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 xbt_dynar_t initial_communications_pattern;
  30 xbt_dynar_t 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 =
 125     xbt_dynar_get_as(initial_communications_pattern, process, simgrid::mc::PatternCommunicationList*);
 126
 127   if (not backtracking) {
 128     e_mc_comm_pattern_difference_t diff = compare_comm_pattern(list->list[list->index_comm].get(), comm);
 129
 130     if (diff != NONE_DIFF) {
 131       if (comm->type == simgrid::mc::PatternCommunicationType::send) {
 132         this->send_deterministic = 0;
 133         if (this->send_diff != nullptr)
 134           xbt_free(this->send_diff);
 135         this->send_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 136       } else {
 137         this->recv_deterministic = 0;
 138         if (this->recv_diff != nullptr)
 139           xbt_free(this->recv_diff);
 140         this->recv_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 141       }
 142       if (_sg_mc_send_determinism && not this->send_deterministic) {
 143         XBT_INFO("*********************************************************");
 144         XBT_INFO("***** Non-send-deterministic communications pattern *****");
 145         XBT_INFO("*********************************************************");
 146         XBT_INFO("%s", this->send_diff);
 147         xbt_free(this->send_diff);
 148         this->send_diff = nullptr;
 149         simgrid::mc::session->logState();
 150         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 151       } else if (_sg_mc_comms_determinism && (not this->send_deterministic && not this->recv_deterministic)) {
 152         XBT_INFO("****************************************************");
 153         XBT_INFO("***** Non-deterministic communications pattern *****");
 154         XBT_INFO("****************************************************");
 155         XBT_INFO("%s", this->send_diff);
 156         XBT_INFO("%s", this->recv_diff);
 157         xbt_free(this->send_diff);
 158         this->send_diff = nullptr;
 159         xbt_free(this->recv_diff);
 160         this->recv_diff = nullptr;
 161         simgrid::mc::session->logState();
 162         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 163       }
 164     }
 165   }
 166 }
 167
 168 /********** Non Static functions ***********/
 169
 170 void CommunicationDeterminismChecker::get_comm_pattern(smx_simcall_t request, e_mc_call_type_t call_type,
 171                                                        int backtracking)
 172 {
 173   const smx_actor_t issuer = MC_smx_simcall_get_issuer(request);
 174   simgrid::mc::PatternCommunicationList* initial_pattern =
 175       xbt_dynar_get_as(initial_communications_pattern, issuer->get_pid(), simgrid::mc::PatternCommunicationList*);
 176   xbt_dynar_t incomplete_pattern = xbt_dynar_get_as(incomplete_communications_pattern, issuer->get_pid(), xbt_dynar_t);
 177
 178   std::unique_ptr<simgrid::mc::PatternCommunication> pattern(new simgrid::mc::PatternCommunication());
 179   pattern->index = initial_pattern->index_comm + xbt_dynar_length(incomplete_pattern);
 180
 181   if (call_type == MC_CALL_TYPE_SEND) {
 182     /* Create comm pattern */
 183     pattern->type = simgrid::mc::PatternCommunicationType::send;
 184     pattern->comm_addr = static_cast<simgrid::kernel::activity::CommImpl*>(simcall_comm_isend__getraw__result(request));
 185
 186     simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_synchro;
 187     mc_model_checker->process().read(temp_synchro,
 188                                      remote(static_cast<simgrid::kernel::activity::CommImpl*>(pattern->comm_addr)));
 189     simgrid::kernel::activity::CommImpl* synchro =
 190         static_cast<simgrid::kernel::activity::CommImpl*>(temp_synchro.getBuffer());
 191
 192     char* remote_name = mc_model_checker->process().read<char*>(
 193         RemotePtr<char*>((uint64_t)(synchro->mbox ? &synchro->mbox->name_ : &synchro->mbox_cpy->name_)));
 194     pattern->rdv      = mc_model_checker->process().read_string(RemotePtr<char>(remote_name));
 195     pattern->src_proc =
 196         mc_model_checker->process().resolveActor(simgrid::mc::remote(synchro->src_actor_.get()))->get_pid();
 197     pattern->src_host = MC_smx_actor_get_host_name(issuer);
 198
 199 #if HAVE_SMPI
 200     simgrid::smpi::Request mpi_request = mc_model_checker->process().read<simgrid::smpi::Request>(
 201         RemotePtr<simgrid::smpi::Request>((std::uint64_t)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         simgrid::mc::PatternCommunicationList* list =
 214             xbt_dynar_get_as(initial_communications_pattern, pattern->src_proc, simgrid::mc::PatternCommunicationList*);
 215         list->list.push_back(std::move(pattern));
 216       } else {
 217         /* Evaluate comm determinism */
 218         this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
 219         xbt_dynar_get_as(initial_communications_pattern, pattern->src_proc, simgrid::mc::PatternCommunicationList*)
 220             ->index_comm++;
 221       }
 222       return;
 223     }
 224 #endif
 225   } else if (call_type == MC_CALL_TYPE_RECV) {
 226     pattern->type = simgrid::mc::PatternCommunicationType::receive;
 227     pattern->comm_addr = static_cast<simgrid::kernel::activity::CommImpl*>(simcall_comm_irecv__getraw__result(request));
 228
 229 #if HAVE_SMPI
 230     simgrid::smpi::Request mpi_request;
 231     mc_model_checker->process().read(&mpi_request,
 232                                      remote((simgrid::smpi::Request*)simcall_comm_irecv__get__data(request)));
 233     pattern->tag = mpi_request.tag();
 234 #endif
 235
 236     simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 237     mc_model_checker->process().read(temp_comm,
 238                                      remote(static_cast<simgrid::kernel::activity::CommImpl*>(pattern->comm_addr)));
 239     simgrid::kernel::activity::CommImpl* comm = temp_comm.getBuffer();
 240
 241     char* remote_name;
 242     mc_model_checker->process().read(
 243         &remote_name, remote(comm->mbox ? &simgrid::xbt::string::to_string_data(comm->mbox->name_).data
 244                                         : &simgrid::xbt::string::to_string_data(comm->mbox_cpy->name_).data));
 245     pattern->rdv      = mc_model_checker->process().read_string(RemotePtr<char>(remote_name));
 246     pattern->dst_proc =
 247         mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_actor_.get()))->get_pid();
 248     pattern->dst_host = MC_smx_actor_get_host_name(issuer);
 249   } else
 250     xbt_die("Unexpected call_type %i", (int) call_type);
 251
 252   XBT_DEBUG("Insert incomplete comm pattern %p for process %ld", pattern.get(), issuer->get_pid());
 253   xbt_dynar_t dynar = xbt_dynar_get_as(incomplete_communications_pattern, issuer->get_pid(), xbt_dynar_t);
 254   simgrid::mc::PatternCommunication* pattern2 = pattern.release();
 255   xbt_dynar_push(dynar, &pattern2);
 256 }
 257
 258 void CommunicationDeterminismChecker::complete_comm_pattern(
 259     simgrid::mc::RemotePtr<simgrid::kernel::activity::CommImpl> comm_addr, unsigned int issuer, int backtracking)
 260 {
 261   simgrid::mc::PatternCommunication* current_comm_pattern;
 262   unsigned int cursor = 0;
 263   std::unique_ptr<simgrid::mc::PatternCommunication> comm_pattern;
 264   int completed = 0;
 265
 266   /* Complete comm pattern */
 267   xbt_dynar_foreach(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, current_comm_pattern)
 268     if (remote(current_comm_pattern->comm_addr) == comm_addr) {
 269       update_comm_pattern(current_comm_pattern, comm_addr);
 270       completed = 1;
 271       simgrid::mc::PatternCommunication* temp;
 272       xbt_dynar_remove_at(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, &temp);
 273       comm_pattern.reset(temp);
 274       XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %u", issuer, cursor);
 275       break;
 276     }
 277
 278   if (not completed)
 279     xbt_die("Corresponding communication not found!");
 280
 281   simgrid::mc::PatternCommunicationList* pattern =
 282       xbt_dynar_get_as(initial_communications_pattern, issuer, simgrid::mc::PatternCommunicationList*);
 283
 284   if (not this->initial_communications_pattern_done)
 285     /* Store comm pattern */
 286     pattern->list.push_back(std::move(comm_pattern));
 287   else {
 288     /* Evaluate comm determinism */
 289     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 290     pattern->index_comm++;
 291   }
 292 }
 293
 294 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& s) : Checker(s)
 295 {
 296 }
 297
 298 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 299
 300 RecordTrace CommunicationDeterminismChecker::getRecordTrace() // override
 301 {
 302   RecordTrace res;
 303   for (auto const& state : stack_)
 304     res.push_back(state->getTransition());
 305   return res;
 306 }
 307
 308 std::vector<std::string> CommunicationDeterminismChecker::getTextualTrace() // override
 309 {
 310   std::vector<std::string> trace;
 311   for (auto const& state : stack_) {
 312     smx_simcall_t req = &state->executed_req;
 313     if (req)
 314       trace.push_back(
 315           simgrid::mc::request_to_string(req, state->transition.argument, simgrid::mc::RequestType::executed));
 316   }
 317   return trace;
 318 }
 319
 320 void CommunicationDeterminismChecker::logState() // override
 321 {
 322   if (_sg_mc_comms_determinism && not this->recv_deterministic && this->send_deterministic) {
 323     XBT_INFO("******************************************************");
 324     XBT_INFO("**** Only-send-deterministic communication pattern ****");
 325     XBT_INFO("******************************************************");
 326     XBT_INFO("%s", this->recv_diff);
 327   } else if (_sg_mc_comms_determinism && not this->send_deterministic && this->recv_deterministic) {
 328     XBT_INFO("******************************************************");
 329     XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 330     XBT_INFO("******************************************************");
 331     XBT_INFO("%s", this->send_diff);
 332   }
 333   XBT_INFO("Expanded states = %lu", expandedStatesCount_);
 334   XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
 335   XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
 336   XBT_INFO("Send-deterministic : %s", not this->send_deterministic ? "No" : "Yes");
 337   if (_sg_mc_comms_determinism)
 338     XBT_INFO("Recv-deterministic : %s", not this->recv_deterministic ? "No" : "Yes");
 339 }
 340
 341 void CommunicationDeterminismChecker::prepare()
 342 {
 343   const int maxpid = MC_smx_get_maxpid();
 344
 345   // Create initial_communications_pattern elements:
 346   initial_communications_pattern = simgrid::xbt::newDeleteDynar<simgrid::mc::PatternCommunicationList*>();
 347   for (int i = 0; i < maxpid; i++) {
 348     simgrid::mc::PatternCommunicationList* process_list_pattern = new simgrid::mc::PatternCommunicationList();
 349     xbt_dynar_insert_at(initial_communications_pattern, i, &process_list_pattern);
 350   }
 351
 352   // Create incomplete_communications_pattern elements:
 353   incomplete_communications_pattern = xbt_dynar_new(sizeof(xbt_dynar_t), xbt_dynar_free_voidp);
 354   for (int i = 0; i < maxpid; i++) {
 355     xbt_dynar_t process_pattern = xbt_dynar_new(sizeof(simgrid::mc::PatternCommunication*), nullptr);
 356     xbt_dynar_insert_at(incomplete_communications_pattern, i, &process_pattern);
 357   }
 358
 359   std::unique_ptr<simgrid::mc::State> initial_state =
 360       std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 361
 362   XBT_DEBUG("********* Start communication determinism verification *********");
 363
 364   /* Get an enabled actor and insert it in the interleave set of the initial state */
 365   for (auto& actor : mc_model_checker->process().actors())
 366     if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 367       initial_state->addInterleavingSet(actor.copy.getBuffer());
 368
 369   stack_.push_back(std::move(initial_state));
 370 }
 371
 372 static inline bool all_communications_are_finished()
 373 {
 374   for (size_t current_actor = 1; current_actor < MC_smx_get_maxpid(); current_actor++) {
 375     xbt_dynar_t pattern = xbt_dynar_get_as(incomplete_communications_pattern, current_actor, xbt_dynar_t);
 376     if (not xbt_dynar_is_empty(pattern)) {
 377       XBT_DEBUG("Some communications are not finished, cannot stop the exploration! State not visited.");
 378       return false;
 379     }
 380   }
 381   return true;
 382 }
 383
 384 void CommunicationDeterminismChecker::restoreState()
 385 {
 386   /* Intermediate backtracking */
 387   simgrid::mc::State* last_state = stack_.back().get();
 388   if (last_state->system_state) {
 389     simgrid::mc::restore_snapshot(last_state->system_state);
 390     MC_restore_communications_pattern(last_state);
 391     return;
 392   }
 393
 394   /* Restore the initial state */
 395   simgrid::mc::session->restoreInitialState();
 396
 397   unsigned n = MC_smx_get_maxpid();
 398   assert(n == xbt_dynar_length(incomplete_communications_pattern));
 399   assert(n == xbt_dynar_length(initial_communications_pattern));
 400   for (unsigned j=0; j < n ; j++) {
 401     xbt_dynar_reset((xbt_dynar_t)xbt_dynar_get_as(incomplete_communications_pattern, j, xbt_dynar_t));
 402     xbt_dynar_get_as(initial_communications_pattern, j, simgrid::mc::PatternCommunicationList*)->index_comm = 0;
 403   }
 404
 405   /* Traverse the stack from the state at position start and re-execute the transitions */
 406   for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
 407     if (state == stack_.back())
 408       break;
 409
 410     int req_num = state->transition.argument;
 411     smx_simcall_t saved_req = &state->executed_req;
 412     xbt_assert(saved_req);
 413
 414     /* because we got a copy of the executed request, we have to fetch the
 415        real one, pointed by the request field of the issuer process */
 416
 417     const smx_actor_t issuer = MC_smx_simcall_get_issuer(saved_req);
 418     smx_simcall_t req = &issuer->simcall;
 419
 420     /* TODO : handle test and testany simcalls */
 421     e_mc_call_type_t call = MC_get_call_type(req);
 422     mc_model_checker->handle_simcall(state->transition);
 423     MC_handle_comm_pattern(call, req, req_num, 1);
 424     mc_model_checker->wait_for_requests();
 425
 426     /* Update statistics */
 427     mc_model_checker->visited_states++;
 428     mc_model_checker->executed_transitions++;
 429   }
 430 }
 431
 432 void CommunicationDeterminismChecker::real_run()
 433 {
 434   std::unique_ptr<simgrid::mc::VisitedState> visited_state = nullptr;
 435   smx_simcall_t req = nullptr;
 436
 437   while (not stack_.empty()) {
 438     /* Get current state */
 439     simgrid::mc::State* cur_state = stack_.back().get();
 440
 441     XBT_DEBUG("**************************************************");
 442     XBT_DEBUG("Exploration depth = %zu (state = %d, interleaved processes = %zu)", stack_.size(), cur_state->num,
 443               cur_state->interleaveSize());
 444
 445     /* Update statistics */
 446     mc_model_checker->visited_states++;
 447
 448     if (stack_.size() <= (std::size_t)_sg_mc_max_depth)
 449       req = MC_state_get_request(cur_state);
 450     else
 451       req = nullptr;
 452
 453     if (req != nullptr && visited_state == nullptr) {
 454
 455       int req_num = cur_state->transition.argument;
 456
 457       XBT_DEBUG("Execute: %s", simgrid::mc::request_to_string(req, req_num, simgrid::mc::RequestType::simix).c_str());
 458
 459       std::string req_str;
 460       if (dot_output != nullptr)
 461         req_str = simgrid::mc::request_get_dot_output(req, req_num);
 462
 463       mc_model_checker->executed_transitions++;
 464
 465       /* TODO : handle test and testany simcalls */
 466       e_mc_call_type_t call = MC_CALL_TYPE_NONE;
 467       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 468         call = MC_get_call_type(req);
 469
 470       /* Answer the request */
 471       mc_model_checker->handle_simcall(cur_state->transition);
 472       /* After this call req is no longer useful */
 473
 474       MC_handle_comm_pattern(call, req, req_num, 0);
 475
 476       /* Wait for requests (schedules processes) */
 477       mc_model_checker->wait_for_requests();
 478
 479       /* Create the new expanded state */
 480       std::unique_ptr<simgrid::mc::State> next_state =
 481           std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 482
 483       /* If comm determinism verification, we cannot stop the exploration if some communications are not finished (at
 484        * least, data are transferred). These communications  are incomplete and they cannot be analyzed and compared
 485        * with the initial pattern. */
 486       bool compare_snapshots = all_communications_are_finished() && this->initial_communications_pattern_done;
 487
 488       if (_sg_mc_max_visited_states != 0)
 489         visited_state = visitedStates_.addVisitedState(expandedStatesCount_, next_state.get(), compare_snapshots);
 490       else
 491         visited_state = nullptr;
 492
 493       if (visited_state == nullptr) {
 494
 495         /* Get enabled actors and insert them in the interleave set of the next state */
 496         for (auto& actor : mc_model_checker->process().actors())
 497           if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 498             next_state->addInterleavingSet(actor.copy.getBuffer());
 499
 500         if (dot_output != nullptr)
 501           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", cur_state->num, next_state->num, req_str.c_str());
 502
 503       } else if (dot_output != nullptr)
 504         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", cur_state->num,
 505                 visited_state->original_num == -1 ? visited_state->num : visited_state->original_num, req_str.c_str());
 506
 507       stack_.push_back(std::move(next_state));
 508
 509     } else {
 510
 511       if (stack_.size() > (std::size_t) _sg_mc_max_depth)
 512         XBT_WARN("/!\\ Max depth reached! /!\\ ");
 513       else if (visited_state != nullptr)
 514         XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
 515             visited_state->original_num == -1 ? visited_state->num : visited_state->original_num);
 516       else
 517         XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size());
 518
 519       if (not this->initial_communications_pattern_done)
 520         this->initial_communications_pattern_done = 1;
 521
 522       /* Trash the current state, no longer needed */
 523       XBT_DEBUG("Delete state %d at depth %zu", cur_state->num, stack_.size());
 524       stack_.pop_back();
 525
 526       visited_state = nullptr;
 527
 528       /* Check for deadlocks */
 529       if (mc_model_checker->checkDeadlock()) {
 530         MC_show_deadlock();
 531         throw simgrid::mc::DeadlockError();
 532       }
 533
 534       while (not stack_.empty()) {
 535         std::unique_ptr<simgrid::mc::State> state = std::move(stack_.back());
 536         stack_.pop_back();
 537         if (state->interleaveSize() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
 538           /* We found a back-tracking point, let's loop */
 539           XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num, stack_.size() + 1);
 540           stack_.push_back(std::move(state));
 541
 542           this->restoreState();
 543
 544           XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num, stack_.size());
 545
 546           break;
 547         } else {
 548           XBT_DEBUG("Delete state %d at depth %zu", state->num, stack_.size() + 1);
 549         }
 550       }
 551     }
 552   }
 553
 554   simgrid::mc::session->logState();
 555 }
 556
 557 void CommunicationDeterminismChecker::run()
 558 {
 559   XBT_INFO("Check communication determinism");
 560   simgrid::mc::session->initialize();
 561
 562   this->prepare();
 563
 564   this->real_run();
 565 }
 566
 567 Checker* createCommunicationDeterminismChecker(Session& s)
 568 {
 569   return new CommunicationDeterminismChecker(s);
 570 }
 571
 572 }
 573 }