src/mc/api.cpp

   1 /* Copyright (c) 2020-2022. 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 "api.hpp"
   7
   8 #include "src/kernel/activity/MailboxImpl.hpp"
   9 #include "src/kernel/activity/MutexImpl.hpp"
  10 #include "src/kernel/actor/SimcallObserver.hpp"
  11 #include "src/mc/Session.hpp"
  12 #include "src/mc/checker/Checker.hpp"
  13 #include "src/mc/mc_base.hpp"
  14 #include "src/mc/mc_comm_pattern.hpp"
  15 #include "src/mc/mc_exit.hpp"
  16 #include "src/mc/mc_pattern.hpp"
  17 #include "src/mc/mc_private.hpp"
  18 #include "src/mc/remote/RemoteProcess.hpp"
  19 #include "src/surf/HostImpl.hpp"
  20
  21 #include <xbt/asserts.h>
  22 #include <xbt/log.h>
  23 #include "simgrid/s4u/Host.hpp"
  24 #include "xbt/string.hpp"
  25 #if HAVE_SMPI
  26 #include "src/smpi/include/smpi_request.hpp"
  27 #endif
  28
  29 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(Api, mc, "Logging specific to MC Facade APIs ");
  30 XBT_LOG_EXTERNAL_CATEGORY(mc_global);
  31
  32 using Simcall = simgrid::simix::Simcall;
  33
  34 namespace simgrid {
  35 namespace mc {
  36
  37 static inline const char* get_color(int id)
  38 {
  39   static constexpr std::array<const char*, 13> colors{{"blue", "red", "green3", "goldenrod", "brown", "purple",
  40                                                        "magenta", "turquoise4", "gray25", "forestgreen", "hotpink",
  41                                                        "lightblue", "tan"}};
  42   return colors[id % colors.size()];
  43 }
  44
  45 static std::string pointer_to_string(void* pointer)
  46 {
  47   return XBT_LOG_ISENABLED(Api, xbt_log_priority_verbose) ? xbt::string_printf("%p", pointer) : "(verbose only)";
  48 }
  49
  50 static std::string buff_size_to_string(size_t buff_size)
  51 {
  52   return XBT_LOG_ISENABLED(Api, xbt_log_priority_verbose) ? std::to_string(buff_size) : "(verbose only)";
  53 }
  54
  55 /* Search an enabled transition for the given process.
  56  *
  57  * This can be seen as an iterator returning the next transition of the process.
  58  *
  59  * We only consider the processes that are both
  60  *  - marked "to be interleaved" in their ActorState (controlled by the checker algorithm).
  61  *  - which simcall can currently be executed (like a comm where the other partner is already known)
  62  * Once we returned the last enabled transition of a process, it is marked done.
  63  *
  64  * Things can get muddled with the WAITANY and TESTANY simcalls, that are rewritten on the fly to a bunch of WAIT
  65  * (resp TEST) transitions using the transition.argument field to remember what was the last returned sub-transition.
  66  */
  67 static inline smx_simcall_t MC_state_choose_request_for_process(const RemoteProcess& process, simgrid::mc::State* state,
  68                                                                 smx_actor_t actor)
  69 {
  70   /* reset the outgoing transition */
  71   simgrid::mc::ActorState* procstate = &state->actor_states_[actor->get_pid()];
  72   state->transition_.aid_              = -1;
  73   state->transition_.times_considered_ = -1;
  74   state->transition_.textual[0]        = '\0';
  75   state->executed_req_.call_         = Simcall::NONE;
  76
  77   if (not simgrid::mc::actor_is_enabled(actor))
  78     return nullptr; // Not executable in the application
  79
  80   smx_simcall_t req = nullptr;
  81   if (actor->simcall_.observer_ != nullptr) {
  82     state->transition_.times_considered_ = procstate->get_times_considered_and_inc();
  83     if (actor->simcall_.mc_max_consider_ <= procstate->get_times_considered())
  84       procstate->set_done();
  85     req = &actor->simcall_;
  86   } else {
  87     procstate->set_done();
  88     state->transition_.times_considered_ = 0;
  89     req                                  = &actor->simcall_;
  90   }
  91   if (not req)
  92     return nullptr;
  93
  94   state->transition_.aid_ = actor->get_pid();
  95   state->executed_req_    = *req;
  96
  97   return req;
  98 }
  99
 100 /** Statically "upcast" a s_smx_actor_t into an ActorInformation
 101  *
 102  *  This gets 'actorInfo' from '&actorInfo->copy'. It upcasts in the
 103  *  sense that we could achieve the same thing by having ActorInformation
 104  *  inherit from s_smx_actor_t but we don't really want to do that.
 105  */
 106 simgrid::mc::ActorInformation* Api::actor_info_cast(smx_actor_t actor) const
 107 {
 108   simgrid::mc::ActorInformation temp;
 109   std::size_t offset = (char*)temp.copy.get_buffer() - (char*)&temp;
 110
 111   auto* process_info = reinterpret_cast<simgrid::mc::ActorInformation*>((char*)actor - offset);
 112   return process_info;
 113 }
 114
 115 bool Api::requests_are_dependent(RemotePtr<kernel::actor::SimcallObserver> obs1,
 116                                  RemotePtr<kernel::actor::SimcallObserver> obs2) const
 117 {
 118   xbt_assert(mc_model_checker != nullptr, "Must be called from MCer");
 119
 120   return mc_model_checker->requests_are_dependent(obs1, obs2);
 121 }
 122
 123 xbt::string const& Api::get_actor_host_name(smx_actor_t actor) const
 124 {
 125   if (mc_model_checker == nullptr)
 126     return actor->get_host()->get_name();
 127
 128   const simgrid::mc::RemoteProcess* process = &mc_model_checker->get_remote_process();
 129
 130   // Read the simgrid::xbt::string in the MCed process:
 131   simgrid::mc::ActorInformation* info = actor_info_cast(actor);
 132
 133   if (not info->hostname) {
 134     Remote<s4u::Host> temp_host = process->read(remote(actor->get_host()));
 135     auto remote_string_address  = remote(&xbt::string::to_string_data(temp_host.get_buffer()->get_impl()->get_name()));
 136     simgrid::xbt::string_data remote_string = process->read(remote_string_address);
 137     std::vector<char> hostname(remote_string.len + 1);
 138     // no need to read the terminating null byte, and thus hostname[remote_string.len] is guaranteed to be '\0'
 139     process->read_bytes(hostname.data(), remote_string.len, remote(remote_string.data));
 140     info->hostname = &mc_model_checker->get_host_name(hostname.data());
 141   }
 142   return *info->hostname;
 143 }
 144
 145 xbt::string const& Api::get_actor_name(smx_actor_t actor) const
 146 {
 147   if (mc_model_checker == nullptr)
 148     return actor->get_name();
 149
 150   simgrid::mc::ActorInformation* info = actor_info_cast(actor);
 151   if (info->name.empty()) {
 152     const simgrid::mc::RemoteProcess* process = &mc_model_checker->get_remote_process();
 153
 154     simgrid::xbt::string_data string_data = simgrid::xbt::string::to_string_data(actor->name_);
 155     info->name = process->read_string(remote(string_data.data), string_data.len);
 156   }
 157   return info->name;
 158 }
 159
 160 std::string Api::get_actor_string(smx_actor_t actor) const
 161 {
 162   std::string res;
 163   if (actor) {
 164     res = "(" + std::to_string(actor->get_pid()) + ")";
 165     if (actor->get_host())
 166       res += std::string(get_actor_host_name(actor)) + " (" + std::string(get_actor_name(actor)) + ")";
 167     else
 168       res += get_actor_name(actor);
 169   } else
 170     res = "(0) ()";
 171   return res;
 172 }
 173
 174 std::string Api::get_actor_dot_label(smx_actor_t actor) const
 175 {
 176   std::string res = "(" + std::to_string(actor->get_pid()) + ")";
 177   if (actor->get_host())
 178     res += get_actor_host_name(actor);
 179   return res;
 180 }
 181
 182 simgrid::mc::Checker* Api::initialize(char** argv, simgrid::mc::CheckerAlgorithm algo) const
 183 {
 184   auto session = new simgrid::mc::Session([argv] {
 185     int i = 1;
 186     while (argv[i] != nullptr && argv[i][0] == '-')
 187       i++;
 188     xbt_assert(argv[i] != nullptr,
 189                "Unable to find a binary to exec on the command line. Did you only pass config flags?");
 190     execvp(argv[i], argv + i);
 191     xbt_die("The model-checked process failed to exec(%s): %s", argv[i], strerror(errno));
 192   });
 193
 194   simgrid::mc::Checker* checker;
 195   switch (algo) {
 196     case CheckerAlgorithm::CommDeterminism:
 197       checker = simgrid::mc::create_communication_determinism_checker(session);
 198       break;
 199
 200     case CheckerAlgorithm::UDPOR:
 201       checker = simgrid::mc::create_udpor_checker(session);
 202       break;
 203
 204     case CheckerAlgorithm::Safety:
 205       checker = simgrid::mc::create_safety_checker(session);
 206       break;
 207
 208     case CheckerAlgorithm::Liveness:
 209       checker = simgrid::mc::create_liveness_checker(session);
 210       break;
 211
 212     default:
 213       THROW_IMPOSSIBLE;
 214   }
 215
 216   // FIXME: session and checker are never deleted
 217   simgrid::mc::session_singleton = session;
 218   mc_model_checker->setChecker(checker);
 219   return checker;
 220 }
 221
 222 std::vector<simgrid::mc::ActorInformation>& Api::get_actors() const
 223 {
 224   return mc_model_checker->get_remote_process().actors();
 225 }
 226
 227 unsigned long Api::get_maxpid() const
 228 {
 229   return mc_model_checker->get_remote_process().get_maxpid();
 230 }
 231
 232 int Api::get_actors_size() const
 233 {
 234   return mc_model_checker->get_remote_process().actors().size();
 235 }
 236
 237 RemotePtr<kernel::activity::CommImpl> Api::get_comm_isend_raw_addr(smx_simcall_t request) const
 238 {
 239   return remote(static_cast<kernel::activity::CommImpl*>(simcall_comm_isend__getraw__result(request)));
 240 }
 241
 242 RemotePtr<kernel::activity::CommImpl> Api::get_comm_waitany_raw_addr(smx_simcall_t request, int value) const
 243 {
 244   auto addr      = simcall_comm_waitany__getraw__comms(request) + value;
 245   auto comm_addr = mc_model_checker->get_remote_process().read(remote(addr));
 246   return RemotePtr<kernel::activity::CommImpl>(static_cast<kernel::activity::CommImpl*>(comm_addr));
 247 }
 248
 249 std::string Api::get_pattern_comm_rdv(RemotePtr<kernel::activity::CommImpl> const& addr) const
 250 {
 251   Remote<kernel::activity::CommImpl> temp_activity;
 252   mc_model_checker->get_remote_process().read(temp_activity, addr);
 253   const kernel::activity::CommImpl* activity = temp_activity.get_buffer();
 254
 255   char* remote_name = mc_model_checker->get_remote_process().read<char*>(RemotePtr<char*>(
 256       (uint64_t)(activity->get_mailbox() ? &activity->get_mailbox()->get_name() : &activity->mbox_cpy->get_name())));
 257   auto rdv          = mc_model_checker->get_remote_process().read_string(RemotePtr<char>(remote_name));
 258   return rdv;
 259 }
 260
 261 unsigned long Api::get_pattern_comm_src_proc(RemotePtr<kernel::activity::CommImpl> const& addr) const
 262 {
 263   Remote<kernel::activity::CommImpl> temp_activity;
 264   mc_model_checker->get_remote_process().read(temp_activity, addr);
 265   const kernel::activity::CommImpl* activity = temp_activity.get_buffer();
 266   auto src_proc =
 267       mc_model_checker->get_remote_process().resolve_actor(mc::remote(activity->src_actor_.get()))->get_pid();
 268   return src_proc;
 269 }
 270
 271 unsigned long Api::get_pattern_comm_dst_proc(RemotePtr<kernel::activity::CommImpl> const& addr) const
 272 {
 273   Remote<kernel::activity::CommImpl> temp_activity;
 274   mc_model_checker->get_remote_process().read(temp_activity, addr);
 275   const kernel::activity::CommImpl* activity = temp_activity.get_buffer();
 276   auto src_proc =
 277       mc_model_checker->get_remote_process().resolve_actor(mc::remote(activity->dst_actor_.get()))->get_pid();
 278   return src_proc;
 279 }
 280
 281 std::vector<char> Api::get_pattern_comm_data(RemotePtr<kernel::activity::CommImpl> const& addr) const
 282 {
 283   simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 284   mc_model_checker->get_remote_process().read(temp_comm, addr);
 285   const simgrid::kernel::activity::CommImpl* comm = temp_comm.get_buffer();
 286
 287   std::vector<char> buffer{};
 288   if (comm->src_buff_ != nullptr) {
 289     buffer.resize(comm->src_buff_size_);
 290     mc_model_checker->get_remote_process().read_bytes(buffer.data(), buffer.size(), remote(comm->src_buff_));
 291   }
 292   return buffer;
 293 }
 294
 295 #if HAVE_SMPI
 296 bool Api::check_send_request_detached(smx_simcall_t const& simcall) const
 297 {
 298   Remote<simgrid::smpi::Request> mpi_request;
 299   mc_model_checker->get_remote_process().read(
 300       mpi_request, remote(static_cast<smpi::Request*>(simcall_comm_isend__get__data(simcall))));
 301   return mpi_request.get_buffer()->detached();
 302 }
 303 #endif
 304
 305 smx_actor_t Api::get_src_actor(RemotePtr<kernel::activity::CommImpl> const& comm_addr) const
 306 {
 307   simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 308   mc_model_checker->get_remote_process().read(temp_comm, comm_addr);
 309   const simgrid::kernel::activity::CommImpl* comm = temp_comm.get_buffer();
 310
 311   auto src_proc = mc_model_checker->get_remote_process().resolve_actor(simgrid::mc::remote(comm->src_actor_.get()));
 312   return src_proc;
 313 }
 314
 315 smx_actor_t Api::get_dst_actor(RemotePtr<kernel::activity::CommImpl> const& comm_addr) const
 316 {
 317   simgrid::mc::Remote<simgrid::kernel::activity::CommImpl> temp_comm;
 318   mc_model_checker->get_remote_process().read(temp_comm, comm_addr);
 319   const simgrid::kernel::activity::CommImpl* comm = temp_comm.get_buffer();
 320
 321   auto dst_proc = mc_model_checker->get_remote_process().resolve_actor(simgrid::mc::remote(comm->dst_actor_.get()));
 322   return dst_proc;
 323 }
 324
 325 std::size_t Api::get_remote_heap_bytes() const
 326 {
 327   RemoteProcess& process    = mc_model_checker->get_remote_process();
 328   auto heap_bytes_used      = mmalloc_get_bytes_used_remote(process.get_heap()->heaplimit, process.get_malloc_info());
 329   return heap_bytes_used;
 330 }
 331
 332 void Api::mc_inc_visited_states() const
 333 {
 334   mc_model_checker->visited_states++;
 335 }
 336
 337 void Api::mc_inc_executed_trans() const
 338 {
 339   mc_model_checker->executed_transitions++;
 340 }
 341
 342 unsigned long Api::mc_get_visited_states() const
 343 {
 344   return mc_model_checker->visited_states;
 345 }
 346
 347 unsigned long Api::mc_get_executed_trans() const
 348 {
 349   return mc_model_checker->executed_transitions;
 350 }
 351
 352 void Api::mc_check_deadlock() const
 353 {
 354   if (mc_model_checker->checkDeadlock()) {
 355     XBT_CINFO(mc_global, "**************************");
 356     XBT_CINFO(mc_global, "*** DEADLOCK DETECTED ***");
 357     XBT_CINFO(mc_global, "**************************");
 358     XBT_CINFO(mc_global, "Counter-example execution trace:");
 359     for (auto const& s : mc_model_checker->getChecker()->get_textual_trace())
 360       XBT_CINFO(mc_global, "  %s", s.c_str());
 361     simgrid::mc::dumpRecordPath();
 362     simgrid::mc::session_singleton->log_state();
 363     throw DeadlockError();
 364   }
 365 }
 366
 367 /** Get the issuer of a simcall (`req->issuer`)
 368  *
 369  *  In split-process mode, it does the black magic necessary to get an address
 370  *  of a (shallow) copy of the data structure the issuer SIMIX actor in the local
 371  *  address space.
 372  *
 373  *  @param process the MCed process
 374  *  @param req     the simcall (copied in the local process)
 375  */
 376 smx_actor_t Api::simcall_get_issuer(s_smx_simcall const* req) const
 377 {
 378   xbt_assert(mc_model_checker != nullptr);
 379
 380   // This is the address of the smx_actor in the MCed process:
 381   auto address = simgrid::mc::remote(req->issuer_);
 382
 383   // Lookup by address:
 384   for (auto& actor : mc_model_checker->get_remote_process().actors())
 385     if (actor.address == address)
 386       return actor.copy.get_buffer();
 387   for (auto& actor : mc_model_checker->get_remote_process().dead_actors())
 388     if (actor.address == address)
 389       return actor.copy.get_buffer();
 390
 391   xbt_die("Issuer not found");
 392 }
 393
 394 RemotePtr<kernel::activity::MailboxImpl> Api::get_mbox_remote_addr(smx_simcall_t const req) const
 395 {
 396   if (req->call_ == Simcall::COMM_ISEND)
 397     return remote(simcall_comm_isend__get__mbox(req));
 398   if (req->call_ == Simcall::COMM_IRECV)
 399     return remote(simcall_comm_irecv__get__mbox(req));
 400   THROW_IMPOSSIBLE;
 401 }
 402
 403 RemotePtr<kernel::activity::ActivityImpl> Api::get_comm_remote_addr(smx_simcall_t const req) const
 404 {
 405   if (req->call_ == Simcall::COMM_ISEND)
 406     return remote(simcall_comm_isend__getraw__result(req));
 407   if (req->call_ == Simcall::COMM_IRECV)
 408     return remote(simcall_comm_irecv__getraw__result(req));
 409   THROW_IMPOSSIBLE;
 410 }
 411
 412 void Api::handle_simcall(Transition const& transition) const
 413 {
 414   mc_model_checker->handle_simcall(transition);
 415 }
 416
 417 void Api::mc_wait_for_requests() const
 418 {
 419   mc_model_checker->wait_for_requests();
 420 }
 421
 422 void Api::mc_exit(int status) const
 423 {
 424   mc_model_checker->exit(status);
 425 }
 426
 427 void Api::dump_record_path() const
 428 {
 429   simgrid::mc::dumpRecordPath();
 430 }
 431
 432 smx_simcall_t Api::mc_state_choose_request(simgrid::mc::State* state) const
 433 {
 434   RemoteProcess& process = mc_model_checker->get_remote_process();
 435   XBT_DEBUG("Search for an actor to run. %zu actors to consider", process.actors().size());
 436   for (auto& actor : process.actors()) {
 437     /* Only consider the actors that were marked as interleaving by the checker algorithm */
 438     if (not state->actor_states_[actor.copy.get_buffer()->get_pid()].is_todo())
 439       continue;
 440
 441     smx_simcall_t res = MC_state_choose_request_for_process(process, state, actor.copy.get_buffer());
 442     if (res) {
 443       XBT_DEBUG("Let's run actor %ld, going for transition %s", actor.copy.get_buffer()->get_pid(),
 444                 SIMIX_simcall_name(*res));
 445       return res;
 446     }
 447   }
 448   return nullptr;
 449 }
 450
 451 std::string Api::request_to_string(smx_simcall_t req, int value) const
 452 {
 453   xbt_assert(mc_model_checker != nullptr, "Must be called from MCer");
 454
 455   smx_actor_t issuer = simcall_get_issuer(req);
 456
 457   if (issuer->simcall_.observer_ != nullptr)
 458     return mc_model_checker->simcall_to_string(issuer->get_pid(), value);
 459   else
 460     return "[" + get_actor_string(issuer) + "] " + SIMIX_simcall_name(*req) + "(unknown?)";
 461 }
 462
 463 std::string Api::request_get_dot_output(smx_simcall_t req, int value) const
 464 {
 465   if (req->observer_ != nullptr) {
 466     const smx_actor_t issuer = simcall_get_issuer(req);
 467     const char* color        = get_color(issuer->get_pid() - 1);
 468     return "label = \"" + mc_model_checker->simcall_dot_label(issuer->get_pid(), value) + "\", color = " + color +
 469            ", fontcolor = " + color;
 470   } else
 471     return "UNIMPLEMENTED";
 472 }
 473
 474 #if HAVE_SMPI
 475 int Api::get_smpi_request_tag(smx_simcall_t const& simcall, simgrid::simix::Simcall type) const
 476 {
 477   void* simcall_data = nullptr;
 478   if (type == Simcall::COMM_ISEND)
 479     simcall_data = simcall_comm_isend__get__data(simcall);
 480   else if (type == Simcall::COMM_IRECV)
 481     simcall_data = simcall_comm_irecv__get__data(simcall);
 482   Remote<simgrid::smpi::Request> mpi_request;
 483   mc_model_checker->get_remote_process().read(mpi_request, remote(static_cast<smpi::Request*>(simcall_data)));
 484   return mpi_request.get_buffer()->tag();
 485 }
 486 #endif
 487
 488 void Api::restore_state(std::shared_ptr<simgrid::mc::Snapshot> system_state) const
 489 {
 490   system_state->restore(&mc_model_checker->get_remote_process());
 491 }
 492
 493 void Api::log_state() const
 494 {
 495   session_singleton->log_state();
 496 }
 497
 498 bool Api::snapshot_equal(const Snapshot* s1, const Snapshot* s2) const
 499 {
 500   return simgrid::mc::snapshot_equal(s1, s2);
 501 }
 502
 503 simgrid::mc::Snapshot* Api::take_snapshot(int num_state) const
 504 {
 505   auto snapshot = new simgrid::mc::Snapshot(num_state);
 506   return snapshot;
 507 }
 508
 509 void Api::s_close() const
 510 {
 511   session_singleton->close();
 512 }
 513
 514 RemotePtr<simgrid::kernel::actor::SimcallObserver> Api::execute(Transition& transition, smx_simcall_t simcall) const
 515 {
 516   /* FIXME: once all simcalls have observers, kill the simcall parameter and use mc_model_checker->simcall_to_string() */
 517   transition.textual = request_to_string(simcall, transition.times_considered_);
 518   return session_singleton->execute(transition);
 519 }
 520
 521 void Api::automaton_load(const char* file) const
 522 {
 523   MC_automaton_load(file);
 524 }
 525
 526 std::vector<int> Api::automaton_propositional_symbol_evaluate() const
 527 {
 528   unsigned int cursor = 0;
 529   std::vector<int> values;
 530   xbt_automaton_propositional_symbol_t ps = nullptr;
 531   xbt_dynar_foreach (mc::property_automaton->propositional_symbols, cursor, ps)
 532     values.push_back(xbt_automaton_propositional_symbol_evaluate(ps));
 533   return values;
 534 }
 535
 536 std::vector<xbt_automaton_state_t> Api::get_automaton_state() const
 537 {
 538   std::vector<xbt_automaton_state_t> automaton_stack;
 539   unsigned int cursor = 0;
 540   xbt_automaton_state_t automaton_state;
 541   xbt_dynar_foreach (mc::property_automaton->states, cursor, automaton_state)
 542     if (automaton_state->type == -1)
 543       automaton_stack.push_back(automaton_state);
 544   return automaton_stack;
 545 }
 546
 547 int Api::compare_automaton_exp_label(const xbt_automaton_exp_label* l) const
 548 {
 549   unsigned int cursor                    = 0;
 550   xbt_automaton_propositional_symbol_t p = nullptr;
 551   xbt_dynar_foreach (simgrid::mc::property_automaton->propositional_symbols, cursor, p) {
 552     if (std::strcmp(xbt_automaton_propositional_symbol_get_name(p), l->u.predicat) == 0)
 553       return cursor;
 554   }
 555   return -1;
 556 }
 557
 558 void Api::set_property_automaton(xbt_automaton_state_t const& automaton_state) const
 559 {
 560   mc::property_automaton->current_state = automaton_state;
 561 }
 562
 563 xbt_automaton_exp_label_t Api::get_automaton_transition_label(xbt_dynar_t const& dynar, int index) const
 564 {
 565   const xbt_automaton_transition* transition = xbt_dynar_get_as(dynar, index, xbt_automaton_transition_t);
 566   return transition->label;
 567 }
 568
 569 xbt_automaton_state_t Api::get_automaton_transition_dst(xbt_dynar_t const& dynar, int index) const
 570 {
 571   const xbt_automaton_transition* transition = xbt_dynar_get_as(dynar, index, xbt_automaton_transition_t);
 572   return transition->dst;
 573 }
 574
 575 } // namespace mc
 576 } // namespace simgrid