11 #include "snapshot-interface.h"
14 #include "threads-model.h"
16 #include "traceanalysis.h"
17 #include "execution.h"
19 #include "bugmessage.h"
22 ModelChecker *model = NULL;
24 /** Wrapper to run the user's main function, with appropriate arguments */
25 void user_main_wrapper(void *)
27 user_main(model->params.argc, model->params.argv);
30 /** @brief Constructor */
31 ModelChecker::ModelChecker() :
32 /* Initialize default scheduler */
35 scheduler(new Scheduler()),
36 execution(new ModelExecution(this, scheduler)),
37 history(new ModelHistory()),
42 memset(&stats,0,sizeof(struct execution_stats));
43 init_thread = new Thread(execution->get_next_id(), (thrd_t *) model_malloc(sizeof(thrd_t)), &user_main_wrapper, NULL, NULL); // L: user_main_wrapper passes the user program
44 execution->add_thread(init_thread);
45 scheduler->set_current_thread(init_thread);
46 execution->setParams(¶ms);
47 param_defaults(¶ms);
51 /** @brief Destructor */
52 ModelChecker::~ModelChecker()
57 /** Method to set parameters */
58 model_params * ModelChecker::getParams() {
63 * Restores user program to initial state and resets all model-checker data
66 void ModelChecker::reset_to_initial_state()
70 * FIXME: if we utilize partial rollback, we will need to free only
71 * those pending actions which were NOT pending before the rollback
74 for (unsigned int i = 0;i < get_num_threads();i++)
75 delete get_thread(int_to_id(i))->get_pending();
77 snapshot_backtrack_before(0);
80 /** @return the number of user threads created during this execution */
81 unsigned int ModelChecker::get_num_threads() const
83 return execution->get_num_threads();
87 * Must be called from user-thread context (e.g., through the global
88 * thread_current() interface)
90 * @return The currently executing Thread.
92 Thread * ModelChecker::get_current_thread() const
94 return scheduler->get_current_thread();
98 * @brief Choose the next thread to execute.
100 * This function chooses the next thread that should execute. It can enforce
101 * execution replay/backtracking or, if the model-checker has no preference
102 * regarding the next thread (i.e., when exploring a new execution ordering),
103 * we defer to the scheduler.
105 * @return The next chosen thread to run, if any exist. Or else if the current
106 * execution should terminate, return NULL.
108 Thread * ModelChecker::get_next_thread()
112 * Have we completed exploring the preselected path? Then let the
115 return scheduler->select_next_thread();
119 * @brief Assert a bug in the executing program.
121 * Use this function to assert any sort of bug in the user program. If the
122 * current trace is feasible (actually, a prefix of some feasible execution),
123 * then this execution will be aborted, printing the appropriate message. If
124 * the current trace is not yet feasible, the error message will be stashed and
125 * printed if the execution ever becomes feasible.
127 * @param msg Descriptive message for the bug (do not include newline char)
128 * @return True if bug is immediately-feasible
130 bool ModelChecker::assert_bug(const char *msg, ...)
136 vsnprintf(str, sizeof(str), msg, ap);
139 return execution->assert_bug(str);
143 * @brief Assert a data race in the executing program.
145 * Different from assert_bug, the program will not be aborted immediately
146 * upon calling this function, unless the number of data races exceeds
149 * @param msg Descriptive message for the bug (do not include newline char)
150 * @return True if bug is immediately-feasible
152 bool ModelChecker::assert_race(const char *msg, ...)
158 vsnprintf(str, sizeof(str), msg, ap);
161 return execution->assert_race(str);
165 * @brief Assert a bug in the executing program, asserted by a user thread
166 * @see ModelChecker::assert_bug
167 * @param msg Descriptive message for the bug (do not include newline char)
169 void ModelChecker::assert_user_bug(const char *msg)
171 /* If feasible bug, bail out now */
173 switch_to_master(NULL);
176 /** @brief Print bug report listing for this execution (if any bugs exist) */
177 void ModelChecker::print_bugs() const
179 SnapVector<bug_message *> *bugs = execution->get_bugs();
181 model_print("Bug report: %zu bug%s detected\n",
183 bugs->size() > 1 ? "s" : "");
184 for (unsigned int i = 0;i < bugs->size();i++)
189 * @brief Record end-of-execution stats
191 * Must be run when exiting an execution. Records various stats.
192 * @see struct execution_stats
194 void ModelChecker::record_stats()
197 if (!execution->isfeasibleprefix())
198 stats.num_infeasible++;
199 else if (execution->have_bug_reports())
200 stats.num_buggy_executions++;
201 else if (execution->is_complete_execution())
202 stats.num_complete++;
204 stats.num_redundant++;
207 * @todo We can violate this ASSERT() when fairness/sleep sets
208 * conflict to cause an execution to terminate, e.g. with:
209 * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
211 //ASSERT(scheduler->all_threads_sleeping());
215 /** @brief Print execution stats */
216 void ModelChecker::print_stats() const
218 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
219 model_print("Number of redundant executions: %d\n", stats.num_redundant);
220 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
221 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
222 model_print("Total executions: %d\n", stats.num_total);
226 * @brief End-of-exeuction print
227 * @param printbugs Should any existing bugs be printed?
229 void ModelChecker::print_execution(bool printbugs) const
231 model_print("Program output from execution %d:\n",
232 get_execution_number());
233 print_program_output();
235 if (params.verbose >= 3) {
239 /* Don't print invalid bugs */
240 if (printbugs && execution->have_bug_reports()) {
246 execution->print_summary();
250 * Queries the model-checker for more executions to explore and, if one
251 * exists, resets the model-checker state to execute a new execution.
253 * @return If there are more executions to explore, return true. Otherwise,
256 bool ModelChecker::next_execution()
259 /* Is this execution a feasible execution that's worth bug-checking? */
260 bool complete = execution->isfeasibleprefix() &&
261 (execution->is_complete_execution() ||
262 execution->have_bug_reports());
264 /* End-of-execution bug checks */
266 if (execution->is_deadlocked())
267 assert_bug("Deadlock detected");
270 run_trace_analyses();
275 if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
276 print_execution(complete);
278 clear_program_output();
286 reset_to_initial_state();
290 /** @brief Run trace analyses on complete trace */
291 void ModelChecker::run_trace_analyses() {
292 for (unsigned int i = 0;i < trace_analyses.size();i++)
293 trace_analyses[i]->analyze(execution->get_action_trace());
297 * @brief Get a Thread reference by its ID
298 * @param tid The Thread's ID
299 * @return A Thread reference
301 Thread * ModelChecker::get_thread(thread_id_t tid) const
303 return execution->get_thread(tid);
307 * @brief Get a reference to the Thread in which a ModelAction was executed
308 * @param act The ModelAction
309 * @return A Thread reference
311 Thread * ModelChecker::get_thread(const ModelAction *act) const
313 return execution->get_thread(act);
317 * Switch from a model-checker context to a user-thread context. This is the
318 * complement of ModelChecker::switch_to_master and must be called from the
319 * model-checker context
321 * @param thread The user-thread to switch to
323 void ModelChecker::switch_from_master(Thread *thread)
325 scheduler->set_current_thread(thread);
326 Thread::swap(&system_context, thread);
330 * Switch from a user-context to the "master thread" context (a.k.a. system
331 * context). This switch is made with the intention of exploring a particular
332 * model-checking action (described by a ModelAction object). Must be called
333 * from a user-thread context.
335 * @param act The current action that will be explored. May be NULL only if
336 * trace is exiting via an assertion (see ModelExecution::set_assert and
337 * ModelExecution::has_asserted).
338 * @return Return the value returned by the current action
340 uint64_t ModelChecker::switch_to_master(ModelAction *act)
343 static bool fork_message_printed = false;
345 if (!fork_message_printed) {
346 model_print("Fork handler trying to call into model checker...\n");
347 fork_message_printed = true;
353 Thread *old = thread_current();
354 scheduler->set_current_thread(NULL);
355 ASSERT(!old->get_pending());
357 if (inspect_plugin != NULL) {
358 inspect_plugin->inspectModelAction(act);
361 old->set_pending(act);
362 if (Thread::swap(old, &system_context) < 0) {
363 perror("swap threads");
366 return old->get_return_value();
369 static void runChecker() {
374 void ModelChecker::startChecker() {
375 startExecution(get_system_context(), runChecker);
378 bool ModelChecker::should_terminate_execution()
380 /* Infeasible -> don't take any more steps */
381 if (execution->is_infeasible())
383 else if (execution->isfeasibleprefix() && execution->have_fatal_bug_reports()) {
384 execution->set_assert();
390 /** @brief Restart ModelChecker upon returning to the run loop of the
392 void ModelChecker::restart()
397 void ModelChecker::do_restart()
399 restart_flag = false;
400 reset_to_initial_state();
401 memset(&stats,0,sizeof(struct execution_stats));
402 execution_number = 1;
405 void ModelChecker::startMainThread() {
406 init_thread->set_state(THREAD_RUNNING);
407 scheduler->set_current_thread(init_thread);
411 static bool is_nonsc_write(const ModelAction *act) {
412 if (act->get_type() == ATOMIC_WRITE) {
413 std::memory_order order = act->get_mo();
415 case std::memory_order_relaxed:
416 case std::memory_order_release:
425 /** @brief Run ModelChecker for the user program */
426 void ModelChecker::run()
428 //Need to initial random number generator state to avoid resets on rollback
429 char random_state[256];
430 initstate(423121, random_state, sizeof(random_state));
432 for(int exec = 0;exec < params.maxexecutions;exec++) {
433 Thread * t = init_thread;
437 * Stash next pending action(s) for thread(s). There
438 * should only need to stash one thread's action--the
439 * thread which just took a step--plus the first step
440 * for any newly-created thread
442 ModelAction * pending;
443 for (unsigned int i = 0;i < get_num_threads();i++) {
444 thread_id_t tid = int_to_id(i);
445 Thread *thr = get_thread(tid);
446 if (!thr->is_model_thread() && !thr->is_complete() && ((!(pending=thr->get_pending())) || is_nonsc_write(pending)) ) {
447 switch_from_master(thr); // L: context swapped, and action type of thr changed.
448 if (thr->is_waiting_on(thr))
449 assert_bug("Deadlock detected (thread %u)", i);
453 /* Don't schedule threads which should be disabled */
454 for (unsigned int i = 0;i < get_num_threads();i++) {
455 Thread *th = get_thread(int_to_id(i));
456 ModelAction *act = th->get_pending();
457 if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
458 scheduler->sleep(th);
462 for (unsigned int i = 1;i < get_num_threads();i++) {
463 Thread *th = get_thread(int_to_id(i));
464 ModelAction *act = th->get_pending();
465 if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ) {
466 if (act->is_write()) {
467 std::memory_order order = act->get_mo();
468 if (order == std::memory_order_relaxed || \
469 order == std::memory_order_release) {
473 } else if (act->get_type() == THREAD_CREATE || \
474 act->get_type() == PTHREAD_CREATE || \
475 act->get_type() == THREAD_START || \
476 act->get_type() == THREAD_FINISH) {
483 /* Catch assertions from prior take_step or from
484 * between-ModelAction bugs (e.g., data races) */
486 if (execution->has_asserted())
489 t = get_next_thread();
490 if (!t || t->is_model_thread())
493 /* Consume the next action for a Thread */
494 ModelAction *curr = t->get_pending();
495 t->set_pending(NULL);
496 t = execution->take_step(curr);
497 } while (!should_terminate_execution());
499 //restore random number generator state after rollback
500 setstate(random_state);
503 model_print("******* Model-checking complete: *******\n");
506 /* Have the trace analyses dump their output. */
507 for (unsigned int i = 0;i < trace_analyses.size();i++)
508 trace_analyses[i]->finish();