src/mc/checker/CommunicationDeterminismChecker.cpp

   1 /* Copyright (c) 2008-2018. 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/log.h>
  10 #include <xbt/sysdep.h>
  11
  12 #include "src/mc/Transition.hpp"
  13 #include "src/mc/VisitedState.hpp"
  14 #include "src/mc/checker/CommunicationDeterminismChecker.hpp"
  15 #include "src/mc/mc_exit.hpp"
  16 #include "src/mc/mc_private.hpp"
  17 #include "src/mc/mc_record.hpp"
  18 #include "src/mc/mc_request.hpp"
  19 #include "src/mc/mc_smx.hpp"
  20 #include "src/mc/mc_state.hpp"
  21 #include "src/mc/remote/Client.hpp"
  22
  23 #include "smpi_request.hpp"
  24
  25 using simgrid::mc::remote;
  26
  27 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_comm_determinism, mc, "Logging specific to MC communication determinism detection");
  28
  29 /********** Global variables **********/
  30
  31 xbt_dynar_t initial_communications_pattern;
  32 xbt_dynar_t incomplete_communications_pattern;
  33
  34 /********** Static functions ***********/
  35
  36 static e_mc_comm_pattern_difference_t compare_comm_pattern(simgrid::mc::PatternCommunication* comm1,
  37                                                            simgrid::mc::PatternCommunication* comm2)
  38 {
  39   if(comm1->type != comm2->type)
  40     return TYPE_DIFF;
  41   if (comm1->rdv != comm2->rdv)
  42     return RDV_DIFF;
  43   if (comm1->src_proc != comm2->src_proc)
  44     return SRC_PROC_DIFF;
  45   if (comm1->dst_proc != comm2->dst_proc)
  46     return DST_PROC_DIFF;
  47   if (comm1->tag != comm2->tag)
  48     return TAG_DIFF;
  49   if (comm1->data.size() != comm2->data.size())
  50     return DATA_SIZE_DIFF;
  51   if (comm1->data != comm2->data)
  52     return DATA_DIFF;
  53   return NONE_DIFF;
  54 }
  55
  56 static char* print_determinism_result(e_mc_comm_pattern_difference_t diff, int process,
  57                                       simgrid::mc::PatternCommunication* comm, unsigned int cursor)
  58 {
  59   char* type;
  60   char* res;
  61
  62   if (comm->type == simgrid::mc::PatternCommunicationType::send)
  63     type = bprintf("The send communications pattern of the process %d is different!", process - 1);
  64   else
  65     type = bprintf("The recv communications pattern of the process %d is different!", process - 1);
  66
  67   switch(diff) {
  68   case TYPE_DIFF:
  69     res = bprintf("%s Different type for communication #%u", type, cursor);
  70     break;
  71   case RDV_DIFF:
  72     res = bprintf("%s Different rdv for communication #%u", type, cursor);
  73     break;
  74   case TAG_DIFF:
  75     res = bprintf("%s Different tag for communication #%u", type, cursor);
  76     break;
  77   case SRC_PROC_DIFF:
  78     res = bprintf("%s Different source for communication #%u", type, cursor);
  79     break;
  80   case DST_PROC_DIFF:
  81     res = bprintf("%s Different destination for communication #%u", type, cursor);
  82     break;
  83   case DATA_SIZE_DIFF:
  84     res = bprintf("%s\n Different data size for communication #%u", type, cursor);
  85     break;
  86   case DATA_DIFF:
  87     res = bprintf("%s\n Different data for communication #%u", type, cursor);
  88     break;
  89   default:
  90     res = nullptr;
  91     break;
  92   }
  93
  94   return res;
  95 }
  96
  97 static void update_comm_pattern(simgrid::mc::PatternCommunication* comm_pattern,
  98                                 simgrid::mc::RemotePtr<simgrid::kernel::activity::CommImpl> comm_addr)
  99 {
 100   // HACK, type punning
 101   simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 102   mc_model_checker->process().read(temp_comm, comm_addr);
 103   simgrid::kernel::activity::CommImpl* comm = temp_comm.getBuffer();
 104
 105   smx_actor_t src_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->src_proc));
 106   smx_actor_t dst_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_proc));
 107   comm_pattern->src_proc = src_proc->pid;
 108   comm_pattern->dst_proc = dst_proc->pid;
 109   comm_pattern->src_host = MC_smx_actor_get_host_name(src_proc);
 110   comm_pattern->dst_host = MC_smx_actor_get_host_name(dst_proc);
 111   if (comm_pattern->data.size() == 0 && comm->src_buff != nullptr) {
 112     size_t buff_size;
 113     mc_model_checker->process().read(&buff_size, remote(comm->dst_buff_size));
 114     comm_pattern->data.resize(buff_size);
 115     mc_model_checker->process().read_bytes(comm_pattern->data.data(), comm_pattern->data.size(),
 116                                            remote(comm->src_buff));
 117   }
 118 }
 119
 120 namespace simgrid {
 121 namespace mc {
 122
 123 void CommunicationDeterminismChecker::deterministic_comm_pattern(int process, simgrid::mc::PatternCommunication* comm,
 124                                                                  int backtracking)
 125 {
 126   simgrid::mc::PatternCommunicationList* list =
 127     xbt_dynar_get_as(initial_communications_pattern, process, simgrid::mc::PatternCommunicationList*);
 128
 129   if (not backtracking) {
 130     e_mc_comm_pattern_difference_t diff = compare_comm_pattern(list->list[list->index_comm].get(), comm);
 131
 132     if (diff != NONE_DIFF) {
 133       if (comm->type == simgrid::mc::PatternCommunicationType::send) {
 134         this->send_deterministic = 0;
 135         if (this->send_diff != nullptr)
 136           xbt_free(this->send_diff);
 137         this->send_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 138       } else {
 139         this->recv_deterministic = 0;
 140         if (this->recv_diff != nullptr)
 141           xbt_free(this->recv_diff);
 142         this->recv_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 143       }
 144       if (_sg_mc_send_determinism && not this->send_deterministic) {
 145         XBT_INFO("*********************************************************");
 146         XBT_INFO("***** Non-send-deterministic communications pattern *****");
 147         XBT_INFO("*********************************************************");
 148         XBT_INFO("%s", this->send_diff);
 149         xbt_free(this->send_diff);
 150         this->send_diff = nullptr;
 151         simgrid::mc::session->logState();
 152         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 153       } else if (_sg_mc_comms_determinism && (not this->send_deterministic && not this->recv_deterministic)) {
 154         XBT_INFO("****************************************************");
 155         XBT_INFO("***** Non-deterministic communications pattern *****");
 156         XBT_INFO("****************************************************");
 157         XBT_INFO("%s", this->send_diff);
 158         XBT_INFO("%s", this->recv_diff);
 159         xbt_free(this->send_diff);
 160         this->send_diff = nullptr;
 161         xbt_free(this->recv_diff);
 162         this->recv_diff = nullptr;
 163         simgrid::mc::session->logState();
 164         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 165       }
 166     }
 167   }
 168 }
 169
 170 /********** Non Static functions ***********/
 171
 172 void CommunicationDeterminismChecker::get_comm_pattern(xbt_dynar_t list, smx_simcall_t request,
 173                                                        e_mc_call_type_t call_type, int backtracking)
 174 {
 175   const smx_actor_t issuer = MC_smx_simcall_get_issuer(request);
 176   simgrid::mc::PatternCommunicationList* initial_pattern =
 177       xbt_dynar_get_as(initial_communications_pattern, issuer->pid, simgrid::mc::PatternCommunicationList*);
 178   xbt_dynar_t incomplete_pattern = xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 179
 180   std::unique_ptr<simgrid::mc::PatternCommunication> pattern =
 181       std::unique_ptr<simgrid::mc::PatternCommunication>(new simgrid::mc::PatternCommunication());
 182   pattern->index = initial_pattern->index_comm + xbt_dynar_length(incomplete_pattern);
 183
 184   if (call_type == MC_CALL_TYPE_SEND) {
 185     /* Create comm pattern */
 186     pattern->type = simgrid::mc::PatternCommunicationType::send;
 187     pattern->comm_addr = static_cast<simgrid::kernel::activity::CommImpl*>(simcall_comm_isend__getraw__result(request));
 188
 189     simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_synchro;
 190     mc_model_checker->process().read(temp_synchro,
 191                                      remote(static_cast<simgrid::kernel::activity::CommImpl*>(pattern->comm_addr)));
 192     simgrid::kernel::activity::CommImpl* synchro =
 193         static_cast<simgrid::kernel::activity::CommImpl*>(temp_synchro.getBuffer());
 194
 195     char* remote_name = mc_model_checker->process().read<char*>(
 196         RemotePtr<char*>((uint64_t)(synchro->mbox ? &synchro->mbox->name_ : &synchro->mbox_cpy->name_)));
 197     pattern->rdv      = mc_model_checker->process().read_string(RemotePtr<char>(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 = mc_model_checker->process().read<simgrid::smpi::Request>(
 202         RemotePtr<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 = static_cast<simgrid::kernel::activity::CommImpl*>(simcall_comm_irecv__getraw__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::CommImpl> temp_comm;
 233     mc_model_checker->process().read(temp_comm,
 234                                      remote(static_cast<simgrid::kernel::activity::CommImpl*>(pattern->comm_addr)));
 235     simgrid::kernel::activity::CommImpl* comm = temp_comm.getBuffer();
 236
 237     char* remote_name;
 238     mc_model_checker->process().read(
 239         &remote_name, remote(comm->mbox ? &simgrid::xbt::string::to_string_data(comm->mbox->name_).data
 240                                         : &simgrid::xbt::string::to_string_data(comm->mbox_cpy->name_).data));
 241     pattern->rdv      = mc_model_checker->process().read_string(RemotePtr<char>(remote_name));
 242     pattern->dst_proc = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_proc))->pid;
 243     pattern->dst_host = MC_smx_actor_get_host_name(issuer);
 244   } else
 245     xbt_die("Unexpected call_type %i", (int) call_type);
 246
 247   XBT_DEBUG("Insert incomplete comm pattern %p for process %ld", pattern.get(), issuer->pid);
 248   xbt_dynar_t dynar = xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 249   simgrid::mc::PatternCommunication* pattern2 = pattern.release();
 250   xbt_dynar_push(dynar, &pattern2);
 251 }
 252
 253 void CommunicationDeterminismChecker::complete_comm_pattern(
 254     xbt_dynar_t list, simgrid::mc::RemotePtr<simgrid::kernel::activity::CommImpl> comm_addr, unsigned int issuer,
 255     int backtracking)
 256 {
 257   simgrid::mc::PatternCommunication* current_comm_pattern;
 258   unsigned int cursor = 0;
 259   std::unique_ptr<simgrid::mc::PatternCommunication> comm_pattern;
 260   int completed = 0;
 261
 262   /* Complete comm pattern */
 263   xbt_dynar_foreach(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, current_comm_pattern)
 264     if (remote(current_comm_pattern->comm_addr) == comm_addr) {
 265       update_comm_pattern(current_comm_pattern, comm_addr);
 266       completed = 1;
 267       simgrid::mc::PatternCommunication* temp;
 268       xbt_dynar_remove_at(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, &temp);
 269       comm_pattern = std::unique_ptr<simgrid::mc::PatternCommunication>(temp);
 270       XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %u", issuer, cursor);
 271       break;
 272     }
 273
 274   if (not completed)
 275     xbt_die("Corresponding communication not found!");
 276
 277   simgrid::mc::PatternCommunicationList* pattern =
 278       xbt_dynar_get_as(initial_communications_pattern, issuer, simgrid::mc::PatternCommunicationList*);
 279
 280   if (not this->initial_communications_pattern_done)
 281     /* Store comm pattern */
 282     pattern->list.push_back(std::move(comm_pattern));
 283   else {
 284     /* Evaluate comm determinism */
 285     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 286     pattern->index_comm++;
 287   }
 288 }
 289
 290 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& session) : Checker(session)
 291 {
 292 }
 293
 294 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 295
 296 RecordTrace CommunicationDeterminismChecker::getRecordTrace() // override
 297 {
 298   RecordTrace res;
 299   for (auto const& state : stack_)
 300     res.push_back(state->getTransition());
 301   return res;
 302 }
 303
 304 std::vector<std::string> CommunicationDeterminismChecker::getTextualTrace() // override
 305 {
 306   std::vector<std::string> trace;
 307   for (auto const& state : stack_) {
 308     smx_simcall_t req = &state->executed_req;
 309     if (req)
 310       trace.push_back(
 311           simgrid::mc::request_to_string(req, state->transition.argument, simgrid::mc::RequestType::executed));
 312   }
 313   return trace;
 314 }
 315
 316 void CommunicationDeterminismChecker::logState() // override
 317 {
 318   if (_sg_mc_comms_determinism && not this->recv_deterministic && this->send_deterministic) {
 319     XBT_INFO("******************************************************");
 320     XBT_INFO("**** Only-send-deterministic communication pattern ****");
 321     XBT_INFO("******************************************************");
 322     XBT_INFO("%s", this->recv_diff);
 323   } else if (_sg_mc_comms_determinism && not this->send_deterministic && this->recv_deterministic) {
 324     XBT_INFO("******************************************************");
 325     XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 326     XBT_INFO("******************************************************");
 327     XBT_INFO("%s", this->send_diff);
 328   }
 329   XBT_INFO("Expanded states = %lu", expandedStatesCount_);
 330   XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
 331   XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
 332   XBT_INFO("Send-deterministic : %s", not this->send_deterministic ? "No" : "Yes");
 333   if (_sg_mc_comms_determinism)
 334     XBT_INFO("Recv-deterministic : %s", not this->recv_deterministic ? "No" : "Yes");
 335 }
 336
 337 void CommunicationDeterminismChecker::prepare()
 338 {
 339   const int maxpid = MC_smx_get_maxpid();
 340
 341   // Create initial_communications_pattern elements:
 342   initial_communications_pattern = simgrid::xbt::newDeleteDynar<simgrid::mc::PatternCommunicationList*>();
 343   for (int i = 0; i < maxpid; i++) {
 344     simgrid::mc::PatternCommunicationList* process_list_pattern = new simgrid::mc::PatternCommunicationList();
 345     xbt_dynar_insert_at(initial_communications_pattern, i, &process_list_pattern);
 346   }
 347
 348   // Create incomplete_communications_pattern elements:
 349   incomplete_communications_pattern = xbt_dynar_new(sizeof(xbt_dynar_t), xbt_dynar_free_voidp);
 350   for (int i = 0; i < maxpid; i++) {
 351     xbt_dynar_t process_pattern = xbt_dynar_new(sizeof(simgrid::mc::PatternCommunication*), nullptr);
 352     xbt_dynar_insert_at(incomplete_communications_pattern, i, &process_pattern);
 353   }
 354
 355   std::unique_ptr<simgrid::mc::State> initial_state =
 356       std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 357
 358   XBT_DEBUG("********* Start communication determinism verification *********");
 359
 360   /* Get an enabled actor and insert it in the interleave set of the initial state */
 361   for (auto& actor : mc_model_checker->process().actors())
 362     if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 363       initial_state->addInterleavingSet(actor.copy.getBuffer());
 364
 365   stack_.push_back(std::move(initial_state));
 366 }
 367
 368 static inline bool all_communications_are_finished()
 369 {
 370   for (size_t current_actor = 1; current_actor < MC_smx_get_maxpid(); current_actor++) {
 371     xbt_dynar_t pattern = xbt_dynar_get_as(incomplete_communications_pattern, current_actor, xbt_dynar_t);
 372     if (not xbt_dynar_is_empty(pattern)) {
 373       XBT_DEBUG("Some communications are not finished, cannot stop the exploration! State not visited.");
 374       return false;
 375     }
 376   }
 377   return true;
 378 }
 379
 380 void CommunicationDeterminismChecker::restoreState()
 381 {
 382   /* Intermediate backtracking */
 383   simgrid::mc::State* state = stack_.back().get();
 384   if (state->system_state) {
 385     simgrid::mc::restore_snapshot(state->system_state);
 386     MC_restore_communications_pattern(state);
 387     return;
 388   }
 389
 390   /* Restore the initial state */
 391   simgrid::mc::session->restoreInitialState();
 392
 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 = %zu (state = %d, interleaved processes = %zu)", 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)
 445       req = MC_state_get_request(state);
 446     else
 447       req = nullptr;
 448
 449     if (req != nullptr && visited_state == nullptr) {
 450
 451       int req_num = state->transition.argument;
 452
 453       XBT_DEBUG("Execute: %s", simgrid::mc::request_to_string(req, req_num, simgrid::mc::RequestType::simix).c_str());
 454
 455       std::string req_str;
 456       if (dot_output != nullptr)
 457         req_str = simgrid::mc::request_get_dot_output(req, req_num);
 458
 459       mc_model_checker->executed_transitions++;
 460
 461       /* TODO : handle test and testany simcalls */
 462       e_mc_call_type_t call = MC_CALL_TYPE_NONE;
 463       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 464         call = MC_get_call_type(req);
 465
 466       /* Answer the request */
 467       mc_model_checker->handle_simcall(state->transition);
 468       /* After this call req is no longer useful */
 469
 470       if (not this->initial_communications_pattern_done)
 471         MC_handle_comm_pattern(call, req, req_num, initial_communications_pattern, 0);
 472       else
 473         MC_handle_comm_pattern(call, req, req_num, nullptr, 0);
 474
 475       /* Wait for requests (schedules processes) */
 476       mc_model_checker->wait_for_requests();
 477
 478       /* Create the new expanded state */
 479       std::unique_ptr<simgrid::mc::State> next_state =
 480           std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 481
 482       /* If comm determinism verification, we cannot stop the exploration if some communications are not finished (at
 483        * least, data are transferred). These communications  are incomplete and they cannot be analyzed and compared
 484        * with the initial pattern. */
 485       bool compare_snapshots = all_communications_are_finished() && this->initial_communications_pattern_done;
 486
 487       if (_sg_mc_max_visited_states != 0)
 488         visited_state = visitedStates_.addVisitedState(expandedStatesCount_, next_state.get(), compare_snapshots);
 489       else
 490         visited_state = nullptr;
 491
 492       if (visited_state == nullptr) {
 493
 494         /* Get enabled actors and insert them in the interleave set of the next state */
 495         for (auto& actor : mc_model_checker->process().actors())
 496           if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 497             next_state->addInterleavingSet(actor.copy.getBuffer());
 498
 499         if (dot_output != nullptr)
 500           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n",
 501             state->num,  next_state->num, req_str.c_str());
 502
 503       } else if (dot_output != nullptr)
 504         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", 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", 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->main();
 565 }
 566
 567 Checker* createCommunicationDeterminismChecker(Session& session)
 568 {
 569   return new CommunicationDeterminismChecker(session);
 570 }
 571
 572 }
 573 }