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
 260   while (xbt_fifo_size(mc_stack_safety) > 0) {
 261
 262     /* Get current state */
 263     state = (mc_state_t)
 264       xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack_safety));
 265
 266     XBT_DEBUG("**************************************************");
 267     XBT_DEBUG("Exploration depth=%d (state=%p)(%u interleave)",
 268               xbt_fifo_size(mc_stack_safety), state,
 269               MC_state_interleave_size(state));
 270
 271     /* Update statistics */
 272     mc_stats->visited_states++;
 273
 274     /* If there are processes to interleave and the maximum depth has not been reached
 275        then perform one step of the exploration algorithm */
 276     if (xbt_fifo_size(mc_stack_safety) <= _sg_mc_max_depth &&
 277         (req = MC_state_get_request(state, &value))) {
 278
 279       /* Debug information */
 280       if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 281         req_str = MC_request_to_string(req, value);
 282         XBT_DEBUG("Execute: %s", req_str);
 283         xbt_free(req_str);
 284       }
 285
 286       req_str = MC_request_get_dot_output(req, value);
 287
 288       MC_state_set_executed_request(state, req, value);
 289       mc_stats->executed_transitions++;
 290
 291       MC_SET_RAW_MEM;
 292       char *key = bprintf("%lu", req->issuer->pid);
 293       xbt_dict_remove(first_enabled_state, key);
 294       xbt_free(key);
 295       MC_UNSET_RAW_MEM;
 296
 297       MC_state_set_executed_request(state, req, value);
 298
 299       /* Answer the request */
 300       SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
 301
 302       /* Wait for requests (schedules processes) */
 303       MC_wait_for_requests();
 304
 305       /* Create the new expanded state */
 306       MC_SET_RAW_MEM;
 307
 308       next_state = MC_state_new();
 309
 310       if((visited_state = is_visited_state()) == -1){
 311
 312         /* Get an enabled process and insert it in the interleave set of the next state */
 313         xbt_swag_foreach(process, simix_global->process_list){
 314           if(MC_process_is_enabled(process)){
 315             MC_state_interleave_process(next_state, process);
 316             if(mc_reduce_kind != e_mc_reduce_none)
 317               break;
 318           }
 319         }
 320
 321         if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
 322           next_state->system_state = MC_take_snapshot();
 323         }
 324
 325         if(dot_output != NULL)
 326           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
 327
 328       }else{
 329
 330         if(dot_output != NULL)
 331           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
 332
 333       }
 334
 335       xbt_fifo_unshift(mc_stack_safety, next_state);
 336
 337       /* Insert in dict all enabled processes, if not included yet */
 338       xbt_swag_foreach(process, simix_global->process_list){
 339         if(MC_process_is_enabled(process)){
 340           char *key = bprintf("%lu", process->pid);
 341           if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
 342             char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
 343             xbt_dict_set(first_enabled_state, key, data, NULL);
 344           }
 345           xbt_free(key);
 346         }
 347       }
 348
 349       MC_UNSET_RAW_MEM;
 350
 351       xbt_free(req_str);
 352
 353       /* Let's loop again */
 354
 355       /* The interleave set is empty or the maximum depth is reached, let's back-track */
 356     } else {
 357
 358       if(xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth)
 359         XBT_WARN("/!\\ Max depth reached ! /!\\ ");
 360       else
 361         XBT_DEBUG("There are no more processes to interleave.");
 362
 363       /* Trash the current state, no longer needed */
 364       MC_SET_RAW_MEM;
 365       xbt_fifo_shift(mc_stack_safety);
 366       MC_state_delete(state);
 367       MC_UNSET_RAW_MEM;
 368
 369       /* Check for deadlocks */
 370       if(MC_deadlock_check()){
 371         MC_show_deadlock(NULL);
 372         return;
 373       }
 374
 375       MC_SET_RAW_MEM;
 376       /* Traverse the stack backwards until a state with a non empty interleave
 377          set is found, deleting all the states that have it empty in the way.
 378          For each deleted state, check if the request that has generated it
 379          (from it's predecesor state), depends on any other previous request
 380          executed before it. If it does then add it to the interleave set of the
 381          state that executed that previous request. */
 382
 383       while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
 384         if(mc_reduce_kind != e_mc_reduce_none){
 385           req = MC_state_get_internal_request(state);
 386           /* If max_depth reached, check only for the last state if the request that has generated
 387              it, depends on any other processes still enabled when max_depth reached */
 388           if(xbt_fifo_size(mc_stack_safety) == _sg_mc_max_depth - 1){
 389             req3 = *req;
 390             xbt_swag_foreach(process, simix_global->process_list){
 391               if(MC_process_is_enabled(process) && !MC_state_process_is_done(state, process)){
 392                 MC_state_interleave_process(state, process);
 393                 req2 = MC_state_get_request(state, &value2);
 394                 MC_state_set_executed_request(state, req2, value2);
 395                 req2 = MC_state_get_internal_request(state);
 396                 if(MC_request_depend(&req3, req2)){
 397                   if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 398                     XBT_DEBUG("Dependent Transitions:");
 399                     req_str = MC_request_to_string(&req3, value);
 400                     XBT_DEBUG("%s (state=%p)", req_str, state);
 401                     xbt_free(req_str);
 402                     req_str = MC_request_to_string(req2, value);
 403                     XBT_DEBUG("%s (state=%p)", req_str, state);
 404                     xbt_free(req_str);
 405                   }
 406                   MC_state_interleave_process(state, process);
 407                   break;
 408                 }
 409               }
 410             }
 411           }
 412           xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
 413             if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
 414               if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
 415                 XBT_DEBUG("Dependent Transitions:");
 416                 prev_req = MC_state_get_executed_request(prev_state, &value);
 417                 req_str = MC_request_to_string(prev_req, value);
 418                 XBT_DEBUG("%s (state=%p)", req_str, prev_state);
 419                 xbt_free(req_str);
 420                 prev_req = MC_state_get_executed_request(state, &value);
 421                 req_str = MC_request_to_string(prev_req, value);
 422                 XBT_DEBUG("%s (state=%p)", req_str, state);
 423                 xbt_free(req_str);
 424               }
 425
 426               if(!MC_state_process_is_done(prev_state, req->issuer))
 427                 MC_state_interleave_process(prev_state, req->issuer);
 428               else
 429                 XBT_DEBUG("Process %p is in done set", req->issuer);
 430
 431               break;
 432
 433             }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
 434
 435               XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
 436               break;
 437
 438             }
 439           }
 440         }
 441
 442         if (MC_state_interleave_size(state)) {
 443           /* We found a back-tracking point, let's loop */
 444           if(_sg_mc_checkpoint){
 445             if(state->system_state != NULL){
 446               MC_restore_snapshot(state->system_state);
 447               xbt_fifo_unshift(mc_stack_safety, state);
 448               MC_UNSET_RAW_MEM;
 449             }else{
 450               pos = xbt_fifo_size(mc_stack_safety);
 451               item = xbt_fifo_get_first_item(mc_stack_safety);
 452               while(pos>0){
 453                 restore_state = (mc_state_t) xbt_fifo_get_item_content(item);
 454                 if(restore_state->system_state != NULL){
 455                   break;
 456                 }else{
 457                   item = xbt_fifo_get_next_item(item);
 458                   pos--;
 459                 }
 460               }
 461               MC_restore_snapshot(restore_state->system_state);
 462               xbt_fifo_unshift(mc_stack_safety, state);
 463               MC_UNSET_RAW_MEM;
 464               MC_replay(mc_stack_safety, pos);
 465             }
 466           }else{
 467             xbt_fifo_unshift(mc_stack_safety, state);
 468             MC_UNSET_RAW_MEM;
 469             MC_replay(mc_stack_safety, -1);
 470           }
 471           XBT_DEBUG("Back-tracking to depth %d", xbt_fifo_size(mc_stack_safety));
 472           break;
 473         } else {
 474           MC_state_delete(state);
 475         }
 476       }
 477       MC_UNSET_RAW_MEM;
 478     }
 479   }
 480   MC_print_statistics(mc_stats);
 481   MC_UNSET_RAW_MEM;
 482
 483   return;
 484 }
 485
 486
 487
 488