model.cc

   1 #include <stdio.h>
   2
   3 #include "model.h"
   4 #include "action.h"
   5 #include "nodestack.h"
   6 #include "schedule.h"
   7 #include "snapshot-interface.h"
   8 #include "common.h"
   9
  10 #define INITIAL_THREAD_ID       0
  11
  12 ModelChecker *model;
  13
  14 ModelChecker::ModelChecker()
  15         :
  16         /* Initialize default scheduler */
  17         scheduler(new Scheduler()),
  18         /* First thread created will have id INITIAL_THREAD_ID */
  19         next_thread_id(INITIAL_THREAD_ID),
  20         used_sequence_numbers(0),
  21
  22         num_executions(0),
  23         current_action(NULL),
  24         diverge(NULL),
  25         nextThread(THREAD_ID_T_NONE),
  26         action_trace(new action_list_t()),
  27         node_stack(new NodeStack()),
  28         next_backtrack(NULL)
  29 {
  30 }
  31
  32 ModelChecker::~ModelChecker()
  33 {
  34         std::map<int, class Thread *, std::less< int >, MyAlloc< std::pair< int, class Thread * > > >::iterator it;
  35         for (it = thread_map.begin(); it != thread_map.end(); it++)
  36                 delete (*it).second;
  37         thread_map.clear();
  38
  39         delete action_trace;
  40
  41         delete node_stack;
  42         delete scheduler;
  43 }
  44
  45 void ModelChecker::reset_to_initial_state()
  46 {
  47         DEBUG("+++ Resetting to initial state +++\n");
  48         std::map<int, class Thread *, std::less< int >, MyAlloc< std::pair< int, class Thread * > > >::iterator it;
  49         for (it = thread_map.begin(); it != thread_map.end(); it++)
  50                 delete (*it).second;
  51         thread_map.clear();
  52         delete action_trace;
  53         action_trace = new action_list_t();
  54         node_stack->reset_execution();
  55         current_action = NULL;
  56         next_thread_id = INITIAL_THREAD_ID;
  57         used_sequence_numbers = 0;
  58         nextThread = 0;
  59         next_backtrack = NULL;
  60         /* scheduler reset ? */
  61 }
  62
  63 thread_id_t ModelChecker::get_next_id()
  64 {
  65         return next_thread_id++;
  66 }
  67
  68 int ModelChecker::get_next_seq_num()
  69 {
  70         return ++used_sequence_numbers;
  71 }
  72
  73 Thread * ModelChecker::schedule_next_thread()
  74 {
  75         Thread *t;
  76         if (nextThread == THREAD_ID_T_NONE)
  77                 return NULL;
  78         t = thread_map[id_to_int(nextThread)];
  79
  80         ASSERT(t != NULL);
  81
  82         return t;
  83 }
  84
  85 /*
  86  * get_next_replay_thread() - Choose the next thread in the replay sequence
  87  *
  88  * If we've reached the 'diverge' point, then we pick a thread from the
  89  *   backtracking set.
  90  * Otherwise, we simply return the next thread in the sequence.
  91  */
  92 thread_id_t ModelChecker::get_next_replay_thread()
  93 {
  94         ModelAction *next;
  95         thread_id_t tid;
  96
  97         /* Have we completed exploring the preselected path? */
  98         if (diverge == NULL)
  99                 return THREAD_ID_T_NONE;
 100
 101         /* Else, we are trying to replay an execution */
 102         next = node_stack->get_next()->get_action();
 103
 104         if (next == diverge) {
 105                 Node *node = next->get_node();
 106
 107                 /* Reached divergence point */
 108                 DEBUG("*** Divergence point ***\n");
 109                 tid = node->get_next_backtrack();
 110                 diverge = NULL;
 111         } else {
 112                 tid = next->get_tid();
 113         }
 114         DEBUG("*** ModelChecker chose next thread = %d ***\n", tid);
 115         return tid;
 116 }
 117
 118 bool ModelChecker::next_execution()
 119 {
 120         DBG();
 121
 122         num_executions++;
 123         print_summary();
 124         if ((diverge = model->get_next_backtrack()) == NULL)
 125                 return false;
 126
 127         if (DBG_ENABLED()) {
 128                 printf("Next execution will diverge at:\n");
 129                 diverge->print();
 130         }
 131
 132         model->reset_to_initial_state();
 133         return true;
 134 }
 135
 136 ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
 137 {
 138         action_type type = act->get_type();
 139
 140         switch (type) {
 141                 case THREAD_CREATE:
 142                 case THREAD_YIELD:
 143                 case THREAD_JOIN:
 144                         return NULL;
 145                 case ATOMIC_READ:
 146                 case ATOMIC_WRITE:
 147                 default:
 148                         break;
 149         }
 150         /* linear search: from most recent to oldest */
 151         action_list_t::reverse_iterator rit;
 152         for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
 153                 ModelAction *prev = *rit;
 154                 if (act->is_dependent(prev))
 155                         return prev;
 156         }
 157         return NULL;
 158 }
 159
 160 void ModelChecker::set_backtracking(ModelAction *act)
 161 {
 162         ModelAction *prev;
 163         Node *node;
 164         Thread *t = get_thread(act->get_tid());
 165
 166         prev = get_last_conflict(act);
 167         if (prev == NULL)
 168                 return;
 169
 170         node = prev->get_node();
 171
 172         while (!node->is_enabled(t))
 173                 t = t->get_parent();
 174
 175         /* Check if this has been explored already */
 176         if (node->has_been_explored(t->get_id()))
 177                 return;
 178
 179         if (!next_backtrack || *prev > *next_backtrack)
 180                 next_backtrack = prev;
 181
 182         /* If this is a new backtracking point, mark the tree */
 183         if (!node->set_backtrack(t->get_id()))
 184                 return;
 185         DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
 186                         prev->get_tid(), t->get_id());
 187         if (DBG_ENABLED()) {
 188                 prev->print();
 189                 act->print();
 190         }
 191 }
 192
 193 ModelAction * ModelChecker::get_next_backtrack()
 194 {
 195         ModelAction *next = next_backtrack;
 196         next_backtrack = NULL;
 197         return next;
 198 }
 199
 200 void ModelChecker::check_current_action(void)
 201 {
 202         Node *currnode;
 203
 204         ModelAction *curr = this->current_action;
 205         current_action = NULL;
 206         if (!curr) {
 207                 DEBUG("trying to push NULL action...\n");
 208                 return;
 209         }
 210
 211         curr = node_stack->explore_action(curr);
 212         nextThread = get_next_replay_thread();
 213
 214         currnode = curr->get_node();
 215
 216         if (!currnode->backtrack_empty())
 217                 if (!next_backtrack || *curr > *next_backtrack)
 218                         next_backtrack = curr;
 219
 220         set_backtracking(curr);
 221         this->action_trace->push_back(curr);
 222 }
 223
 224 void ModelChecker::print_summary(void)
 225 {
 226         printf("\n");
 227         printf("Number of executions: %d\n", num_executions);
 228         printf("Total nodes created: %d\n", Node::get_total_nodes());
 229
 230         scheduler->print();
 231
 232         print_list(action_trace);
 233         printf("\n");
 234 }
 235
 236 void ModelChecker::print_list(action_list_t *list)
 237 {
 238         action_list_t::iterator it;
 239
 240         printf("---------------------------------------------------------------------\n");
 241         printf("Trace:\n");
 242
 243         for (it = list->begin(); it != list->end(); it++) {
 244                 (*it)->print();
 245         }
 246         printf("---------------------------------------------------------------------\n");
 247 }
 248
 249 int ModelChecker::add_thread(Thread *t)
 250 {
 251         thread_map[id_to_int(t->get_id())] = t;
 252         scheduler->add_thread(t);
 253         return 0;
 254 }
 255
 256 void ModelChecker::remove_thread(Thread *t)
 257 {
 258         scheduler->remove_thread(t);
 259 }
 260
 261 int ModelChecker::switch_to_master(ModelAction *act)
 262 {
 263         Thread *old;
 264
 265         DBG();
 266         old = thread_current();
 267         set_current_action(act);
 268         old->set_state(THREAD_READY);
 269         return Thread::swap(old, get_system_context());
 270 }