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/mc_state.h"
  14 #include "src/mc/mc_comm_pattern.h"
  15 #include "src/mc/mc_request.h"
  16 #include "src/mc/mc_safety.h"
  17 #include "src/mc/mc_private.h"
  18 #include "src/mc/mc_record.h"
  19 #include "src/mc/mc_smx.h"
  20 #include "src/mc/Client.hpp"
  21 #include "src/mc/checker/CommunicationDeterminismChecker.hpp"
  22 #include "src/mc/mc_exit.h"
  23 #include "src/mc/VisitedState.hpp"
  24 #include "src/mc/Transition.hpp"
  25
  26 using simgrid::mc::remote;
  27
  28 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_comm_determinism, mc,
  29                                 "Logging specific to MC communication determinism detection");
  30
  31 /********** Global variables **********/
  32
  33 xbt_dynar_t initial_communications_pattern;
  34 xbt_dynar_t incomplete_communications_pattern;
  35
  36 /********** Static functions ***********/
  37
  38 static e_mc_comm_pattern_difference_t compare_comm_pattern(simgrid::mc::PatternCommunication* comm1, 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, simgrid::mc::PatternCommunication* comm, unsigned int cursor) {
  58   char *type, *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 #%d", type, cursor);
  68     break;
  69   case RDV_DIFF:
  70     res = bprintf("%s Different rdv for communication #%d", type, cursor);
  71     break;
  72   case TAG_DIFF:
  73     res = bprintf("%s Different tag for communication #%d", type, cursor);
  74     break;
  75   case SRC_PROC_DIFF:
  76       res = bprintf("%s Different source for communication #%d", type, cursor);
  77     break;
  78   case DST_PROC_DIFF:
  79       res = bprintf("%s Different destination for communication #%d", type, cursor);
  80     break;
  81   case DATA_SIZE_DIFF:
  82     res = bprintf("%s\n Different data size for communication #%d", type, cursor);
  83     break;
  84   case DATA_DIFF:
  85     res = bprintf("%s\n Different data for communication #%d", type, cursor);
  86     break;
  87   default:
  88     res = nullptr;
  89     break;
  90   }
  91
  92   return res;
  93 }
  94
  95 static void update_comm_pattern(
  96   simgrid::mc::PatternCommunication* comm_pattern,
  97   simgrid::mc::RemotePtr<simgrid::kernel::activity::Comm> comm_addr)
  98 {
  99   // HACK, type punning
 100   simgrid::mc::Remote<simgrid::kernel::activity::Comm> temp_comm;
 101   mc_model_checker->process().read(temp_comm, comm_addr);
 102   simgrid::kernel::activity::Comm* comm = temp_comm.getBuffer();
 103
 104   smx_actor_t src_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->src_proc));
 105   smx_actor_t dst_proc   = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_proc));
 106   comm_pattern->src_proc = src_proc->pid;
 107   comm_pattern->dst_proc = dst_proc->pid;
 108   comm_pattern->src_host = MC_smx_actor_get_host_name(src_proc);
 109   comm_pattern->dst_host = MC_smx_actor_get_host_name(dst_proc);
 110   if (comm_pattern->data.size() == 0 && comm->src_buff != nullptr) {
 111     size_t buff_size;
 112     mc_model_checker->process().read(
 113       &buff_size, remote(comm->dst_buff_size));
 114     comm_pattern->data.resize(buff_size);
 115     mc_model_checker->process().read_bytes(
 116       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(
 125   int process, simgrid::mc::PatternCommunication* comm, int backtracking)
 126 {
 127   simgrid::mc::PatternCommunicationList* list =
 128     xbt_dynar_get_as(initial_communications_pattern, process, simgrid::mc::PatternCommunicationList*);
 129
 130   if(!backtracking){
 131     e_mc_comm_pattern_difference_t diff =
 132       compare_comm_pattern(list->list[list->index_comm].get(), comm);
 133
 134     if (diff != NONE_DIFF) {
 135       if (comm->type == simgrid::mc::PatternCommunicationType::send) {
 136         this->send_deterministic = 0;
 137         if (this->send_diff != nullptr)
 138           xbt_free(this->send_diff);
 139         this->send_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 140       } else {
 141         this->recv_deterministic = 0;
 142         if (this->recv_diff != nullptr)
 143           xbt_free(this->recv_diff);
 144         this->recv_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
 145       }
 146       if(_sg_mc_send_determinism && !this->send_deterministic){
 147         XBT_INFO("*********************************************************");
 148         XBT_INFO("***** Non-send-deterministic communications pattern *****");
 149         XBT_INFO("*********************************************************");
 150         XBT_INFO("%s", this->send_diff);
 151         xbt_free(this->send_diff);
 152         this->send_diff = nullptr;
 153         simgrid::mc::session->logState();
 154         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 155       }else if(_sg_mc_comms_determinism
 156           && (!this->send_deterministic && !this->recv_deterministic)) {
 157         XBT_INFO("****************************************************");
 158         XBT_INFO("***** Non-deterministic communications pattern *****");
 159         XBT_INFO("****************************************************");
 160         XBT_INFO("%s", this->send_diff);
 161         XBT_INFO("%s", this->recv_diff);
 162         xbt_free(this->send_diff);
 163         this->send_diff = nullptr;
 164         xbt_free(this->recv_diff);
 165         this->recv_diff = nullptr;
 166         simgrid::mc::session->logState();
 167         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 168       }
 169     }
 170   }
 171 }
 172
 173 /********** Non Static functions ***********/
 174
 175 void CommunicationDeterminismChecker::get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, e_mc_call_type_t call_type, int backtracking)
 176 {
 177   const smx_actor_t issuer = MC_smx_simcall_get_issuer(request);
 178   simgrid::mc::PatternCommunicationList* initial_pattern = xbt_dynar_get_as(
 179     initial_communications_pattern, issuer->pid, simgrid::mc::PatternCommunicationList*);
 180   xbt_dynar_t incomplete_pattern = xbt_dynar_get_as(
 181     incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 182
 183   std::unique_ptr<simgrid::mc::PatternCommunication> pattern =
 184     std::unique_ptr<simgrid::mc::PatternCommunication>(
 185       new simgrid::mc::PatternCommunication());
 186   pattern->index =
 187     initial_pattern->index_comm + xbt_dynar_length(incomplete_pattern);
 188
 189   if (call_type == MC_CALL_TYPE_SEND) {
 190     /* Create comm pattern */
 191     pattern->type = simgrid::mc::PatternCommunicationType::send;
 192     pattern->comm_addr = simcall_comm_isend__get__result(request);
 193
 194     simgrid::mc::Remote<simgrid::kernel::activity::Comm> temp_synchro;
 195     mc_model_checker->process().read(temp_synchro, remote(
 196       static_cast<simgrid::kernel::activity::Comm*>(pattern->comm_addr)));
 197     simgrid::kernel::activity::Comm* synchro =
 198       static_cast<simgrid::kernel::activity::Comm*>(temp_synchro.getBuffer());
 199
 200     char* remote_name = mc_model_checker->process().read<char*>(
 201       (std::uint64_t)(synchro->mbox ? &synchro->mbox->name : &synchro->mbox_cpy->name));
 202     pattern->rdv = mc_model_checker->process().read_string(remote_name);
 203     pattern->src_proc = mc_model_checker->process().resolveActor(simgrid::mc::remote(synchro->src_proc))->pid;
 204     pattern->src_host = MC_smx_actor_get_host_name(issuer);
 205
 206     struct s_smpi_mpi_request mpi_request =
 207       mc_model_checker->process().read<s_smpi_mpi_request>(
 208         (std::uint64_t) simcall_comm_isend__get__data(request));
 209     pattern->tag = mpi_request.tag;
 210
 211     if (synchro->src_buff != nullptr){
 212       pattern->data.resize(synchro->src_buff_size);
 213       mc_model_checker->process().read_bytes(
 214         pattern->data.data(), pattern->data.size(),
 215         remote(synchro->src_buff));
 216     }
 217     if(mpi_request.detached){
 218       if (!this->initial_communications_pattern_done) {
 219         /* Store comm pattern */
 220         simgrid::mc::PatternCommunicationList* list = xbt_dynar_get_as(
 221           initial_communications_pattern, pattern->src_proc,
 222           simgrid::mc::PatternCommunicationList*);
 223         list->list.push_back(std::move(pattern));
 224       } else {
 225         /* Evaluate comm determinism */
 226         this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
 227         xbt_dynar_get_as(
 228           initial_communications_pattern, pattern->src_proc, simgrid::mc::PatternCommunicationList*
 229         )->index_comm++;
 230       }
 231       return;
 232     }
 233   } else if (call_type == MC_CALL_TYPE_RECV) {
 234     pattern->type = simgrid::mc::PatternCommunicationType::receive;
 235     pattern->comm_addr = simcall_comm_irecv__get__result(request);
 236
 237     struct s_smpi_mpi_request mpi_request;
 238     mc_model_checker->process().read(
 239       &mpi_request, remote((struct s_smpi_mpi_request*)simcall_comm_irecv__get__data(request)));
 240     pattern->tag = mpi_request.tag;
 241
 242     simgrid::mc::Remote<simgrid::kernel::activity::Comm> temp_comm;
 243     mc_model_checker->process().read(temp_comm, remote(
 244       static_cast<simgrid::kernel::activity::Comm*>(pattern->comm_addr)));
 245     simgrid::kernel::activity::Comm* comm = temp_comm.getBuffer();
 246
 247     char* remote_name;
 248     mc_model_checker->process().read(&remote_name,
 249       remote(comm->mbox ? &comm->mbox->name : &comm->mbox_cpy->name));
 250     pattern->rdv = mc_model_checker->process().read_string(remote_name);
 251     pattern->dst_proc = mc_model_checker->process().resolveActor(simgrid::mc::remote(comm->dst_proc))->pid;
 252     pattern->dst_host = MC_smx_actor_get_host_name(issuer);
 253   } else
 254     xbt_die("Unexpected call_type %i", (int) call_type);
 255
 256   XBT_DEBUG("Insert incomplete comm pattern %p for process %lu",
 257     pattern.get(), issuer->pid);
 258   xbt_dynar_t dynar =
 259     xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 260   simgrid::mc::PatternCommunication* pattern2 = pattern.release();
 261   xbt_dynar_push(dynar, &pattern2);
 262 }
 263
 264
 265 void CommunicationDeterminismChecker::complete_comm_pattern(
 266   xbt_dynar_t list, simgrid::mc::RemotePtr<simgrid::kernel::activity::Comm> comm_addr,
 267   unsigned int issuer, int backtracking)
 268 {
 269   simgrid::mc::PatternCommunication* current_comm_pattern;
 270   unsigned int cursor = 0;
 271   std::unique_ptr<simgrid::mc::PatternCommunication> comm_pattern;
 272   int completed = 0;
 273
 274   /* Complete comm pattern */
 275   xbt_dynar_foreach(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, current_comm_pattern)
 276     if (remote(current_comm_pattern->comm_addr) == comm_addr) {
 277       update_comm_pattern(current_comm_pattern, comm_addr);
 278       completed = 1;
 279       simgrid::mc::PatternCommunication* temp;
 280       xbt_dynar_remove_at(
 281         xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t),
 282         cursor, &temp);
 283       comm_pattern = std::unique_ptr<simgrid::mc::PatternCommunication>(temp);
 284       XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %u", issuer, cursor);
 285       break;
 286     }
 287
 288   if(!completed)
 289     xbt_die("Corresponding communication not found!");
 290
 291   simgrid::mc::PatternCommunicationList* pattern = xbt_dynar_get_as(
 292     initial_communications_pattern, issuer, simgrid::mc::PatternCommunicationList*);
 293
 294   if (!this->initial_communications_pattern_done)
 295     /* Store comm pattern */
 296     pattern->list.push_back(std::move(comm_pattern));
 297   else {
 298     /* Evaluate comm determinism */
 299     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 300     pattern->index_comm++;
 301   }
 302 }
 303
 304 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& session)
 305   : Checker(session)
 306 {
 307
 308 }
 309
 310 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 311
 312 RecordTrace CommunicationDeterminismChecker::getRecordTrace() // override
 313 {
 314   RecordTrace res;
 315   for (auto const& state : stack_)
 316     res.push_back(state->getTransition());
 317   return res;
 318 }
 319
 320 std::vector<std::string> CommunicationDeterminismChecker::getTextualTrace() // override
 321 {
 322   std::vector<std::string> trace;
 323   for (auto const& state : stack_) {
 324     smx_simcall_t req = &state->executed_req;
 325     if (req)
 326       trace.push_back(simgrid::mc::request_to_string(
 327         req, state->transition.argument, simgrid::mc::RequestType::executed));
 328   }
 329   return trace;
 330 }
 331
 332 void CommunicationDeterminismChecker::logState() // override
 333 {
 334   Checker::logState();
 335   if (_sg_mc_comms_determinism &&
 336       !this->recv_deterministic &&
 337       this->send_deterministic) {
 338     XBT_INFO("******************************************************");
 339     XBT_INFO("**** Only-send-deterministic communication pattern ****");
 340     XBT_INFO("******************************************************");
 341     XBT_INFO("%s", this->recv_diff);
 342   } else if(_sg_mc_comms_determinism &&
 343       !this->send_deterministic &&
 344       this->recv_deterministic) {
 345     XBT_INFO("******************************************************");
 346     XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 347     XBT_INFO("******************************************************");
 348     XBT_INFO("%s", this->send_diff);
 349   }
 350   XBT_INFO("Expanded states = %lu", expandedStatesCount_);
 351   XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
 352   XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
 353   XBT_INFO("Send-deterministic : %s", !this->send_deterministic ? "No" : "Yes");
 354   if (_sg_mc_comms_determinism)
 355     XBT_INFO("Recv-deterministic : %s",
 356       !this->recv_deterministic ? "No" : "Yes");
 357 }
 358
 359 void CommunicationDeterminismChecker::prepare()
 360 {
 361   const int maxpid = MC_smx_get_maxpid();
 362
 363   // Create initial_communications_pattern elements:
 364   initial_communications_pattern = simgrid::xbt::newDeleteDynar<simgrid::mc::PatternCommunicationList*>();
 365   for (int i = 0; i < maxpid; i++) {
 366     simgrid::mc::PatternCommunicationList* process_list_pattern = new simgrid::mc::PatternCommunicationList();
 367     xbt_dynar_insert_at(initial_communications_pattern, i, &process_list_pattern);
 368   }
 369
 370   // Create incomplete_communications_pattern elements:
 371   incomplete_communications_pattern = xbt_dynar_new(sizeof(xbt_dynar_t), xbt_dynar_free_voidp);
 372   for (int i = 0; i < maxpid; i++) {
 373     xbt_dynar_t process_pattern = xbt_dynar_new(sizeof(simgrid::mc::PatternCommunication*), nullptr);
 374     xbt_dynar_insert_at(incomplete_communications_pattern, i, &process_pattern);
 375   }
 376
 377   std::unique_ptr<simgrid::mc::State> initial_state =
 378       std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 379
 380   XBT_DEBUG("********* Start communication determinism verification *********");
 381
 382   /* Get an enabled actor and insert it in the interleave set of the initial state */
 383   for (auto& actor : mc_model_checker->process().actors())
 384     if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 385       initial_state->interleave(actor.copy.getBuffer());
 386
 387   stack_.push_back(std::move(initial_state));
 388 }
 389
 390 static inline
 391 bool all_communications_are_finished()
 392 {
 393   for (size_t current_actor = 1; current_actor < MC_smx_get_maxpid(); current_actor++) {
 394     xbt_dynar_t pattern = xbt_dynar_get_as(incomplete_communications_pattern, current_actor, xbt_dynar_t);
 395     if (!xbt_dynar_is_empty(pattern)) {
 396       XBT_DEBUG("Some communications are not finished, cannot stop the exploration ! State not visited.");
 397       return false;
 398     }
 399   }
 400   return true;
 401 }
 402
 403 void CommunicationDeterminismChecker::restoreState()
 404 {
 405   /* Intermediate backtracking */
 406   {
 407     simgrid::mc::State* state = stack_.back().get();
 408     if (state->system_state) {
 409       simgrid::mc::restore_snapshot(state->system_state);
 410       MC_restore_communications_pattern(state);
 411       return;
 412     }
 413   }
 414
 415   /* Restore the initial state */
 416   simgrid::mc::session->restoreInitialState();
 417
 418   // int n = xbt_dynar_length(incomplete_communications_pattern);
 419   unsigned n = MC_smx_get_maxpid();
 420   assert(n == xbt_dynar_length(incomplete_communications_pattern));
 421   assert(n == xbt_dynar_length(initial_communications_pattern));
 422   for (unsigned j=0; j < n ; j++) {
 423     xbt_dynar_reset((xbt_dynar_t)xbt_dynar_get_as(incomplete_communications_pattern, j, xbt_dynar_t));
 424     xbt_dynar_get_as(initial_communications_pattern, j, simgrid::mc::PatternCommunicationList*)->index_comm = 0;
 425   }
 426
 427   /* Traverse the stack from the state at position start and re-execute the transitions */
 428   for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
 429     if (state == stack_.back())
 430       break;
 431
 432     int req_num = state->transition.argument;
 433     smx_simcall_t saved_req = &state->executed_req;
 434     xbt_assert(saved_req);
 435
 436     /* because we got a copy of the executed request, we have to fetch the
 437        real one, pointed by the request field of the issuer process */
 438
 439     const smx_actor_t issuer = MC_smx_simcall_get_issuer(saved_req);
 440     smx_simcall_t req = &issuer->simcall;
 441
 442     /* TODO : handle test and testany simcalls */
 443     e_mc_call_type_t call = MC_get_call_type(req);
 444     mc_model_checker->handle_simcall(state->transition);
 445     MC_handle_comm_pattern(call, req, req_num, nullptr, 1);
 446     mc_model_checker->wait_for_requests();
 447
 448     /* Update statistics */
 449     mc_model_checker->visited_states++;
 450     mc_model_checker->executed_transitions++;
 451   }
 452 }
 453
 454 void CommunicationDeterminismChecker::main(void)
 455 {
 456   std::unique_ptr<simgrid::mc::VisitedState> visited_state = nullptr;
 457   smx_simcall_t req = nullptr;
 458
 459   while (!stack_.empty()) {
 460
 461     /* Get current state */
 462     simgrid::mc::State* state = stack_.back().get();
 463
 464     XBT_DEBUG("**************************************************");
 465     XBT_DEBUG("Exploration depth = %zi (state = %d, interleaved processes = %zd)",
 466               stack_.size(), state->num,
 467               state->interleaveSize());
 468
 469     /* Update statistics */
 470     mc_model_checker->visited_states++;
 471
 472     if (stack_.size() <= (std::size_t) _sg_mc_max_depth
 473         && (req = MC_state_get_request(state)) != nullptr
 474         && (visited_state == nullptr)) {
 475
 476       int req_num = state->transition.argument;
 477
 478       XBT_DEBUG("Execute: %s",
 479         simgrid::mc::request_to_string(
 480           req, req_num, simgrid::mc::RequestType::simix).c_str());
 481
 482       std::string req_str;
 483       if (dot_output != nullptr)
 484         req_str = simgrid::mc::request_get_dot_output(req, req_num);
 485
 486       mc_model_checker->executed_transitions++;
 487
 488       /* TODO : handle test and testany simcalls */
 489       e_mc_call_type_t call = MC_CALL_TYPE_NONE;
 490       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 491         call = MC_get_call_type(req);
 492
 493       /* Answer the request */
 494       mc_model_checker->handle_simcall(state->transition);
 495       /* After this call req is no longer useful */
 496
 497       if (!this->initial_communications_pattern_done)
 498         MC_handle_comm_pattern(call, req, req_num, initial_communications_pattern, 0);
 499       else
 500         MC_handle_comm_pattern(call, req, req_num, nullptr, 0);
 501
 502       /* Wait for requests (schedules processes) */
 503       mc_model_checker->wait_for_requests();
 504
 505       /* Create the new expanded state */
 506       std::unique_ptr<simgrid::mc::State> next_state =
 507           std::unique_ptr<simgrid::mc::State>(new simgrid::mc::State(++expandedStatesCount_));
 508
 509       /* If comm determinism verification, we cannot stop the exploration if
 510          some communications are not finished (at least, data are transferred).
 511          These communications  are incomplete and they cannot be analyzed and
 512          compared with the initial pattern. */
 513       bool compare_snapshots = all_communications_are_finished()
 514         && this->initial_communications_pattern_done;
 515
 516       if (_sg_mc_visited == 0
 517           || (visited_state = visitedStates_.addVisitedState(
 518             expandedStatesCount_, next_state.get(), compare_snapshots)) == nullptr) {
 519
 520         /* Get enabled actors and insert them in the interleave set of the next state */
 521         for (auto& actor : mc_model_checker->process().actors())
 522           if (simgrid::mc::actor_is_enabled(actor.copy.getBuffer()))
 523             next_state->interleave(actor.copy.getBuffer());
 524
 525         if (dot_output != nullptr)
 526           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n",
 527             state->num,  next_state->num, req_str.c_str());
 528
 529       } else if (dot_output != nullptr)
 530         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n",
 531           state->num, visited_state->other_num == -1 ? visited_state->num : visited_state->other_num, req_str.c_str());
 532
 533       stack_.push_back(std::move(next_state));
 534
 535     } else {
 536
 537       if (stack_.size() > (std::size_t) _sg_mc_max_depth)
 538         XBT_WARN("/!\\ Max depth reached ! /!\\ ");
 539       else if (visited_state != nullptr)
 540         XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.", visited_state->other_num == -1 ? visited_state->num : visited_state->other_num);
 541       else
 542         XBT_DEBUG("There are no more processes to interleave. (depth %zi)",
 543           stack_.size());
 544
 545       if (!this->initial_communications_pattern_done)
 546         this->initial_communications_pattern_done = 1;
 547
 548       /* Trash the current state, no longer needed */
 549       XBT_DEBUG("Delete state %d at depth %zi",
 550         state->num, stack_.size());
 551       stack_.pop_back();
 552
 553       visited_state = nullptr;
 554
 555       /* Check for deadlocks */
 556       if (mc_model_checker->checkDeadlock()) {
 557         MC_show_deadlock();
 558         throw new simgrid::mc::DeadlockError();
 559       }
 560
 561       while (!stack_.empty()) {
 562         std::unique_ptr<simgrid::mc::State> state = std::move(stack_.back());
 563         stack_.pop_back();
 564         if (state->interleaveSize()
 565             && stack_.size() < (std::size_t) _sg_mc_max_depth) {
 566           /* We found a back-tracking point, let's loop */
 567           XBT_DEBUG("Back-tracking to state %d at depth %zi",
 568             state->num, stack_.size() + 1);
 569           stack_.push_back(std::move(state));
 570
 571           this->restoreState();
 572
 573           XBT_DEBUG("Back-tracking to state %d at depth %zi done",
 574             stack_.back()->num, stack_.size());
 575
 576           break;
 577         } else {
 578           XBT_DEBUG("Delete state %d at depth %zi",
 579             state->num, stack_.size() + 1);
 580         }
 581       }
 582     }
 583   }
 584
 585   simgrid::mc::session->logState();
 586 }
 587
 588 void CommunicationDeterminismChecker::run()
 589 {
 590   XBT_INFO("Check communication determinism");
 591   simgrid::mc::session->initialize();
 592
 593   this->prepare();
 594
 595   this->main();
 596 }
 597
 598 Checker* createCommunicationDeterminismChecker(Session& session)
 599 {
 600   return new CommunicationDeterminismChecker(session);
 601 }
 602
 603 }
 604 }