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[mc] Fix MC with the class-hierarchification of simgrid::simix::Synchro
[simgrid.git] / src / mc / CommunicationDeterminismChecker.cpp
index 15f19f0..dc3ac5f 100644 (file)
@@ -22,6 +22,7 @@
 #include "src/mc/CommunicationDeterminismChecker.hpp"
 #include "src/mc/mc_exit.h"
 #include "src/mc/VisitedState.hpp"
+#include "src/mc/Transition.hpp"
 
 using simgrid::mc::remote;
 
@@ -35,7 +36,8 @@ xbt_dynar_t incomplete_communications_pattern;
 
 /********** Static functions ***********/
 
-static e_mc_comm_pattern_difference_t compare_comm_pattern(mc_comm_pattern_t comm1, mc_comm_pattern_t comm2) {
+static e_mc_comm_pattern_difference_t compare_comm_pattern(simgrid::mc::PatternCommunication* comm1, simgrid::mc::PatternCommunication* comm2)
+{
   if(comm1->type != comm2->type)
     return TYPE_DIFF;
   if (comm1->rdv != comm2->rdv)
@@ -53,10 +55,10 @@ static e_mc_comm_pattern_difference_t compare_comm_pattern(mc_comm_pattern_t com
   return NONE_DIFF;
 }
 
-static char* print_determinism_result(e_mc_comm_pattern_difference_t diff, int process, mc_comm_pattern_t comm, unsigned int cursor) {
+static char* print_determinism_result(e_mc_comm_pattern_difference_t diff, int process, simgrid::mc::PatternCommunication* comm, unsigned int cursor) {
   char *type, *res;
 
-  if(comm->type == SIMIX_COMM_SEND)
+  if (comm->type == simgrid::mc::PatternCommunicationType::send)
     type = bprintf("The send communications pattern of the process %d is different!", process - 1);
   else
     type = bprintf("The recv communications pattern of the process %d is different!", process - 1);
@@ -91,108 +93,119 @@ static char* print_determinism_result(e_mc_comm_pattern_difference_t diff, int p
   return res;
 }
 
-static void update_comm_pattern(mc_comm_pattern_t comm_pattern, smx_synchro_t comm_addr)
+static void update_comm_pattern(
+  simgrid::mc::PatternCommunication* comm_pattern,
+  simgrid::mc::RemotePtr<simgrid::simix::Comm> comm_addr)
 {
-  s_smx_synchro_t comm;
-  mc_model_checker->process().read(&comm, remote(comm_addr));
-
-  smx_process_t src_proc = MC_smx_resolve_process(comm.comm.src_proc);
-  smx_process_t dst_proc = MC_smx_resolve_process(comm.comm.dst_proc);
+  // HACK, type punning
+  simgrid::mc::Remote<simgrid::simix::Comm> temp_comm;
+  mc_model_checker->process().read(temp_comm, comm_addr);
+  simgrid::simix::Comm* comm =
+    static_cast<simgrid::simix::Comm*>(temp_comm.data());
+
+  smx_process_t src_proc = mc_model_checker->process().resolveProcess(
+    simgrid::mc::remote(comm->src_proc));
+  smx_process_t dst_proc = mc_model_checker->process().resolveProcess(
+    simgrid::mc::remote(comm->dst_proc));
   comm_pattern->src_proc = src_proc->pid;
   comm_pattern->dst_proc = dst_proc->pid;
   comm_pattern->src_host = MC_smx_process_get_host_name(src_proc);
   comm_pattern->dst_host = MC_smx_process_get_host_name(dst_proc);
-  if (comm_pattern->data.size() == 0 && comm.comm.src_buff != nullptr) {
+  if (comm_pattern->data.size() == 0 && comm->src_buff != nullptr) {
     size_t buff_size;
     mc_model_checker->process().read(
-      &buff_size, remote(comm.comm.dst_buff_size));
+      &buff_size, remote(comm->dst_buff_size));
     comm_pattern->data.resize(buff_size);
     mc_model_checker->process().read_bytes(
       comm_pattern->data.data(), comm_pattern->data.size(),
-      remote(comm.comm.src_buff));
+      remote(comm->src_buff));
   }
 }
 
-static void deterministic_comm_pattern(int process, mc_comm_pattern_t comm, int backtracking) {
+namespace simgrid {
+namespace mc {
 
-  mc_list_comm_pattern_t list =
-    xbt_dynar_get_as(initial_communications_pattern, process, mc_list_comm_pattern_t);
+void CommunicationDeterminismChecker::deterministic_comm_pattern(
+  int process, simgrid::mc::PatternCommunication* comm, int backtracking)
+{
+  simgrid::mc::PatternCommunicationList* list =
+    xbt_dynar_get_as(initial_communications_pattern, process, simgrid::mc::PatternCommunicationList*);
 
   if(!backtracking){
-    mc_comm_pattern_t initial_comm =
-      xbt_dynar_get_as(list->list, list->index_comm, mc_comm_pattern_t);
     e_mc_comm_pattern_difference_t diff =
-      compare_comm_pattern(initial_comm, comm);
+      compare_comm_pattern(list->list[list->index_comm].get(), comm);
 
     if (diff != NONE_DIFF) {
-      if (comm->type == SIMIX_COMM_SEND){
-        simgrid::mc::initial_global_state->send_deterministic = 0;
-        if(simgrid::mc::initial_global_state->send_diff != nullptr)
-          xbt_free(simgrid::mc::initial_global_state->send_diff);
-        simgrid::mc::initial_global_state->send_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
-      }else{
-        simgrid::mc::initial_global_state->recv_deterministic = 0;
-        if(simgrid::mc::initial_global_state->recv_diff != nullptr)
-          xbt_free(simgrid::mc::initial_global_state->recv_diff);
-        simgrid::mc::initial_global_state->recv_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
+      if (comm->type == simgrid::mc::PatternCommunicationType::send) {
+        this->send_deterministic = 0;
+        if (this->send_diff != nullptr)
+          xbt_free(this->send_diff);
+        this->send_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
+      } else {
+        this->recv_deterministic = 0;
+        if (this->recv_diff != nullptr)
+          xbt_free(this->recv_diff);
+        this->recv_diff = print_determinism_result(diff, process, comm, list->index_comm + 1);
       }
-      if(_sg_mc_send_determinism && !simgrid::mc::initial_global_state->send_deterministic){
+      if(_sg_mc_send_determinism && !this->send_deterministic){
         XBT_INFO("*********************************************************");
         XBT_INFO("***** Non-send-deterministic communications pattern *****");
         XBT_INFO("*********************************************************");
-        XBT_INFO("%s", simgrid::mc::initial_global_state->send_diff);
-        xbt_free(simgrid::mc::initial_global_state->send_diff);
-        simgrid::mc::initial_global_state->send_diff = nullptr;
-        MC_print_statistics(mc_stats);
+        XBT_INFO("%s", this->send_diff);
+        xbt_free(this->send_diff);
+        this->send_diff = nullptr;
+        simgrid::mc::session->logState();
         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
       }else if(_sg_mc_comms_determinism
-          && (!simgrid::mc::initial_global_state->send_deterministic
-            && !simgrid::mc::initial_global_state->recv_deterministic)) {
+          && (!this->send_deterministic && !this->recv_deterministic)) {
         XBT_INFO("****************************************************");
         XBT_INFO("***** Non-deterministic communications pattern *****");
         XBT_INFO("****************************************************");
-        XBT_INFO("%s", simgrid::mc::initial_global_state->send_diff);
-        XBT_INFO("%s", simgrid::mc::initial_global_state->recv_diff);
-        xbt_free(simgrid::mc::initial_global_state->send_diff);
-        simgrid::mc::initial_global_state->send_diff = nullptr;
-        xbt_free(simgrid::mc::initial_global_state->recv_diff);
-        simgrid::mc::initial_global_state->recv_diff = nullptr;
-        MC_print_statistics(mc_stats);
+        XBT_INFO("%s", this->send_diff);
+        XBT_INFO("%s", this->recv_diff);
+        xbt_free(this->send_diff);
+        this->send_diff = nullptr;
+        xbt_free(this->recv_diff);
+        this->recv_diff = nullptr;
+        simgrid::mc::session->logState();
         mc_model_checker->exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
       }
     }
   }
-
-  MC_comm_pattern_free(comm);
-
 }
 
 /********** Non Static functions ***********/
 
-void MC_get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, e_mc_call_type_t call_type, int backtracking)
+void CommunicationDeterminismChecker::get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, e_mc_call_type_t call_type, int backtracking)
 {
   const smx_process_t issuer = MC_smx_simcall_get_issuer(request);
-  mc_list_comm_pattern_t initial_pattern = xbt_dynar_get_as(
-    initial_communications_pattern, issuer->pid, mc_list_comm_pattern_t);
+  simgrid::mc::PatternCommunicationList* initial_pattern = xbt_dynar_get_as(
+    initial_communications_pattern, issuer->pid, simgrid::mc::PatternCommunicationList*);
   xbt_dynar_t incomplete_pattern = xbt_dynar_get_as(
     incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
 
-  mc_comm_pattern_t pattern = new s_mc_comm_pattern_t();
+  std::unique_ptr<simgrid::mc::PatternCommunication> pattern =
+    std::unique_ptr<simgrid::mc::PatternCommunication>(
+      new simgrid::mc::PatternCommunication());
   pattern->index =
     initial_pattern->index_comm + xbt_dynar_length(incomplete_pattern);
 
   if (call_type == MC_CALL_TYPE_SEND) {
     /* Create comm pattern */
-    pattern->type = SIMIX_COMM_SEND;
+    pattern->type = simgrid::mc::PatternCommunicationType::send;
     pattern->comm_addr = simcall_comm_isend__get__result(request);
 
-    s_smx_synchro_t synchro = mc_model_checker->process().read<s_smx_synchro_t>(
-      (std::uint64_t) pattern->comm_addr);
+    simgrid::mc::Remote<simgrid::simix::Comm> temp_synchro;
+    mc_model_checker->process().read(temp_synchro, remote(
+      static_cast<simgrid::simix::Comm*>(pattern->comm_addr)));
+    simgrid::simix::Comm* synchro =
+      static_cast<simgrid::simix::Comm*>(temp_synchro.data());
 
     char* remote_name = mc_model_checker->process().read<char*>(
-      (std::uint64_t)(synchro.comm.rdv ? &synchro.comm.rdv->name : &synchro.comm.rdv_cpy->name));
+      (std::uint64_t)(synchro->mbox ? &synchro->mbox->name : &synchro->mbox_cpy->name));
     pattern->rdv = mc_model_checker->process().read_string(remote_name);
-    pattern->src_proc = MC_smx_resolve_process(synchro.comm.src_proc)->pid;
+    pattern->src_proc = mc_model_checker->process().resolveProcess(
+      simgrid::mc::remote(synchro->src_proc))->pid;
     pattern->src_host = MC_smx_process_get_host_name(issuer);
 
     struct s_smpi_mpi_request mpi_request =
@@ -200,31 +213,30 @@ void MC_get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, e_mc_call_type
         (std::uint64_t) simcall_comm_isend__get__data(request));
     pattern->tag = mpi_request.tag;
 
-    if(synchro.comm.src_buff != nullptr){
-      pattern->data.resize(synchro.comm.src_buff_size);
+    if (synchro->src_buff != nullptr){
+      pattern->data.resize(synchro->src_buff_size);
       mc_model_checker->process().read_bytes(
         pattern->data.data(), pattern->data.size(),
-        remote(synchro.comm.src_buff));
+        remote(synchro->src_buff));
     }
     if(mpi_request.detached){
-      if (!simgrid::mc::initial_global_state->initial_communications_pattern_done) {
+      if (!this->initial_communications_pattern_done) {
         /* Store comm pattern */
-        xbt_dynar_push(
-          xbt_dynar_get_as(
-            initial_communications_pattern, pattern->src_proc, mc_list_comm_pattern_t
-          )->list,
-          &pattern);
+        simgrid::mc::PatternCommunicationList* list = xbt_dynar_get_as(
+          initial_communications_pattern, pattern->src_proc,
+          simgrid::mc::PatternCommunicationList*);
+        list->list.push_back(std::move(pattern));
       } else {
         /* Evaluate comm determinism */
-        deterministic_comm_pattern(pattern->src_proc, pattern, backtracking);
+        this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
         xbt_dynar_get_as(
-          initial_communications_pattern, pattern->src_proc, mc_list_comm_pattern_t
+          initial_communications_pattern, pattern->src_proc, simgrid::mc::PatternCommunicationList*
         )->index_comm++;
       }
       return;
     }
   } else if (call_type == MC_CALL_TYPE_RECV) {
-    pattern->type = SIMIX_COMM_RECEIVE;
+    pattern->type = simgrid::mc::PatternCommunicationType::receive;
     pattern->comm_addr = simcall_comm_irecv__get__result(request);
 
     struct s_smpi_mpi_request mpi_request;
@@ -232,39 +244,50 @@ void MC_get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, e_mc_call_type
       &mpi_request, remote((struct s_smpi_mpi_request*)simcall_comm_irecv__get__data(request)));
     pattern->tag = mpi_request.tag;
 
-    s_smx_synchro_t synchro;
-    mc_model_checker->process().read(&synchro, remote(pattern->comm_addr));
+    simgrid::mc::Remote<simgrid::simix::Comm> temp_comm;
+    mc_model_checker->process().read(temp_comm, remote(
+      static_cast<simgrid::simix::Comm*>(pattern->comm_addr)));
+    simgrid::simix::Comm* comm =
+      static_cast<simgrid::simix::Comm*>(temp_comm.data());
 
     char* remote_name;
     mc_model_checker->process().read(&remote_name,
-      remote(synchro.comm.rdv ? &synchro.comm.rdv->name : &synchro.comm.rdv_cpy->name));
+      remote(comm->mbox ? &comm->mbox->name : &comm->mbox_cpy->name));
     pattern->rdv = mc_model_checker->process().read_string(remote_name);
-    pattern->dst_proc = MC_smx_resolve_process(synchro.comm.dst_proc)->pid;
+    pattern->dst_proc = mc_model_checker->process().resolveProcess(
+      simgrid::mc::remote(comm->dst_proc))->pid;
     pattern->dst_host = MC_smx_process_get_host_name(issuer);
   } else
     xbt_die("Unexpected call_type %i", (int) call_type);
 
-  xbt_dynar_push(
-    xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t),
-    &pattern);
-
-  XBT_DEBUG("Insert incomplete comm pattern %p for process %lu", pattern, issuer->pid);
+  XBT_DEBUG("Insert incomplete comm pattern %p for process %lu",
+    pattern.get(), issuer->pid);
+  xbt_dynar_t dynar =
+    xbt_dynar_get_as(incomplete_communications_pattern, issuer->pid, xbt_dynar_t);
+  simgrid::mc::PatternCommunication* pattern2 = pattern.release();
+  xbt_dynar_push(dynar, &pattern2);
 }
 
-void MC_complete_comm_pattern(xbt_dynar_t list, smx_synchro_t comm_addr, unsigned int issuer, int backtracking) {
-  mc_comm_pattern_t current_comm_pattern;
+
+void CommunicationDeterminismChecker::complete_comm_pattern(
+  xbt_dynar_t list, simgrid::mc::RemotePtr<simgrid::simix::Comm> comm_addr,
+  unsigned int issuer, int backtracking)
+{
+  simgrid::mc::PatternCommunication* current_comm_pattern;
   unsigned int cursor = 0;
-  mc_comm_pattern_t comm_pattern;
+  std::unique_ptr<simgrid::mc::PatternCommunication> comm_pattern;
   int completed = 0;
 
   /* Complete comm pattern */
   xbt_dynar_foreach(xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t), cursor, current_comm_pattern)
-    if (current_comm_pattern->comm_addr == comm_addr) {
+    if (remote(current_comm_pattern->comm_addr) == comm_addr) {
       update_comm_pattern(current_comm_pattern, comm_addr);
       completed = 1;
+      simgrid::mc::PatternCommunication* temp;
       xbt_dynar_remove_at(
         xbt_dynar_get_as(incomplete_communications_pattern, issuer, xbt_dynar_t),
-        cursor, &comm_pattern);
+        cursor, &temp);
+      comm_pattern = std::unique_ptr<simgrid::mc::PatternCommunication>(temp);
       XBT_DEBUG("Remove incomplete comm pattern for process %u at cursor %u", issuer, cursor);
       break;
     }
@@ -272,25 +295,19 @@ void MC_complete_comm_pattern(xbt_dynar_t list, smx_synchro_t comm_addr, unsigne
   if(!completed)
     xbt_die("Corresponding communication not found!");
 
-  mc_list_comm_pattern_t pattern = xbt_dynar_get_as(
-    initial_communications_pattern, issuer, mc_list_comm_pattern_t);
+  simgrid::mc::PatternCommunicationList* pattern = xbt_dynar_get_as(
+    initial_communications_pattern, issuer, simgrid::mc::PatternCommunicationList*);
 
-  if (!simgrid::mc::initial_global_state->initial_communications_pattern_done)
+  if (!this->initial_communications_pattern_done)
     /* Store comm pattern */
-    xbt_dynar_push(pattern->list, &comm_pattern);
+    pattern->list.push_back(std::move(comm_pattern));
   else {
     /* Evaluate comm determinism */
-    deterministic_comm_pattern(issuer, comm_pattern, backtracking);
+    this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
     pattern->index_comm++;
   }
 }
 
-
-/************************ Main algorithm ************************/
-
-namespace simgrid {
-namespace mc {
-
 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session& session)
   : Checker(session)
 {
@@ -302,34 +319,53 @@ CommunicationDeterminismChecker::~CommunicationDeterminismChecker()
 
 }
 
-// TODO, deduplicate with SafetyChecker
 RecordTrace CommunicationDeterminismChecker::getRecordTrace() // override
 {
   RecordTrace res;
-  for (auto const& state : stack_) {
-    int value = 0;
-    smx_simcall_t saved_req = MC_state_get_executed_request(state.get(), &value);
-    const smx_process_t issuer = MC_smx_simcall_get_issuer(saved_req);
-    const int pid = issuer->pid;
-    res.push_back(RecordTraceElement(pid, value));
-  }
+  for (auto const& state : stack_)
+    res.push_back(state->getTransition());
   return res;
 }
 
-// TODO, deduplicate with SafetyChecker
 std::vector<std::string> CommunicationDeterminismChecker::getTextualTrace() // override
 {
   std::vector<std::string> trace;
   for (auto const& state : stack_) {
-    int value;
-    smx_simcall_t req = MC_state_get_executed_request(state.get(), &value);
+    smx_simcall_t req = &state->executed_req;
     if (req)
       trace.push_back(simgrid::mc::request_to_string(
-        req, value, simgrid::mc::RequestType::executed));
+        req, state->transition.argument, simgrid::mc::RequestType::executed));
   }
   return trace;
 }
 
+void CommunicationDeterminismChecker::logState() // override
+{
+  Checker::logState();
+  if (_sg_mc_comms_determinism &&
+      !this->recv_deterministic &&
+      this->send_deterministic) {
+    XBT_INFO("******************************************************");
+    XBT_INFO("**** Only-send-deterministic communication pattern ****");
+    XBT_INFO("******************************************************");
+    XBT_INFO("%s", this->recv_diff);
+  } else if(_sg_mc_comms_determinism &&
+      !this->send_deterministic &&
+      this->recv_deterministic) {
+    XBT_INFO("******************************************************");
+    XBT_INFO("**** Only-recv-deterministic communication pattern ****");
+    XBT_INFO("******************************************************");
+    XBT_INFO("%s", this->send_diff);
+  }
+  XBT_INFO("Expanded states = %lu", expandedStatesCount_);
+  XBT_INFO("Visited states = %lu", mc_model_checker->visited_states);
+  XBT_INFO("Executed transitions = %lu", mc_model_checker->executed_transitions);
+  XBT_INFO("Send-deterministic : %s", !this->send_deterministic ? "No" : "Yes");
+  if (_sg_mc_comms_determinism)
+    XBT_INFO("Recv-deterministic : %s",
+      !this->recv_deterministic ? "No" : "Yes");
+}
+
 void CommunicationDeterminismChecker::prepare()
 {
 
@@ -337,33 +373,28 @@ void CommunicationDeterminismChecker::prepare()
   const int maxpid = MC_smx_get_maxpid();
 
   // Create initial_communications_pattern elements:
-  initial_communications_pattern = xbt_dynar_new(sizeof(mc_list_comm_pattern_t), MC_list_comm_pattern_free_voidp);
+  initial_communications_pattern = simgrid::xbt::newDeleteDynar<simgrid::mc::PatternCommunicationList*>();
   for (i=0; i < maxpid; i++){
-    mc_list_comm_pattern_t process_list_pattern = xbt_new0(s_mc_list_comm_pattern_t, 1);
-    process_list_pattern->list = xbt_dynar_new(sizeof(mc_comm_pattern_t), MC_comm_pattern_free_voidp);
-    process_list_pattern->index_comm = 0;
+    simgrid::mc::PatternCommunicationList* process_list_pattern = new simgrid::mc::PatternCommunicationList();
     xbt_dynar_insert_at(initial_communications_pattern, i, &process_list_pattern);
   }
 
   // Create incomplete_communications_pattern elements:
   incomplete_communications_pattern = xbt_dynar_new(sizeof(xbt_dynar_t), xbt_dynar_free_voidp);
   for (i=0; i < maxpid; i++){
-    xbt_dynar_t process_pattern = xbt_dynar_new(sizeof(mc_comm_pattern_t), nullptr);
+    xbt_dynar_t process_pattern = xbt_dynar_new(sizeof(simgrid::mc::PatternCommunication*), nullptr);
     xbt_dynar_insert_at(incomplete_communications_pattern, i, &process_pattern);
   }
 
   std::unique_ptr<simgrid::mc::State> initial_state =
-    std::unique_ptr<simgrid::mc::State>(MC_state_new());
+    std::unique_ptr<simgrid::mc::State>(MC_state_new(++expandedStatesCount_));
 
   XBT_DEBUG("********* Start communication determinism verification *********");
 
-  /* Wait for requests (schedules processes) */
-  mc_model_checker->wait_for_requests();
-
   /* Get an enabled process and insert it in the interleave set of the initial state */
   for (auto& p : mc_model_checker->process().simix_processes())
     if (simgrid::mc::process_is_enabled(&p.copy))
-      MC_state_interleave_process(initial_state.get(), &p.copy);
+      initial_state->interleave(&p.copy);
 
   stack_.push_back(std::move(initial_state));
 }
@@ -382,9 +413,59 @@ bool all_communications_are_finished()
   return true;
 }
 
+void CommunicationDeterminismChecker::restoreState()
+{
+  /* Intermediate backtracking */
+  {
+    simgrid::mc::State* state = stack_.back().get();
+    if (state->system_state) {
+      simgrid::mc::restore_snapshot(state->system_state);
+      MC_restore_communications_pattern(state);
+      return;
+    }
+  }
+
+  /* Restore the initial state */
+  simgrid::mc::session->restoreInitialState();
+
+  // int n = xbt_dynar_length(incomplete_communications_pattern);
+  unsigned n = MC_smx_get_maxpid();
+  assert(n == xbt_dynar_length(incomplete_communications_pattern));
+  assert(n == xbt_dynar_length(initial_communications_pattern));
+  for (unsigned j=0; j < n ; j++) {
+    xbt_dynar_reset((xbt_dynar_t)xbt_dynar_get_as(incomplete_communications_pattern, j, xbt_dynar_t));
+    xbt_dynar_get_as(initial_communications_pattern, j, simgrid::mc::PatternCommunicationList*)->index_comm = 0;
+  }
+
+  /* Traverse the stack from the state at position start and re-execute the transitions */
+  for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
+    if (state == stack_.back())
+      break;
+
+    int req_num = state->transition.argument;
+    smx_simcall_t saved_req = &state->executed_req;
+    xbt_assert(saved_req);
+
+    /* because we got a copy of the executed request, we have to fetch the
+       real one, pointed by the request field of the issuer process */
+
+    const smx_process_t issuer = MC_smx_simcall_get_issuer(saved_req);
+    smx_simcall_t req = &issuer->simcall;
+
+    /* TODO : handle test and testany simcalls */
+    e_mc_call_type_t call = MC_get_call_type(req);
+    mc_model_checker->handle_simcall(state->transition);
+    MC_handle_comm_pattern(call, req, req_num, nullptr, 1);
+    mc_model_checker->wait_for_requests();
+
+    /* Update statistics */
+    mc_model_checker->visited_states++;
+    mc_model_checker->executed_transitions++;
+  }
+}
+
 int CommunicationDeterminismChecker::main(void)
 {
-  int value;
   std::unique_ptr<simgrid::mc::VisitedState> visited_state = nullptr;
   smx_simcall_t req = nullptr;
 
@@ -399,22 +480,23 @@ int CommunicationDeterminismChecker::main(void)
               state->interleaveSize());
 
     /* Update statistics */
-    mc_stats->visited_states++;
+    mc_model_checker->visited_states++;
 
     if (stack_.size() <= (std::size_t) _sg_mc_max_depth
-        && (req = MC_state_get_request(state, &value))
+        && (req = MC_state_get_request(state)) != nullptr
         && (visited_state == nullptr)) {
 
+      int req_num = state->transition.argument;
+
       XBT_DEBUG("Execute: %s",
         simgrid::mc::request_to_string(
-          req, value, simgrid::mc::RequestType::simix).c_str());
+          req, req_num, simgrid::mc::RequestType::simix).c_str());
 
-      char* req_str = nullptr;
+      std::string req_str;
       if (dot_output != nullptr)
-        req_str = simgrid::mc::request_get_dot_output(req, value);
+        req_str = simgrid::mc::request_get_dot_output(req, req_num);
 
-      MC_state_set_executed_request(state, req, value);
-      mc_stats->executed_transitions++;
+      mc_model_checker->executed_transitions++;
 
       /* TODO : handle test and testany simcalls */
       e_mc_call_type_t call = MC_CALL_TYPE_NONE;
@@ -422,47 +504,47 @@ int CommunicationDeterminismChecker::main(void)
         call = MC_get_call_type(req);
 
       /* Answer the request */
-      simgrid::mc::handle_simcall(req, value);    /* After this call req is no longer useful */
+      mc_model_checker->handle_simcall(state->transition);
+      /* After this call req is no longer useful */
 
-      if(!initial_global_state->initial_communications_pattern_done)
-        MC_handle_comm_pattern(call, req, value, initial_communications_pattern, 0);
+      if (!this->initial_communications_pattern_done)
+        MC_handle_comm_pattern(call, req, req_num, initial_communications_pattern, 0);
       else
-        MC_handle_comm_pattern(call, req, value, nullptr, 0);
+        MC_handle_comm_pattern(call, req, req_num, nullptr, 0);
 
       /* Wait for requests (schedules processes) */
       mc_model_checker->wait_for_requests();
 
       /* Create the new expanded state */
       std::unique_ptr<simgrid::mc::State> next_state =
-        std::unique_ptr<simgrid::mc::State>(MC_state_new());
+        std::unique_ptr<simgrid::mc::State>(MC_state_new(++expandedStatesCount_));
 
       /* If comm determinism verification, we cannot stop the exploration if
          some communications are not finished (at least, data are transfered).
          These communications  are incomplete and they cannot be analyzed and
          compared with the initial pattern. */
       bool compare_snapshots = all_communications_are_finished()
-        && initial_global_state->initial_communications_pattern_done;
+        && this->initial_communications_pattern_done;
 
       if (_sg_mc_visited == 0
-          || (visited_state = visitedStates_.addVisitedState(next_state.get(), compare_snapshots)) == nullptr) {
+          || (visited_state = visitedStates_.addVisitedState(
+            expandedStatesCount_, next_state.get(), compare_snapshots)) == nullptr) {
 
         /* Get enabled processes and insert them in the interleave set of the next state */
         for (auto& p : mc_model_checker->process().simix_processes())
           if (simgrid::mc::process_is_enabled(&p.copy))
-            MC_state_interleave_process(next_state.get(), &p.copy);
+            next_state->interleave(&p.copy);
 
         if (dot_output != nullptr)
-          fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num,  next_state->num, req_str);
+          fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n",
+            state->num,  next_state->num, req_str.c_str());
 
       } else if (dot_output != nullptr)
         fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n",
-          state->num, visited_state->other_num == -1 ? visited_state->num : visited_state->other_num, req_str);
+          state->num, visited_state->other_num == -1 ? visited_state->num : visited_state->other_num, req_str.c_str());
 
       stack_.push_back(std::move(next_state));
 
-      if (dot_output != nullptr)
-        xbt_free(req_str);
-
     } else {
 
       if (stack_.size() > (std::size_t) _sg_mc_max_depth)
@@ -473,8 +555,8 @@ int CommunicationDeterminismChecker::main(void)
         XBT_DEBUG("There are no more processes to interleave. (depth %zi)",
           stack_.size());
 
-      if (!initial_global_state->initial_communications_pattern_done)
-        initial_global_state->initial_communications_pattern_done = 1;
+      if (!this->initial_communications_pattern_done)
+        this->initial_communications_pattern_done = 1;
 
       /* Trash the current state, no longer needed */
       XBT_DEBUG("Delete state %d at depth %zi",
@@ -499,7 +581,7 @@ int CommunicationDeterminismChecker::main(void)
             state->num, stack_.size() + 1);
           stack_.push_back(std::move(state));
 
-          simgrid::mc::replay(stack_);
+          this->restoreState();
 
           XBT_DEBUG("Back-tracking to state %d at depth %zi done",
             stack_.back()->num, stack_.size());
@@ -513,31 +595,24 @@ int CommunicationDeterminismChecker::main(void)
     }
   }
 
-  MC_print_statistics(mc_stats);
+  simgrid::mc::session->logState();
   return SIMGRID_MC_EXIT_SUCCESS;
 }
 
 int CommunicationDeterminismChecker::run()
 {
   XBT_INFO("Check communication determinism");
-  mc_model_checker->wait_for_requests();
-
-  if (mc_mode == MC_MODE_CLIENT)
-    // This will move somehwere else:
-    simgrid::mc::Client::get()->handleMessages();
+  simgrid::mc::session->initialize();
 
   this->prepare();
 
-  initial_global_state = std::unique_ptr<s_mc_global_t>(new s_mc_global_t());
-  initial_global_state->snapshot = simgrid::mc::take_snapshot(0);
-  initial_global_state->initial_communications_pattern_done = 0;
-  initial_global_state->recv_deterministic = 1;
-  initial_global_state->send_deterministic = 1;
-  initial_global_state->recv_diff = nullptr;
-  initial_global_state->send_diff = nullptr;
+  this->initial_communications_pattern_done = 0;
+  this->recv_deterministic = 1;
+  this->send_deterministic = 1;
+  this->recv_diff = nullptr;
+  this->send_diff = nullptr;
 
   int res = this->main();
-  initial_global_state = nullptr;
   return res;
 }
 
@@ -547,4 +622,4 @@ Checker* createCommunicationDeterminismChecker(Session& session)
 }
 
 }
-}
\ No newline at end of file
+}