src/s4u/s4u_Comm.cpp

   1 /* Copyright (c) 2006-2023. 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 <cmath>
   7 #include <simgrid/Exception.hpp>
   8 #include <simgrid/comm.h>
   9 #include <simgrid/s4u/Comm.hpp>
  10 #include <simgrid/s4u/Engine.hpp>
  11 #include <simgrid/s4u/Mailbox.hpp>
  12
  13 #include "src/kernel/activity/CommImpl.hpp"
  14 #include "src/kernel/actor/ActorImpl.hpp"
  15 #include "src/kernel/actor/SimcallObserver.hpp"
  16 #include "src/mc/mc.h"
  17 #include "src/mc/mc_replay.hpp"
  18
  19 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(s4u_comm, s4u_activity, "S4U asynchronous communications");
  20
  21 namespace simgrid::s4u {
  22 xbt::signal<void(Comm const&)> Comm::on_send;
  23 xbt::signal<void(Comm const&)> Comm::on_recv;
  24
  25 CommPtr Comm::set_copy_data_callback(const std::function<void(kernel::activity::CommImpl*, void*, size_t)>& callback)
  26 {
  27   copy_data_function_ = callback;
  28   return this;
  29 }
  30
  31 void Comm::copy_buffer_callback(kernel::activity::CommImpl* comm, void* buff,
  32                                 size_t buff_size) // XBT_ATTRIB_DEPRECATED_v338
  33 {
  34   XBT_DEBUG("Copy the data over");
  35   memcpy(comm->dst_buff_, buff, buff_size);
  36   if (comm->is_detached()) { // if this is a detached send, the source buffer was duplicated by SMPI sender to make the
  37                              // original buffer available to the application ASAP
  38     xbt_free(buff);
  39     comm->src_buff_ = nullptr;
  40   }
  41 }
  42
  43 void Comm::copy_pointer_callback(kernel::activity::CommImpl* comm, void* buff,
  44                                  size_t buff_size) // XBT_ATTRIB_DEPRECATED_v338
  45 {
  46   xbt_assert((buff_size == sizeof(void*)), "Cannot copy %zu bytes: must be sizeof(void*)", buff_size);
  47   *(void**)(comm->dst_buff_) = buff;
  48 }
  49
  50 Comm::~Comm()
  51 {
  52   if (state_ == State::STARTED && not detached_ &&
  53       (pimpl_ == nullptr || pimpl_->get_state() == kernel::activity::State::RUNNING)) {
  54     XBT_INFO("Comm %p freed before its completion. Did you forget to detach it? (state: %s)", this, get_state_str());
  55     if (pimpl_ != nullptr)
  56       XBT_INFO("pimpl_->state: %s", pimpl_->get_state_str());
  57     else
  58       XBT_INFO("pimpl_ is null");
  59     xbt_backtrace_display_current();
  60   }
  61 }
  62
  63 void Comm::send(kernel::actor::ActorImpl* sender, const Mailbox* mbox, double task_size, double rate, void* src_buff,
  64                 size_t src_buff_size,
  65                 const std::function<bool(void*, void*, simgrid::kernel::activity::CommImpl*)>& match_fun,
  66                 const std::function<void(simgrid::kernel::activity::CommImpl*, void*, size_t)>& copy_data_fun,
  67                 void* data, double timeout)
  68 {
  69   /* checking for infinite values */
  70   xbt_assert(std::isfinite(task_size), "task_size is not finite!");
  71   xbt_assert(std::isfinite(rate), "rate is not finite!");
  72   xbt_assert(std::isfinite(timeout), "timeout is not finite!");
  73
  74   xbt_assert(mbox, "No rendez-vous point defined for send");
  75
  76   if (MC_is_active() || MC_record_replay_is_active()) {
  77     /* the model-checker wants two separate simcalls, and wants comm to be nullptr during the simcall */
  78     simgrid::kernel::activity::ActivityImplPtr comm = nullptr;
  79
  80     simgrid::kernel::actor::CommIsendSimcall send_observer{
  81         sender,        mbox->get_impl(), task_size, rate,          static_cast<unsigned char*>(src_buff),
  82         src_buff_size, match_fun,        nullptr,   copy_data_fun, data,
  83         false,         "Isend"};
  84     comm = simgrid::kernel::actor::simcall_answered(
  85         [&send_observer] { return simgrid::kernel::activity::CommImpl::isend(&send_observer); }, &send_observer);
  86
  87     if (simgrid::kernel::actor::ActivityWaitSimcall wait_observer{sender, comm.get(), timeout, "Wait"};
  88         simgrid::kernel::actor::simcall_blocking(
  89             [&wait_observer] {
  90               wait_observer.get_activity()->wait_for(wait_observer.get_issuer(), wait_observer.get_timeout());
  91             },
  92             &wait_observer)) {
  93       throw simgrid::TimeoutException(XBT_THROW_POINT, "Timeouted");
  94     }
  95     comm = nullptr;
  96   } else {
  97     simgrid::kernel::actor::CommIsendSimcall observer(sender, mbox->get_impl(), task_size, rate,
  98                                                       static_cast<unsigned char*>(src_buff), src_buff_size, match_fun,
  99                                                       nullptr, copy_data_fun, data, false, "Isend");
 100     simgrid::kernel::actor::simcall_blocking([&observer, timeout] {
 101       simgrid::kernel::activity::ActivityImplPtr comm = simgrid::kernel::activity::CommImpl::isend(&observer);
 102       comm->wait_for(observer.get_issuer(), timeout);
 103     });
 104   }
 105 }
 106
 107 void Comm::recv(kernel::actor::ActorImpl* receiver, const Mailbox* mbox, void* dst_buff, size_t* dst_buff_size,
 108                 const std::function<bool(void*, void*, simgrid::kernel::activity::CommImpl*)>& match_fun,
 109                 const std::function<void(simgrid::kernel::activity::CommImpl*, void*, size_t)>& copy_data_fun,
 110                 void* data, double timeout, double rate)
 111 {
 112   xbt_assert(std::isfinite(timeout), "timeout is not finite!");
 113   xbt_assert(mbox, "No rendez-vous point defined for recv");
 114
 115   if (MC_is_active() || MC_record_replay_is_active()) {
 116     /* the model-checker wants two separate simcalls, and wants comm to be nullptr during the simcall */
 117     simgrid::kernel::activity::ActivityImplPtr comm = nullptr;
 118
 119     simgrid::kernel::actor::CommIrecvSimcall observer{receiver,
 120                                                       mbox->get_impl(),
 121                                                       static_cast<unsigned char*>(dst_buff),
 122                                                       dst_buff_size,
 123                                                       match_fun,
 124                                                       copy_data_fun,
 125                                                       data,
 126                                                       rate,
 127                                                       "Irecv"};
 128     comm = simgrid::kernel::actor::simcall_answered(
 129         [&observer] { return simgrid::kernel::activity::CommImpl::irecv(&observer); }, &observer);
 130
 131     if (simgrid::kernel::actor::ActivityWaitSimcall wait_observer{receiver, comm.get(), timeout, "wait"};
 132         simgrid::kernel::actor::simcall_blocking(
 133             [&wait_observer] {
 134               wait_observer.get_activity()->wait_for(wait_observer.get_issuer(), wait_observer.get_timeout());
 135             },
 136             &wait_observer)) {
 137       throw simgrid::TimeoutException(XBT_THROW_POINT, "Timeouted");
 138     }
 139     comm = nullptr;
 140   } else {
 141     simgrid::kernel::actor::CommIrecvSimcall observer(receiver, mbox->get_impl(), static_cast<unsigned char*>(dst_buff),
 142                                                       dst_buff_size, match_fun, copy_data_fun, data, rate, "Irecv");
 143     simgrid::kernel::actor::simcall_blocking([&observer, timeout] {
 144       simgrid::kernel::activity::ActivityImplPtr comm = simgrid::kernel::activity::CommImpl::irecv(&observer);
 145       comm->wait_for(observer.get_issuer(), timeout);
 146     });
 147   }
 148 }
 149
 150 CommPtr Comm::sendto_init()
 151 {
 152   CommPtr res(new Comm());
 153   res->pimpl_ = kernel::activity::CommImplPtr(new kernel::activity::CommImpl());
 154   boost::static_pointer_cast<kernel::activity::CommImpl>(res->pimpl_)->detach();
 155   res->sender_ = kernel::actor::ActorImpl::self();
 156   return res;
 157 }
 158
 159 CommPtr Comm::sendto_init(Host* from, Host* to)
 160 {
 161   auto res = Comm::sendto_init()->set_source(from)->set_destination(to);
 162   res->set_state(State::STARTING);
 163   return res;
 164 }
 165
 166 CommPtr Comm::sendto_async(Host* from, Host* to, uint64_t simulated_size_in_bytes)
 167 {
 168   return Comm::sendto_init()->set_payload_size(simulated_size_in_bytes)->set_source(from)->set_destination(to);
 169 }
 170
 171 void Comm::sendto(Host* from, Host* to, uint64_t simulated_size_in_bytes)
 172 {
 173   sendto_async(from, to, simulated_size_in_bytes)->wait();
 174 }
 175
 176 CommPtr Comm::set_source(Host* from)
 177 {
 178   xbt_assert(state_ == State::INITED || state_ == State::STARTING,
 179              "Cannot change the source of a Comm once it's started (state: %s)", to_c_str(state_));
 180   boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->set_source(from);
 181   // Setting 'source' may allow to start the activity, let's try
 182   if (state_ == State::STARTING && remains_ <= 0)
 183     XBT_DEBUG("This communication has a payload size of 0 byte. It cannot start yet");
 184   else
 185     start();
 186
 187   return this;
 188 }
 189 Host* Comm::get_source() const
 190 {
 191   return pimpl_ ? boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->get_source() : nullptr;
 192 }
 193
 194 CommPtr Comm::set_destination(Host* to)
 195 {
 196   xbt_assert(state_ == State::INITED || state_ == State::STARTING,
 197              "Cannot change the destination of a Comm once it's started (state: %s)", to_c_str(state_));
 198   boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->set_destination(to);
 199   // Setting 'destination' may allow to start the activity, let's try
 200   if (state_ == State::STARTING && remains_ <= 0)
 201     XBT_DEBUG("This communication has a payload size of 0 byte. It cannot start yet");
 202   else
 203     start();
 204
 205   return this;
 206 }
 207
 208 Host* Comm::get_destination() const
 209 {
 210   return pimpl_ ? boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->get_destination() : nullptr;
 211 }
 212
 213 CommPtr Comm::set_rate(double rate)
 214 {
 215   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 216              __FUNCTION__);
 217   rate_ = rate;
 218   return this;
 219 }
 220
 221 CommPtr Comm::set_mailbox(Mailbox* mailbox)
 222 {
 223   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 224              __FUNCTION__);
 225   mailbox_ = mailbox;
 226   return this;
 227 }
 228
 229 CommPtr Comm::set_src_data(void* buff)
 230 {
 231   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 232              __FUNCTION__);
 233   xbt_assert(dst_buff_ == nullptr, "Cannot set the src and dst buffers at the same time");
 234   src_buff_ = buff;
 235   return this;
 236 }
 237
 238 CommPtr Comm::set_src_data_size(size_t size)
 239 {
 240   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 241              __FUNCTION__);
 242   src_buff_size_ = size;
 243   return this;
 244 }
 245
 246 CommPtr Comm::set_src_data(void* buff, size_t size)
 247 {
 248   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 249              __FUNCTION__);
 250
 251   xbt_assert(dst_buff_ == nullptr, "Cannot set the src and dst buffers at the same time");
 252   src_buff_      = buff;
 253   src_buff_size_ = size;
 254   return this;
 255 }
 256
 257 CommPtr Comm::set_dst_data(void** buff)
 258 {
 259   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 260              __FUNCTION__);
 261   xbt_assert(src_buff_ == nullptr, "Cannot set the src and dst buffers at the same time");
 262   dst_buff_ = buff;
 263   return this;
 264 }
 265
 266 CommPtr Comm::set_dst_data(void** buff, size_t size)
 267 {
 268   xbt_assert(state_ == State::INITED, "You cannot use %s() once your communication started (not implemented)",
 269              __FUNCTION__);
 270
 271   xbt_assert(src_buff_ == nullptr, "Cannot set the src and dst buffers at the same time");
 272   dst_buff_      = buff;
 273   dst_buff_size_ = size;
 274   return this;
 275 }
 276
 277 CommPtr Comm::set_payload_size(uint64_t bytes)
 278 {
 279   set_remaining(bytes);
 280   if (pimpl_) {
 281     boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->set_size(bytes);
 282   }
 283   return this;
 284 }
 285
 286 Actor* Comm::get_sender() const
 287 {
 288   kernel::actor::ActorImplPtr sender = nullptr;
 289   if (pimpl_)
 290     sender = boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->src_actor_;
 291   return sender ? sender->get_ciface() : nullptr;
 292 }
 293
 294 Actor* Comm::get_receiver() const
 295 {
 296   kernel::actor::ActorImplPtr receiver = nullptr;
 297   if (pimpl_)
 298     receiver = boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->dst_actor_;
 299   return receiver ? receiver->get_ciface() : nullptr;
 300 }
 301
 302 bool Comm::is_assigned() const
 303 {
 304   return (pimpl_ && boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->is_assigned()) ||
 305          mailbox_ != nullptr;
 306 }
 307
 308 Comm* Comm::do_start()
 309 {
 310   xbt_assert(get_state() == State::INITED || get_state() == State::STARTING,
 311              "You cannot use %s() once your communication started (not implemented)", __FUNCTION__);
 312   if (get_source() != nullptr || get_destination() != nullptr) {
 313     xbt_assert(is_assigned(), "When either from_ or to_ is specified, both must be.");
 314     xbt_assert(src_buff_ == nullptr && dst_buff_ == nullptr,
 315                "Direct host-to-host communications cannot carry any data.");
 316     XBT_DEBUG("host-to-host Comm. Pimpl already created and set, just start it.");
 317     on_start(*this);
 318     on_this_start(*this);
 319     kernel::actor::simcall_answered([this] {
 320       pimpl_->set_state(kernel::activity::State::READY);
 321       boost::static_pointer_cast<kernel::activity::CommImpl>(pimpl_)->start();
 322     });
 323   } else if (src_buff_ != nullptr) { // Sender side
 324     on_send(*this);
 325     on_this_send(*this);
 326     kernel::actor::CommIsendSimcall observer{sender_,
 327                                              mailbox_->get_impl(),
 328                                              remains_,
 329                                              rate_,
 330                                              static_cast<unsigned char*>(src_buff_),
 331                                              src_buff_size_,
 332                                              match_fun_,
 333                                              clean_fun_,
 334                                              copy_data_function_,
 335                                              get_data<void>(),
 336                                              detached_,
 337                                              "Isend"};
 338     pimpl_ = kernel::actor::simcall_answered([&observer] { return kernel::activity::CommImpl::isend(&observer); },
 339                                              &observer);
 340   } else if (dst_buff_ != nullptr) { // Receiver side
 341     xbt_assert(not detached_, "Receive cannot be detached");
 342     on_recv(*this);
 343     on_this_recv(*this);
 344     kernel::actor::CommIrecvSimcall observer{receiver_,
 345                                              mailbox_->get_impl(),
 346                                              static_cast<unsigned char*>(dst_buff_),
 347                                              &dst_buff_size_,
 348                                              match_fun_,
 349                                              copy_data_function_,
 350                                              get_data<void>(),
 351                                              rate_,
 352                                              "Irecv"};
 353     pimpl_ = kernel::actor::simcall_answered([&observer] { return kernel::activity::CommImpl::irecv(&observer); },
 354                                              &observer);
 355   } else {
 356     xbt_die("Cannot start a communication before specifying whether we are the sender or the receiver");
 357   }
 358
 359   if (suspended_)
 360     pimpl_->suspend();
 361
 362   if (not detached_) {
 363     pimpl_->set_iface(this);
 364     pimpl_->set_actor(sender_);
 365     // Only throw the signal when both sides are here and the status is READY
 366     if (pimpl_->get_state() != kernel::activity::State::WAITING) {
 367       on_start(*this);
 368       on_this_start(*this);
 369     }
 370   }
 371
 372   state_ = State::STARTED;
 373   return this;
 374 }
 375
 376 Comm* Comm::detach()
 377 {
 378   xbt_assert(state_ == State::INITED || state_ == State::STARTING,
 379              "You cannot use %s() once your communication is %s (not implemented)", __FUNCTION__, get_state_str());
 380   xbt_assert(dst_buff_ == nullptr && dst_buff_size_ == 0, "You can only detach sends, not recvs");
 381   detached_ = true;
 382   start();
 383   return this;
 384 }
 385
 386 ssize_t Comm::test_any(const std::vector<CommPtr>& comms)
 387 {
 388   std::vector<ActivityPtr> activities;
 389   for (const auto& comm : comms)
 390     activities.push_back(boost::dynamic_pointer_cast<Activity>(comm));
 391   return Activity::test_any(activities);
 392 }
 393
 394 /** @brief Block the calling actor until the communication is finished, or until timeout
 395  *
 396  * On timeout, an exception is thrown and the communication is invalidated.
 397  *
 398  * @param timeout the amount of seconds to wait for the comm termination.
 399  *                Negative values denote infinite wait times. 0 as a timeout returns immediately. */
 400 Comm* Comm::wait_for(double timeout)
 401 {
 402   XBT_DEBUG("Calling Comm::wait_for with state %s", get_state_str());
 403   kernel::actor::ActorImpl* issuer = nullptr;
 404   switch (state_) {
 405     case State::FINISHED:
 406       break;
 407     case State::FAILED:
 408       throw NetworkFailureException(XBT_THROW_POINT, "Cannot wait for a failed communication");
 409     case State::INITED:
 410     case State::STARTING: // It's not started yet. Do it in one simcall if it's a regular communication
 411       if (get_source() != nullptr || get_destination() != nullptr) {
 412         return start()->wait_for(timeout); // In the case of host2host comm, do it in two simcalls
 413       } else if (src_buff_ != nullptr) {
 414         on_send(*this);
 415         on_this_send(*this);
 416         send(sender_, mailbox_, remains_, rate_, src_buff_, src_buff_size_, match_fun_, copy_data_function_,
 417              get_data<void>(), timeout);
 418
 419       } else { // Receiver
 420         on_recv(*this);
 421         on_this_recv(*this);
 422         recv(receiver_, mailbox_, dst_buff_, &dst_buff_size_, match_fun_, copy_data_function_, get_data<void>(),
 423              timeout, rate_);
 424       }
 425       break;
 426     case State::STARTED:
 427       try {
 428         issuer = kernel::actor::ActorImpl::self();
 429         kernel::actor::ActivityWaitSimcall observer{issuer, pimpl_.get(), timeout, "Wait"};
 430         if (kernel::actor::simcall_blocking(
 431                 [&observer] { observer.get_activity()->wait_for(observer.get_issuer(), observer.get_timeout()); },
 432                 &observer)) {
 433           throw TimeoutException(XBT_THROW_POINT, "Timeouted");
 434         }
 435       } catch (const NetworkFailureException& e) {
 436         issuer->simcall_.observer_ = nullptr; // Comm failed on network failure, reset the observer to nullptr
 437         complete(State::FAILED);
 438         e.rethrow_nested(XBT_THROW_POINT, boost::core::demangle(typeid(e).name()) + " raised in kernel mode.");
 439       }
 440       break;
 441
 442     case State::CANCELED:
 443       throw CancelException(XBT_THROW_POINT, "Communication canceled");
 444
 445     default:
 446       THROW_IMPOSSIBLE;
 447   }
 448   complete(State::FINISHED);
 449   return this;
 450 }
 451
 452 ssize_t Comm::wait_any_for(const std::vector<CommPtr>& comms, double timeout)
 453 {
 454   std::vector<ActivityPtr> activities;
 455   for (const auto& comm : comms)
 456     activities.push_back(boost::dynamic_pointer_cast<Activity>(comm));
 457   ssize_t changed_pos;
 458   try {
 459     changed_pos = Activity::wait_any_for(activities, timeout);
 460   } catch (const NetworkFailureException& e) {
 461     changed_pos = -1;
 462     for (auto c : comms) {
 463       if (c->pimpl_->get_state() == kernel::activity::State::FAILED) {
 464         c->complete(State::FAILED);
 465       }
 466     }
 467     e.rethrow_nested(XBT_THROW_POINT, boost::core::demangle(typeid(e).name()) + " raised in kernel mode.");
 468   }
 469   return changed_pos;
 470 }
 471
 472 void Comm::wait_all(const std::vector<CommPtr>& comms)
 473 {
 474   // TODO: this should be a simcall or something
 475   for (const auto& comm : comms)
 476     comm->wait();
 477 }
 478
 479 size_t Comm::wait_all_for(const std::vector<CommPtr>& comms, double timeout)
 480 {
 481   if (timeout < 0.0) {
 482     wait_all(comms);
 483     return comms.size();
 484   }
 485
 486   double deadline = Engine::get_clock() + timeout;
 487   std::vector<CommPtr> waited_comm(1, nullptr);
 488   for (size_t i = 0; i < comms.size(); i++) {
 489     double wait_timeout = std::max(0.0, deadline - Engine::get_clock());
 490     waited_comm[0]      = comms[i];
 491     // Using wait_any_for() here (and not wait_for) because we don't want comms to be invalidated on timeout
 492     if (wait_any_for(waited_comm, wait_timeout) == -1) {
 493       XBT_DEBUG("Timeout (%g): i = %zu", wait_timeout, i);
 494       return i;
 495     }
 496   }
 497   return comms.size();
 498 }
 499 } // namespace simgrid::s4u
 500 /* **************************** Public C interface *************************** */
 501 void sg_comm_detach(sg_comm_t comm, void (*clean_function)(void*))
 502 {
 503   comm->detach(clean_function);
 504   comm->unref();
 505 }
 506 void sg_comm_unref(sg_comm_t comm)
 507 {
 508   comm->unref();
 509 }
 510 int sg_comm_test(sg_comm_t comm)
 511 {
 512   bool finished = comm->test();
 513   if (finished)
 514     comm->unref();
 515   return finished;
 516 }
 517
 518 sg_error_t sg_comm_wait(sg_comm_t comm)
 519 {
 520   return sg_comm_wait_for(comm, -1);
 521 }
 522
 523 sg_error_t sg_comm_wait_for(sg_comm_t comm, double timeout)
 524 {
 525   sg_error_t status = SG_OK;
 526
 527   simgrid::s4u::CommPtr s4u_comm(comm, false);
 528   try {
 529     s4u_comm->wait_for(timeout);
 530   } catch (const simgrid::TimeoutException&) {
 531     status = SG_ERROR_TIMEOUT;
 532   } catch (const simgrid::CancelException&) {
 533     status = SG_ERROR_CANCELED;
 534   } catch (const simgrid::NetworkFailureException&) {
 535     status = SG_ERROR_NETWORK;
 536   }
 537   return status;
 538 }
 539
 540 void sg_comm_wait_all(sg_comm_t* comms, size_t count)
 541 {
 542   sg_comm_wait_all_for(comms, count, -1);
 543 }
 544
 545 size_t sg_comm_wait_all_for(sg_comm_t* comms, size_t count, double timeout)
 546 {
 547   std::vector<simgrid::s4u::CommPtr> s4u_comms;
 548   for (size_t i = 0; i < count; i++)
 549     s4u_comms.emplace_back(comms[i], false);
 550
 551   size_t pos = simgrid::s4u::Comm::wait_all_for(s4u_comms, timeout);
 552   for (size_t i = pos; i < count; i++)
 553     s4u_comms[i]->add_ref();
 554   return pos;
 555 }
 556
 557 ssize_t sg_comm_wait_any(sg_comm_t* comms, size_t count)
 558 {
 559   return sg_comm_wait_any_for(comms, count, -1);
 560 }
 561
 562 ssize_t sg_comm_wait_any_for(sg_comm_t* comms, size_t count, double timeout)
 563 {
 564   std::vector<simgrid::s4u::CommPtr> s4u_comms;
 565   for (size_t i = 0; i < count; i++)
 566     s4u_comms.emplace_back(comms[i], false);
 567
 568   ssize_t pos = simgrid::s4u::Comm::wait_any_for(s4u_comms, timeout);
 569   for (size_t i = 0; i < count; i++) {
 570     if (pos != -1 && static_cast<size_t>(pos) != i)
 571       s4u_comms[i]->add_ref();
 572   }
 573   return pos;
 574 }