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model-checker : conflit
[simgrid.git] / src / mc / mc_dpor.c
index bdc859e..a3e2949 100644 (file)
-/* Copyright (c) 2008 Martin Quinson, Cristian Rosa.
  All rights reserved.                                          */
+/* Copyright (c) 2008-2013. The SimGrid Team.
* All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
-#include "private.h"
+#include "mc_private.h"
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dpor, mc,
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dpor, mc,
-                               "Logging specific to MC DPOR exploration");
+                                "Logging specific to MC DPOR exploration");
+
+/********** Global variables **********/
+
+xbt_dynar_t visited_states;
+xbt_dict_t first_enabled_state;
+xbt_dynar_t initial_communications_pattern;
+xbt_dynar_t communications_pattern;
+int nb_comm_pattern;
+
+/********** Static functions ***********/
+
+static void comm_pattern_free(mc_comm_pattern_t p){
+  xbt_free(p->rdv);
+  xbt_free(p->data);
+  xbt_free(p);
+  p = NULL;
+}
+
+static void comm_pattern_free_voidp( void *p){
+  comm_pattern_free((mc_comm_pattern_t) * (void **)p);
+}
+
+static mc_comm_pattern_t get_comm_pattern_from_idx(xbt_dynar_t pattern, unsigned int *idx, e_smx_comm_type_t type, unsigned long proc){
+  mc_comm_pattern_t current_comm;
+  while(*idx < xbt_dynar_length(pattern)){
+    current_comm = (mc_comm_pattern_t)xbt_dynar_get_as(pattern, *idx, mc_comm_pattern_t);
+    if(current_comm->type == type && type == SIMIX_COMM_SEND){
+      if(current_comm->src_proc == proc)
+        return current_comm;
+    }else if(current_comm->type == type && type == SIMIX_COMM_RECEIVE){
+      if(current_comm->dst_proc == proc)
+        return current_comm;
+    }
+    (*idx)++;
+  }
+  return NULL;
+}
+
+static int compare_comm_pattern(mc_comm_pattern_t comm1, mc_comm_pattern_t comm2){
+  if(strcmp(comm1->rdv, comm2->rdv) != 0)
+    return 1;
+  if(comm1->src_proc != comm2->src_proc)
+    return 1;
+  if(comm1->dst_proc != comm2->dst_proc)
+    return 1;
+  if(comm1->data_size != comm2->data_size)
+    return 1;
+  if(memcmp(comm1->data, comm2->data, comm1->data_size) != 0)
+    return 1;
+  return 0;
+}
+
+static void deterministic_pattern(xbt_dynar_t initial_pattern, xbt_dynar_t pattern){
+  unsigned int cursor = 0, send_index = 0, recv_index = 0;
+  mc_comm_pattern_t comm1, comm2;
+  int comm_comparison = 0;
+  int current_process = 0;
+  while(current_process < simix_process_maxpid){
+    while(cursor < xbt_dynar_length(initial_pattern)){
+      comm1 = (mc_comm_pattern_t)xbt_dynar_get_as(initial_pattern, cursor, mc_comm_pattern_t);
+      if(comm1->type == SIMIX_COMM_SEND && comm1->src_proc == current_process){
+        comm2 = get_comm_pattern_from_idx(pattern, &send_index, comm1->type, current_process);
+        comm_comparison = compare_comm_pattern(comm1, comm2);
+        if(comm_comparison == 1){
+          initial_state_safety->send_deterministic = 0;
+          initial_state_safety->comm_deterministic = 0;
+          return;
+        }
+        send_index++;
+      }else if(comm1->type == SIMIX_COMM_RECEIVE && comm1->dst_proc == current_process){
+        comm2 = get_comm_pattern_from_idx(pattern, &recv_index, comm1->type, current_process);
+        comm_comparison = compare_comm_pattern(comm1, comm2);
+        if(comm_comparison == 1){
+          initial_state_safety->comm_deterministic = 0;
+        }
+        recv_index++;
+      }
+      cursor++;
+    }
+    cursor = 0;
+    send_index = 0;
+    recv_index = 0;
+    current_process++;
+  }
+  // XBT_DEBUG("Communication-deterministic : %d, Send-deterministic : %d", initial_state_safety->comm_deterministic, initial_state_safety->send_deterministic);
+}
+
+static int complete_comm_pattern(xbt_dynar_t list, mc_comm_pattern_t pattern){
+  mc_comm_pattern_t current_pattern;
+  unsigned int cursor = 0;
+  xbt_dynar_foreach(list, cursor, current_pattern){
+    if(current_pattern->comm == pattern->comm){
+      if(!current_pattern->completed){
+        current_pattern->src_proc = pattern->comm->comm.src_proc->pid;
+        current_pattern->dst_proc = pattern->comm->comm.dst_proc->pid;
+        current_pattern->data_size = pattern->comm->comm.src_buff_size;
+        current_pattern->data = xbt_malloc0(current_pattern->data_size);
+        current_pattern->matched_comm = pattern->num;
+        memcpy(current_pattern->data, current_pattern->comm->comm.src_buff, current_pattern->data_size);
+        current_pattern->completed = 1;
+        return current_pattern->num;
+      }
+    }
+  }
+  return -1;
+}
+
+void get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, int call){
+  mc_comm_pattern_t pattern = NULL;
+  pattern = xbt_new0(s_mc_comm_pattern_t, 1);
+  pattern->num = ++nb_comm_pattern;
+  pattern->completed = 0;
+  if(call == 1){ // ISEND
+    pattern->comm = simcall_comm_isend__get__result(request);
+    pattern->type = SIMIX_COMM_SEND;
+    if(pattern->comm->comm.dst_proc != NULL){
+      pattern->matched_comm = complete_comm_pattern(list, pattern);
+      pattern->dst_proc = pattern->comm->comm.dst_proc->pid;
+      pattern->completed = 1;
+    }
+    pattern->src_proc = pattern->comm->comm.src_proc->pid;
+    pattern->data_size = pattern->comm->comm.src_buff_size;
+    pattern->data=xbt_malloc0(pattern->data_size);
+    memcpy(pattern->data, pattern->comm->comm.src_buff, pattern->data_size);
+  }else{ // IRECV
+    pattern->comm = simcall_comm_irecv__get__result(request);
+    pattern->type = SIMIX_COMM_RECEIVE;
+    if(pattern->comm->comm.src_proc != NULL){
+      pattern->matched_comm = complete_comm_pattern(list, pattern);
+      pattern->src_proc = pattern->comm->comm.src_proc->pid;
+      pattern->completed = 1;
+      pattern->data_size = pattern->comm->comm.src_buff_size;
+      pattern->data=xbt_malloc0(pattern->data_size);
+      memcpy(pattern->data, pattern->comm->comm.src_buff, pattern->data_size);
+    }
+    pattern->dst_proc = pattern->comm->comm.dst_proc->pid;
+  }
+  if(pattern->comm->comm.rdv != NULL)
+    pattern->rdv = strdup(pattern->comm->comm.rdv->name);
+  else
+    pattern->rdv = strdup(pattern->comm->comm.rdv_cpy->name);
+  xbt_dynar_push(list, &pattern);
+}
+
+static void print_communications_pattern(xbt_dynar_t comms_pattern){
+  unsigned int cursor = 0;
+  mc_comm_pattern_t current_comm;
+  xbt_dynar_foreach(comms_pattern, cursor, current_comm){
+    // fprintf(stderr, "%s (%d - comm %p, src : %lu, dst %lu, rdv name %s, data %p, matched with %d)\n", current_comm->type == SIMIX_COMM_SEND ? "iSend" : "iRecv", current_comm->num, current_comm->comm, current_comm->src_proc, current_comm->dst_proc, current_comm->rdv, current_comm->data, current_comm->matched_comm);
+  }
+}
+
+static void visited_state_free(mc_visited_state_t state){
+  if(state){
+    MC_free_snapshot(state->system_state);
+    xbt_free(state);
+  }
+}
+
+static void visited_state_free_voidp(void *s){
+  visited_state_free((mc_visited_state_t) * (void **) s);
+}
+
+static mc_visited_state_t visited_state_new(){
+
+  mc_visited_state_t new_state = NULL;
+  new_state = xbt_new0(s_mc_visited_state_t, 1);
+  new_state->heap_bytes_used = mmalloc_get_bytes_used(std_heap);
+  new_state->nb_processes = xbt_swag_size(simix_global->process_list);
+  new_state->system_state = MC_take_snapshot(mc_stats->expanded_states);
+  new_state->num = mc_stats->expanded_states;
+  new_state->other_num = -1;
+
+  return new_state;
+  
+}
+
+static int get_search_interval(xbt_dynar_t all_states, mc_visited_state_t state, int *min, int *max){
+
+  int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
+
+  MC_SET_RAW_MEM;
+
+  int cursor = 0, previous_cursor, next_cursor;
+  mc_visited_state_t state_test;
+  int start = 0;
+  int end = xbt_dynar_length(all_states) - 1;
+  
+  while(start <= end){
+    cursor = (start + end) / 2;
+    state_test = (mc_visited_state_t)xbt_dynar_get_as(all_states, cursor, mc_visited_state_t);
+    if(state_test->nb_processes < state->nb_processes){
+      start = cursor + 1;
+    }else if(state_test->nb_processes > state->nb_processes){
+      end = cursor - 1;
+    }else{
+      if(state_test->heap_bytes_used < state->heap_bytes_used){
+        start = cursor +1;
+      }else if(state_test->heap_bytes_used > state->heap_bytes_used){
+        end = cursor - 1;
+      }else{
+        *min = *max = cursor;
+        previous_cursor = cursor - 1;
+        while(previous_cursor >= 0){
+          state_test = (mc_visited_state_t)xbt_dynar_get_as(all_states, previous_cursor, mc_visited_state_t);
+          if(state_test->nb_processes != state->nb_processes || state_test->heap_bytes_used != state->heap_bytes_used)
+            break;
+          *min = previous_cursor;
+          previous_cursor--;
+        }
+        next_cursor = cursor + 1;
+        while(next_cursor < xbt_dynar_length(all_states)){
+          state_test = (mc_visited_state_t)xbt_dynar_get_as(all_states, next_cursor, mc_visited_state_t);
+          if(state_test->nb_processes != state->nb_processes || state_test->heap_bytes_used != state->heap_bytes_used)
+            break;
+          *max = next_cursor;
+          next_cursor++;
+        }
+        if(!raw_mem_set)
+          MC_UNSET_RAW_MEM;
+        return -1;
+      }
+     }
+  }
+
+  if(!raw_mem_set)
+    MC_UNSET_RAW_MEM;
+
+  return cursor;
+}
+
+static int is_visited_state(){
+
+  if(_sg_mc_visited == 0)
+    return -1;
+
+  int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
+
+  MC_SET_RAW_MEM;
+
+  mc_visited_state_t new_state = visited_state_new();
+  
+  if(xbt_dynar_is_empty(visited_states)){
+
+    xbt_dynar_push(visited_states, &new_state); 
+
+    if(!raw_mem_set)
+      MC_UNSET_RAW_MEM;
+
+    return -1;
+
+  }else{
+
+    int min = -1, max = -1, index;
+    //int res;
+    mc_visited_state_t state_test;
+    int cursor;
+
+    index = get_search_interval(visited_states, new_state, &min, &max);
+
+    if(min != -1 && max != -1){
+      /*res = xbt_parmap_mc_apply(parmap, snapshot_compare, xbt_dynar_get_ptr(visited_states, min), (max-min)+1, new_state);
+      if(res != -1){
+        state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, (min+res)-1, mc_visited_state_t);
+        if(state_test->other_num == -1)
+          new_state->other_num = state_test->num;
+        else
+          new_state->other_num = state_test->other_num;
+        if(dot_output == NULL)
+          XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
+        else
+          XBT_DEBUG("State %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
+        xbt_dynar_remove_at(visited_states, (min + res) - 1, NULL);
+        xbt_dynar_insert_at(visited_states, (min+res) - 1, &new_state);
+        if(!raw_mem_set)
+          MC_UNSET_RAW_MEM;
+        return new_state->other_num;
+        }*/
+      cursor = min;
+      while(cursor <= max){
+        state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, cursor, mc_visited_state_t);
+        if(snapshot_compare(state_test, new_state) == 0){
+          if(state_test->other_num == -1)
+            new_state->other_num = state_test->num;
+          else
+            new_state->other_num = state_test->other_num;
+          if(dot_output == NULL)
+            XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
+          else
+            XBT_DEBUG("State %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
+          xbt_dynar_remove_at(visited_states, cursor, NULL);
+          xbt_dynar_insert_at(visited_states, cursor, &new_state);
+          if(!raw_mem_set)
+            MC_UNSET_RAW_MEM;
+          return new_state->other_num;
+        }
+        cursor++;
+      }
+      xbt_dynar_insert_at(visited_states, min, &new_state);
+    }else{
+      state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, index, mc_visited_state_t);
+      if(state_test->nb_processes < new_state->nb_processes){
+        xbt_dynar_insert_at(visited_states, index+1, &new_state);
+      }else{
+        if(state_test->heap_bytes_used < new_state->heap_bytes_used)
+          xbt_dynar_insert_at(visited_states, index + 1, &new_state);
+        else
+          xbt_dynar_insert_at(visited_states, index, &new_state);
+      }
+    }
+
+    if(xbt_dynar_length(visited_states) > _sg_mc_visited){
+      int min2 = mc_stats->expanded_states;
+      unsigned int cursor2 = 0;
+      unsigned int index2 = 0;
+      xbt_dynar_foreach(visited_states, cursor2, state_test){
+        if(state_test->num < min2){
+          index2 = cursor2;
+          min2 = state_test->num;
+        }
+      }
+      xbt_dynar_remove_at(visited_states, index2, NULL);
+    }
+
+    if(!raw_mem_set)
+      MC_UNSET_RAW_MEM;
+    
+    return -1;
+    
+  }
+}
 
 /**
  *  \brief Initialize the DPOR exploration algorithm
  */
 void MC_dpor_init()
 {
 
 /**
  *  \brief Initialize the DPOR exploration algorithm
  */
 void MC_dpor_init()
 {
+  
+  int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
+
   mc_state_t initial_state = NULL;
   mc_state_t initial_state = NULL;
-  mc_transition_t trans, trans_tmp = NULL;
-  xbt_setset_cursor_t cursor = NULL;
+  smx_process_t process;
   
   /* Create the initial state and push it into the exploration stack */
   MC_SET_RAW_MEM;
   
   /* Create the initial state and push it into the exploration stack */
   MC_SET_RAW_MEM;
+
+  if(_sg_mc_visited > 0)
+    visited_states = xbt_dynar_new(sizeof(mc_visited_state_t), visited_state_free_voidp);
+
+  first_enabled_state = xbt_dict_new_homogeneous(&xbt_free_f);
+
+  initial_communications_pattern = xbt_dynar_new(sizeof(mc_comm_pattern_t), comm_pattern_free_voidp);
+  communications_pattern = xbt_dynar_new(sizeof(mc_comm_pattern_t), comm_pattern_free_voidp);
+  nb_comm_pattern = 0;
+
   initial_state = MC_state_new();
   initial_state = MC_state_new();
-  xbt_fifo_unshift(mc_stack, initial_state);
+
   MC_UNSET_RAW_MEM;
 
   MC_UNSET_RAW_MEM;
 
-  /* Schedule all the processes to detect the transitions of the initial state */
-  DEBUG0("**************************************************"); 
-  DEBUG0("Initial state");
+  XBT_DEBUG("**************************************************");
+  XBT_DEBUG("Initial state");
 
 
-  while(xbt_swag_size(simix_global->process_to_run)){
-    MC_schedule_enabled_processes();
-    MC_execute_surf_actions();
-  }
+  /* Wait for requests (schedules processes) */
+  MC_wait_for_requests();
+
+  MC_ignore_heap(simix_global->process_to_run->data, 0);
+  MC_ignore_heap(simix_global->process_that_ran->data, 0);
 
   MC_SET_RAW_MEM;
 
   MC_SET_RAW_MEM;
-  MC_trans_compute_enabled(initial_state->enabled_transitions,
-                           initial_state->transitions);
-
-  /* Fill the interleave set of the initial state with an enabled process */
-  trans = xbt_setset_set_choose(initial_state->enabled_transitions);  
-  if(trans){
-    DEBUG1("Choosing process %s for next interleave", trans->process->name);
-    xbt_setset_foreach(initial_state->enabled_transitions, cursor, trans_tmp){
-      if(trans_tmp->process == trans->process)
-        xbt_setset_set_insert(initial_state->interleave, trans_tmp);    
+  /* Get an enabled process and insert it in the interleave set of the initial state */
+  xbt_swag_foreach(process, simix_global->process_list){
+    if(MC_process_is_enabled(process)){
+      MC_state_interleave_process(initial_state, process);
+      if(mc_reduce_kind != e_mc_reduce_none)
+        break;
+    }
+  }
+
+  xbt_fifo_unshift(mc_stack_safety, initial_state);
+
+  /* To ensure the soundness of DPOR, we have to keep a list of 
+     processes which are still enabled at each step of the exploration. 
+     If max depth is reached, we interleave them in the state in which they have 
+     been enabled for the first time. */
+  xbt_swag_foreach(process, simix_global->process_list){
+    if(MC_process_is_enabled(process)){
+      char *key = bprintf("%lu", process->pid);
+      char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
+      xbt_dict_set(first_enabled_state, key, data, NULL);
+      xbt_free(key);
     }
   }
     }
   }
+
   MC_UNSET_RAW_MEM;
 
   MC_UNSET_RAW_MEM;
 
-  /* Update Statistics */
-  mc_stats->state_size += xbt_setset_set_size(initial_state->enabled_transitions);
+  if(raw_mem_set)
+    MC_SET_RAW_MEM;
+  else
+    MC_UNSET_RAW_MEM;
+  
 }
 
 
 /**
 }
 
 
 /**
- *     \brief Perform the model-checking operation using a depth-first search exploration
+ *   \brief Perform the model-checking operation using a depth-first search exploration
  *         with Dynamic Partial Order Reductions
  */
 void MC_dpor(void)
 {
  *         with Dynamic Partial Order Reductions
  */
 void MC_dpor(void)
 {
-  mc_transition_t trans, trans_tmp = NULL;  
-  mc_state_t next_state = NULL;
-  xbt_setset_cursor_t cursor = NULL;
-  
-  while(xbt_fifo_size(mc_stack) > 0){
-  
-    DEBUG0("**************************************************");
 
 
-    /* FIXME: Think about what happen if there are no transitions but there are
-       some actions on the models. (ex. all the processes do a sleep(0) in a round). */
+  char *req_str = NULL;
+  int value;
+  smx_simcall_t req = NULL, prev_req = NULL;
+  mc_state_t state = NULL, prev_state = NULL, next_state = NULL, restored_state=NULL;
+  smx_process_t process = NULL;
+  xbt_fifo_item_t item = NULL;
+  mc_state_t state_test = NULL;
+  int pos;
+  int visited_state = -1;
+  int enabled = 0;
+  int interleave_size = 0;
+  int comm_pattern = 0;
+
+  while (xbt_fifo_size(mc_stack_safety) > 0) {
 
     /* Get current state */
 
     /* Get current state */
-    mc_current_state = (mc_state_t) xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack));
-   
-    /* If there are transitions to execute and the maximun depth has not been reached 
-       then perform one step of the exploration algorithm */
-    if(xbt_setset_set_size(mc_current_state->interleave) > 0 && xbt_fifo_size(mc_stack) < MAX_DEPTH){
+    state = (mc_state_t) 
+      xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack_safety));
 
 
-      DEBUG4("Exploration detph=%d (state=%p)(%d interleave) (%d enabled)", xbt_fifo_size(mc_stack),
-        mc_current_state, xbt_setset_set_size(mc_current_state->interleave),
-        xbt_setset_set_size(mc_current_state->enabled_transitions));
-      
-      /* Update statistics */
-      mc_stats->visited_states++;
-      mc_stats->executed_transitions++;
+    XBT_DEBUG("**************************************************");
+    XBT_DEBUG("Exploration depth=%d (state=%p, num %d)(%u interleave, user_max_depth %d, first_enabled_state size : %d)",
+              xbt_fifo_size(mc_stack_safety), state, state->num,
+              MC_state_interleave_size(state), user_max_depth_reached, xbt_dict_size(first_enabled_state));
       
       
-      /* Choose a transition to execute from the interleave set of the current
-         state, and create the data structures for the new expanded state in the
-         exploration stack. */
-      MC_SET_RAW_MEM;
-      trans = xbt_setset_set_extract(mc_current_state->interleave);
+    interleave_size = MC_state_interleave_size(state);
 
 
-      /* Add the transition in the done set of the current state */
-      xbt_setset_set_insert(mc_current_state->done, trans);
-      
-      next_state = MC_state_new();
-      xbt_fifo_unshift(mc_stack, next_state);
+    /* Update statistics */
+    mc_stats->visited_states++;
+
+    /* If there are processes to interleave and the maximum depth has not been reached
+       then perform one step of the exploration algorithm */
+    if (xbt_fifo_size(mc_stack_safety) <= _sg_mc_max_depth && !user_max_depth_reached &&
+        (req = MC_state_get_request(state, &value)) && visited_state == -1) {
+
+      /* Debug information */
+      if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
+        req_str = MC_request_to_string(req, value);
+        XBT_DEBUG("Execute: %s", req_str);
+        xbt_free(req_str);
+      }
       
       
-      /* Set it as the executed transition of the current state */
-      mc_current_state->executed_transition = trans;
+      MC_SET_RAW_MEM;
+      if(dot_output != NULL)
+        req_str = MC_request_get_dot_output(req, value);
       MC_UNSET_RAW_MEM;
 
       MC_UNSET_RAW_MEM;
 
-      /* Execute the selected transition by scheduling it's associated process.
-         Then schedule every process that got ready to run due to the execution
-         of the transition */
-      DEBUG1("Executing transition %s", trans->name);
-      SIMIX_process_schedule(trans->process);
-      MC_execute_surf_actions();
+      MC_state_set_executed_request(state, req, value);
+      mc_stats->executed_transitions++;
+
+      MC_SET_RAW_MEM;
+      char *key = bprintf("%lu", req->issuer->pid);
+      xbt_dict_remove(first_enabled_state, key); 
+      xbt_free(key);
+      MC_UNSET_RAW_MEM;
       
       
-      while(xbt_swag_size(simix_global->process_to_run)){
-        MC_schedule_enabled_processes();
-        MC_execute_surf_actions();
+      if(_sg_mc_comms_determinism){
+        if(req->call == SIMCALL_COMM_ISEND)
+          comm_pattern = 1;
+        else if(req->call == SIMCALL_COMM_IRECV)
+          comm_pattern = 2;
       }
       }
-      
-      /* Calculate the enabled transitions set of the next state */
+
+      /* Answer the request */
+      SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
+
+      if(_sg_mc_comms_determinism){
+        MC_SET_RAW_MEM;
+        if(comm_pattern != 0){
+          if(!initial_state_safety->initial_communications_pattern_done)
+            get_comm_pattern(initial_communications_pattern, req, comm_pattern);
+          else
+            get_comm_pattern(communications_pattern, req, comm_pattern);
+        }
+        MC_UNSET_RAW_MEM; 
+        comm_pattern = 0;
+      }
+
+      /* Wait for requests (schedules processes) */
+      MC_wait_for_requests();
+
+      /* Create the new expanded state */
       MC_SET_RAW_MEM;
 
       MC_SET_RAW_MEM;
 
-      xbt_setset_foreach(mc_current_state->transitions, cursor, trans_tmp){
-        if(trans_tmp->process != trans->process){
-          xbt_setset_set_insert(next_state->transitions, trans_tmp);
+      next_state = MC_state_new();
+
+      if((visited_state = is_visited_state()) == -1){
+     
+        /* Get an enabled process and insert it in the interleave set of the next state */
+        xbt_swag_foreach(process, simix_global->process_list){
+          if(MC_process_is_enabled(process)){
+            MC_state_interleave_process(next_state, process);
+            if(mc_reduce_kind != e_mc_reduce_none)
+              break;
+          }
         }
         }
+
+        if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
+          next_state->system_state = MC_take_snapshot(next_state->num);
+        }
+
+        if(dot_output != NULL)
+          fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
+
+      }else{
+
+        if(dot_output != NULL)
+          fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
+
       }
       }
-      
-      MC_trans_compute_enabled(next_state->enabled_transitions, next_state->transitions);
-      
-      /* Choose one transition to interleave from the enabled transition set */      
-      trans = xbt_setset_set_choose(next_state->enabled_transitions);
-      if(trans){
-        DEBUG1("Choosing process %s for next interleave", trans->process->name);
-        xbt_setset_foreach(next_state->enabled_transitions, cursor, trans_tmp){
-          if(trans_tmp->process == trans->process)
-            xbt_setset_set_insert(next_state->interleave, trans_tmp);    
+
+      xbt_fifo_unshift(mc_stack_safety, next_state);
+
+      /* Insert in dict all enabled processes, if not included yet */
+      xbt_swag_foreach(process, simix_global->process_list){
+        if(MC_process_is_enabled(process)){
+          char *key = bprintf("%lu", process->pid);
+          if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
+            char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
+            xbt_dict_set(first_enabled_state, key, data, NULL); 
+          }
+          xbt_free(key);
         }
       }
         }
       }
-      MC_UNSET_RAW_MEM;
+      
+      if(dot_output != NULL)
+        xbt_free(req_str);
 
 
-      /* Update Statistics */
-      mc_stats->state_size += xbt_setset_set_size(next_state->enabled_transitions);
+      MC_UNSET_RAW_MEM;
 
       /* Let's loop again */
 
       /* Let's loop again */
-      
-    /* The interleave set is empty or the maximum depth is reached, let's back-track */
-    }else{
-      DEBUG0("There are no more transitions to interleave.");
 
 
-  
-      /* Check for deadlocks */
-      xbt_setset_substract(mc_current_state->transitions, mc_current_state->done);
-      if(xbt_setset_set_size(mc_current_state->transitions) > 0){
-        INFO0("**************************");
-        INFO0("*** DEAD-LOCK DETECTED ***");
-        INFO0("**************************");
-        INFO0("Locked transitions:");
-        xbt_setset_foreach(mc_current_state->transitions, cursor, trans){
-          INFO3("%s [src=%p, dst=%p]", trans->name, trans->wait.comm->src_proc,
-                trans->wait.comm->dst_proc);
+      /* The interleave set is empty or the maximum depth is reached, let's back-track */
+    } else {
+
+      if((xbt_fifo_size(mc_stack_safety) > _sg_mc_max_depth) || user_max_depth_reached || visited_state != -1){  
+
+        if(user_max_depth_reached && visited_state == -1)
+          XBT_DEBUG("User max depth reached !");
+        else if(visited_state == -1)
+          XBT_WARN("/!\\ Max depth reached ! /!\\ ");
+
+        visited_state = -1;
+
+        /* Interleave enabled processes in the state in which they have been enabled for the first time */
+        xbt_swag_foreach(process, simix_global->process_list){
+          if(MC_process_is_enabled(process)){
+            char *key = bprintf("%lu", process->pid);
+            enabled = (int)strtoul(xbt_dict_get_or_null(first_enabled_state, key), 0, 10);
+            xbt_free(key);
+            int cursor = xbt_fifo_size(mc_stack_safety);
+            xbt_fifo_foreach(mc_stack_safety, item, state_test, mc_state_t){
+              if(cursor-- == enabled){ 
+                if(!MC_state_process_is_done(state_test, process) && state_test->num != state->num){ 
+                  XBT_DEBUG("Interleave process %lu in state %d", process->pid, state_test->num);
+                  MC_state_interleave_process(state_test, process);
+                  break;
+                }
+              }
+            }
+          }
         }
 
         }
 
-        INFO0("Counter-example execution trace:");
-        MC_dump_stack(mc_stack);
-        
-        MC_print_statistics(mc_stats);
-        xbt_abort();
+      }else{
+
+        XBT_DEBUG("There are no more processes to interleave. (depth %d)", xbt_fifo_size(mc_stack_safety) + 1);
+
       }
       }
-              
-      mc_transition_t q = NULL;
-      xbt_fifo_item_t item = NULL;
-      mc_state_t state = NULL;
-
-      /*
-      INFO0("*********************************");
-      MC_show_stack(mc_stack);*/
-      
-      /* Trash the current state, no longer needed */
+
       MC_SET_RAW_MEM;
       MC_SET_RAW_MEM;
-      xbt_fifo_shift(mc_stack);
-      MC_state_delete(mc_current_state);
+
+      if(_sg_mc_comms_determinism){
+        if(!initial_state_safety->initial_communications_pattern_done){
+          //print_communications_pattern(initial_communications_pattern);
+        }else{
+          if(interleave_size == 0){ /* if (interleave_size > 0), process interleaved but not enabled => "incorrect" path, determinism not evaluated */
+            //print_communications_pattern(communications_pattern);
+            deterministic_pattern(initial_communications_pattern, communications_pattern);
+          }
+        }
+        initial_state_safety->initial_communications_pattern_done = 1;
+      }
+
+      /* Trash the current state, no longer needed */
+      xbt_fifo_shift(mc_stack_safety);
+      MC_state_delete(state);
+      XBT_DEBUG("Delete state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
+
+      MC_UNSET_RAW_MEM;        
       
       
+      /* Check for deadlocks */
+      if(MC_deadlock_check()){
+        MC_show_deadlock(NULL);
+        return;
+      }
+
+      MC_SET_RAW_MEM;
       /* Traverse the stack backwards until a state with a non empty interleave
          set is found, deleting all the states that have it empty in the way.
       /* Traverse the stack backwards until a state with a non empty interleave
          set is found, deleting all the states that have it empty in the way.
-         For each deleted state, check if the transition that has generated it 
-         (from it's predecesor state), depends on any other previous transition 
+         For each deleted state, check if the request that has generated it 
+         (from it's predecesor state), depends on any other previous request 
          executed before it. If it does then add it to the interleave set of the
          executed before it. If it does then add it to the interleave set of the
-         state that executed that previous transition. */
-      while((mc_current_state = xbt_fifo_shift(mc_stack)) != NULL){
-        q = mc_current_state->executed_transition;
-        xbt_fifo_foreach(mc_stack, item, state, mc_state_t){
-          if(MC_transition_depend(q, state->executed_transition)){
-            xbt_setset_foreach(state->enabled_transitions, cursor, trans){
-              if((trans->process == q->process) && !xbt_setset_set_belongs(state->done, trans)){
-                DEBUG3("%s depend with %s at %p", q->name, 
-                       state->executed_transition->name, state);
-
-                xbt_setset_foreach(state->enabled_transitions, cursor, trans){
-                  if(trans->process == q->process)
-                    xbt_setset_set_insert(state->interleave, trans);    
-                }
-                /* FIXME: hack to make it work*/
-                trans = q;
-                break;
+         state that executed that previous request. */
+      
+      while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
+        if(mc_reduce_kind != e_mc_reduce_none){
+          req = MC_state_get_internal_request(state);
+          xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
+            if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
+              if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
+                XBT_DEBUG("Dependent Transitions:");
+                prev_req = MC_state_get_executed_request(prev_state, &value);
+                req_str = MC_request_to_string(prev_req, value);
+                XBT_DEBUG("%s (state=%d)", req_str, prev_state->num);
+                xbt_free(req_str);
+                prev_req = MC_state_get_executed_request(state, &value);
+                req_str = MC_request_to_string(prev_req, value);
+                XBT_DEBUG("%s (state=%d)", req_str, state->num);
+                xbt_free(req_str);              
               }
               }
-            }
-            if(trans)
+
+              if(!MC_state_process_is_done(prev_state, req->issuer))
+                MC_state_interleave_process(prev_state, req->issuer);
+              else
+                XBT_DEBUG("Process %p is in done set", req->issuer);
+
               break;
               break;
+
+            }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
+
+              XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
+              break;
+
+            }else{
+
+              XBT_DEBUG("Simcall %d, process %lu (state %d) and simcall %d, process %lu (state %d) are independant", req->call, req->issuer->pid, state->num, MC_state_get_internal_request(prev_state)->call, MC_state_get_internal_request(prev_state)->issuer->pid, prev_state->num);
+
+            }
           }
         }
           }
         }
-        if(xbt_setset_set_size(mc_current_state->interleave) > 0){
+             
+        if (MC_state_interleave_size(state) && xbt_fifo_size(mc_stack_safety) < _sg_mc_max_depth) {
           /* We found a back-tracking point, let's loop */
           /* We found a back-tracking point, let's loop */
-          xbt_fifo_unshift(mc_stack, mc_current_state);
-          DEBUG1("Back-tracking to depth %d", xbt_fifo_size(mc_stack));
-          MC_replay(mc_stack);
-          MC_UNSET_RAW_MEM;
+          XBT_DEBUG("Back-tracking to state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
+          if(_sg_mc_checkpoint){
+            if(state->system_state != NULL){
+              MC_restore_snapshot(state->system_state);
+              xbt_fifo_unshift(mc_stack_safety, state);
+              MC_UNSET_RAW_MEM;
+            }else{
+              pos = xbt_fifo_size(mc_stack_safety);
+              item = xbt_fifo_get_first_item(mc_stack_safety);
+              while(pos>0){
+                restored_state = (mc_state_t) xbt_fifo_get_item_content(item);
+                if(restored_state->system_state != NULL){
+                  break;
+                }else{
+                  item = xbt_fifo_get_next_item(item);
+                  pos--;
+                }
+              }
+              MC_restore_snapshot(restored_state->system_state);
+              xbt_fifo_unshift(mc_stack_safety, state);
+              MC_UNSET_RAW_MEM;
+              MC_replay(mc_stack_safety, pos);
+            }
+          }else{
+            xbt_fifo_unshift(mc_stack_safety, state);
+            MC_UNSET_RAW_MEM;
+            MC_replay(mc_stack_safety, -1);
+          }
+          XBT_DEBUG("Back-tracking to state %d at depth %d done", state->num, xbt_fifo_size(mc_stack_safety));
           break;
           break;
-        }else{
-          MC_state_delete(mc_current_state);
-        }        
+        } else {
+          req = MC_state_get_internal_request(state);
+          if(_sg_mc_comms_determinism){
+            if(req->call == SIMCALL_COMM_ISEND || req->call == SIMCALL_COMM_IRECV){
+              if(!xbt_dynar_is_empty(communications_pattern))
+                xbt_dynar_remove_at(communications_pattern, xbt_dynar_length(communications_pattern) - 1, NULL);
+            }
+          }
+          XBT_DEBUG("Delete state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1); 
+          MC_state_delete(state);
+        }
       }
       }
+      MC_UNSET_RAW_MEM;
     }
   }
     }
   }
-  DEBUG0("We are done");
-  /* We are done, show the statistics and return */
   MC_print_statistics(mc_stats);
   MC_print_statistics(mc_stats);
-}
\ No newline at end of file
+  MC_UNSET_RAW_MEM;  
+
+  return;
+}
+
+
+
+