */
 413     simgrid::mc::State* cur_state = stack_.back().get();
 414
 415     XBT_DEBUG("**************************************************");
 416     XBT_DEBUG("Exploration depth = %zu (state = %d, interleaved processes = %zu)", stack_.size(), cur_state->num,
 417               cur_state->interleaveSize());
 418
 419     /* Update statistics */
 420     mc_model_checker->visited_states++;
 421
 422     if (stack_.size() <= (std::size_t)_sg_mc_max_depth)
 423       req = MC_state_get_request(cur_state);
 424     else
 425       req = nullptr;
 426
 427     if (req != nullptr && visited_state == nullptr) {
 428
 429       int req_num = cur_state->transition.argument;
 430
 431       XBT_DEBUG("Execute: %s", simgrid::mc::request_to_string(req, req_num, simgrid::mc::RequestType::simix).c_str());
 432
 433       std::string req_str;
 434       if (dot_output != nullptr)
 435         req_str = simgrid::mc::request_get_dot_output(req, req_num);
 436
 437       mc_model_checker->executed_transitions++;
 438
 439       /* TODO : handle test and testany simcalls */
 440       e_mc_call_type_t call = MC_CALL_TYPE_NONE;
 441       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 442         call = MC_get_call_type(req);
 443
 444       /* Answer the request */
 445       mc_model_checker->handle_simcall(cur_state->transition);
 446       /* After this call req is no longer useful */
 447
 448       MC_handle_comm_pattern(call, req, req_num, 0);
 449
 450       /* Wait for requests (schedules processes) */
 451       mc_model_checker->wait_for_requests();
 452
 453       /* Create the new expanded state */
 454       std::unique_ptr<simgrid::mc::State> next_state =
 455           std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 456
 457       /* If comm determinism verification, we cannot stop the exploration if some communications are not finished (at
 458        * least, data are transferred). These communications  are incomplete and they cannot be analyzed and compared
 459        * with the initial pattern. */
 460       bool compare_snapshots = all_communications_are_finished() && this->initial_communications_pattern_done;
 461
 462       if (_sg_mc_max_visited_states != 0)
 463         visited_state = visitedStates_.addVisitedState(expandedStatesCount_, next_state.get(), compare_snapshots);
 464       else
 465         visited_state = nullptr;
 466
 467       if (visited_state == nullptr) {
 468
 469         /* Get enabled actors and insert them in the interleave set of the next state */
 470         for (auto& actor : mc_model_checker->process().actors())
 471           if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 472             next_state->addInterleavingSet(actor.copy.getBuffer());
 473
 474         if (dot_output != nullptr)
 475           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", cur_state->num, next_state->num, req_str.c_str());
 476
 477       } else if (dot_output != nullptr)
 478         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", cur_state->num,
 479                 visited_state->original_num == -1 ? visited_state->num : visited_state->original_num, req_str.c_str());
 480
 481       stack_.push_back(std::move(next_state));
 482
 483     } else {
 484
 485       if (stack_.size() > (std::size_t) _sg_mc_max_depth)
 486         XBT_WARN("/!\\ Max depth reached! /!\\ ");
 487       else if (visited_state != nullptr)
 488         XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
 489             visited_state->original_num == -1 ? visited_state->num : visited_state->original_num);
 490       else
 491         XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size());
 492
 493       if (not this->initial_communications_pattern_done)
 494         this->initial_communications_pattern_done = 1;
 495
 496       /* Trash the current state, no longer needed */
 497       XBT_DEBUG("Delete state %d at depth %zu", cur_state->num, stack_.size());
 498       stack_.pop_back();
 499
 500       visited_state = nullptr;
 501
 502       /* Check for deadlocks */
 503       if (mc_model_checker->checkDeadlock()) {
 504         MC_show_deadlock();
 505         throw simgrid::mc::DeadlockError();
 506       }
 507
 508       while (not stack_.empty()) {
 509         std::unique_ptr<simgrid::mc::State> state = std::move(stack_.back());
 510         stack_.pop_back();
 511         if (state->interleaveSize() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
 512           /* We found a back-tracking point, let's loop */
 513           XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num, stack_.size() + 1);
 514           stack_.push_back(std::move(state));
 515
 516           this->restoreState();
 517
 518           XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num, stack_.size());
 519
 520           break;
 521         } else {
 522           XBT_DEBUG("Delete state %d at depth %zu", state->num, stack_.size() + 1);
 523         }
 524       }
 525     }
 526   }
 527
 528   simgrid::mc::session->logState();
 529 }
 530
 531 void CommunicationDeterminismChecker::run()
 532 {
 533   XBT_INFO("Check communication determinism");
 534   simgrid::mc::session->initialize();
 535
 536   this->prepare();
 537
 538   this->real_run();
 539 }
 540
 541 Checker* createCommunicationDeterminismChecker(Session& s)
 542 {
 543   return new CommunicationDeterminismChecker(s);
 544 }
 545
 546 }
 547 }