src/mc/checker/CommunicationDeterminismChecker.cpp

   1 /* Copyright (c) 2008-2017. 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 <cstdint>
   7
   8 #include <xbt/dynar.h>
   9 #include <xbt/dynar.hpp>
  10 #include <xbt/log.h>
  11 #include <xbt/sysdep.h>
  12
  13 #include "src/mc/Transition.hpp"
  14 #include "src/mc/VisitedState.hpp"
  15 #include "src/mc/checker/CommunicationDeterminismChecker.hpp"
  16 #include "src/mc/mc_exit.h"
  17 #include "src/mc/mc_private.h"
  18 #include "src/mc/mc_record.h"
  19 #include "src/mc/mc_request.h"
  20 #include "src/mc/mc_smx.h"
  21 #include "src/mc/mc_state.h"
  22 #include "src/mc/remote/Client.hpp"
  23
  24 #include "src/smpi/smpi_request.hpp"
  25
  26 using simgrid::mc::remote;
  27
  28 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_comm_determinism, mc, "Logging specific to MC communication determinism detection");
  29
  30 /********** Global variables **********/
  31
  32 xbt_dynar_t initial_communications_pattern;
  33 xbt_dynar_t incomplete_communications_pattern;
  34
  35 /********** Static functions ***********/
  36
  37 static e_mc_comm_pattern_difference_t compare_comm_pattern(simgrid::mc::PatternCommunication* comm1,
  38                                                            simgrid::mc::PatternCommunication* comm2)
  39 {
  40   if(comm1->type != comm2->type)
  41     return TYPE_DIFF;
  42   if (comm1->rdv != comm2->rdv)
  43     return RDV_DIFF;
  44   if (comm1->src_proc != comm2->src_proc)
  45     return SRC_PROC_DIFF;
  46   if (comm1->dst_proc != comm2->dst_proc)
  47     return DST_PROC_DIFF;
  48   if (comm1->tag != comm2->tag)
  49     return TAG_DIFF;
  50   if (comm1->data.size() != comm2->data.size())
  51     return DATA_SIZE_DIFF;
  52   if (comm1->data != comm2->data)
  53     return DATA_DIFF;
  54   return NONE_DIFF;
  55 }
  56
  57 static char* print_determinism_result(e_mc_comm_pattern_difference_t diff, int process,
  58                                       simgrid::mc::PatternCommunication* comm, unsigned int cursor)
  59 {
  60   char* type;
  61   char* res;
  62
  63   if (comm->type == simgrid::mc::PatternCommunicationType::send)
  64     type = bprintf("The send communications pattern of the process %d is different!", process - 1);
  65   else
  66     type = bprintf("The recv communications pattern of the process %d is different!", process - 1);
  67
  68   switch(diff) {
  69   case TYPE_DIFF:
  70     res = bprintf("%s Different type for communication #%d", type, cursor);
  71     break;
  72   case RDV_DIFF:
  73     res = bprintf("%s Different rdv for communication #%d", type, cursor);
  74     break;
  75   case TAG_DIFF:
  76     res = bprintf("%s Different tag for communication #%d", type, cursor);
  77     break;
  78   case SRC_PROC_DIFF:
  79       res = bprintf("%s Different source for communication #%d", type, cursor);
  80     break;
  81   case DST_PROC_DIFF:
  82       res = bprintf("%s Different destination for communication #%d", type, cursor);
  83     break;
  84   case DATA_SIZE_DIFF:
  85     res = bprintf("%s\n Different data size for communication #%d", type, cursor);
  86     break;
  87   case DATA_DIFF:
  88     res = bprintf("%s\n Different data for communication #%d", type, cursor);
  89     break;
  90   default:
  91     res = nullptr;
  92     break;
  93   }
  94
  95   return res;
  96 }
  97
  98 static void update_comm_pattern(simgrid::mc::PatternCommunication* comm_pattern,
  99                                 simgrid::mc::RemotePtr<simgrid::kernel::activity::Comm> comm_addr)
 100 {
 101   // HACK, type punning
 102   simgrid::mc::Remote<simgrid::kernel::activity::Comm> temp_comm;
 103   mc_model_checker->process().read(temp_comm, comm_addr);
 104   simgrid::kernel::activity::Comm* comm = temp_comm.getBuffer();
 105
 106   smx_actor_t src_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->src_proc));
 107   smx_actor_t dst_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_proc));
 108   comm_pattern->src_proc = src_proc->pid;
 109   comm_pattern->dst_proc = dst_proc->pid;
 110   comm_pattern->src_host = MC_smx_actor_get_host_name(src_proc);
 111   comm_pattern->dst_host = MC_smx_actor_get_host_name(dst_proc);
 112   if (comm_pattern->data.size() == 0 && comm->src_buff != nullptr) {
 113     size_t buff_size;
 114     mc_model_checker->process().read(&buff_size, remote(comm->dst_buff_size));
 115     comm_pattern->data.resize(buff_size);
 116     mc_model_checker->process().read_bytes(comm_pattern->data.data(), comm_pattern->data.size(),
 117                                            remote(comm->src_buff));
 118   }
 119 }
 120
 121 namespace simgrid {
 122 namespace mc {
 123
 124 void CommunicationDeterminismChecker::deterministic_comm_pattern(int process, simgrid::mc::PatternCommunication* comm,
 125                                                                  int backtracking)
 126 {
 127   simgrid::mc::PatternCommunicationList* list =
 128     xbt_dynar_get_as(initial_communications_pattern, process, simgrid::mc::PatternCommunicationList*);
 129
 130   if (not backtracking) {
 131     e_mc_comm_pattern_difference_t diff = compare_comm_pattern(list->list[list->index_comm].get(), comm);
 132
 133     if (diff != NONE_DIFF) {
 134       if (comm->type == simgrid::mc::PatternCommunicationType::send) {
 135         this->send_deterministic = 0;
 136         if (this->send_diff != nullptr)
 137           xbt_free(this->send_diff);
 138         this->send_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 139       } else {
 140         this->recv_deterministic = 0;
 141         if (this->recv_diff != nullptr)
 142           xbt_free(this->recv_diff);
 143         this->recv_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 144       }
 145       if (_sg_mc_send_determinism && not this->send_deterministic) {
 146         XBT_INFO("*********************************************************");
 147         XBT_INFO("***** Non-send-deterministic communications pattern *****");
 148         XBT_INFO("*********************************************************");
 149         XBT_INFO("%s", this->send_diff);
 150         xbt_free(this->send_diff);
 151         this->send_diff = nullptr;
 152         simgrid::mc::session->logState();
 153         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 154       } else if (_sg_mc_comms_determinism && (not this->send_deterministic && not this->recv_deterministic)) {
 155         XBT_INFO("****************************************************");
 156         XBT_INFO("***** Non-deterministic communications pattern *****");
 157         XBT_INFO("****************************************************");
 158         XBT_INFO("%s", this->send_diff);
 159         XBT_INFO("%s", this->recv_diff);
 160         xbt_free(this->send_diff);
 161         this->send_diff = nullptr;
 162         xbt_free(this->recv_diff);
 163         this->recv_diff = nullptr;
 164         simgrid::mc::session->logState();
 165         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 166       }
 167     }
 168   }
 169 }
 170
 171 /********** Non Static functions ***********/
 172
 173 void CommunicationDeterminismChecker::get_comm_pattern(xbt_dynar_t list, smx_simcall_t request,
 174                                                        e_mc_call_type_t call_type, int backtracking)
 175 {
 176   const smx_actor_t issuer = MC_smx_simcall_get_issuer(request);
 177   simgrid::mc::PatternCommunicationList* initial_pattern =
 178       xbt_dynar_get_as(initial_communications_pattern, issuer->pid, simgrid::mc::PatternCommunicationList*);
 179   xbt_dynar_t incomplete_pattern = xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 180
 181   std::unique_ptr<simgrid::mc::PatternCommunication> pattern =
 182       std::unique_ptr<simgrid::mc::PatternCommunication>(new simgrid::mc::PatternCommunication());
 183   pattern->index = initial_pattern->index_comm + xbt_dynar_length(incomplete_pattern);
 184
 185   if (call_type == MC_CALL_TYPE_SEND) {
 186     /* Create comm pattern */
 187     pattern->type = simgrid::mc::PatternCommunicationType::send;
 188     pattern->comm_addr = simcall_comm_isend__get__result(request);
 189
 190     simgrid::mc::Remote<simgrid::kernel::activity::Comm> temp_synchro;
 191     mc_model_checker->process().read(temp_synchro,
 192                                      remote(static_cast<simgrid::kernel::activity::Comm*>(pattern->comm_addr)));
 193     simgrid::kernel::activity::Comm* synchro = static_cast<simgrid::kernel::activity::Comm*>(temp_synchro.getBuffer());
 194
 195     char* remote_name = mc_model_checker->process().read<char*>(
 196         (std::uint64_t)(synchro->mbox ? &synchro->mbox->name_ : &synchro->mbox_cpy->name_));
 197     pattern->rdv = mc_model_checker->process().read_string(remote_name);
 198     pattern->src_proc = mc_model_checker->process().resolveActor(simgrid::mc::remote(synchro->src_proc))->pid;
 199     pattern->src_host = MC_smx_actor_get_host_name(issuer);
 200
 201     simgrid::smpi::Request mpi_request =
 202         mc_model_checker->process().read<simgrid::smpi::Request>((std::uint64_t)simcall_comm_isend__get__data(request));
 203     pattern->tag = mpi_request.tag();
 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(mpi_request.detached()){
 210       if (not this->initial_communications_pattern_done) {
 211         /* Store comm pattern */
 212         simgrid::mc::PatternCommunicationList* list =
 213             xbt_dynar_get_as(initial_communications_pattern, pattern->src_proc, simgrid::mc::PatternCommunicationList*);
 214         list->list.push_back(std::move(pattern));
 215       } else {
 216         /* Evaluate comm determinism */
 217         this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
 218         xbt_dynar_get_as(initial_communications_pattern, pattern->src_proc, simgrid::mc::PatternCommunicationList*)
 219             ->index_comm++;
 220       }
 221       return;
 222     }
 223   } else if (call_type == MC_CALL_TYPE_RECV) {
 224     pattern->type = simgrid::mc::PatternCommunicationType::receive;
 225     pattern->comm_addr = simcall_comm_irecv__get__result(request);
 226
 227     simgrid::smpi::Request mpi_request;
 228     mc_model_checker->process().read(&mpi_request,
 229                                      remote((simgrid::smpi::Request*)simcall_comm_irecv__get__data(request)));
 230     pattern->tag = mpi_request.tag();
 231
 232     simgrid::mc::Remote<simgrid::kernel::activity::Comm> temp_comm;
 233     mc_model_checker->process().read(temp_comm,
 234                                      remote(static_cast<simgrid::kernel::activity::Comm*>(pattern->comm_addr)));
 235     simgrid::kernel::activity::Comm* comm = temp_comm.getBuffer();
 236
 237     char* remote_name;
 238     mc_model_checker->process().read(&remote_name, remote(comm->mbox ? &comm->mbox->name_ : &comm->mbox_cpy->name_));
 239     pattern->rdv = mc_model_checker->process().read_string(remote_name);
 240     pattern->dst_proc = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_proc))->pid;
 241     pattern->dst_host = MC_smx_actor_get_host_name(issuer);
 242   } else
 243     xbt_die("Unexpected call_type %i", (int) call_type);
 244
 245   XBT_DEBUG("Insert incomplete comm pattern %p for process %lu", pattern.get(), issuer->pid);
 246   xbt_dynar_t dynar = xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 247   simgrid::mc::PatternCommunication* pattern2 = pattern.release();
 248   xbt_dynar_push(dynar, &pattern2);
 249 }
 250
 251 void CommunicationDeterminismChecker::complete_comm_pattern(
 252     xbt_dynar_t list, simgrid::mc::RemotePtr<simgrid::kernel::activity::Comm> comm_addr, unsigned int issuer,
 253     int backtracking)
 254 {
 255   simgrid::mc::PatternCommunication* current_comm_pattern;
 256   unsigned int cursor = 0;
 257   std::unique_ptr<simgrid::mc::PatternCommunication> comm_pattern;
 258   int completed = 0;
 259
 260   /* Complete comm pattern */
 261   xbt_dynar_foreach(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, current_comm_pattern)
 262     if (remote(current_comm_pattern->comm_addr) == comm_addr) {
 263       update_comm_pattern(current_comm_pattern, comm_addr);
 264       completed = 1;
 265       simgrid::mc::PatternCommunication* temp;
 266       xbt_dynar_remove_at(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, &temp);
 267       comm_pattern = std::unique_ptr<simgrid::mc::PatternCommunication>(temp);
 268       XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %u", issuer, cursor);
 269       break;
 270     }
 271
 272   if (not completed)
 273     xbt_die("Corresponding communication not found!");
 274
 275   simgrid::mc::PatternCommunicationList* pattern =
 276       xbt_dynar_get_as(initial_communications_pattern, issuer, simgrid::mc::PatternCommunicationList*);
 277
 278   if (not this->initial_communications_pattern_done)
 279     /* Store comm pattern */
 280     pattern->list.push_back(std::move(comm_pattern));
 281   else {
 282     /* Evaluate comm determinism */
 283     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 284     pattern->index_comm++;
 285   }
 286 }
 287
 288 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& session) : Checker(session)
 289 {
 290 }
 291
 292 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 293
 294 RecordTrace CommunicationDeterminismChecker::getRecordTrace() // override
 295 {
 296   RecordTrace res;
 297   for (auto const& state : stack_)
 298     res.push_back(state->getTransition());
 299   return res;
 300 }
 301
 302 std::vector<std::string> CommunicationDeterminismChecker::getTextualTrace() // override
 303 {
 304   std::vector<std::string> trace;
 305   for (auto const& state : stack_) {
 306     smx_simcall_t req = &state->executed_req;
 307     if (req)
 308       trace.push_back(
 309           simgrid::mc::request_to_string(req, state->transition.argument, simgrid::mc::RequestType::executed));
 310   }
 311   return trace;
 312 }
 313
 314 void CommunicationDeterminismChecker::logState() // override
 315 {
 316   Checker::logState();
 317   if (_sg_mc_comms_determinism && not this->recv_deterministic && this->send_deterministic) {
 318     XBT_INFO("******************************************************");
 319     XBT_INFO("**** Only-send-deterministic communication pattern ****");
 320     XBT_INFO("******************************************************");
 321     XBT_INFO("%s", this->recv_diff);
 322   } else if (_sg_mc_comms_determinism && not this->send_deterministic && this->recv_deterministic) {
 323     XBT_INFO("******************************************************");
 324     XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 325     XBT_INFO("******************************************************");
 326     XBT_INFO("%s", this->send_diff);
 327   }
 328   XBT_INFO("Expanded states = %lu", expandedStatesCount_);
 329   XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
 330   XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
 331   XBT_INFO("Send-deterministic : %s", not this->send_deterministic ? "No" : "Yes");
 332   if (_sg_mc_comms_determinism)
 333     XBT_INFO("Recv-deterministic : %s", not this->recv_deterministic ? "No" : "Yes");
 334 }
 335
 336 void CommunicationDeterminismChecker::prepare()
 337 {
 338   const int maxpid = MC_smx_get_maxpid();
 339
 340   // Create initial_communications_pattern elements:
 341   initial_communications_pattern = simgrid::xbt::newDeleteDynar<simgrid::mc::PatternCommunicationList*>();
 342   for (int i = 0; i < maxpid; i++) {
 343     simgrid::mc::PatternCommunicationList* process_list_pattern = new simgrid::mc::PatternCommunicationList();
 344     xbt_dynar_insert_at(initial_communications_pattern, i, &process_list_pattern);
 345   }
 346
 347   // Create incomplete_communications_pattern elements:
 348   incomplete_communications_pattern = xbt_dynar_new(sizeof(xbt_dynar_t), xbt_dynar_free_voidp);
 349   for (int i = 0; i < maxpid; i++) {
 350     xbt_dynar_t process_pattern = xbt_dynar_new(sizeof(simgrid::mc::PatternCommunication*), nullptr);
 351     xbt_dynar_insert_at(incomplete_communications_pattern, i, &process_pattern);
 352   }
 353
 354   std::unique_ptr<simgrid::mc::State> initial_state =
 355       std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 356
 357   XBT_DEBUG("********* Start communication determinism verification *********");
 358
 359   /* Get an enabled actor and insert it in the interleave set of the initial state */
 360   for (auto& actor : mc_model_checker->process().actors())
 361     if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 362       initial_state->interleave(actor.copy.getBuffer());
 363
 364   stack_.push_back(std::move(initial_state));
 365 }
 366
 367 static inline bool all_communications_are_finished()
 368 {
 369   for (size_t current_actor = 1; current_actor < MC_smx_get_maxpid(); current_actor++) {
 370     xbt_dynar_t pattern = xbt_dynar_get_as(incomplete_communications_pattern, current_actor, xbt_dynar_t);
 371     if (not xbt_dynar_is_empty(pattern)) {
 372       XBT_DEBUG("Some communications are not finished, cannot stop the exploration! State not visited.");
 373       return false;
 374     }
 375   }
 376   return true;
 377 }
 378
 379 void CommunicationDeterminismChecker::restoreState()
 380 {
 381   /* Intermediate backtracking */
 382   simgrid::mc::State* state = stack_.back().get();
 383   if (state->system_state) {
 384     simgrid::mc::restore_snapshot(state->system_state);
 385     MC_restore_communications_pattern(state);
 386     return;
 387   }
 388
 389   /* Restore the initial state */
 390   simgrid::mc::session->restoreInitialState();
 391
 392   // int n = xbt_dynar_length(incomplete_communications_pattern);
 393   unsigned n = MC_smx_get_maxpid();
 394   assert(n == xbt_dynar_length(incomplete_communications_pattern));
 395   assert(n == xbt_dynar_length(initial_communications_pattern));
 396   for (unsigned j=0; j < n ; j++) {
 397     xbt_dynar_reset((xbt_dynar_t)xbt_dynar_get_as(incomplete_communications_pattern, j, xbt_dynar_t));
 398     xbt_dynar_get_as(initial_communications_pattern, j, simgrid::mc::PatternCommunicationList*)->index_comm = 0;
 399   }
 400
 401   /* Traverse the stack from the state at position start and re-execute the transitions */
 402   for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
 403     if (state == stack_.back())
 404       break;
 405
 406     int req_num = state->transition.argument;
 407     smx_simcall_t saved_req = &state->executed_req;
 408     xbt_assert(saved_req);
 409
 410     /* because we got a copy of the executed request, we have to fetch the
 411        real one, pointed by the request field of the issuer process */
 412
 413     const smx_actor_t issuer = MC_smx_simcall_get_issuer(saved_req);
 414     smx_simcall_t req = &issuer->simcall;
 415
 416     /* TODO : handle test and testany simcalls */
 417     e_mc_call_type_t call = MC_get_call_type(req);
 418     mc_model_checker->handle_simcall(state->transition);
 419     MC_handle_comm_pattern(call, req, req_num, nullptr, 1);
 420     mc_model_checker->wait_for_requests();
 421
 422     /* Update statistics */
 423     mc_model_checker->visited_states++;
 424     mc_model_checker->executed_transitions++;
 425   }
 426 }
 427
 428 void CommunicationDeterminismChecker::main()
 429 {
 430   std::unique_ptr<simgrid::mc::VisitedState> visited_state = nullptr;
 431   smx_simcall_t req = nullptr;
 432
 433   while (not stack_.empty()) {
 434     /* Get current state */
 435     simgrid::mc::State* state = stack_.back().get();
 436
 437     XBT_DEBUG("**************************************************");
 438     XBT_DEBUG("Exploration depth = %zi (state = %d, interleaved processes = %zd)", stack_.size(), state->num,
 439               state->interleaveSize());
 440
 441     /* Update statistics */
 442     mc_model_checker->visited_states++;
 443
 444     if (stack_.size() <= (std::size_t)_sg_mc_max_depth && (req = MC_state_get_request(state)) != nullptr &&
 445         (visited_state == nullptr)) {
 446
 447       int req_num = state->transition.argument;
 448
 449       XBT_DEBUG("Execute: %s", simgrid::mc::request_to_string(req, req_num, simgrid::mc::RequestType::simix).c_str());
 450
 451       std::string req_str;
 452       if (dot_output != nullptr)
 453         req_str = simgrid::mc::request_get_dot_output(req, req_num);
 454
 455       mc_model_checker->executed_transitions++;
 456
 457       /* TODO : handle test and testany simcalls */
 458       e_mc_call_type_t call = MC_CALL_TYPE_NONE;
 459       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 460         call = MC_get_call_type(req);
 461
 462       /* Answer the request */
 463       mc_model_checker->handle_simcall(state->transition);
 464       /* After this call req is no longer useful */
 465
 466       if (not this->initial_communications_pattern_done)
 467         MC_handle_comm_pattern(call, req, req_num, initial_communications_pattern, 0);
 468       else
 469         MC_handle_comm_pattern(call, req, req_num, nullptr, 0);
 470
 471       /* Wait for requests (schedules processes) */
 472       mc_model_checker->wait_for_requests();
 473
 474       /* Create the new expanded state */
 475       std::unique_ptr<simgrid::mc::State> next_state =
 476           std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 477
 478       /* If comm determinism verification, we cannot stop the exploration if some communications are not finished (at
 479        * least, data are transferred). These communications  are incomplete and they cannot be analyzed and compared
 480        * with the initial pattern. */
 481       bool compare_snapshots = all_communications_are_finished() && this->initial_communications_pattern_done;
 482
 483       if (_sg_mc_max_visited_states == 0 ||
 484           (visited_state = visitedStates_.addVisitedState(expandedStatesCount_, next_state.get(), compare_snapshots)) ==
 485               nullptr) {
 486
 487         /* Get enabled actors and insert them in the interleave set of the next state */
 488         for (auto& actor : mc_model_checker->process().actors())
 489           if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 490             next_state->interleave(actor.copy.getBuffer());
 491
 492         if (dot_output != nullptr)
 493           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n",
 494             state->num,  next_state->num, req_str.c_str());
 495
 496       } else if (dot_output != nullptr)
 497         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num,
 498                 visited_state->original_num == -1 ? visited_state->num : visited_state->original_num, req_str.c_str());
 499
 500       stack_.push_back(std::move(next_state));
 501
 502     } else {
 503
 504       if (stack_.size() > (std::size_t) _sg_mc_max_depth)
 505         XBT_WARN("/!\\ Max depth reached! /!\\ ");
 506       else if (visited_state != nullptr)
 507         XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
 508             visited_state->original_num == -1 ? visited_state->num : visited_state->original_num);
 509       else
 510         XBT_DEBUG("There are no more processes to interleave. (depth %zi)", stack_.size());
 511
 512       if (not this->initial_communications_pattern_done)
 513         this->initial_communications_pattern_done = 1;
 514
 515       /* Trash the current state, no longer needed */
 516       XBT_DEBUG("Delete state %d at depth %zi", state->num, stack_.size());
 517       stack_.pop_back();
 518
 519       visited_state = nullptr;
 520
 521       /* Check for deadlocks */
 522       if (mc_model_checker->checkDeadlock()) {
 523         MC_show_deadlock();
 524         throw new simgrid::mc::DeadlockError();
 525       }
 526
 527       while (not stack_.empty()) {
 528         std::unique_ptr<simgrid::mc::State> state = std::move(stack_.back());
 529         stack_.pop_back();
 530         if (state->interleaveSize() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
 531           /* We found a back-tracking point, let's loop */
 532           XBT_DEBUG("Back-tracking to state %d at depth %zi", state->num, stack_.size() + 1);
 533           stack_.push_back(std::move(state));
 534
 535           this->restoreState();
 536
 537           XBT_DEBUG("Back-tracking to state %d at depth %zi done", stack_.back()->num, stack_.size());
 538
 539           break;
 540         } else {
 541           XBT_DEBUG("Delete state %d at depth %zi", state->num, stack_.size() + 1);
 542         }
 543       }
 544     }
 545   }
 546
 547   simgrid::mc::session->logState();
 548 }
 549
 550 void CommunicationDeterminismChecker::run()
 551 {
 552   XBT_INFO("Check communication determinism");
 553   simgrid::mc::session->initialize();
 554
 555   this->prepare();
 556
 557   this->main();
 558 }
 559
 560 Checker* createCommunicationDeterminismChecker(Session& session)
 561 {
 562   return new CommunicationDeterminismChecker(session);
 563 }
 564
 565 }
 566 }