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 * @brief Assert a bug in the executing program.
109 * Use this function to assert any sort of bug in the user program. If the
110 * current trace is feasible (actually, a prefix of some feasible execution),
111 * then this execution will be aborted, printing the appropriate message. If
112 * the current trace is not yet feasible, the error message will be stashed and
113 * printed if the execution ever becomes feasible.
115 * @param msg Descriptive message for the bug (do not include newline char)
116 * @return True if bug is immediately-feasible
118 bool ModelChecker::assert_bug(const char *msg, ...)
124 vsnprintf(str, sizeof(str), msg, ap);
127 return execution->assert_bug(str);
131 * @brief Assert a bug in the executing program, asserted by a user thread
132 * @see ModelChecker::assert_bug
133 * @param msg Descriptive message for the bug (do not include newline char)
135 void ModelChecker::assert_user_bug(const char *msg)
137 /* If feasible bug, bail out now */
139 switch_to_master(NULL);
142 /** @brief Print bug report listing for this execution (if any bugs exist) */
143 void ModelChecker::print_bugs() const
145 SnapVector<bug_message *> *bugs = execution->get_bugs();
147 model_print("Bug report: %zu bug%s detected\n",
149 bugs->size() > 1 ? "s" : "");
150 for (unsigned int i = 0; i < bugs->size(); i++)
155 * @brief Record end-of-execution stats
157 * Must be run when exiting an execution. Records various stats.
158 * @see struct execution_stats
160 void ModelChecker::record_stats()
163 if (!execution->isfeasibleprefix())
164 stats.num_infeasible++;
165 else if (execution->have_bug_reports())
166 stats.num_buggy_executions++;
167 else if (execution->is_complete_execution())
168 stats.num_complete++;
170 stats.num_redundant++;
173 * @todo We can violate this ASSERT() when fairness/sleep sets
174 * conflict to cause an execution to terminate, e.g. with:
175 * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
177 //ASSERT(scheduler->all_threads_sleeping());
181 /** @brief Print execution stats */
182 void ModelChecker::print_stats() const
184 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
185 model_print("Number of redundant executions: %d\n", stats.num_redundant);
186 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
187 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
188 model_print("Total executions: %d\n", stats.num_total);
190 model_print("Total nodes created: %d\n", node_stack->get_total_nodes());
194 * @brief End-of-exeuction print
195 * @param printbugs Should any existing bugs be printed?
197 void ModelChecker::print_execution(bool printbugs) const
199 model_print("Program output from execution %d:\n",
200 get_execution_number());
201 print_program_output();
203 if (params.verbose >= 3) {
204 model_print("\nEarliest divergence point since last feasible execution:\n");
205 if (earliest_diverge)
206 earliest_diverge->print();
208 model_print("(Not set)\n");
214 /* Don't print invalid bugs */
215 if (printbugs && execution->have_bug_reports()) {
221 execution->print_summary();
225 * Queries the model-checker for more executions to explore and, if one
226 * exists, resets the model-checker state to execute a new execution.
228 * @return If there are more executions to explore, return true. Otherwise,
231 bool ModelChecker::next_execution()
234 /* Is this execution a feasible execution that's worth bug-checking? */
235 bool complete = execution->isfeasibleprefix() &&
236 (execution->is_complete_execution() ||
237 execution->have_bug_reports());
239 /* End-of-execution bug checks */
241 if (execution->is_deadlocked())
242 assert_bug("Deadlock detected");
245 run_trace_analyses();
250 if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
251 print_execution(complete);
253 clear_program_output();
261 reset_to_initial_state();
262 node_stack->full_reset();
267 earliest_diverge = NULL;
272 // diverge = execution->get_next_backtrack();
273 if (diverge == NULL) {
275 reset_to_initial_state();
276 model_print("Does not diverge\n");
281 model_print("Next execution will diverge at:\n");
287 if (params.maxexecutions != 0 && stats.num_complete >= params.maxexecutions)
290 reset_to_initial_state();
296 /** @brief Run trace analyses on complete trace */
297 void ModelChecker::run_trace_analyses() {
298 for (unsigned int i = 0; i < trace_analyses.size(); i++)
299 trace_analyses[i]->analyze(execution->get_action_trace());
303 * @brief Get a Thread reference by its ID
304 * @param tid The Thread's ID
305 * @return A Thread reference
307 Thread * ModelChecker::get_thread(thread_id_t tid) const
309 return execution->get_thread(tid);
313 * @brief Get a reference to the Thread in which a ModelAction was executed
314 * @param act The ModelAction
315 * @return A Thread reference
317 Thread * ModelChecker::get_thread(const ModelAction *act) const
319 return execution->get_thread(act);
323 * Switch from a model-checker context to a user-thread context. This is the
324 * complement of ModelChecker::switch_to_master and must be called from the
325 * model-checker context
327 * @param thread The user-thread to switch to
329 void ModelChecker::switch_from_master(Thread *thread)
331 scheduler->set_current_thread(thread);
332 Thread::swap(&system_context, thread);
336 * Switch from a user-context to the "master thread" context (a.k.a. system
337 * context). This switch is made with the intention of exploring a particular
338 * model-checking action (described by a ModelAction object). Must be called
339 * from a user-thread context.
341 * @param act The current action that will be explored. May be NULL only if
342 * trace is exiting via an assertion (see ModelExecution::set_assert and
343 * ModelExecution::has_asserted).
344 * @return Return the value returned by the current action
346 uint64_t ModelChecker::switch_to_master(ModelAction *act)
349 Thread *old = thread_current();
350 scheduler->set_current_thread(NULL);
351 ASSERT(!old->get_pending());
353 if (inspect_plugin != NULL) {
354 inspect_plugin->inspectModelAction(act);
356 old->set_pending(act);
357 if (Thread::swap(old, &system_context) < 0) {
358 perror("swap threads");
361 return old->get_return_value();
364 /** Wrapper to run the user's main function, with appropriate arguments */
365 void user_main_wrapper(void *)
367 user_main(model->params.argc, model->params.argv);
370 bool ModelChecker::should_terminate_execution()
372 /* Infeasible -> don't take any more steps */
373 if (execution->is_infeasible())
375 else if (execution->isfeasibleprefix() && execution->have_bug_reports()) {
376 execution->set_assert();
380 if (execution->too_many_steps())
385 /** @brief Exit ModelChecker upon returning to the run loop of the
387 void ModelChecker::exit_model_checker()
392 /** @brief Restart ModelChecker upon returning to the run loop of the
394 void ModelChecker::restart()
399 void ModelChecker::do_restart()
401 restart_flag = false;
403 earliest_diverge = NULL;
404 reset_to_initial_state();
405 node_stack->full_reset();
406 memset(&stats,0,sizeof(struct execution_stats));
407 execution_number = 1;
410 /** @brief Run ModelChecker for the user program */
411 void ModelChecker::run()
414 //Need to initial random number generator state to avoid resets on rollback
415 char random_state[256];
416 initstate(423121, random_state, sizeof(random_state));
419 Thread *t = new Thread(execution->get_next_id(), &user_thread, &user_main_wrapper, NULL, NULL); // L: user_main_wrapper passes the user program
420 execution->add_thread(t);
421 //Need to seed random number generator, otherwise its state gets reset
424 * Stash next pending action(s) for thread(s). There
425 * should only need to stash one thread's action--the
426 * thread which just took a step--plus the first step
427 * for any newly-created thread
430 for (unsigned int i = 0; i < get_num_threads(); i++) {
431 thread_id_t tid = int_to_id(i);
432 Thread *thr = get_thread(tid);
433 if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) {
434 switch_from_master(thr); // L: context swapped, and action type of thr changed.
435 if (thr->is_waiting_on(thr))
436 assert_bug("Deadlock detected (thread %u)", i);
440 /* Don't schedule threads which should be disabled */
441 for (unsigned int i = 0; i < get_num_threads(); i++) {
442 Thread *th = get_thread(int_to_id(i));
443 ModelAction *act = th->get_pending();
444 if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
445 scheduler->sleep(th);
449 for (unsigned int i = 1; i < get_num_threads(); i++) {
450 Thread *th = get_thread(int_to_id(i));
451 ModelAction *act = th->get_pending();
452 if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ){
453 if (act->is_write()){
454 std::memory_order order = act->get_mo();
455 if (order == std::memory_order_relaxed || \
456 order == std::memory_order_release) {
460 } else if (act->get_type() == THREAD_CREATE || \
461 act->get_type() == PTHREAD_CREATE || \
462 act->get_type() == THREAD_START || \
463 act->get_type() == THREAD_FINISH) {
470 /* Catch assertions from prior take_step or from
471 * between-ModelAction bugs (e.g., data races) */
473 if (execution->has_asserted())
476 t = get_next_thread();
477 if (!t || t->is_model_thread())
480 /* Consume the next action for a Thread */
481 ModelAction *curr = t->get_pending();
482 t->set_pending(NULL);
483 t = execution->take_step(curr);
484 } while (!should_terminate_execution());
487 //restore random number generator state after rollback
488 setstate(random_state);
489 } while (i<5); // while (has_next);
491 model_print("******* Model-checking complete: *******\n");
494 /* Have the trace analyses dump their output. */
495 for (unsigned int i = 0; i < trace_analyses.size(); i++)
496 trace_analyses[i]->finish();