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
 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       MC_state_set_executed_request(state, req, value);
 297
 298       /* Answer the request */
 299       SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
 300
 301       /* Wait for requests (schedules processes) */
 302       MC_wait_for_requests();
 303
 304       /* Create the new expanded state */
 305       MC_SET_RAW_MEM;
 306
 307       next_state = MC_state_new();
 308
 309       if((visited_state = is_visited_state()) == -1){
 310
 311         /* Get an enabled process and insert it in the interleave set of the next state */
 312         xbt_swag_foreach(process, simix_global->process_list){
 313           if(MC_process_is_enabled(process)){
 314             MC_state_interleave_process(next_state, process);
 315             if(mc_reduce_kind != e_mc_reduce_none)
 316               break;
 317           }
 318         }
 319
 320         if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
 321           next_state->system_state = MC_take_snapshot();
 322         }
 323
 324         if(dot_output != NULL)
 325           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
 326
 327       }else{
 328
 329         if(dot_output != NULL)
 330           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
 331
 332       }
 333
 334       xbt_fifo_unshift(mc_stack_safety, next_state);
 335
 336       /* Insert in dict all enabled processes, if not included yet */
 337       xbt_swag_foreach(process, simix_global->process_list){
 338         if(MC_process_is_enabled(process)){
 339           char *key = bprintf("%lu", process->pid);
 340           if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
 341             char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 342             xbt_dict_set(first_enabled_state, key, data, NULL);
 343           }
 344           xbt_free(key);
 345         }
 346       }
 347
 348       MC_UNSET_RAW_MEM;
 349
 350       xbt_free(req_str);
 351
 352       /* Let's loop again */
 353
 354       /* The interleave set is empty or the maximum depth is reached, let's back-track */
 355     } else {
 356
 357       if(xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth)
 358         XBT_WARN("/!\\ Max depth reached ! /!\\ ");
 359       else
 360         XBT_DEBUG("There are no more processes to interleave.");
 361
 362       /* Trash the current state, no longer needed */
 363       MC_SET_RAW_MEM;
 364       xbt_fifo_shift(mc_stack_safety);
 365       MC_state_delete(state);
 366       MC_UNSET_RAW_MEM;
 367
 368       /* Check for deadlocks */
 369       if(MC_deadlock_check()){
 370         MC_show_deadlock(NULL);
 371         return;
 372       }
 373
 374       MC_SET_RAW_MEM;
 375       /* Traverse the stack backwards until a state with a non empty interleave
 376          set is found, deleting all the states that have it empty in the way.
 377          For each deleted state, check if the request that has generated it
 378          (from it's predecesor state), depends on any other previous request
 379          executed before it. If it does then add it to the interleave set of the
 380          state that executed that previous request. */
 381
 382       while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
 383         if(mc_reduce_kind != e_mc_reduce_none){
 384           req = MC_state_get_internal_request(state);
 385           /* If max_depth reached, check only for the last state if the request that has generated
 386              it, depends on any other processes still enabled when max_depth reached */
 387           if(xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth - 1){
 388             req3 = *req;
 389             xbt_swag_foreach(process, simix_global->process_list){
 390               if(MC_process_is_enabled(process) && !MC_state_process_is_done(state, process)){
 391                 MC_state_interleave_process(state, process);
 392                 req2 = MC_state_get_request(state, &value2);
 393                 MC_state_set_executed_request(state, req2, value2);
 394                 req2 = MC_state_get_internal_request(state);
 395                 if(MC_request_depend(&req3, req2)){
 396                   if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 397                     XBT_DEBUG("Dependent Transitions:");
 398                     req_str = MC_request_to_string(&req3, value);
 399                     XBT_DEBUG("%s (state=%p)", req_str, state);
 400                     xbt_free(req_str);
 401                     req_str = MC_request_to_string(req2, value);
 402                     XBT_DEBUG("%s (state=%p)", req_str, state);
 403                     xbt_free(req_str);
 404                   }
 405                   MC_state_interleave_process(state, process);
 406                   break;
 407                 }
 408               }
 409             }
 410           }
 411           xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
 412             if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
 413               if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 414                 XBT_DEBUG("Dependent Transitions:");
 415                 prev_req = MC_state_get_executed_request(prev_state, &value);
 416                 req_str = MC_request_to_string(prev_req, value);
 417                 XBT_DEBUG("%s (state=%p)", req_str, prev_state);
 418                 xbt_free(req_str);
 419                 prev_req = MC_state_get_executed_request(state, &value);
 420                 req_str = MC_request_to_string(prev_req, value);
 421                 XBT_DEBUG("%s (state=%p)", req_str, state);
 422                 xbt_free(req_str);
 423               }
 424
 425               if(!MC_state_process_is_done(prev_state, req->issuer))
 426                 MC_state_interleave_process(prev_state, req->issuer);
 427               else
 428                 XBT_DEBUG("Process %p is in done set", req->issuer);
 429
 430               break;
 431
 432             }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
 433
 434               XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
 435               break;
 436
 437             }
 438           }
 439         }
 440
 441         if (MC_state_interleave_size(state)) {
 442           /* We found a back-tracking point, let's loop */
 443           if(_sg_mc_checkpoint){
 444             if(state->system_state != NULL){
 445               MC_restore_snapshot(state->system_state);
 446               xbt_fifo_unshift(mc_stack_safety, state);
 447               MC_UNSET_RAW_MEM;
 448             }else{
 449               pos = xbt_fifo_size(mc_stack_safety);
 450               item = xbt_fifo_get_first_item(mc_stack_safety);
 451               while(pos>0){
 452                 restore_state = (mc_state_t) xbt_fifo_get_item_content(item);
 453                 if(restore_state->system_state != NULL){
 454                   break;
 455                 }else{
 456                   item = xbt_fifo_get_next_item(item);
 457                   pos--;
 458                 }
 459               }
 460               MC_restore_snapshot(restore_state->system_state);
 461               xbt_fifo_unshift(mc_stack_safety, state);
 462               MC_UNSET_RAW_MEM;
 463               MC_replay(mc_stack_safety, pos);
 464             }
 465           }else{
 466             xbt_fifo_unshift(mc_stack_safety, state);
 467             MC_UNSET_RAW_MEM;
 468             MC_replay(mc_stack_safety, -1);
 469           }
 470           XBT_DEBUG("Back-tracking to depth %d", xbt_fifo_size(mc_stack_safety));
 471           break;
 472         } else {
 473           MC_state_delete(state);
 474         }
 475       }
 476       MC_UNSET_RAW_MEM;
 477     }
 478   }
 479   MC_print_statistics(mc_stats);
 480   MC_UNSET_RAW_MEM;
 481
 482   return;
 483 }
 484
 485
 486
 487