9 #define INITIAL_THREAD_ID 0
13 Backtrack(ModelAction *d, action_list_t *t) {
16 iter = actionTrace->begin();
18 ModelAction * get_diverge() { return diverge; }
19 action_list_t * get_trace() { return actionTrace; }
20 void advance_state() { iter++; }
21 ModelAction * get_state() {
22 return iter == actionTrace->end() ? NULL : *iter;
26 action_list_t *actionTrace;
27 /* points to position in actionTrace as we replay */
28 action_list_t::iterator iter;
33 ModelChecker::ModelChecker()
35 /* First thread created will have id INITIAL_THREAD_ID */
36 this->next_thread_id = INITIAL_THREAD_ID;
37 used_sequence_numbers = 0;
38 /* Initialize default scheduler */
39 this->scheduler = new Scheduler();
42 this->current_action = NULL;
43 this->exploring = NULL;
44 this->nextThread = THREAD_ID_T_NONE;
46 rootNode = new TreeNode();
47 currentNode = rootNode;
48 action_trace = new action_list_t();
51 ModelChecker::~ModelChecker()
54 delete this->scheduler;
58 void ModelChecker::reset_to_initial_state()
60 DEBUG("+++ Resetting to initial state +++\n");
61 std::map<int, class Thread *>::iterator it;
62 for (it = thread_map.begin(); it != thread_map.end(); it++)
65 action_trace = new action_list_t();
66 currentNode = rootNode;
67 current_action = NULL;
68 next_thread_id = INITIAL_THREAD_ID;
69 used_sequence_numbers = 0;
70 /* scheduler reset ? */
73 thread_id_t ModelChecker::get_next_id()
75 return next_thread_id++;
78 int ModelChecker::get_next_seq_num()
80 return ++used_sequence_numbers;
83 Thread * ModelChecker::schedule_next_thread()
86 if (nextThread == THREAD_ID_T_NONE)
88 t = thread_map[id_to_int(nextThread)];
96 * get_next_replay_thread() - Choose the next thread in the replay sequence
98 * If we've reached the 'diverge' point, then we pick a thread from the
100 * Otherwise, we simply return the next thread in the sequence.
102 thread_id_t ModelChecker::get_next_replay_thread()
107 next = exploring->get_state();
109 if (next == exploring->get_diverge()) {
110 TreeNode *node = next->get_node();
112 /* Reached divergence point; discard our current 'exploring' */
113 DEBUG("*** Discard 'Backtrack' object ***\n");
114 tid = node->getNextBacktrack();
118 tid = next->get_tid();
120 DEBUG("*** ModelChecker chose next thread = %d ***\n", tid);
124 thread_id_t ModelChecker::advance_backtracking_state()
126 /* Have we completed exploring the preselected path? */
127 if (exploring == NULL)
128 return THREAD_ID_T_NONE;
130 /* Else, we are trying to replay an execution */
131 exploring->advance_state();
133 ASSERT(exploring->get_state() != NULL);
135 return get_next_replay_thread();
138 bool ModelChecker::next_execution()
144 if ((exploring = model->get_next_backtrack()) == NULL)
148 printf("Next execution will diverge at:\n");
149 exploring->get_diverge()->print();
150 print_list(exploring->get_trace());
153 model->reset_to_initial_state();
154 nextThread = get_next_replay_thread();
158 ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
160 action_type type = act->get_type();
172 /* linear search: from most recent to oldest */
173 action_list_t::reverse_iterator rit;
174 for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
175 ModelAction *prev = *rit;
176 if (act->is_dependent(prev))
182 void ModelChecker::set_backtracking(ModelAction *act)
186 Thread *t = get_thread(act->get_tid());
188 prev = get_last_conflict(act);
192 node = prev->get_node();
194 while (t && !node->is_enabled(t))
197 /* Check if this has been explored already */
198 if (node->hasBeenExplored(t->get_id()))
200 /* If this is a new backtracking point, mark the tree */
201 if (node->setBacktrack(t->get_id()) != 0)
204 DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
205 prev->get_tid(), t->get_id());
211 Backtrack *back = new Backtrack(prev, action_trace);
212 backtrack_list.push_back(back);
215 Backtrack * ModelChecker::get_next_backtrack()
218 if (backtrack_list.empty())
220 next = backtrack_list.back();
221 backtrack_list.pop_back();
225 void ModelChecker::check_current_action(void)
227 ModelAction *next = this->current_action;
230 DEBUG("trying to push NULL action...\n");
233 current_action = NULL;
234 nextThread = advance_backtracking_state();
235 next->set_node(currentNode);
236 set_backtracking(next);
237 currentNode = currentNode->explore_child(next);
238 this->action_trace->push_back(next);
241 void ModelChecker::print_summary(void)
244 printf("Number of executions: %d\n", num_executions);
245 printf("Total nodes created: %d\n", TreeNode::getTotalNodes());
249 print_list(action_trace);
254 void ModelChecker::print_list(action_list_t *list)
256 action_list_t::iterator it;
258 printf("---------------------------------------------------------------------\n");
261 for (it = list->begin(); it != list->end(); it++) {
264 printf("---------------------------------------------------------------------\n");
267 int ModelChecker::add_thread(Thread *t)
269 thread_map[id_to_int(t->get_id())] = t;
270 scheduler->add_thread(t);
274 void ModelChecker::remove_thread(Thread *t)
276 scheduler->remove_thread(t);
279 int ModelChecker::switch_to_master(ModelAction *act)
284 old = thread_current();
285 set_current_action(act);
286 old->set_state(THREAD_READY);
287 return Thread::swap(old, get_system_context());
290 ModelAction::ModelAction(action_type_t type, memory_order order, void *loc, int value)
292 Thread *t = thread_current();
293 ModelAction *act = this;
298 act->tid = t->get_id();
300 act->seq_number = model->get_next_seq_num();
303 bool ModelAction::is_read()
305 return type == ATOMIC_READ;
308 bool ModelAction::is_write()
310 return type == ATOMIC_WRITE;
313 bool ModelAction::is_acquire()
316 case memory_order_acquire:
317 case memory_order_acq_rel:
318 case memory_order_seq_cst:
325 bool ModelAction::is_release()
328 case memory_order_release:
329 case memory_order_acq_rel:
330 case memory_order_seq_cst:
337 bool ModelAction::same_var(ModelAction *act)
339 return location == act->location;
342 bool ModelAction::same_thread(ModelAction *act)
344 return tid == act->tid;
347 bool ModelAction::is_dependent(ModelAction *act)
349 if (!is_read() && !is_write())
351 if (!act->is_read() && !act->is_write())
353 if (same_var(act) && !same_thread(act) &&
354 (is_write() || act->is_write()))
359 void ModelAction::print(void)
361 const char *type_str;
362 switch (this->type) {
364 type_str = "thread create";
367 type_str = "thread yield";
370 type_str = "thread join";
373 type_str = "atomic read";
376 type_str = "atomic write";
379 type_str = "unknown type";
382 printf("(%4d) Thread: %d\tAction: %s\tMO: %d\tLoc: %14p\tValue: %d\n",
383 seq_number, id_to_int(tid), type_str, order, location, value);