src/simix/smx_network.cpp

   1 /* Copyright (c) 2009-2019. 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 "mc/mc.h"
   7 #include "simgrid/Exception.hpp"
   8 #include "src/kernel/activity/MailboxImpl.hpp"
   9 #include "src/mc/mc_replay.hpp"
  10 #include "src/simix/smx_private.hpp"
  11 #include "src/surf/cpu_interface.hpp"
  12 #include "src/surf/network_interface.hpp"
  13
  14 #include <boost/range/algorithm.hpp>
  15
  16 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_network, simix, "SIMIX network-related synchronization");
  17
  18 static void SIMIX_waitany_remove_simcall_from_actions(smx_simcall_t simcall);
  19
  20 /******************************************************************************/
  21 /*                          Communication synchros                            */
  22 /******************************************************************************/
  23 XBT_PRIVATE void simcall_HANDLER_comm_send(smx_simcall_t simcall, smx_actor_t src, smx_mailbox_t mbox, double task_size,
  24                                            double rate, void* src_buff, size_t src_buff_size,
  25                                            int (*match_fun)(void*, void*, simgrid::kernel::activity::CommImpl*),
  26                                            void (*copy_data_fun)(smx_activity_t, void*, size_t), void* data,
  27                                            double timeout)
  28 {
  29   smx_activity_t comm = simcall_HANDLER_comm_isend(simcall, src, mbox, task_size, rate,
  30                            src_buff, src_buff_size, match_fun, nullptr, copy_data_fun,
  31                data, 0);
  32   SIMCALL_SET_MC_VALUE(simcall, 0);
  33   simcall_HANDLER_comm_wait(simcall, comm, timeout);
  34 }
  35
  36 XBT_PRIVATE smx_activity_t simcall_HANDLER_comm_isend(
  37     smx_simcall_t /*simcall*/, smx_actor_t src_proc, smx_mailbox_t mbox, double task_size, double rate, void* src_buff,
  38     size_t src_buff_size, int (*match_fun)(void*, void*, simgrid::kernel::activity::CommImpl*),
  39     void (*clean_fun)(void*), // used to free the synchro in case of problem after a detached send
  40     void (*copy_data_fun)(smx_activity_t, void*, size_t), // used to copy data if not default one
  41     void* data, int detached)
  42 {
  43   XBT_DEBUG("send from mailbox %p", mbox);
  44
  45   /* Prepare a synchro describing us, so that it gets passed to the user-provided filter of other side */
  46   simgrid::kernel::activity::CommImplPtr this_comm = simgrid::kernel::activity::CommImplPtr(
  47       new simgrid::kernel::activity::CommImpl(simgrid::kernel::activity::CommImpl::Type::SEND));
  48
  49   /* Look for communication synchro matching our needs. We also provide a description of
  50    * ourself so that the other side also gets a chance of choosing if it wants to match with us.
  51    *
  52    * If it is not found then push our communication into the rendez-vous point */
  53   simgrid::kernel::activity::CommImplPtr other_comm =
  54       mbox->find_matching_comm(simgrid::kernel::activity::CommImpl::Type::RECEIVE, match_fun, data, this_comm,
  55                                /*done*/ false, /*remove_matching*/ true);
  56
  57   if (not other_comm) {
  58     other_comm = std::move(this_comm);
  59
  60     if (mbox->permanent_receiver_ != nullptr) {
  61       //this mailbox is for small messages, which have to be sent right now
  62       other_comm->state_  = SIMIX_READY;
  63       other_comm->dst_actor_ = mbox->permanent_receiver_.get();
  64       mbox->done_comm_queue_.push_back(other_comm);
  65       XBT_DEBUG("pushing a message into the permanent receive list %p, comm %p", mbox, other_comm.get());
  66
  67     }else{
  68       mbox->push(other_comm);
  69     }
  70   } else {
  71     XBT_DEBUG("Receive already pushed");
  72
  73     other_comm->state_ = SIMIX_READY;
  74     other_comm->type   = simgrid::kernel::activity::CommImpl::Type::READY;
  75   }
  76   src_proc->comms.push_back(other_comm);
  77
  78   if (detached) {
  79     other_comm->detached = true;
  80     other_comm->clean_fun = clean_fun;
  81   } else {
  82     other_comm->clean_fun = nullptr;
  83   }
  84
  85   /* Setup the communication synchro */
  86   other_comm->src_actor_     = src_proc;
  87   other_comm->task_size_     = task_size;
  88   other_comm->rate_          = rate;
  89   other_comm->src_buff_      = src_buff;
  90   other_comm->src_buff_size_ = src_buff_size;
  91   other_comm->src_data_      = data;
  92
  93   other_comm->match_fun = match_fun;
  94   other_comm->copy_data_fun = copy_data_fun;
  95
  96
  97   if (MC_is_active() || MC_record_replay_is_active()) {
  98     other_comm->state_ = SIMIX_RUNNING;
  99     return (detached ? nullptr : other_comm);
 100   }
 101
 102   other_comm->start();
 103
 104   return (detached ? nullptr : other_comm);
 105 }
 106
 107 XBT_PRIVATE void simcall_HANDLER_comm_recv(smx_simcall_t simcall, smx_actor_t receiver, smx_mailbox_t mbox,
 108                                            void* dst_buff, size_t* dst_buff_size,
 109                                            int (*match_fun)(void*, void*, simgrid::kernel::activity::CommImpl*),
 110                                            void (*copy_data_fun)(smx_activity_t, void*, size_t), void* data,
 111                                            double timeout, double rate)
 112 {
 113   smx_activity_t comm = simcall_HANDLER_comm_irecv(simcall, receiver, mbox, dst_buff, dst_buff_size, match_fun,
 114                                                    copy_data_fun, data, rate);
 115   SIMCALL_SET_MC_VALUE(simcall, 0);
 116   simcall_HANDLER_comm_wait(simcall, comm, timeout);
 117 }
 118
 119 XBT_PRIVATE smx_activity_t simcall_HANDLER_comm_irecv(smx_simcall_t /*simcall*/, smx_actor_t receiver,
 120                                                       smx_mailbox_t mbox, void* dst_buff, size_t* dst_buff_size,
 121                                                       simix_match_func_t match_fun,
 122                                                       void (*copy_data_fun)(smx_activity_t, void*, size_t), void* data,
 123                                                       double rate)
 124 {
 125   simgrid::kernel::activity::CommImplPtr this_synchro = simgrid::kernel::activity::CommImplPtr(
 126       new simgrid::kernel::activity::CommImpl(simgrid::kernel::activity::CommImpl::Type::RECEIVE));
 127   XBT_DEBUG("recv from mbox %p. this_synchro=%p", mbox, this_synchro.get());
 128
 129   simgrid::kernel::activity::CommImplPtr other_comm;
 130   //communication already done, get it inside the list of completed comms
 131   if (mbox->permanent_receiver_ != nullptr && not mbox->done_comm_queue_.empty()) {
 132
 133     XBT_DEBUG("We have a comm that has probably already been received, trying to match it, to skip the communication");
 134     //find a match in the list of already received comms
 135     other_comm = mbox->find_matching_comm(simgrid::kernel::activity::CommImpl::Type::SEND, match_fun, data,
 136                                           this_synchro, /*done*/ true,
 137                                           /*remove_matching*/ true);
 138     //if not found, assume the receiver came first, register it to the mailbox in the classical way
 139     if (not other_comm) {
 140       XBT_DEBUG("We have messages in the permanent receive list, but not the one we are looking for, pushing request into list");
 141       other_comm = std::move(this_synchro);
 142       mbox->push(other_comm);
 143     } else {
 144       if (other_comm->surf_action_ && other_comm->remains() < 1e-12) {
 145         XBT_DEBUG("comm %p has been already sent, and is finished, destroy it", other_comm.get());
 146         other_comm->state_ = SIMIX_DONE;
 147         other_comm->type   = simgrid::kernel::activity::CommImpl::Type::DONE;
 148         other_comm->mbox = nullptr;
 149       }
 150     }
 151   } else {
 152     /* Prepare a comm describing us, so that it gets passed to the user-provided filter of other side */
 153
 154     /* Look for communication activity matching our needs. We also provide a description of
 155      * ourself so that the other side also gets a chance of choosing if it wants to match with us.
 156      *
 157      * If it is not found then push our communication into the rendez-vous point */
 158     other_comm = mbox->find_matching_comm(simgrid::kernel::activity::CommImpl::Type::SEND, match_fun, data,
 159                                           this_synchro, /*done*/ false,
 160                                           /*remove_matching*/ true);
 161
 162     if (other_comm == nullptr) {
 163       XBT_DEBUG("Receive pushed first (%zu comm enqueued so far)", mbox->comm_queue_.size());
 164       other_comm = std::move(this_synchro);
 165       mbox->push(other_comm);
 166     } else {
 167       XBT_DEBUG("Match my %p with the existing %p", this_synchro.get(), other_comm.get());
 168
 169       other_comm->state_ = SIMIX_READY;
 170       other_comm->type   = simgrid::kernel::activity::CommImpl::Type::READY;
 171     }
 172     receiver->comms.push_back(other_comm);
 173   }
 174
 175   /* Setup communication synchro */
 176   other_comm->dst_actor_     = receiver;
 177   other_comm->dst_buff_      = dst_buff;
 178   other_comm->dst_buff_size_ = dst_buff_size;
 179   other_comm->dst_data_      = data;
 180
 181   if (rate > -1.0 && (other_comm->rate_ < 0.0 || rate < other_comm->rate_))
 182     other_comm->rate_ = rate;
 183
 184   other_comm->match_fun = match_fun;
 185   other_comm->copy_data_fun = copy_data_fun;
 186
 187   if (MC_is_active() || MC_record_replay_is_active()) {
 188     other_comm->state_ = SIMIX_RUNNING;
 189     return other_comm;
 190   }
 191   other_comm->start();
 192   return other_comm;
 193 }
 194
 195 void simcall_HANDLER_comm_wait(smx_simcall_t simcall, smx_activity_t synchro, double timeout)
 196 {
 197   /* Associate this simcall to the wait synchro */
 198   XBT_DEBUG("simcall_HANDLER_comm_wait, %p", synchro.get());
 199
 200   synchro->simcalls_.push_back(simcall);
 201   simcall->issuer->waiting_synchro = synchro;
 202
 203   if (MC_is_active() || MC_record_replay_is_active()) {
 204     int idx = SIMCALL_GET_MC_VALUE(simcall);
 205     if (idx == 0) {
 206       synchro->state_ = SIMIX_DONE;
 207     } else {
 208       /* If we reached this point, the wait simcall must have a timeout */
 209       /* Otherwise it shouldn't be enabled and executed by the MC */
 210       if (timeout < 0.0)
 211         THROW_IMPOSSIBLE;
 212
 213       simgrid::kernel::activity::CommImplPtr comm =
 214           boost::static_pointer_cast<simgrid::kernel::activity::CommImpl>(synchro);
 215       if (comm->src_actor_ == simcall->issuer)
 216         comm->state_ = SIMIX_SRC_TIMEOUT;
 217       else
 218         comm->state_ = SIMIX_DST_TIMEOUT;
 219     }
 220
 221     SIMIX_comm_finish(synchro);
 222     return;
 223   }
 224
 225   /* If the synchro has already finish perform the error handling, */
 226   /* otherwise set up a waiting timeout on the right side          */
 227   if (synchro->state_ != SIMIX_WAITING && synchro->state_ != SIMIX_RUNNING) {
 228     SIMIX_comm_finish(synchro);
 229   } else { /* we need a sleep action (even when there is no timeout) to be notified of host failures */
 230     simgrid::kernel::resource::Action* sleep = simcall->issuer->get_host()->pimpl_cpu->sleep(timeout);
 231     sleep->set_data(synchro.get());
 232
 233     simgrid::kernel::activity::CommImplPtr comm =
 234         boost::static_pointer_cast<simgrid::kernel::activity::CommImpl>(synchro);
 235     if (simcall->issuer == comm->src_actor_)
 236       comm->src_timeout_ = sleep;
 237     else
 238       comm->dst_timeout_ = sleep;
 239   }
 240 }
 241
 242 void simcall_HANDLER_comm_test(smx_simcall_t simcall, smx_activity_t synchro)
 243 {
 244   simgrid::kernel::activity::CommImplPtr comm =
 245       boost::static_pointer_cast<simgrid::kernel::activity::CommImpl>(synchro);
 246
 247   int res;
 248
 249   if (MC_is_active() || MC_record_replay_is_active()){
 250     res = comm->src_actor_ && comm->dst_actor_;
 251     if (res)
 252       synchro->state_ = SIMIX_DONE;
 253   } else {
 254     res = synchro->state_ != SIMIX_WAITING && synchro->state_ != SIMIX_RUNNING;
 255   }
 256
 257   simcall_comm_test__set__result(simcall, res);
 258   if (simcall_comm_test__get__result(simcall)) {
 259     synchro->simcalls_.push_back(simcall);
 260     SIMIX_comm_finish(synchro);
 261   } else {
 262     SIMIX_simcall_answer(simcall);
 263   }
 264 }
 265
 266 void simcall_HANDLER_comm_testany(smx_simcall_t simcall, simgrid::kernel::activity::ActivityImplPtr comms[],
 267                                   size_t count)
 268 {
 269   // The default result is -1 -- this means, "nothing is ready".
 270   // It can be changed below, but only if something matches.
 271   simcall_comm_testany__set__result(simcall, -1);
 272
 273   if (MC_is_active() || MC_record_replay_is_active()){
 274     int idx = SIMCALL_GET_MC_VALUE(simcall);
 275     if(idx == -1){
 276       SIMIX_simcall_answer(simcall);
 277     }else{
 278       simgrid::kernel::activity::ActivityImplPtr synchro = comms[idx];
 279       simcall_comm_testany__set__result(simcall, idx);
 280       synchro->simcalls_.push_back(simcall);
 281       synchro->state_ = SIMIX_DONE;
 282       SIMIX_comm_finish(synchro);
 283     }
 284     return;
 285   }
 286
 287   for (std::size_t i = 0; i != count; ++i) {
 288     simgrid::kernel::activity::ActivityImplPtr synchro = comms[i];
 289     if (synchro->state_ != SIMIX_WAITING && synchro->state_ != SIMIX_RUNNING) {
 290       simcall_comm_testany__set__result(simcall, i);
 291       synchro->simcalls_.push_back(simcall);
 292       SIMIX_comm_finish(synchro);
 293       return;
 294     }
 295   }
 296   SIMIX_simcall_answer(simcall);
 297 }
 298
 299 void simcall_HANDLER_comm_waitany(smx_simcall_t simcall, xbt_dynar_t synchros, double timeout)
 300 {
 301   if (MC_is_active() || MC_record_replay_is_active()){
 302     if (timeout > 0.0)
 303       xbt_die("Timeout not implemented for waitany in the model-checker");
 304     int idx = SIMCALL_GET_MC_VALUE(simcall);
 305     smx_activity_t synchro = xbt_dynar_get_as(synchros, idx, smx_activity_t);
 306     synchro->simcalls_.push_back(simcall);
 307     simcall_comm_waitany__set__result(simcall, idx);
 308     synchro->state_ = SIMIX_DONE;
 309     SIMIX_comm_finish(synchro);
 310     return;
 311   }
 312
 313   if (timeout < 0.0){
 314     simcall->timer = NULL;
 315   } else {
 316     simcall->timer = SIMIX_timer_set(SIMIX_get_clock() + timeout, [simcall]() {
 317       SIMIX_waitany_remove_simcall_from_actions(simcall);
 318       simcall_comm_waitany__set__result(simcall, -1);
 319       SIMIX_simcall_answer(simcall);
 320     });
 321   }
 322
 323   unsigned int cursor;
 324   simgrid::kernel::activity::ActivityImpl* ptr;
 325   xbt_dynar_foreach(synchros, cursor, ptr){
 326     smx_activity_t synchro = simgrid::kernel::activity::ActivityImplPtr(ptr);
 327     /* associate this simcall to the the synchro */
 328     synchro->simcalls_.push_back(simcall);
 329
 330     /* see if the synchro is already finished */
 331     if (synchro->state_ != SIMIX_WAITING && synchro->state_ != SIMIX_RUNNING) {
 332       SIMIX_comm_finish(synchro);
 333       break;
 334     }
 335   }
 336 }
 337
 338 void SIMIX_waitany_remove_simcall_from_actions(smx_simcall_t simcall)
 339 {
 340   unsigned int cursor = 0;
 341   xbt_dynar_t synchros = simcall_comm_waitany__get__comms(simcall);
 342
 343   simgrid::kernel::activity::ActivityImpl* ptr;
 344   xbt_dynar_foreach(synchros, cursor, ptr){
 345     smx_activity_t synchro = simgrid::kernel::activity::ActivityImplPtr(ptr);
 346
 347     // Remove the first occurence of simcall:
 348     auto i = boost::range::find(synchro->simcalls_, simcall);
 349     if (i != synchro->simcalls_.end())
 350       synchro->simcalls_.erase(i);
 351   }
 352 }
 353
 354 /**
 355  * @brief Answers the SIMIX simcalls associated to a communication synchro.
 356  * @param synchro a finished communication synchro
 357  */
 358 void SIMIX_comm_finish(smx_activity_t synchro)
 359 {
 360   simgrid::kernel::activity::CommImplPtr comm =
 361       boost::static_pointer_cast<simgrid::kernel::activity::CommImpl>(synchro);
 362
 363   while (not synchro->simcalls_.empty()) {
 364     smx_simcall_t simcall = synchro->simcalls_.front();
 365     synchro->simcalls_.pop_front();
 366
 367     /* If a waitany simcall is waiting for this synchro to finish, then remove it from the other synchros in the waitany
 368      * list. Afterwards, get the position of the actual synchro in the waitany dynar and return it as the result of the
 369      * simcall */
 370
 371     if (simcall->call == SIMCALL_NONE) //FIXME: maybe a better way to handle this case
 372       continue; // if process handling comm is killed
 373     if (simcall->call == SIMCALL_COMM_WAITANY) {
 374       SIMIX_waitany_remove_simcall_from_actions(simcall);
 375       if (simcall->timer) {
 376         SIMIX_timer_remove(simcall->timer);
 377         simcall->timer = nullptr;
 378       }
 379       if (not MC_is_active() && not MC_record_replay_is_active())
 380         simcall_comm_waitany__set__result(simcall,
 381                                           xbt_dynar_search(simcall_comm_waitany__get__comms(simcall), &synchro));
 382     }
 383
 384     /* If the synchro is still in a rendez-vous point then remove from it */
 385     if (comm->mbox)
 386       comm->mbox->remove(comm);
 387
 388     XBT_DEBUG("SIMIX_comm_finish: synchro state = %d", (int)synchro->state_);
 389
 390     /* Check out for errors */
 391
 392     if (not simcall->issuer->get_host()->is_on()) {
 393       simcall->issuer->context_->iwannadie = true;
 394       simcall->issuer->exception_ =
 395           std::make_exception_ptr(simgrid::HostFailureException(XBT_THROW_POINT, "Host failed"));
 396     } else {
 397       switch (comm->state_) {
 398
 399         case SIMIX_DONE:
 400           XBT_DEBUG("Communication %p complete!", synchro.get());
 401           comm->copy_data();
 402           break;
 403
 404         case SIMIX_SRC_TIMEOUT:
 405           simcall->issuer->exception_ = std::make_exception_ptr(
 406               simgrid::TimeoutError(XBT_THROW_POINT, "Communication timeouted because of the sender"));
 407           break;
 408
 409         case SIMIX_DST_TIMEOUT:
 410           simcall->issuer->exception_ = std::make_exception_ptr(
 411               simgrid::TimeoutError(XBT_THROW_POINT, "Communication timeouted because of the receiver"));
 412           break;
 413
 414         case SIMIX_SRC_HOST_FAILURE:
 415           if (simcall->issuer == comm->src_actor_)
 416             simcall->issuer->context_->iwannadie = true;
 417           else
 418             simcall->issuer->exception_ =
 419                 std::make_exception_ptr(simgrid::NetworkFailureException(XBT_THROW_POINT, "Remote peer failed"));
 420           break;
 421
 422         case SIMIX_DST_HOST_FAILURE:
 423           if (simcall->issuer == comm->dst_actor_)
 424             simcall->issuer->context_->iwannadie = true;
 425           else
 426             simcall->issuer->exception_ =
 427                 std::make_exception_ptr(simgrid::NetworkFailureException(XBT_THROW_POINT, "Remote peer failed"));
 428           break;
 429
 430         case SIMIX_LINK_FAILURE:
 431           XBT_DEBUG("Link failure in synchro %p between '%s' and '%s': posting an exception to the issuer: %s (%p) "
 432                     "detached:%d",
 433                     synchro.get(), comm->src_actor_ ? comm->src_actor_->get_host()->get_cname() : nullptr,
 434                     comm->dst_actor_ ? comm->dst_actor_->get_host()->get_cname() : nullptr,
 435                     simcall->issuer->get_cname(), simcall->issuer, comm->detached);
 436           if (comm->src_actor_ == simcall->issuer) {
 437             XBT_DEBUG("I'm source");
 438           } else if (comm->dst_actor_ == simcall->issuer) {
 439             XBT_DEBUG("I'm dest");
 440           } else {
 441             XBT_DEBUG("I'm neither source nor dest");
 442           }
 443           simcall->issuer->throw_exception(
 444               std::make_exception_ptr(simgrid::NetworkFailureException(XBT_THROW_POINT, "Link failure")));
 445           break;
 446
 447         case SIMIX_CANCELED:
 448           if (simcall->issuer == comm->dst_actor_)
 449             simcall->issuer->exception_ = std::make_exception_ptr(
 450                 simgrid::CancelException(XBT_THROW_POINT, "Communication canceled by the sender"));
 451           else
 452             simcall->issuer->exception_ = std::make_exception_ptr(
 453                 simgrid::CancelException(XBT_THROW_POINT, "Communication canceled by the receiver"));
 454           break;
 455
 456         default:
 457           xbt_die("Unexpected synchro state in SIMIX_comm_finish: %d", (int)synchro->state_);
 458       }
 459     }
 460
 461     /* if there is an exception during a waitany or a testany, indicate the position of the failed communication */
 462     if (simcall->issuer->exception_ &&
 463         (simcall->call == SIMCALL_COMM_WAITANY || simcall->call == SIMCALL_COMM_TESTANY)) {
 464       // First retrieve the rank of our failing synchro
 465       int rank = -1;
 466       if (simcall->call == SIMCALL_COMM_WAITANY) {
 467         rank = xbt_dynar_search(simcall_comm_waitany__get__comms(simcall), &synchro);
 468       } else if (simcall->call == SIMCALL_COMM_TESTANY) {
 469         rank         = -1;
 470         auto* comms  = simcall_comm_testany__get__comms(simcall);
 471         auto count   = simcall_comm_testany__get__count(simcall);
 472         auto element = std::find(comms, comms + count, synchro);
 473         if (element == comms + count)
 474           rank = -1;
 475         else
 476           rank = element - comms;
 477       }
 478
 479       // In order to modify the exception we have to rethrow it:
 480       try {
 481         std::rethrow_exception(simcall->issuer->exception_);
 482       } catch (simgrid::TimeoutError& e) {
 483         e.value                    = rank;
 484         simcall->issuer->exception_ = std::make_exception_ptr(e);
 485       } catch (simgrid::NetworkFailureException& e) {
 486         e.value                    = rank;
 487         simcall->issuer->exception_ = std::make_exception_ptr(e);
 488       } catch (simgrid::CancelException& e) {
 489         e.value                    = rank;
 490         simcall->issuer->exception_ = std::make_exception_ptr(e);
 491       }
 492     }
 493
 494     simcall->issuer->waiting_synchro = nullptr;
 495     simcall->issuer->comms.remove(synchro);
 496     if(comm->detached){
 497       if (simcall->issuer == comm->src_actor_) {
 498         if (comm->dst_actor_)
 499           comm->dst_actor_->comms.remove(synchro);
 500       } else if (simcall->issuer == comm->dst_actor_) {
 501         if (comm->src_actor_)
 502           comm->src_actor_->comms.remove(synchro);
 503       }
 504       else{
 505         comm->dst_actor_->comms.remove(synchro);
 506         comm->src_actor_->comms.remove(synchro);
 507       }
 508     }
 509
 510     if (simcall->issuer->get_host()->is_on())
 511       SIMIX_simcall_answer(simcall);
 512     else
 513       simcall->issuer->context_->iwannadie = true;
 514   }
 515 }
 516
 517 void SIMIX_comm_copy_buffer_callback(smx_activity_t synchro, void* buff, size_t buff_size)
 518 {
 519   simgrid::kernel::activity::CommImplPtr comm =
 520       boost::static_pointer_cast<simgrid::kernel::activity::CommImpl>(synchro);
 521
 522   XBT_DEBUG("Copy the data over");
 523   memcpy(comm->dst_buff_, buff, buff_size);
 524   if (comm->detached) { // if this is a detached send, the source buffer was duplicated by SMPI sender to make the original buffer available to the application ASAP
 525     xbt_free(buff);
 526     comm->src_buff_ = nullptr;
 527   }
 528 }