src/mc/mc_dpor.c

   1 /* Copyright (c) 2008-2013. The SimGrid Team.
   2  * All rights reserved.                                                     */
   3
   4 /* This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the license (GNU LGPL) which comes with this package. */
   6
   7 #include "mc_private.h"
   8
   9 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dpor, mc,
  10                                 "Logging specific to MC DPOR exploration");
  11
  12 xbt_dynar_t visited_states;
  13 xbt_dict_t first_enabled_state;
  14
  15 static void visited_state_free(mc_visited_state_t state){
  16   if(state){
  17     MC_free_snapshot(state->system_state);
  18     xbt_free(state);
  19   }
  20 }
  21
  22 static void visited_state_free_voidp(void *s){
  23   visited_state_free((mc_visited_state_t) * (void **) s);
  24 }
  25
  26 static mc_visited_state_t visited_state_new(){
  27
  28   mc_visited_state_t new_state = NULL;
  29   new_state = xbt_new0(s_mc_visited_state_t, 1);
  30   new_state->heap_bytes_used = mmalloc_get_bytes_used(std_heap);
  31   new_state->nb_processes = xbt_swag_size(simix_global->process_list);
  32   new_state->system_state = MC_take_snapshot();
  33   new_state->num = mc_stats->expanded_states;
  34   new_state->other_num = -1;
  35
  36   return new_state;
  37
  38 }
  39
  40 /* Dichotomic search in visited_states dynar.
  41  * States are ordered by the number of processes then the number of bytes used in std_heap */
  42
  43 static int is_visited_state(){
  44
  45   if(_sg_mc_visited == 0)
  46     return -1;
  47
  48   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
  49
  50   MC_SET_RAW_MEM;
  51   mc_visited_state_t new_state = visited_state_new();
  52   MC_UNSET_RAW_MEM;
  53
  54   if(xbt_dynar_is_empty(visited_states)){
  55
  56     MC_SET_RAW_MEM;
  57     xbt_dynar_push(visited_states, &new_state);
  58     MC_UNSET_RAW_MEM;
  59
  60     if(raw_mem_set)
  61       MC_SET_RAW_MEM;
  62
  63     return -1;
  64
  65   }else{
  66
  67     MC_SET_RAW_MEM;
  68
  69     size_t current_bytes_used = new_state->heap_bytes_used;
  70     int current_nb_processes = new_state->nb_processes;
  71
  72     unsigned int cursor = 0;
  73     int previous_cursor = 0, next_cursor = 0;
  74     int start = 0;
  75     int end = xbt_dynar_length(visited_states) - 1;
  76
  77     mc_visited_state_t state_test = NULL;
  78     size_t bytes_used_test;
  79     int nb_processes_test;
  80     int same_processes_and_bytes_not_found = 1;
  81
  82     while(start <= end && same_processes_and_bytes_not_found){
  83       cursor = (start + end) / 2;
  84       state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, cursor, mc_visited_state_t);
  85       bytes_used_test = state_test->heap_bytes_used;
  86       nb_processes_test = state_test->nb_processes;
  87       if(nb_processes_test < current_nb_processes){
  88         start = cursor + 1;
  89       }else if(nb_processes_test > current_nb_processes){
  90         end = cursor - 1;
  91       }else if(nb_processes_test == current_nb_processes){
  92         if(bytes_used_test < current_bytes_used)
  93           start = cursor + 1;
  94         if(bytes_used_test > current_bytes_used)
  95           end = cursor - 1;
  96         if(bytes_used_test == current_bytes_used){
  97           same_processes_and_bytes_not_found = 0;
  98           if(snapshot_compare(new_state->system_state, state_test->system_state) == 0){
  99             if(state_test->other_num == -1)
 100               new_state->other_num = state_test->num;
 101             else
 102               new_state->other_num = state_test->other_num;
 103             if(dot_output == NULL)
 104               XBT_DEBUG("Next state %d already visited ! (equal to state %d)", new_state->num, state_test->num);
 105             else
 106               XBT_DEBUG("Next state %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
 107             xbt_dynar_remove_at(visited_states, cursor, NULL);
 108             xbt_dynar_insert_at(visited_states, cursor, &new_state);
 109             if(raw_mem_set)
 110               MC_SET_RAW_MEM;
 111             else
 112               MC_UNSET_RAW_MEM;
 113             return new_state->other_num;
 114           }else{
 115             /* Search another state with same number of bytes used in std_heap */
 116             previous_cursor = cursor - 1;
 117             while(previous_cursor >= 0){
 118               state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, previous_cursor, mc_visited_state_t);
 119               bytes_used_test = state_test->system_state->heap_bytes_used;
 120               if(bytes_used_test != current_bytes_used)
 121                 break;
 122               if(snapshot_compare(new_state->system_state, state_test->system_state) == 0){
 123                 if(state_test->other_num == -1)
 124                   new_state->other_num = state_test->num;
 125                 else
 126                   new_state->other_num = state_test->other_num;
 127                 if(dot_output == NULL)
 128                   XBT_DEBUG("Next state %d already visited ! (equal to state %d)", new_state->num, state_test->num);
 129                 else
 130                   XBT_DEBUG("Next state %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
 131                 xbt_dynar_remove_at(visited_states, previous_cursor, NULL);
 132                 xbt_dynar_insert_at(visited_states, cursor, &new_state);
 133                 if(raw_mem_set)
 134                   MC_SET_RAW_MEM;
 135                 else
 136                   MC_UNSET_RAW_MEM;
 137                 return new_state->other_num;
 138               }
 139               previous_cursor--;
 140             }
 141             next_cursor = cursor + 1;
 142             while(next_cursor < xbt_dynar_length(visited_states)){
 143               state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, next_cursor, mc_visited_state_t);
 144               bytes_used_test = state_test->system_state->heap_bytes_used;
 145               if(bytes_used_test != current_bytes_used)
 146                 break;
 147               if(snapshot_compare(new_state->system_state, state_test->system_state) == 0){
 148                 if(state_test->other_num == -1)
 149                   new_state->other_num = state_test->num;
 150                 else
 151                   new_state->other_num = state_test->other_num;
 152                 if(dot_output == NULL)
 153                   XBT_DEBUG("Next state %d already visited ! (equal to state %d)", new_state->num, state_test->num);
 154                 else
 155                   XBT_DEBUG("Next state %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
 156                 xbt_dynar_remove_at(visited_states, next_cursor, NULL);
 157                 xbt_dynar_insert_at(visited_states, next_cursor, &new_state);
 158                 if(raw_mem_set)
 159                   MC_SET_RAW_MEM;
 160                 else
 161                   MC_UNSET_RAW_MEM;
 162                 return new_state->other_num;
 163               }
 164               next_cursor++;
 165             }
 166           }
 167         }
 168       }
 169     }
 170
 171     state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, cursor, mc_visited_state_t);
 172     bytes_used_test = state_test->heap_bytes_used;
 173
 174     if(bytes_used_test < current_bytes_used)
 175       xbt_dynar_insert_at(visited_states, cursor + 1, &new_state);
 176     else
 177       xbt_dynar_insert_at(visited_states, cursor, &new_state);
 178
 179     if(xbt_dynar_length(visited_states) > _sg_mc_visited){
 180       int min = mc_stats->expanded_states;
 181       unsigned int cursor2 = 0;
 182       unsigned int index = 0;
 183       xbt_dynar_foreach(visited_states, cursor2, state_test){
 184         if(state_test->num < min){
 185           index = cursor2;
 186           min = state_test->num;
 187         }
 188       }
 189       xbt_dynar_remove_at(visited_states, index, NULL);
 190     }
 191
 192     MC_UNSET_RAW_MEM;
 193
 194     if(raw_mem_set)
 195       MC_SET_RAW_MEM;
 196
 197     return -1;
 198
 199   }
 200 }
 201
 202 /**
 203  *  \brief Initialize the DPOR exploration algorithm
 204  */
 205 void MC_dpor_init()
 206 {
 207
 208   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
 209
 210   mc_state_t initial_state = NULL;
 211   smx_process_t process;
 212
 213   /* Create the initial state and push it into the exploration stack */
 214   MC_SET_RAW_MEM;
 215
 216   initial_state = MC_state_new();
 217   visited_states = xbt_dynar_new(sizeof(mc_visited_state_t), visited_state_free_voidp);
 218
 219   first_enabled_state = xbt_dict_new_homogeneous(&xbt_free_f);
 220
 221   MC_UNSET_RAW_MEM;
 222
 223   XBT_DEBUG("**************************************************");
 224   XBT_DEBUG("Initial state");
 225
 226   /* Wait for requests (schedules processes) */
 227   MC_wait_for_requests();
 228
 229   MC_SET_RAW_MEM;
 230
 231   /* Get an enabled process and insert it in the interleave set of the initial state */
 232   xbt_swag_foreach(process, simix_global->process_list){
 233     if(MC_process_is_enabled(process)){
 234       MC_state_interleave_process(initial_state, process);
 235       if(mc_reduce_kind != e_mc_reduce_none)
 236         break;
 237     }
 238   }
 239
 240   xbt_fifo_unshift(mc_stack_safety, initial_state);
 241
 242   /* To ensure the soundness of DPOR, we have to keep a list of
 243      processes which are still enabled at each step of the exploration.
 244      If max depth is reached, we interleave them in the state in which they have
 245      been enabled for the first time. */
 246   xbt_swag_foreach(process, simix_global->process_list){
 247     if(MC_process_is_enabled(process)){
 248       char *key = bprintf("%lu", process->pid);
 249       char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 250       xbt_dict_set(first_enabled_state, key, data, NULL);
 251       xbt_free(key);
 252     }
 253   }
 254
 255   MC_UNSET_RAW_MEM;
 256
 257   if(raw_mem_set)
 258     MC_SET_RAW_MEM;
 259   else
 260     MC_UNSET_RAW_MEM;
 261
 262 }
 263
 264
 265 /**
 266  *   \brief Perform the model-checking operation using a depth-first search exploration
 267  *         with Dynamic Partial Order Reductions
 268  */
 269 void MC_dpor(void)
 270 {
 271
 272   char *req_str = NULL;
 273   int value;
 274   smx_simcall_t req = NULL, prev_req = NULL;
 275   mc_state_t state = NULL, prev_state = NULL, next_state = NULL, restore_state=NULL;
 276   smx_process_t process = NULL;
 277   xbt_fifo_item_t item = NULL;
 278   int pos;
 279   int visited_state = -1;
 280   int enabled = 0;
 281
 282   while (xbt_fifo_size(mc_stack_safety) > 0) {
 283
 284     /* Get current state */
 285     state = (mc_state_t)
 286       xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack_safety));
 287
 288     XBT_DEBUG("**************************************************");
 289     XBT_DEBUG("Exploration depth=%d (state=%p, num %d)(%u interleave, user_max_depth %d)",
 290               xbt_fifo_size(mc_stack_safety), state, state->num,
 291               MC_state_interleave_size(state), user_max_depth_reached);
 292
 293     /* Update statistics */
 294     mc_stats->visited_states++;
 295
 296     /* If there are processes to interleave and the maximum depth has not been reached
 297        then perform one step of the exploration algorithm */
 298     if (xbt_fifo_size(mc_stack_safety) <= _sg_mc_max_depth && !user_max_depth_reached &&
 299         (req = MC_state_get_request(state, &value)) && visited_state == -1) {
 300
 301       /* Debug information */
 302       if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 303         req_str = MC_request_to_string(req, value);
 304         XBT_DEBUG("Execute: %s", req_str);
 305         xbt_free(req_str);
 306       }
 307
 308       MC_SET_RAW_MEM;
 309       if(dot_output != NULL)
 310         req_str = MC_request_get_dot_output(req, value);
 311       MC_UNSET_RAW_MEM;
 312
 313       MC_state_set_executed_request(state, req, value);
 314       mc_stats->executed_transitions++;
 315
 316       MC_SET_RAW_MEM;
 317       char *key = bprintf("%lu", req->issuer->pid);
 318       xbt_dict_remove(first_enabled_state, key);
 319       xbt_free(key);
 320       MC_UNSET_RAW_MEM;
 321
 322       /* Answer the request */
 323       SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
 324
 325       /* Wait for requests (schedules processes) */
 326       MC_wait_for_requests();
 327
 328       /* Create the new expanded state */
 329       MC_SET_RAW_MEM;
 330
 331       next_state = MC_state_new();
 332
 333       if((visited_state = is_visited_state()) == -1){
 334
 335         /* Get an enabled process and insert it in the interleave set of the next state */
 336         xbt_swag_foreach(process, simix_global->process_list){
 337           if(MC_process_is_enabled(process)){
 338             MC_state_interleave_process(next_state, process);
 339             if(mc_reduce_kind != e_mc_reduce_none)
 340               break;
 341           }
 342         }
 343
 344         if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
 345           next_state->system_state = MC_take_snapshot();
 346         }
 347
 348         if(dot_output != NULL)
 349           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
 350
 351       }else{
 352
 353         if(dot_output != NULL)
 354           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
 355
 356       }
 357
 358       xbt_fifo_unshift(mc_stack_safety, next_state);
 359
 360       /* Insert in dict all enabled processes, if not included yet */
 361       xbt_swag_foreach(process, simix_global->process_list){
 362         if(MC_process_is_enabled(process)){
 363           char *key = bprintf("%lu", process->pid);
 364           if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
 365             char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 366             xbt_dict_set(first_enabled_state, key, data, NULL);
 367           }
 368           xbt_free(key);
 369         }
 370       }
 371
 372       if(dot_output != NULL)
 373         xbt_free(req_str);
 374
 375       MC_UNSET_RAW_MEM;
 376
 377       /* Let's loop again */
 378
 379       /* The interleave set is empty or the maximum depth is reached, let's back-track */
 380     } else {
 381
 382       if((xbt_fifo_size(mc_stack_safety) > _sg_mc_max_depth) || user_max_depth_reached || visited_state != -1){
 383
 384         if(user_max_depth_reached && visited_state == -1)
 385           XBT_DEBUG("User max depth reached !");
 386         else if(visited_state == -1)
 387           XBT_WARN("/!\\ Max depth reached ! /!\\ ");
 388
 389         visited_state = -1;
 390
 391         /* Interleave enabled processes in the state in which they have been enabled for the first time */
 392         xbt_swag_foreach(process, simix_global->process_list){
 393           if(MC_process_is_enabled(process)){
 394             char *key = bprintf("%lu", process->pid);
 395             enabled = (int)strtoul(xbt_dict_get_or_null(first_enabled_state, key), 0, 10);
 396             xbt_free(key);
 397             mc_state_t state_test = NULL;
 398             xbt_fifo_item_t item = NULL;
 399             int cursor = xbt_fifo_size(mc_stack_safety);
 400             xbt_fifo_foreach(mc_stack_safety, item, state_test, mc_state_t){
 401               if(cursor-- == enabled){
 402                 if(!MC_state_process_is_done(state_test, process) && state_test->num != state->num){
 403                   XBT_DEBUG("Interleave process %lu in state %d", process->pid, state_test->num);
 404                   MC_state_interleave_process(state_test, process);
 405                   break;
 406                 }
 407               }
 408             }
 409           }
 410         }
 411
 412       }else{
 413
 414         XBT_DEBUG("There are no more processes to interleave. (depth %d)", xbt_fifo_size(mc_stack_safety) + 1);
 415
 416       }
 417
 418       /* Trash the current state, no longer needed */
 419       MC_SET_RAW_MEM;
 420       xbt_fifo_shift(mc_stack_safety);
 421       MC_state_delete(state);
 422       XBT_DEBUG("Delete state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
 423       MC_UNSET_RAW_MEM;
 424
 425       /* Check for deadlocks */
 426       if(MC_deadlock_check()){
 427         MC_show_deadlock(NULL);
 428         return;
 429       }
 430
 431       MC_SET_RAW_MEM;
 432       /* Traverse the stack backwards until a state with a non empty interleave
 433          set is found, deleting all the states that have it empty in the way.
 434          For each deleted state, check if the request that has generated it
 435          (from it's predecesor state), depends on any other previous request
 436          executed before it. If it does then add it to the interleave set of the
 437          state that executed that previous request. */
 438
 439       while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
 440         if(mc_reduce_kind != e_mc_reduce_none){
 441           req = MC_state_get_internal_request(state);
 442           xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
 443             if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
 444               if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 445                 XBT_DEBUG("Dependent Transitions:");
 446                 prev_req = MC_state_get_executed_request(prev_state, &value);
 447                 req_str = MC_request_to_string(prev_req, value);
 448                 XBT_DEBUG("%s (state=%d)", req_str, prev_state->num);
 449                 xbt_free(req_str);
 450                 prev_req = MC_state_get_executed_request(state, &value);
 451                 req_str = MC_request_to_string(prev_req, value);
 452                 XBT_DEBUG("%s (state=%d)", req_str, state->num);
 453                 xbt_free(req_str);
 454               }
 455
 456               if(!MC_state_process_is_done(prev_state, req->issuer))
 457                 MC_state_interleave_process(prev_state, req->issuer);
 458               else
 459                 XBT_DEBUG("Process %p is in done set", req->issuer);
 460
 461               break;
 462
 463             }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
 464
 465               XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
 466               break;
 467
 468             }else{
 469
 470               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);
 471
 472             }
 473           }
 474         }
 475
 476         if (MC_state_interleave_size(state) && xbt_fifo_size(mc_stack_safety) < _sg_mc_max_depth) {
 477           /* We found a back-tracking point, let's loop */
 478           XBT_DEBUG("Back-tracking to state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
 479           if(_sg_mc_checkpoint){
 480             if(state->system_state != NULL){
 481               MC_restore_snapshot(state->system_state);
 482               xbt_fifo_unshift(mc_stack_safety, state);
 483               MC_UNSET_RAW_MEM;
 484             }else{
 485               pos = xbt_fifo_size(mc_stack_safety);
 486               item = xbt_fifo_get_first_item(mc_stack_safety);
 487               while(pos>0){
 488                 restore_state = (mc_state_t) xbt_fifo_get_item_content(item);
 489                 if(restore_state->system_state != NULL){
 490                   break;
 491                 }else{
 492                   item = xbt_fifo_get_next_item(item);
 493                   pos--;
 494                 }
 495               }
 496               MC_restore_snapshot(restore_state->system_state);
 497               xbt_fifo_unshift(mc_stack_safety, state);
 498               MC_UNSET_RAW_MEM;
 499               MC_replay(mc_stack_safety, pos);
 500             }
 501           }else{
 502             xbt_fifo_unshift(mc_stack_safety, state);
 503             MC_UNSET_RAW_MEM;
 504             MC_replay(mc_stack_safety, -1);
 505           }
 506           XBT_DEBUG("Back-tracking to state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety));
 507           break;
 508         } else {
 509           XBT_DEBUG("Delete state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
 510           MC_state_delete(state);
 511         }
 512       }
 513       MC_UNSET_RAW_MEM;
 514     }
 515   }
 516   MC_print_statistics(mc_stats);
 517   MC_UNSET_RAW_MEM;
 518
 519   return;
 520 }
 521
 522
 523
 524