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;
 251   smx_simcall_t req = NULL, prev_req = NULL;
 252   mc_state_t state = NULL, prev_state = NULL, next_state = NULL, restore_state=NULL;
 253   smx_process_t process = NULL;
 254   xbt_fifo_item_t item = NULL;
 255   int pos;
 256   int visited_state;
 257   int max_depth_reached = 0;
 258
 259   while (xbt_fifo_size(mc_stack_safety) > 0) {
 260
 261     /* Get current state */
 262     state = (mc_state_t)
 263       xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack_safety));
 264
 265     XBT_DEBUG("**************************************************");
 266     XBT_DEBUG("Exploration depth=%d (state=%p)(%u interleave)",
 267               xbt_fifo_size(mc_stack_safety), state,
 268               MC_state_interleave_size(state));
 269
 270     /* Update statistics */
 271     mc_stats->visited_states++;
 272
 273     /* If there are processes to interleave and the maximum depth has not been reached
 274        then perform one step of the exploration algorithm */
 275     if (xbt_fifo_size(mc_stack_safety) <= _sg_mc_max_depth &&
 276         (req = MC_state_get_request(state, &value))) {
 277
 278       /* Debug information */
 279       if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 280         req_str = MC_request_to_string(req, value);
 281         XBT_DEBUG("Execute: %s", req_str);
 282         xbt_free(req_str);
 283       }
 284
 285       req_str = MC_request_get_dot_output(req, value);
 286
 287       MC_state_set_executed_request(state, req, value);
 288       mc_stats->executed_transitions++;
 289
 290       MC_SET_RAW_MEM;
 291       char *key = bprintf("%lu", req->issuer->pid);
 292       xbt_dict_remove(first_enabled_state, key);
 293       xbt_free(key);
 294       MC_UNSET_RAW_MEM;
 295
 296       /* Answer the request */
 297       SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
 298
 299       /* Wait for requests (schedules processes) */
 300       MC_wait_for_requests();
 301
 302       /* Create the new expanded state */
 303       MC_SET_RAW_MEM;
 304
 305       next_state = MC_state_new();
 306
 307       if((visited_state = is_visited_state()) == -1){
 308
 309         /* Get an enabled process and insert it in the interleave set of the next state */
 310         xbt_swag_foreach(process, simix_global->process_list){
 311           if(MC_process_is_enabled(process)){
 312             MC_state_interleave_process(next_state, process);
 313             if(mc_reduce_kind != e_mc_reduce_none)
 314               break;
 315           }
 316         }
 317
 318         if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
 319           next_state->system_state = MC_take_snapshot();
 320         }
 321
 322         if(dot_output != NULL)
 323           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
 324
 325       }else{
 326
 327         if(dot_output != NULL)
 328           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
 329
 330       }
 331
 332       xbt_fifo_unshift(mc_stack_safety, next_state);
 333
 334       /* Insert in dict all enabled processes, if not included yet */
 335       xbt_swag_foreach(process, simix_global->process_list){
 336         if(MC_process_is_enabled(process)){
 337           char *key = bprintf("%lu", process->pid);
 338           if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
 339             char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 340             xbt_dict_set(first_enabled_state, key, data, NULL);
 341           }
 342           xbt_free(key);
 343         }
 344       }
 345
 346       MC_UNSET_RAW_MEM;
 347
 348       xbt_free(req_str);
 349
 350       /* Let's loop again */
 351
 352       /* The interleave set is empty or the maximum depth is reached, let's back-track */
 353     } else {
 354
 355       if(xbt_fifo_size(mc_stack_safety) > _sg_mc_max_depth){
 356
 357         XBT_WARN("/!\\ Max depth reached ! /!\\ ");
 358
 359         /* Interleave enabled processes in the state in which they have been enabled for the first time */
 360         xbt_swag_foreach(process, simix_global->process_list){
 361           if(MC_process_is_enabled(process)){
 362             char *key = bprintf("%lu", process->pid);
 363             enabled = (int)strtoul(xbt_dict_get_or_null(first_enabled_state, key), 0, 10);
 364             xbt_free(key);
 365             mc_state_t state_test = NULL;
 366             xbt_fifo_item_t item = NULL;
 367             int cursor = xbt_fifo_size(mc_stack_safety);
 368             xbt_fifo_foreach(mc_stack_safety, item, state_test, mc_state_t){
 369               if(cursor-- == enabled){
 370                 if(!MC_state_process_is_done(state_test, process)){
 371                   MC_state_interleave_process(state_test, process);
 372                   break;
 373                 }
 374               }
 375             }
 376           }
 377         }
 378
 379         max_depth_reached = 1;
 380
 381       }else{
 382
 383         XBT_DEBUG("There are no more processes to interleave.");
 384
 385         /* Trash the current state, no longer needed */
 386         MC_SET_RAW_MEM;
 387         xbt_fifo_shift(mc_stack_safety);
 388         MC_state_delete(state);
 389         MC_UNSET_RAW_MEM;
 390
 391         max_depth_reached = 0;
 392       }
 393
 394       /* Check for deadlocks */
 395       if(MC_deadlock_check()){
 396         MC_show_deadlock(NULL);
 397         return;
 398       }
 399
 400       MC_SET_RAW_MEM;
 401       /* Traverse the stack backwards until a state with a non empty interleave
 402          set is found, deleting all the states that have it empty in the way.
 403          For each deleted state, check if the request that has generated it
 404          (from it's predecesor state), depends on any other previous request
 405          executed before it. If it does then add it to the interleave set of the
 406          state that executed that previous request. */
 407
 408       while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
 409         if(mc_reduce_kind != e_mc_reduce_none){
 410           if((xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth) && max_depth_reached){
 411             req = MC_state_get_request(state, &value);
 412             MC_state_set_executed_request(state, req, value);
 413           }
 414           req = MC_state_get_internal_request(state);
 415           xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
 416             if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
 417               if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 418                 XBT_DEBUG("Dependent Transitions:");
 419                 prev_req = MC_state_get_executed_request(prev_state, &value);
 420                 req_str = MC_request_to_string(prev_req, value);
 421                 XBT_DEBUG("%s (state=%p)", req_str, prev_state);
 422                 xbt_free(req_str);
 423                 prev_req = MC_state_get_executed_request(state, &value);
 424                 req_str = MC_request_to_string(prev_req, value);
 425                 XBT_DEBUG("%s (state=%p)", req_str, state);
 426                 xbt_free(req_str);
 427               }
 428
 429               if(!MC_state_process_is_done(prev_state, req->issuer))
 430                 MC_state_interleave_process(prev_state, req->issuer);
 431               else
 432                 XBT_DEBUG("Process %p is in done set", req->issuer);
 433
 434               break;
 435
 436             }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
 437
 438               XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
 439               break;
 440
 441             }
 442           }
 443         }
 444
 445         if (MC_state_interleave_size(state) && xbt_fifo_size(mc_stack_safety) < _sg_mc_max_depth) {
 446           /* We found a back-tracking point, let's loop */
 447           XBT_DEBUG("Back-tracking to depth %d", xbt_fifo_size(mc_stack_safety) + 1);
 448           if(_sg_mc_checkpoint){
 449             if(state->system_state != NULL){
 450               MC_restore_snapshot(state->system_state);
 451               xbt_fifo_unshift(mc_stack_safety, state);
 452               MC_UNSET_RAW_MEM;
 453             }else{
 454               pos = xbt_fifo_size(mc_stack_safety);
 455               item = xbt_fifo_get_first_item(mc_stack_safety);
 456               while(pos>0){
 457                 restore_state = (mc_state_t) xbt_fifo_get_item_content(item);
 458                 if(restore_state->system_state != NULL){
 459                   break;
 460                 }else{
 461                   item = xbt_fifo_get_next_item(item);
 462                   pos--;
 463                 }
 464               }
 465               MC_restore_snapshot(restore_state->system_state);
 466               xbt_fifo_unshift(mc_stack_safety, state);
 467               MC_UNSET_RAW_MEM;
 468               MC_replay(mc_stack_safety, pos);
 469             }
 470           }else{
 471             xbt_fifo_unshift(mc_stack_safety, state);
 472             MC_UNSET_RAW_MEM;
 473             MC_replay(mc_stack_safety, -1);
 474           }
 475           XBT_DEBUG("Back-tracking to depth %d", xbt_fifo_size(mc_stack_safety));
 476           break;
 477         } else {
 478           MC_state_delete(state);
 479         }
 480       }
 481       MC_UNSET_RAW_MEM;
 482     }
 483   }
 484   MC_print_statistics(mc_stats);
 485   MC_UNSET_RAW_MEM;
 486
 487   return;
 488 }
 489
 490
 491
 492