src/mc/mc_dpor.c

   1 /* Copyright (c) 2008 Martin Quinson, Cristian Rosa.
   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 "private.h"
   8
   9 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dpor, mc,
  10                                 "Logging specific to MC DPOR exploration");
  11
  12 /**
  13  *  \brief Initialize the DPOR exploration algorithm
  14  */
  15 void MC_dpor_init()
  16 {
  17   mc_state_t initial_state = NULL;
  18   mc_transition_t trans = NULL;
  19
  20   /* Create the initial state and push it into the exploration stack */
  21   MC_SET_RAW_MEM;
  22   initial_state = MC_state_new();
  23   xbt_fifo_unshift(mc_stack, initial_state);
  24   MC_UNSET_RAW_MEM;
  25
  26   /* Schedule all the processes to detect the transitions of the initial state */
  27   DEBUG0("**************************************************");
  28   DEBUG0("Initial state");
  29   MC_schedule_enabled_processes();
  30
  31   MC_SET_RAW_MEM;
  32   MC_trans_compute_enabled(initial_state->enabled_transitions,
  33                            initial_state->transitions);
  34
  35   /* Fill the interleave set of the initial state with an enabled process */
  36   trans = xbt_setset_set_choose(initial_state->enabled_transitions);
  37   if(trans)
  38     xbt_setset_set_insert(initial_state->interleave, trans);
  39   MC_UNSET_RAW_MEM;
  40
  41   /* Update Statistics */
  42   mc_stats->state_size += xbt_setset_set_size(initial_state->enabled_transitions);
  43 }
  44
  45
  46 /**
  47  *      \brief Perform the model-checking operation using a depth-first search exploration
  48  *         with Dynamic Partial Order Reductions
  49  */
  50 void MC_dpor(void)
  51 {
  52   mc_transition_t trans = NULL;
  53   mc_state_t next_state = NULL;
  54   xbt_setset_cursor_t cursor = NULL;
  55
  56   while(xbt_fifo_size(mc_stack) > 0){
  57
  58     DEBUG0("**************************************************");
  59
  60     /* FIXME: Think about what happen if there are no transitions but there are
  61        some actions on the models. (ex. all the processes do a sleep(0) in a round). */
  62
  63     /* Get current state */
  64     mc_current_state = (mc_state_t) xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack));
  65
  66     /* If there are transitions to execute and the maximun depth has not been reached
  67        then perform one step of the exploration algorithm */
  68     if(xbt_setset_set_size(mc_current_state->interleave) > 0 && xbt_fifo_size(mc_stack) < MAX_DEPTH){
  69
  70       DEBUG4("Exploration detph=%d (state=%p)(%d interleave) (%d enabled)", xbt_fifo_size(mc_stack),
  71         mc_current_state, xbt_setset_set_size(mc_current_state->interleave),
  72         xbt_setset_set_size(mc_current_state->enabled_transitions));
  73
  74       xbt_setset_foreach(mc_current_state->enabled_transitions, cursor, trans){
  75         DEBUG1("\t %s", trans->name);
  76       }
  77
  78       /* Update statistics */
  79       mc_stats->visited_states++;
  80       mc_stats->executed_transitions++;
  81
  82       /* Choose a transition to execute from the interleave set of the current
  83          state, and create the data structures for the new expanded state in the
  84          exploration stack. */
  85       MC_SET_RAW_MEM;
  86       trans = xbt_setset_set_choose(mc_current_state->interleave);
  87       if(!trans->type == mc_random){
  88         xbt_setset_set_remove(mc_current_state->interleave, trans);
  89         /* Add the transition in the done set of the current state */
  90         xbt_setset_set_insert(mc_current_state->done, trans);
  91       }
  92
  93       next_state = MC_state_new();
  94       xbt_fifo_unshift(mc_stack, next_state);
  95
  96       /* Set it as the executed transition of the current state */
  97       mc_current_state->executed_transition = trans;
  98       MC_UNSET_RAW_MEM;
  99
 100       /* Execute the selected transition by scheduling it's associated process.
 101          Then schedule every process that got ready to run due to the execution
 102          of the transition */
 103       DEBUG1("Executing transition %s", trans->name);
 104       SIMIX_process_schedule(trans->process);
 105       MC_execute_surf_actions();        /* Do surf's related black magic */
 106       MC_schedule_enabled_processes();
 107
 108       if(trans->type == mc_random && trans->random.current_value < trans->random.max){
 109         trans->random.current_value++;
 110       }else{
 111         trans->random.current_value = trans->random.min;
 112         xbt_setset_set_remove(mc_current_state->interleave, trans);
 113         xbt_setset_set_insert(mc_current_state->done, trans);
 114       }
 115
 116       /* Calculate the enabled transitions set of the next state */
 117       MC_SET_RAW_MEM;
 118       xbt_setset_add(next_state->transitions, mc_current_state->transitions);
 119       xbt_setset_set_remove(next_state->transitions, trans);
 120       MC_trans_compute_enabled(next_state->enabled_transitions, next_state->transitions);
 121
 122       /* Choose one transition to interleave from the enabled transition set */
 123       trans = xbt_setset_set_choose(next_state->enabled_transitions);
 124       if(trans)
 125         xbt_setset_set_insert(next_state->interleave, trans);
 126       MC_UNSET_RAW_MEM;
 127
 128       /* Update Statistics */
 129       mc_stats->state_size += xbt_setset_set_size(next_state->enabled_transitions);
 130
 131       /* Let's loop again */
 132
 133     /* The interleave set is empty or the maximum depth is reached, let's back-track */
 134     }else{
 135       DEBUG0("There are no more transitions to interleave.");
 136
 137
 138       /* Check for deadlocks */
 139       xbt_setset_substract(mc_current_state->transitions, mc_current_state->done);
 140       if(xbt_setset_set_size(mc_current_state->transitions) > 0){
 141         INFO0("**************************");
 142         INFO0("*** DEAD-LOCK DETECTED ***");
 143         INFO0("**************************");
 144         INFO0("Counter-example execution trace:");
 145         MC_dump_stack(mc_stack);
 146         MC_print_statistics(mc_stats);
 147         xbt_abort();
 148       }
 149
 150       mc_transition_t q = NULL;
 151       xbt_fifo_item_t item = NULL;
 152       mc_state_t state = NULL;
 153
 154       //MC_show_stack(mc_stack);
 155
 156       /* Trash the current state, no longer needed */
 157       MC_SET_RAW_MEM;
 158       xbt_fifo_shift(mc_stack);
 159       MC_state_delete(mc_current_state);
 160
 161       /* Traverse the stack backwards until a state with a non empty interleave
 162          set is found, deleting all the states that have it empty in the way.
 163          For each deleted state, check if the transition that has generated it
 164          (from it's predecesor state), depends on any other previous transition
 165          executed before it. If it does then add it to the interleave set of the
 166          state that executed that previous transition. */
 167       while((mc_current_state = xbt_fifo_shift(mc_stack)) != NULL){
 168         q = mc_current_state->executed_transition;
 169         xbt_fifo_foreach(mc_stack, item, state, mc_state_t){
 170           if(MC_transition_depend(q, state->executed_transition)){
 171             DEBUG3("Dependence found at state %p (%p,%p)", state, state->executed_transition, q);
 172             xbt_setset_foreach(state->enabled_transitions, cursor, trans){
 173               if((trans->process == q->process) && !xbt_setset_set_belongs(state->done, trans)){
 174                 DEBUG2("Unexplored interleaving found at state %p (%p)", state, trans);
 175                 xbt_setset_set_insert(state->interleave, trans);
 176                 break;
 177               }
 178             }
 179             if(trans)
 180               break;
 181           }
 182         }
 183         if(xbt_setset_set_size(mc_current_state->interleave) > 0){
 184           /* We found a back-tracking point, let's loop */
 185           xbt_fifo_unshift(mc_stack, mc_current_state);
 186           DEBUG1("Back-tracking to depth %d", xbt_fifo_size(mc_stack));
 187           MC_replay(mc_stack);
 188           MC_UNSET_RAW_MEM;
 189           break;
 190         }else{
 191           MC_state_delete(mc_current_state);
 192         }
 193       }
 194     }
 195   }
 196   DEBUG0("We are done");
 197   /* We are done, show the statistics and return */
 198   MC_print_statistics(mc_stats);
 199 }