model.cc

   1 #include <stdio.h>
   2
   3 #include "model.h"
   4 #include "schedule.h"
   5 #include "common.h"
   6
   7 ModelChecker *model;
   8
   9 ModelChecker::ModelChecker()
  10 {
  11         /* First thread created (system_thread) will have id 1 */
  12         this->used_thread_id = 0;
  13         /* Initialize default scheduler */
  14         this->scheduler = new Scheduler();
  15
  16         num_executions = 0;
  17         this->current_action = NULL;
  18         this->exploring = NULL;
  19         this->nextThread = THREAD_ID_T_NONE;
  20
  21         rootNode = new TreeNode(NULL);
  22         currentNode = rootNode;
  23         action_trace = new action_list_t();
  24 }
  25
  26 ModelChecker::~ModelChecker()
  27 {
  28         delete action_trace;
  29         delete this->scheduler;
  30         delete rootNode;
  31 }
  32
  33 void ModelChecker::assign_id(Thread *t)
  34 {
  35         t->set_id(++used_thread_id);
  36 }
  37
  38 void ModelChecker::add_system_thread(Thread *t)
  39 {
  40         this->system_thread = t;
  41 }
  42
  43 Thread *ModelChecker::schedule_next_thread()
  44 {
  45         Thread *t;
  46         if (nextThread == THREAD_ID_T_NONE)
  47                 return NULL;
  48         t = thread_map[nextThread];
  49         if (t == NULL)
  50                 DEBUG("*** error: thread not in thread_map: id = %d\n", nextThread);
  51         return t;
  52 }
  53
  54 /*
  55  * get_next_replay_thread() - Choose the next thread in the replay sequence
  56  *
  57  * If we've reached the 'diverge' point, then we pick a thread from the
  58  *   backtracking set.
  59  * Otherwise, we simply return the next thread in the sequence.
  60  */
  61 thread_id_t ModelChecker::get_next_replay_thread()
  62 {
  63         ModelAction *next;
  64         thread_id_t tid;
  65
  66         next = exploring->get_state();
  67
  68         if (next == exploring->get_diverge()) {
  69                 TreeNode *node = next->get_node();
  70
  71                 /* Reached divergence point; discard our current 'exploring' */
  72                 DEBUG("*** Discard 'Backtrack' object ***\n");
  73                 tid = node->getNextBacktrack();
  74                 delete exploring;
  75                 exploring = NULL;
  76         } else {
  77                 tid = next->get_tid();
  78         }
  79         DEBUG("*** ModelChecker chose next thread = %d ***\n", tid);
  80         return tid;
  81 }
  82
  83 thread_id_t ModelChecker::advance_backtracking_state()
  84 {
  85         /* Have we completed exploring the preselected path? */
  86         if (exploring == NULL)
  87                 return THREAD_ID_T_NONE;
  88
  89         /* Else, we are trying to replay an execution */
  90         exploring->advance_state();
  91         if (exploring->get_state() == NULL)
  92                 DEBUG("*** error: reached end of backtrack trace\n");
  93
  94         return get_next_replay_thread();
  95 }
  96
  97 bool ModelChecker::next_execution()
  98 {
  99         return false;
 100 }
 101
 102 ModelAction *ModelChecker::get_last_conflict(ModelAction *act)
 103 {
 104         void *loc = act->get_location();
 105         action_type type = act->get_type();
 106         thread_id_t id = act->get_tid();
 107
 108         switch (type) {
 109                 case THREAD_CREATE:
 110                 case THREAD_YIELD:
 111                 case THREAD_JOIN:
 112                         return NULL;
 113                 case ATOMIC_READ:
 114                 case ATOMIC_WRITE:
 115                 default:
 116                         break;
 117         }
 118         /* linear search: from most recent to oldest */
 119         action_list_t::reverse_iterator rit;
 120         for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
 121                 ModelAction *prev = *rit;
 122                 if (prev->get_location() != loc)
 123                         continue;
 124                 if (type == ATOMIC_READ && prev->get_type() != ATOMIC_WRITE)
 125                         continue;
 126                 /* Conflict from the same thread is not really a conflict */
 127                 if (id == prev->get_tid())
 128                         return NULL;
 129                 return prev;
 130         }
 131         return NULL;
 132 }
 133
 134 void ModelChecker::set_backtracking(ModelAction *act)
 135 {
 136         ModelAction *prev;
 137         TreeNode *node;
 138
 139         prev = get_last_conflict(act);
 140         if (prev == NULL)
 141                 return;
 142
 143         node = prev->get_node();
 144
 145         /* Check if this has been explored already */
 146         if (node->hasBeenExplored(act->get_tid()))
 147                 return;
 148         /* If this is a new backtracking point, mark the tree */
 149         if (node->setBacktrack(act->get_tid()) != 0)
 150                 return;
 151
 152         printf("Setting backtrack: conflict = %d, instead tid = %d\n",
 153                         prev->get_tid(), act->get_tid());
 154         prev->print();
 155         act->print();
 156
 157         Backtrack *back = new Backtrack(prev, action_trace);
 158         backtrack_list.push_back(back);
 159 }
 160
 161 void ModelChecker::check_current_action(void)
 162 {
 163         ModelAction *next = this->current_action;
 164
 165         if (!next) {
 166                 DEBUG("trying to push NULL action...\n");
 167                 return;
 168         }
 169         nextThread = advance_backtracking_state();
 170         next->set_node(currentNode);
 171         set_backtracking(next);
 172         currentNode = currentNode->exploreChild(next->get_tid());
 173         this->action_trace->push_back(next);
 174 }
 175
 176 void ModelChecker::print_trace(void)
 177 {
 178         action_list_t::iterator it;
 179
 180         printf("\n");
 181         printf("---------------------------------------------------------------------\n");
 182         printf("Number of executions: %d\n", num_executions);
 183         printf("Total nodes created: %d\n\n", TreeNode::getTotalNodes());
 184
 185         scheduler->print();
 186
 187         printf("\nTrace:\n\n");
 188
 189         for (it = action_trace->begin(); it != action_trace->end(); it++) {
 190                 DBG();
 191                 (*it)->print();
 192         }
 193         printf("---------------------------------------------------------------------\n");
 194 }
 195
 196 int ModelChecker::add_thread(Thread *t)
 197 {
 198         thread_map[t->get_id()] = t;
 199         return 0;
 200 }
 201
 202 int ModelChecker::switch_to_master(ModelAction *act)
 203 {
 204         Thread *old, *next;
 205
 206         DBG();
 207         old = thread_current();
 208         set_current_action(act);
 209         old->set_state(THREAD_READY);
 210         next = system_thread;
 211         return old->swap(next);
 212 }
 213
 214 ModelAction::ModelAction(action_type_t type, memory_order order, void *loc, int value)
 215 {
 216         Thread *t = thread_current();
 217         ModelAction *act = this;
 218
 219         act->type = type;
 220         act->order = order;
 221         act->location = loc;
 222         act->tid = t->get_id();
 223         act->value = value;
 224 }
 225
 226 void ModelAction::print(void)
 227 {
 228         const char *type_str;
 229         switch (this->type) {
 230         case THREAD_CREATE:
 231                 type_str = "thread create";
 232                 break;
 233         case THREAD_YIELD:
 234                 type_str = "thread yield";
 235                 break;
 236         case THREAD_JOIN:
 237                 type_str = "thread join";
 238                 break;
 239         case ATOMIC_READ:
 240                 type_str = "atomic read";
 241                 break;
 242         case ATOMIC_WRITE:
 243                 type_str = "atomic write";
 244                 break;
 245         default:
 246                 type_str = "unknown type";
 247         }
 248
 249         printf("Thread: %d\tAction: %s\tMO: %d\tLoc: %#014zx\tValue: %d\n", tid, type_str, order, (size_t)location, value);
 250 }