src/mc/mc_dpor.c

   1 /* Copyright (c) 2008-2013. Da 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_private.h"
   7
   8 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dpor, mc,
   9                                 "Logging specific to MC DPOR exploration");
  10
  11 xbt_dynar_t visited_states;
  12 xbt_dict_t first_enabled_state;
  13
  14 static void visited_state_free(mc_visited_state_t state){
  15   if(state){
  16     MC_free_snapshot(state->system_state);
  17     xbt_free(state);
  18   }
  19 }
  20
  21 static void visited_state_free_voidp(void *s){
  22   visited_state_free((mc_visited_state_t) * (void **) s);
  23 }
  24
  25 static mc_visited_state_t visited_state_new(){
  26
  27   mc_visited_state_t new_state = NULL;
  28   new_state = xbt_new0(s_mc_visited_state_t, 1);
  29   new_state->heap_bytes_used = mmalloc_get_bytes_used(std_heap);
  30   new_state->nb_processes = xbt_swag_size(simix_global->process_list);
  31   new_state->system_state = MC_take_snapshot();
  32   new_state->num = mc_stats->expanded_states - 1;
  33
  34   return new_state;
  35
  36 }
  37
  38 /* Dichotomic search in visited_states dynar.
  39  * States are ordered by the number of processes then the number of bytes used in std_heap */
  40
  41 static int is_visited_state(){
  42
  43   if(_sg_mc_visited == 0)
  44     return -1;
  45
  46   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
  47
  48   MC_SET_RAW_MEM;
  49   mc_visited_state_t new_state = visited_state_new();
  50   MC_UNSET_RAW_MEM;
  51
  52   if(xbt_dynar_is_empty(visited_states)){
  53
  54     MC_SET_RAW_MEM;
  55     xbt_dynar_push(visited_states, &new_state);
  56     MC_UNSET_RAW_MEM;
  57
  58     if(raw_mem_set)
  59       MC_SET_RAW_MEM;
  60
  61     return -1;
  62
  63   }else{
  64
  65     MC_SET_RAW_MEM;
  66
  67     size_t current_bytes_used = new_state->heap_bytes_used;
  68     int current_nb_processes = new_state->nb_processes;
  69
  70     unsigned int cursor = 0;
  71     int previous_cursor = 0, next_cursor = 0;
  72     int start = 0;
  73     int end = xbt_dynar_length(visited_states) - 1;
  74
  75     mc_visited_state_t state_test = NULL;
  76     size_t bytes_used_test;
  77     int nb_processes_test;
  78     int same_processes_and_bytes_not_found = 1;
  79
  80     while(start <= end && same_processes_and_bytes_not_found){
  81       cursor = (start + end) / 2;
  82       state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, cursor, mc_visited_state_t);
  83       bytes_used_test = state_test->heap_bytes_used;
  84       nb_processes_test = state_test->nb_processes;
  85       if(nb_processes_test < current_nb_processes)
  86         start = cursor + 1;
  87       if(nb_processes_test > current_nb_processes)
  88         end = cursor - 1;
  89       if(nb_processes_test == current_nb_processes){
  90         if(bytes_used_test < current_bytes_used)
  91           start = cursor + 1;
  92         if(bytes_used_test > current_bytes_used)
  93           end = cursor - 1;
  94         if(bytes_used_test == current_bytes_used){
  95           same_processes_and_bytes_not_found = 0;
  96           if(snapshot_compare(new_state->system_state, state_test->system_state) == 0){
  97             xbt_dynar_remove_at(visited_states, cursor, NULL);
  98             xbt_dynar_insert_at(visited_states, cursor, &new_state);
  99             XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
 100             if(raw_mem_set)
 101               MC_SET_RAW_MEM;
 102             else
 103               MC_UNSET_RAW_MEM;
 104             return state_test->num;
 105           }else{
 106             /* Search another state with same number of bytes used in std_heap */
 107             previous_cursor = cursor - 1;
 108             while(previous_cursor >= 0){
 109               state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, previous_cursor, mc_visited_state_t);
 110               bytes_used_test = state_test->system_state->heap_bytes_used;
 111               if(bytes_used_test != current_bytes_used)
 112                 break;
 113               if(snapshot_compare(new_state->system_state, state_test->system_state) == 0){
 114                 xbt_dynar_remove_at(visited_states, previous_cursor, NULL);
 115                 xbt_dynar_insert_at(visited_states, previous_cursor, &new_state);
 116                 XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
 117                 if(raw_mem_set)
 118                   MC_SET_RAW_MEM;
 119                 else
 120                   MC_UNSET_RAW_MEM;
 121                 return state_test->num;
 122               }
 123               previous_cursor--;
 124             }
 125             next_cursor = cursor + 1;
 126             while(next_cursor < xbt_dynar_length(visited_states)){
 127               state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, next_cursor, mc_visited_state_t);
 128               bytes_used_test = state_test->system_state->heap_bytes_used;
 129               if(bytes_used_test != current_bytes_used)
 130                 break;
 131               if(snapshot_compare(new_state->system_state, state_test->system_state) == 0){
 132                 xbt_dynar_remove_at(visited_states, next_cursor, NULL);
 133                 xbt_dynar_insert_at(visited_states, next_cursor, &new_state);
 134                 XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
 135                 if(raw_mem_set)
 136                   MC_SET_RAW_MEM;
 137                 else
 138                   MC_UNSET_RAW_MEM;
 139                 return state_test->num;
 140               }
 141               next_cursor++;
 142             }
 143           }
 144         }
 145       }
 146     }
 147
 148     state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, cursor, mc_visited_state_t);
 149     bytes_used_test = state_test->heap_bytes_used;
 150
 151     if(bytes_used_test < current_bytes_used)
 152       xbt_dynar_insert_at(visited_states, cursor + 1, &new_state);
 153     else
 154       xbt_dynar_insert_at(visited_states, cursor, &new_state);
 155
 156     if(xbt_dynar_length(visited_states) > _sg_mc_visited){
 157       int min = mc_stats->expanded_states;
 158       unsigned int cursor2 = 0;
 159       unsigned int index = 0;
 160       xbt_dynar_foreach(visited_states, cursor2, state_test){
 161         if(state_test->num < min){
 162           index = cursor2;
 163           min = state_test->num;
 164         }
 165       }
 166       xbt_dynar_remove_at(visited_states, index, NULL);
 167     }
 168
 169     MC_UNSET_RAW_MEM;
 170
 171     if(raw_mem_set)
 172       MC_SET_RAW_MEM;
 173
 174     return -1;
 175
 176   }
 177 }
 178
 179 /**
 180  *  \brief Initialize the DPOR exploration algorithm
 181  */
 182 void MC_dpor_init()
 183 {
 184
 185   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
 186
 187   mc_state_t initial_state = NULL;
 188   smx_process_t process;
 189
 190   /* Create the initial state and push it into the exploration stack */
 191   MC_SET_RAW_MEM;
 192
 193   initial_state = MC_state_new();
 194   visited_states = xbt_dynar_new(sizeof(mc_visited_state_t), visited_state_free_voidp);
 195
 196   first_enabled_state = xbt_dict_new_homogeneous(&xbt_free_f);
 197
 198   MC_UNSET_RAW_MEM;
 199
 200   XBT_DEBUG("**************************************************");
 201   XBT_DEBUG("Initial state");
 202
 203   /* Wait for requests (schedules processes) */
 204   MC_wait_for_requests();
 205
 206   MC_SET_RAW_MEM;
 207
 208   /* Get an enabled process and insert it in the interleave set of the initial state */
 209   xbt_swag_foreach(process, simix_global->process_list){
 210     if(MC_process_is_enabled(process)){
 211       MC_state_interleave_process(initial_state, process);
 212       if(mc_reduce_kind != e_mc_reduce_none)
 213         break;
 214     }
 215   }
 216
 217   xbt_fifo_unshift(mc_stack_safety, initial_state);
 218
 219   /* To ensure the soundness of DPOR, we have to keep a list of
 220      processes which are still enabled at each step of the exploration.
 221      If max depth is reached, we interleave them in the state in which they have
 222      been enabled for the first time. */
 223   xbt_swag_foreach(process, simix_global->process_list){
 224     if(MC_process_is_enabled(process)){
 225       char *key = bprintf("%lu", process->pid);
 226       char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 227       xbt_dict_set(first_enabled_state, key, data, NULL);
 228       xbt_free(key);
 229     }
 230   }
 231
 232   MC_UNSET_RAW_MEM;
 233
 234   if(raw_mem_set)
 235     MC_SET_RAW_MEM;
 236   else
 237     MC_UNSET_RAW_MEM;
 238
 239 }
 240
 241
 242 /**
 243  *   \brief Perform the model-checking operation using a depth-first search exploration
 244  *         with Dynamic Partial Order Reductions
 245  */
 246 void MC_dpor(void)
 247 {
 248
 249   char *req_str;
 250   int value, value2;
 251   smx_simcall_t req = NULL, prev_req = NULL, req2 = NULL;
 252   s_smx_simcall_t req3;
 253   mc_state_t state = NULL, prev_state = NULL, next_state = NULL, restore_state=NULL;
 254   smx_process_t process = NULL;
 255   xbt_fifo_item_t item = NULL;
 256   int pos;
 257   int visited_state;
 258   int enabled = 0;
 259
 260
 261   while (xbt_fifo_size(mc_stack_safety) > 0) {
 262
 263     /* Get current state */
 264     state = (mc_state_t)
 265       xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack_safety));
 266
 267     XBT_DEBUG("**************************************************");
 268     XBT_DEBUG("Exploration depth=%d (state=%p)(%u interleave)",
 269               xbt_fifo_size(mc_stack_safety), state,
 270               MC_state_interleave_size(state));
 271
 272     /* Update statistics */
 273     mc_stats->visited_states++;
 274
 275     /* If there are processes to interleave and the maximum depth has not been reached
 276        then perform one step of the exploration algorithm */
 277     if (xbt_fifo_size(mc_stack_safety) <= _sg_mc_max_depth &&
 278         (req = MC_state_get_request(state, &value))) {
 279
 280       /* Debug information */
 281       if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 282         req_str = MC_request_to_string(req, value);
 283         XBT_DEBUG("Execute: %s", req_str);
 284         xbt_free(req_str);
 285       }
 286
 287       req_str = MC_request_get_dot_output(req, value);
 288
 289       MC_state_set_executed_request(state, req, value);
 290       mc_stats->executed_transitions++;
 291
 292       MC_SET_RAW_MEM;
 293       char *key = bprintf("%lu", req->issuer->pid);
 294       xbt_dict_remove(first_enabled_state, key);
 295       xbt_free(key);
 296       MC_UNSET_RAW_MEM;
 297
 298       MC_state_set_executed_request(state, req, value);
 299
 300       /* Answer the request */
 301       SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
 302
 303       /* Wait for requests (schedules processes) */
 304       MC_wait_for_requests();
 305
 306       /* Create the new expanded state */
 307       MC_SET_RAW_MEM;
 308
 309       next_state = MC_state_new();
 310
 311       if((visited_state = is_visited_state()) == -1){
 312
 313         /* Get an enabled process and insert it in the interleave set of the next state */
 314         xbt_swag_foreach(process, simix_global->process_list){
 315           if(MC_process_is_enabled(process)){
 316             MC_state_interleave_process(next_state, process);
 317             if(mc_reduce_kind != e_mc_reduce_none)
 318               break;
 319           }
 320         }
 321
 322         if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
 323           next_state->system_state = MC_take_snapshot();
 324         }
 325
 326         if(dot_output != NULL)
 327           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
 328
 329       }else{
 330
 331         if(dot_output != NULL)
 332           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
 333
 334       }
 335
 336       xbt_fifo_unshift(mc_stack_safety, next_state);
 337
 338       /* Insert in dict all enabled processes, if not included yet */
 339       xbt_swag_foreach(process, simix_global->process_list){
 340         if(MC_process_is_enabled(process)){
 341           char *key = bprintf("%lu", process->pid);
 342           if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
 343             char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 344             xbt_dict_set(first_enabled_state, key, data, NULL);
 345           }
 346           xbt_free(key);
 347         }
 348       }
 349
 350       MC_UNSET_RAW_MEM;
 351
 352       xbt_free(req_str);
 353
 354       /* Let's loop again */
 355
 356       /* The interleave set is empty or the maximum depth is reached, let's back-track */
 357     } else {
 358
 359       if(xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth)
 360         XBT_WARN("/!\\ Max depth reached ! /!\\ ");
 361       else
 362         XBT_DEBUG("There are no more processes to interleave.");
 363
 364       /* Trash the current state, no longer needed */
 365       MC_SET_RAW_MEM;
 366       xbt_fifo_shift(mc_stack_safety);
 367       MC_state_delete(state);
 368       MC_UNSET_RAW_MEM;
 369
 370       /* Check for deadlocks */
 371       if(MC_deadlock_check()){
 372         MC_show_deadlock(NULL);
 373         return;
 374       }
 375
 376       MC_SET_RAW_MEM;
 377       /* Traverse the stack backwards until a state with a non empty interleave
 378          set is found, deleting all the states that have it empty in the way.
 379          For each deleted state, check if the request that has generated it
 380          (from it's predecesor state), depends on any other previous request
 381          executed before it. If it does then add it to the interleave set of the
 382          state that executed that previous request. */
 383
 384       while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
 385         if(mc_reduce_kind != e_mc_reduce_none){
 386           req = MC_state_get_internal_request(state);
 387           /* If max_depth reached, check only for the last state if the request that has generated
 388              it, depends on any other processes still enabled when max_depth reached */
 389           if(xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth - 1){
 390             req3 = *req;
 391             xbt_swag_foreach(process, simix_global->process_list){
 392               if(MC_process_is_enabled(process) && !MC_state_process_is_done(state, process)){
 393                 MC_state_interleave_process(state, process);
 394                 req2 = MC_state_get_request(state, &value2);
 395                 MC_state_set_executed_request(state, req2, value2);
 396                 req2 = MC_state_get_internal_request(state);
 397                 if(MC_request_depend(&req3, req2)){
 398                   if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 399                     XBT_DEBUG("Dependent Transitions:");
 400                     req_str = MC_request_to_string(&req3, value);
 401                     XBT_DEBUG("%s (state=%p)", req_str, state);
 402                     xbt_free(req_str);
 403                     req_str = MC_request_to_string(req2, value);
 404                     XBT_DEBUG("%s (state=%p)", req_str, state);
 405                     xbt_free(req_str);
 406                   }
 407                   MC_state_interleave_process(state, process);
 408                   break;
 409                 }
 410               }
 411             }
 412           }
 413           xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
 414             if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
 415               if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 416                 XBT_DEBUG("Dependent Transitions:");
 417                 prev_req = MC_state_get_executed_request(prev_state, &value);
 418                 req_str = MC_request_to_string(prev_req, value);
 419                 XBT_DEBUG("%s (state=%p)", req_str, prev_state);
 420                 xbt_free(req_str);
 421                 prev_req = MC_state_get_executed_request(state, &value);
 422                 req_str = MC_request_to_string(prev_req, value);
 423                 XBT_DEBUG("%s (state=%p)", req_str, state);
 424                 xbt_free(req_str);
 425               }
 426
 427               if(!MC_state_process_is_done(prev_state, req->issuer))
 428                 MC_state_interleave_process(prev_state, req->issuer);
 429               else
 430                 XBT_DEBUG("Process %p is in done set", req->issuer);
 431
 432               break;
 433
 434             }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
 435
 436               XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
 437               break;
 438
 439             }
 440           }
 441         }
 442
 443         if (MC_state_interleave_size(state)) {
 444           /* We found a back-tracking point, let's loop */
 445           if(_sg_mc_checkpoint){
 446             if(state->system_state != NULL){
 447               MC_restore_snapshot(state->system_state);
 448               xbt_fifo_unshift(mc_stack_safety, state);
 449               MC_UNSET_RAW_MEM;
 450             }else{
 451               pos = xbt_fifo_size(mc_stack_safety);
 452               item = xbt_fifo_get_first_item(mc_stack_safety);
 453               while(pos>0){
 454                 restore_state = (mc_state_t) xbt_fifo_get_item_content(item);
 455                 if(restore_state->system_state != NULL){
 456                   break;
 457                 }else{
 458                   item = xbt_fifo_get_next_item(item);
 459                   pos--;
 460                 }
 461               }
 462               MC_restore_snapshot(restore_state->system_state);
 463               xbt_fifo_unshift(mc_stack_safety, state);
 464               MC_UNSET_RAW_MEM;
 465               MC_replay(mc_stack_safety, pos);
 466             }
 467           }else{
 468             xbt_fifo_unshift(mc_stack_safety, state);
 469             MC_UNSET_RAW_MEM;
 470             MC_replay(mc_stack_safety, -1);
 471           }
 472           XBT_DEBUG("Back-tracking to depth %d", xbt_fifo_size(mc_stack_safety));
 473           break;
 474         } else {
 475           MC_state_delete(state);
 476         }
 477       }
 478       MC_UNSET_RAW_MEM;
 479     }
 480   }
 481   MC_print_statistics(mc_stats);
 482   MC_UNSET_RAW_MEM;
 483
 484   return;
 485 }
 486
 487
 488
 489