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