src/mc/checker/CommunicationDeterminismChecker.cpp

   1 /* Copyright (c) 2008-2020. 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/Session.hpp"
   9 #include "src/mc/mc_config.hpp"
  10 #include "src/mc/mc_exit.hpp"
  11 #include "src/mc/mc_private.hpp"
  12 #include "src/mc/mc_request.hpp"
  13 #include "src/mc/mc_smx.hpp"
  14
  15 #if HAVE_SMPI
  16 #include "smpi_request.hpp"
  17 #endif
  18
  19 #include <cstdint>
  20
  21 using simgrid::mc::remote;
  22
  23 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_comm_determinism, mc, "Logging specific to MC communication determinism detection");
  24
  25 /********** Global variables **********/
  26
  27 std::vector<simgrid::mc::PatternCommunicationList> initial_communications_pattern;
  28 std::vector<std::vector<simgrid::mc::PatternCommunication*>> incomplete_communications_pattern;
  29
  30 /********** Static functions ***********/
  31
  32 static simgrid::mc::CommPatternDifference compare_comm_pattern(const simgrid::mc::PatternCommunication* comm1,
  33                                                                const simgrid::mc::PatternCommunication* comm2)
  34 {
  35   using simgrid::mc::CommPatternDifference;
  36   if(comm1->type != comm2->type)
  37     return CommPatternDifference::TYPE;
  38   if (comm1->rdv != comm2->rdv)
  39     return CommPatternDifference::RDV;
  40   if (comm1->src_proc != comm2->src_proc)
  41     return CommPatternDifference::SRC_PROC;
  42   if (comm1->dst_proc != comm2->dst_proc)
  43     return CommPatternDifference::DST_PROC;
  44   if (comm1->tag != comm2->tag)
  45     return CommPatternDifference::TAG;
  46   if (comm1->data.size() != comm2->data.size())
  47     return CommPatternDifference::DATA_SIZE;
  48   if (comm1->data != comm2->data)
  49     return CommPatternDifference::DATA;
  50   return CommPatternDifference::NONE;
  51 }
  52
  53 static char* print_determinism_result(simgrid::mc::CommPatternDifference diff, int process,
  54                                       const simgrid::mc::PatternCommunication* comm, unsigned int cursor)
  55 {
  56   char* type;
  57   char* res;
  58
  59   if (comm->type == simgrid::mc::PatternCommunicationType::send)
  60     type = bprintf("The send communications pattern of the process %d is different!", process - 1);
  61   else
  62     type = bprintf("The recv communications pattern of the process %d is different!", process - 1);
  63
  64   using simgrid::mc::CommPatternDifference;
  65   switch(diff) {
  66     case CommPatternDifference::TYPE:
  67       res = bprintf("%s Different type for communication #%u", type, cursor);
  68       break;
  69     case CommPatternDifference::RDV:
  70       res = bprintf("%s Different rdv for communication #%u", type, cursor);
  71       break;
  72     case CommPatternDifference::TAG:
  73       res = bprintf("%s Different tag for communication #%u", type, cursor);
  74       break;
  75     case CommPatternDifference::SRC_PROC:
  76       res = bprintf("%s Different source for communication #%u", type, cursor);
  77       break;
  78     case CommPatternDifference::DST_PROC:
  79       res = bprintf("%s Different destination for communication #%u", type, cursor);
  80       break;
  81     case CommPatternDifference::DATA_SIZE:
  82       res = bprintf("%s Different data size for communication #%u", type, cursor);
  83       break;
  84     case CommPatternDifference::DATA:
  85       res = bprintf("%s 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->get_remote_simulation().read(temp_comm, comm_addr);
 101   const simgrid::kernel::activity::CommImpl* comm = temp_comm.get_buffer();
 102
 103   smx_actor_t src_proc =
 104       mc_model_checker->get_remote_simulation().resolve_actor(simgrid::mc::remote(comm->src_actor_.get()));
 105   smx_actor_t dst_proc =
 106       mc_model_checker->get_remote_simulation().resolve_actor(simgrid::mc::remote(comm->dst_actor_.get()));
 107   comm_pattern->src_proc = src_proc->get_pid();
 108   comm_pattern->dst_proc = dst_proc->get_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.empty() && comm->src_buff_ != nullptr) {
 112     size_t buff_size;
 113     mc_model_checker->get_remote_simulation().read(&buff_size, remote(comm->dst_buff_size_));
 114     comm_pattern->data.resize(buff_size);
 115     mc_model_checker->get_remote_simulation().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, const PatternCommunication* comm,
 124                                                                  int backtracking)
 125 {
 126   if (not backtracking) {
 127     PatternCommunicationList& list      = initial_communications_pattern[process];
 128     CommPatternDifference diff          = compare_comm_pattern(list.list[list.index_comm].get(), comm);
 129
 130     if (diff != CommPatternDifference::NONE) {
 131       if (comm->type == PatternCommunicationType::send) {
 132         this->send_deterministic = false;
 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 = false;
 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         mc::session->log_state();
 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         if (this->send_diff) {
 156           XBT_INFO("%s", this->send_diff);
 157           xbt_free(this->send_diff);
 158           this->send_diff = nullptr;
 159         }
 160         if (this->recv_diff) {
 161           XBT_INFO("%s", this->recv_diff);
 162           xbt_free(this->recv_diff);
 163           this->recv_diff = nullptr;
 164         }
 165         mc::session->log_state();
 166         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 167       }
 168     }
 169   }
 170 }
 171
 172 /********** Non Static functions ***********/
 173
 174 void CommunicationDeterminismChecker::get_comm_pattern(smx_simcall_t request, CallType call_type, int backtracking)
 175 {
 176   const smx_actor_t issuer = MC_smx_simcall_get_issuer(request);
 177   const mc::PatternCommunicationList& initial_pattern          = initial_communications_pattern[issuer->get_pid()];
 178   const std::vector<PatternCommunication*>& incomplete_pattern = incomplete_communications_pattern[issuer->get_pid()];
 179
 180   auto pattern   = std::make_unique<PatternCommunication>();
 181   pattern->index = initial_pattern.index_comm + incomplete_pattern.size();
 182
 183   if (call_type == CallType::SEND) {
 184     /* Create comm pattern */
 185     pattern->type      = PatternCommunicationType::send;
 186     pattern->comm_addr = static_cast<kernel::activity::CommImpl*>(simcall_comm_isend__getraw__result(request));
 187
 188     Remote<kernel::activity::CommImpl> temp_synchro;
 189     mc_model_checker->get_remote_simulation().read(temp_synchro, remote(pattern->comm_addr));
 190     const kernel::activity::CommImpl* synchro = temp_synchro.get_buffer();
 191
 192     char* remote_name = mc_model_checker->get_remote_simulation().read<char*>(RemotePtr<char*>(
 193         (uint64_t)(synchro->get_mailbox() ? &synchro->get_mailbox()->name_ : &synchro->mbox_cpy->name_)));
 194     pattern->rdv      = mc_model_checker->get_remote_simulation().read_string(RemotePtr<char>(remote_name));
 195     pattern->src_proc =
 196         mc_model_checker->get_remote_simulation().resolve_actor(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;
 201     mc_model_checker->get_remote_simulation().read(
 202         &mpi_request, remote(static_cast<smpi::Request*>(simcall_comm_isend__get__data(request))));
 203     pattern->tag = mpi_request.tag();
 204 #endif
 205
 206     if (synchro->src_buff_ != nullptr) {
 207       pattern->data.resize(synchro->src_buff_size_);
 208       mc_model_checker->get_remote_simulation().read_bytes(pattern->data.data(), pattern->data.size(),
 209                                                            remote(synchro->src_buff_));
 210     }
 211 #if HAVE_SMPI
 212     if(mpi_request.detached()){
 213       if (this->initial_communications_pattern_done) {
 214         /* Evaluate comm determinism */
 215         this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
 216         initial_communications_pattern[pattern->src_proc].index_comm++;
 217       } else {
 218         /* Store comm pattern */
 219         initial_communications_pattern[pattern->src_proc].list.push_back(std::move(pattern));
 220       }
 221       return;
 222     }
 223 #endif
 224   } else if (call_type == CallType::RECV) {
 225     pattern->type      = PatternCommunicationType::receive;
 226     pattern->comm_addr = static_cast<kernel::activity::CommImpl*>(simcall_comm_irecv__getraw__result(request));
 227
 228 #if HAVE_SMPI
 229     smpi::Request mpi_request;
 230     mc_model_checker->get_remote_simulation().read(
 231         &mpi_request, remote(static_cast<smpi::Request*>(simcall_comm_irecv__get__data(request))));
 232     pattern->tag = mpi_request.tag();
 233 #endif
 234
 235     Remote<kernel::activity::CommImpl> temp_comm;
 236     mc_model_checker->get_remote_simulation().read(temp_comm, remote(pattern->comm_addr));
 237     const kernel::activity::CommImpl* comm = temp_comm.get_buffer();
 238
 239     char* remote_name;
 240     mc_model_checker->get_remote_simulation().read(
 241         &remote_name, remote(comm->get_mailbox() ? &xbt::string::to_string_data(comm->get_mailbox()->name_).data
 242                                                  : &xbt::string::to_string_data(comm->mbox_cpy->name_).data));
 243     pattern->rdv = mc_model_checker->get_remote_simulation().read_string(RemotePtr<char>(remote_name));
 244     pattern->dst_proc =
 245         mc_model_checker->get_remote_simulation().resolve_actor(mc::remote(comm->dst_actor_.get()))->get_pid();
 246     pattern->dst_host = MC_smx_actor_get_host_name(issuer);
 247   } else
 248     xbt_die("Unexpected call_type %i", (int) call_type);
 249
 250   XBT_DEBUG("Insert incomplete comm pattern %p for process %ld", pattern.get(), issuer->get_pid());
 251   incomplete_communications_pattern[issuer->get_pid()].push_back(pattern.release());
 252 }
 253
 254 void CommunicationDeterminismChecker::complete_comm_pattern(RemotePtr<kernel::activity::CommImpl> comm_addr,
 255                                                             unsigned int issuer, int backtracking)
 256 {
 257   /* Complete comm pattern */
 258   std::vector<PatternCommunication*>& incomplete_pattern = incomplete_communications_pattern[issuer];
 259   auto current_comm_pattern =
 260       std::find_if(begin(incomplete_pattern), end(incomplete_pattern),
 261                    [&comm_addr](const PatternCommunication* comm) { return remote(comm->comm_addr) == comm_addr; });
 262   if (current_comm_pattern == std::end(incomplete_pattern))
 263     xbt_die("Corresponding communication not found!");
 264
 265   update_comm_pattern(*current_comm_pattern, comm_addr);
 266   std::unique_ptr<PatternCommunication> comm_pattern(*current_comm_pattern);
 267   XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %zd", issuer,
 268             std::distance(begin(incomplete_pattern), current_comm_pattern));
 269   incomplete_pattern.erase(current_comm_pattern);
 270
 271   if (this->initial_communications_pattern_done) {
 272     /* Evaluate comm determinism */
 273     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 274     initial_communications_pattern[issuer].index_comm++;
 275   } else {
 276     /* Store comm pattern */
 277     initial_communications_pattern[issuer].list.push_back(std::move(comm_pattern));
 278   }
 279 }
 280
 281 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& s) : Checker(s)
 282 {
 283 }
 284
 285 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 286
 287 RecordTrace CommunicationDeterminismChecker::get_record_trace() // override
 288 {
 289   RecordTrace res;
 290   for (auto const& state : stack_)
 291     res.push_back(state->get_transition());
 292   return res;
 293 }
 294
 295 std::vector<std::string> CommunicationDeterminismChecker::get_textual_trace() // override
 296 {
 297   std::vector<std::string> trace;
 298   for (auto const& state : stack_) {
 299     smx_simcall_t req = &state->executed_req_;
 300     trace.push_back(request_to_string(req, state->transition_.argument_, RequestType::executed));
 301   }
 302   return trace;
 303 }
 304
 305 void CommunicationDeterminismChecker::log_state() // override
 306 {
 307   if (_sg_mc_comms_determinism) {
 308     if (this->send_deterministic && not this->recv_deterministic) {
 309       XBT_INFO("*******************************************************");
 310       XBT_INFO("**** Only-send-deterministic communication pattern ****");
 311       XBT_INFO("*******************************************************");
 312       XBT_INFO("%s", this->recv_diff);
 313     }
 314     if (not this->send_deterministic && this->recv_deterministic) {
 315       XBT_INFO("*******************************************************");
 316       XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 317       XBT_INFO("*******************************************************");
 318       XBT_INFO("%s", this->send_diff);
 319     }
 320   }
 321   XBT_INFO("Expanded states = %lu", expanded_states_count_);
 322   XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
 323   XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
 324   XBT_INFO("Send-deterministic : %s", this->send_deterministic ? "Yes" : "No");
 325   if (_sg_mc_comms_determinism)
 326     XBT_INFO("Recv-deterministic : %s", this->recv_deterministic ? "Yes" : "No");
 327 }
 328
 329 void CommunicationDeterminismChecker::prepare()
 330 {
 331   const int maxpid = MC_smx_get_maxpid();
 332
 333   initial_communications_pattern.resize(maxpid);
 334   incomplete_communications_pattern.resize(maxpid);
 335
 336   ++expanded_states_count_;
 337   auto initial_state = std::make_unique<State>(expanded_states_count_);
 338
 339   XBT_DEBUG("********* Start communication determinism verification *********");
 340
 341   /* Get an enabled actor and insert it in the interleave set of the initial state */
 342   for (auto& actor : mc_model_checker->get_remote_simulation().actors())
 343     if (mc::actor_is_enabled(actor.copy.get_buffer()))
 344       initial_state->add_interleaving_set(actor.copy.get_buffer());
 345
 346   stack_.push_back(std::move(initial_state));
 347 }
 348
 349 static inline bool all_communications_are_finished()
 350 {
 351   for (size_t current_actor = 1; current_actor < MC_smx_get_maxpid(); current_actor++) {
 352     if (not incomplete_communications_pattern[current_actor].empty()) {
 353       XBT_DEBUG("Some communications are not finished, cannot stop the exploration! State not visited.");
 354       return false;
 355     }
 356   }
 357   return true;
 358 }
 359
 360 void CommunicationDeterminismChecker::restoreState()
 361 {
 362   /* Intermediate backtracking */
 363   State* last_state = stack_.back().get();
 364   if (last_state->system_state_) {
 365     last_state->system_state_->restore(&mc_model_checker->get_remote_simulation());
 366     MC_restore_communications_pattern(last_state);
 367     return;
 368   }
 369
 370   /* Restore the initial state */
 371   mc::session->restore_initial_state();
 372
 373   unsigned n = MC_smx_get_maxpid();
 374   assert(n == incomplete_communications_pattern.size());
 375   assert(n == initial_communications_pattern.size());
 376   for (unsigned j=0; j < n ; j++) {
 377     incomplete_communications_pattern[j].clear();
 378     initial_communications_pattern[j].index_comm = 0;
 379   }
 380
 381   /* Traverse the stack from the state at position start and re-execute the transitions */
 382   for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
 383     if (state == stack_.back())
 384       break;
 385
 386     int req_num             = state->transition_.argument_;
 387     const s_smx_simcall* saved_req = &state->executed_req_;
 388     xbt_assert(saved_req);
 389
 390     /* because we got a copy of the executed request, we have to fetch the
 391        real one, pointed by the request field of the issuer process */
 392
 393     const smx_actor_t issuer = MC_smx_simcall_get_issuer(saved_req);
 394     smx_simcall_t req        = &issuer->simcall_;
 395
 396     /* TODO : handle test and testany simcalls */
 397     CallType call = MC_get_call_type(req);
 398     mc_model_checker->handle_simcall(state->transition_);
 399     MC_handle_comm_pattern(call, req, req_num, 1);
 400     mc_model_checker->wait_for_requests();
 401
 402     /* Update statistics */
 403     mc_model_checker->visited_states++;
 404     mc_model_checker->executed_transitions++;
 405   }
 406 }
 407
 408 void CommunicationDeterminismChecker::real_run()
 409 {
 410   std::unique_ptr<VisitedState> visited_state = nullptr;
 411   smx_simcall_t req = nullptr;
 412
 413   while (not stack_.empty()) {
 414     /* Get current state */
 415     State* cur_state = stack_.back().get();
 416
 417     XBT_DEBUG("**************************************************");
 418     XBT_DEBUG("Exploration depth = %zu (state = %d, interleaved processes = %zu)", stack_.size(), cur_state->num_,
 419               cur_state->interleave_size());
 420
 421     /* Update statistics */
 422     mc_model_checker->visited_states++;
 423
 424     if (stack_.size() <= (std::size_t)_sg_mc_max_depth)
 425       req = MC_state_choose_request(cur_state);
 426     else
 427       req = nullptr;
 428
 429     if (req != nullptr && visited_state == nullptr) {
 430       int req_num = cur_state->transition_.argument_;
 431
 432       XBT_DEBUG("Execute: %s", request_to_string(req, req_num, RequestType::simix).c_str());
 433
 434       std::string req_str;
 435       if (dot_output != nullptr)
 436         req_str = request_get_dot_output(req, req_num);
 437
 438       mc_model_checker->executed_transitions++;
 439
 440       /* TODO : handle test and testany simcalls */
 441       CallType call = CallType::NONE;
 442       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 443         call = MC_get_call_type(req);
 444
 445       /* Answer the request */
 446       mc_model_checker->handle_simcall(cur_state->transition_);
 447       /* After this call req is no longer useful */
 448
 449       MC_handle_comm_pattern(call, req, req_num, 0);
 450
 451       /* Wait for requests (schedules processes) */
 452       mc_model_checker->wait_for_requests();
 453
 454       /* Create the new expanded state */
 455       ++expanded_states_count_;
 456       auto next_state = std::make_unique<State>(expanded_states_count_);
 457
 458       /* If comm determinism verification, we cannot stop the exploration if some communications are not finished (at
 459        * least, data are transferred). These communications  are incomplete and they cannot be analyzed and compared
 460        * with the initial pattern. */
 461       bool compare_snapshots = this->initial_communications_pattern_done && all_communications_are_finished();
 462
 463       if (_sg_mc_max_visited_states != 0)
 464         visited_state = visited_states_.addVisitedState(expanded_states_count_, next_state.get(), compare_snapshots);
 465       else
 466         visited_state = nullptr;
 467
 468       if (visited_state == nullptr) {
 469         /* Get enabled actors and insert them in the interleave set of the next state */
 470         for (auto& actor : mc_model_checker->get_remote_simulation().actors())
 471           if (simgrid::mc::actor_is_enabled(actor.copy.get_buffer()))
 472             next_state->add_interleaving_set(actor.copy.get_buffer());
 473
 474         if (dot_output != nullptr)
 475           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", cur_state->num_, next_state->num_, req_str.c_str());
 476
 477       } else if (dot_output != nullptr)
 478         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", cur_state->num_,
 479                 visited_state->original_num == -1 ? visited_state->num : visited_state->original_num, req_str.c_str());
 480
 481       stack_.push_back(std::move(next_state));
 482     } else {
 483       if (stack_.size() > (std::size_t) _sg_mc_max_depth)
 484         XBT_WARN("/!\\ Max depth reached! /!\\ ");
 485       else if (visited_state != nullptr)
 486         XBT_DEBUG("State already visited (equal to state %d), exploration stopped on this path.",
 487             visited_state->original_num == -1 ? visited_state->num : visited_state->original_num);
 488       else
 489         XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size());
 490
 491       this->initial_communications_pattern_done = true;
 492
 493       /* Trash the current state, no longer needed */
 494       XBT_DEBUG("Delete state %d at depth %zu", cur_state->num_, stack_.size());
 495       stack_.pop_back();
 496
 497       visited_state = nullptr;
 498
 499       /* Check for deadlocks */
 500       if (mc_model_checker->checkDeadlock()) {
 501         MC_show_deadlock();
 502         throw simgrid::mc::DeadlockError();
 503       }
 504
 505       while (not stack_.empty()) {
 506         std::unique_ptr<State> state(std::move(stack_.back()));
 507         stack_.pop_back();
 508         if (state->interleave_size() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
 509           /* We found a back-tracking point, let's loop */
 510           XBT_DEBUG("Back-tracking to state %d at depth %zu", state->num_, stack_.size() + 1);
 511           stack_.push_back(std::move(state));
 512
 513           this->restoreState();
 514
 515           XBT_DEBUG("Back-tracking to state %d at depth %zu done", stack_.back()->num_, stack_.size());
 516
 517           break;
 518         } else {
 519           XBT_DEBUG("Delete state %d at depth %zu", state->num_, stack_.size() + 1);
 520         }
 521       }
 522     }
 523   }
 524
 525   mc::session->log_state();
 526 }
 527
 528 void CommunicationDeterminismChecker::run()
 529 {
 530   XBT_INFO("Check communication determinism");
 531   mc::session->initialize();
 532
 533   this->prepare();
 534   this->real_run();
 535 }
 536
 537 Checker* createCommunicationDeterminismChecker(Session& s)
 538 {
 539   return new CommunicationDeterminismChecker(s);
 540 }
 541
 542 } // namespace mc
 543 } // namespace simgrid