10 #include "nodestack.h"
12 #include "snapshot-interface.h"
15 #include "threads-model.h"
17 #include "traceanalysis.h"
18 #include "execution.h"
19 #include "bugmessage.h"
23 /** @brief Constructor */
24 ModelChecker::ModelChecker(struct model_params params) :
25 /* Initialize default scheduler */
29 scheduler(new Scheduler()),
30 node_stack(new NodeStack()),
31 execution(new ModelExecution(this, &this->params, scheduler, node_stack)),
34 earliest_diverge(NULL),
38 memset(&stats,0,sizeof(struct execution_stats));
41 /** @brief Destructor */
42 ModelChecker::~ModelChecker()
49 * Restores user program to initial state and resets all model-checker data
52 void ModelChecker::reset_to_initial_state()
54 DEBUG("+++ Resetting to initial state +++\n");
55 node_stack->reset_execution();
58 * FIXME: if we utilize partial rollback, we will need to free only
59 * those pending actions which were NOT pending before the rollback
62 for (unsigned int i = 0; i < get_num_threads(); i++)
63 delete get_thread(int_to_id(i))->get_pending();
65 snapshot_backtrack_before(0);
68 /** @return the number of user threads created during this execution */
69 unsigned int ModelChecker::get_num_threads() const
71 return execution->get_num_threads();
75 * Must be called from user-thread context (e.g., through the global
76 * thread_current() interface)
78 * @return The currently executing Thread.
80 Thread * ModelChecker::get_current_thread() const
82 return scheduler->get_current_thread();
86 * @brief Choose the next thread to execute.
88 * This function chooses the next thread that should execute. It can enforce
89 * execution replay/backtracking or, if the model-checker has no preference
90 * regarding the next thread (i.e., when exploring a new execution ordering),
91 * we defer to the scheduler.
93 * @return The next chosen thread to run, if any exist. Or else if the current
94 * execution should terminate, return NULL.
96 Thread * ModelChecker::get_next_thread()
100 * Have we completed exploring the preselected path? Then let the
103 return scheduler->select_next_thread(node_stack->get_head());
107 * We need to know what the next actions of all threads in the sleep
108 * set will be. This method computes them and stores the actions at
109 * the corresponding thread object's pending action.
111 void ModelChecker::execute_sleep_set()
113 for (unsigned int i = 0; i < get_num_threads(); i++) {
114 thread_id_t tid = int_to_id(i);
115 Thread *thr = get_thread(tid);
116 if (scheduler->is_sleep_set(thr) && thr->get_pending()) {
117 thr->get_pending()->set_sleep_flag();
123 * @brief Assert a bug in the executing program.
125 * Use this function to assert any sort of bug in the user program. If the
126 * current trace is feasible (actually, a prefix of some feasible execution),
127 * then this execution will be aborted, printing the appropriate message. If
128 * the current trace is not yet feasible, the error message will be stashed and
129 * printed if the execution ever becomes feasible.
131 * @param msg Descriptive message for the bug (do not include newline char)
132 * @return True if bug is immediately-feasible
134 bool ModelChecker::assert_bug(const char *msg, ...)
140 vsnprintf(str, sizeof(str), msg, ap);
143 return execution->assert_bug(str);
147 * @brief Assert a bug in the executing program, asserted by a user thread
148 * @see ModelChecker::assert_bug
149 * @param msg Descriptive message for the bug (do not include newline char)
151 void ModelChecker::assert_user_bug(const char *msg)
153 /* If feasible bug, bail out now */
155 switch_to_master(NULL);
158 /** @brief Print bug report listing for this execution (if any bugs exist) */
159 void ModelChecker::print_bugs() const
161 SnapVector<bug_message *> *bugs = execution->get_bugs();
163 model_print("Bug report: %zu bug%s detected\n",
165 bugs->size() > 1 ? "s" : "");
166 for (unsigned int i = 0; i < bugs->size(); i++)
171 * @brief Record end-of-execution stats
173 * Must be run when exiting an execution. Records various stats.
174 * @see struct execution_stats
176 void ModelChecker::record_stats()
179 if (!execution->isfeasibleprefix())
180 stats.num_infeasible++;
181 else if (execution->have_bug_reports())
182 stats.num_buggy_executions++;
183 else if (execution->is_complete_execution())
184 stats.num_complete++;
186 stats.num_redundant++;
189 * @todo We can violate this ASSERT() when fairness/sleep sets
190 * conflict to cause an execution to terminate, e.g. with:
191 * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
193 //ASSERT(scheduler->all_threads_sleeping());
197 /** @brief Print execution stats */
198 void ModelChecker::print_stats() const
200 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
201 model_print("Number of redundant executions: %d\n", stats.num_redundant);
202 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
203 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
204 model_print("Total executions: %d\n", stats.num_total);
206 model_print("Total nodes created: %d\n", node_stack->get_total_nodes());
210 * @brief End-of-exeuction print
211 * @param printbugs Should any existing bugs be printed?
213 void ModelChecker::print_execution(bool printbugs) const
215 model_print("Program output from execution %d:\n",
216 get_execution_number());
217 print_program_output();
219 if (params.verbose >= 3) {
220 model_print("\nEarliest divergence point since last feasible execution:\n");
221 if (earliest_diverge)
222 earliest_diverge->print();
224 model_print("(Not set)\n");
230 /* Don't print invalid bugs */
231 if (printbugs && execution->have_bug_reports()) {
237 execution->print_summary();
241 * Queries the model-checker for more executions to explore and, if one
242 * exists, resets the model-checker state to execute a new execution.
244 * @return If there are more executions to explore, return true. Otherwise,
247 bool ModelChecker::next_execution()
250 /* Is this execution a feasible execution that's worth bug-checking? */
251 bool complete = execution->isfeasibleprefix() &&
252 (execution->is_complete_execution() ||
253 execution->have_bug_reports());
255 /* End-of-execution bug checks */
257 if (execution->is_deadlocked())
258 assert_bug("Deadlock detected");
261 run_trace_analyses();
266 if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
267 print_execution(complete);
269 clear_program_output();
277 reset_to_initial_state();
278 node_stack->full_reset();
283 earliest_diverge = NULL;
288 // diverge = execution->get_next_backtrack();
289 if (diverge == NULL) {
291 reset_to_initial_state();
292 model_print("Does not diverge\n");
297 model_print("Next execution will diverge at:\n");
303 if (params.maxexecutions != 0 && stats.num_complete >= params.maxexecutions)
306 reset_to_initial_state();
312 /** @brief Run trace analyses on complete trace */
313 void ModelChecker::run_trace_analyses() {
314 for (unsigned int i = 0; i < trace_analyses.size(); i++)
315 trace_analyses[i]->analyze(execution->get_action_trace());
319 * @brief Get a Thread reference by its ID
320 * @param tid The Thread's ID
321 * @return A Thread reference
323 Thread * ModelChecker::get_thread(thread_id_t tid) const
325 return execution->get_thread(tid);
329 * @brief Get a reference to the Thread in which a ModelAction was executed
330 * @param act The ModelAction
331 * @return A Thread reference
333 Thread * ModelChecker::get_thread(const ModelAction *act) const
335 return execution->get_thread(act);
339 * Switch from a model-checker context to a user-thread context. This is the
340 * complement of ModelChecker::switch_to_master and must be called from the
341 * model-checker context
343 * @param thread The user-thread to switch to
345 void ModelChecker::switch_from_master(Thread *thread)
347 scheduler->set_current_thread(thread);
348 Thread::swap(&system_context, thread);
352 * Switch from a user-context to the "master thread" context (a.k.a. system
353 * context). This switch is made with the intention of exploring a particular
354 * model-checking action (described by a ModelAction object). Must be called
355 * from a user-thread context.
357 * @param act The current action that will be explored. May be NULL only if
358 * trace is exiting via an assertion (see ModelExecution::set_assert and
359 * ModelExecution::has_asserted).
360 * @return Return the value returned by the current action
362 uint64_t ModelChecker::switch_to_master(ModelAction *act)
365 Thread *old = thread_current();
366 scheduler->set_current_thread(NULL);
367 ASSERT(!old->get_pending());
369 if (inspect_plugin != NULL) {
370 inspect_plugin->inspectModelAction(act);
372 old->set_pending(act);
373 if (Thread::swap(old, &system_context) < 0) {
374 perror("swap threads");
377 return old->get_return_value();
380 /** Wrapper to run the user's main function, with appropriate arguments */
381 void user_main_wrapper(void *)
383 user_main(model->params.argc, model->params.argv);
386 bool ModelChecker::should_terminate_execution()
388 /* Infeasible -> don't take any more steps */
389 if (execution->is_infeasible())
391 else if (execution->isfeasibleprefix() && execution->have_bug_reports()) {
392 execution->set_assert();
396 if (execution->too_many_steps())
401 /** @brief Exit ModelChecker upon returning to the run loop of the
403 void ModelChecker::exit_model_checker()
408 /** @brief Restart ModelChecker upon returning to the run loop of the
410 void ModelChecker::restart()
415 void ModelChecker::do_restart()
417 restart_flag = false;
419 earliest_diverge = NULL;
420 reset_to_initial_state();
421 node_stack->full_reset();
422 memset(&stats,0,sizeof(struct execution_stats));
423 execution_number = 1;
426 /** @brief Run ModelChecker for the user program */
427 void ModelChecker::run()
430 //Need to initial random number generator state to avoid resets on rollback
431 char random_state[256];
432 initstate(423121, random_state, sizeof(random_state));
435 Thread *t = new Thread(execution->get_next_id(), &user_thread, &user_main_wrapper, NULL, NULL); // L: user_main_wrapper passes the user program
436 execution->add_thread(t);
437 //Need to seed random number generator, otherwise its state gets reset
440 * Stash next pending action(s) for thread(s). There
441 * should only need to stash one thread's action--the
442 * thread which just took a step--plus the first step
443 * for any newly-created thread
446 for (unsigned int i = 0; i < get_num_threads(); i++) {
447 thread_id_t tid = int_to_id(i);
448 Thread *thr = get_thread(tid);
449 if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) {
450 switch_from_master(thr); // L: context swapped, and action type of thr changed.
451 if (thr->is_waiting_on(thr))
452 assert_bug("Deadlock detected (thread %u)", i);
456 /* Don't schedule threads which should be disabled */
457 for (unsigned int i = 0; i < get_num_threads(); i++) {
458 Thread *th = get_thread(int_to_id(i));
459 ModelAction *act = th->get_pending();
460 if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
461 scheduler->sleep(th);
465 for (unsigned int i = 1; i < get_num_threads(); i++) {
466 Thread *th = get_thread(int_to_id(i));
467 ModelAction *act = th->get_pending();
468 if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ){
469 if (act->is_write()){
470 std::memory_order order = act->get_mo();
471 if (order == std::memory_order_relaxed || \
472 order == std::memory_order_release) {
476 } else if (act->get_type() == THREAD_CREATE || \
477 act->get_type() == PTHREAD_CREATE || \
478 act->get_type() == THREAD_START || \
479 act->get_type() == THREAD_FINISH) {
486 /* Catch assertions from prior take_step or from
487 * between-ModelAction bugs (e.g., data races) */
489 if (execution->has_asserted())
492 t = get_next_thread();
493 if (!t || t->is_model_thread())
496 /* Consume the next action for a Thread */
497 ModelAction *curr = t->get_pending();
498 t->set_pending(NULL);
499 t = execution->take_step(curr);
500 } while (!should_terminate_execution());
503 //restore random number generator state after rollback
504 setstate(random_state);
505 } while (i<5); // while (has_next);
507 model_print("******* Model-checking complete: *******\n");
510 /* Have the trace analyses dump their output. */
511 for (unsigned int i = 0; i < trace_analyses.size(); i++)
512 trace_analyses[i]->finish();