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)), // L: Model thread is created inside
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()
101 * Have we completed exploring the preselected path? Then let the
104 return scheduler->select_next_thread(node_stack->get_head());
108 * We need to know what the next actions of all threads in the sleep
109 * set will be. This method computes them and stores the actions at
110 * the corresponding thread object's pending action.
112 void ModelChecker::execute_sleep_set()
114 for (unsigned int i = 0; i < get_num_threads(); i++) {
115 thread_id_t tid = int_to_id(i);
116 Thread *thr = get_thread(tid);
117 if (scheduler->is_sleep_set(thr) && thr->get_pending()) {
118 thr->get_pending()->set_sleep_flag();
124 * @brief Assert a bug in the executing program.
126 * Use this function to assert any sort of bug in the user program. If the
127 * current trace is feasible (actually, a prefix of some feasible execution),
128 * then this execution will be aborted, printing the appropriate message. If
129 * the current trace is not yet feasible, the error message will be stashed and
130 * printed if the execution ever becomes feasible.
132 * @param msg Descriptive message for the bug (do not include newline char)
133 * @return True if bug is immediately-feasible
135 bool ModelChecker::assert_bug(const char *msg, ...)
141 vsnprintf(str, sizeof(str), msg, ap);
144 return execution->assert_bug(str);
148 * @brief Assert a bug in the executing program, asserted by a user thread
149 * @see ModelChecker::assert_bug
150 * @param msg Descriptive message for the bug (do not include newline char)
152 void ModelChecker::assert_user_bug(const char *msg)
154 /* If feasible bug, bail out now */
156 switch_to_master(NULL);
159 /** @brief Print bug report listing for this execution (if any bugs exist) */
160 void ModelChecker::print_bugs() const
162 SnapVector<bug_message *> *bugs = execution->get_bugs();
164 model_print("Bug report: %zu bug%s detected\n",
166 bugs->size() > 1 ? "s" : "");
167 for (unsigned int i = 0; i < bugs->size(); i++)
172 * @brief Record end-of-execution stats
174 * Must be run when exiting an execution. Records various stats.
175 * @see struct execution_stats
177 void ModelChecker::record_stats()
180 if (!execution->isfeasibleprefix())
181 stats.num_infeasible++;
182 else if (execution->have_bug_reports())
183 stats.num_buggy_executions++;
184 else if (execution->is_complete_execution())
185 stats.num_complete++;
187 stats.num_redundant++;
190 * @todo We can violate this ASSERT() when fairness/sleep sets
191 * conflict to cause an execution to terminate, e.g. with:
192 * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
194 //ASSERT(scheduler->all_threads_sleeping());
198 /** @brief Print execution stats */
199 void ModelChecker::print_stats() const
201 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
202 model_print("Number of redundant executions: %d\n", stats.num_redundant);
203 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
204 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
205 model_print("Total executions: %d\n", stats.num_total);
207 model_print("Total nodes created: %d\n", node_stack->get_total_nodes());
211 * @brief End-of-exeuction print
212 * @param printbugs Should any existing bugs be printed?
214 void ModelChecker::print_execution(bool printbugs) const
216 model_print("Program output from execution %d:\n",
217 get_execution_number());
218 print_program_output();
220 if (params.verbose >= 3) {
221 model_print("\nEarliest divergence point since last feasible execution:\n");
222 if (earliest_diverge)
223 earliest_diverge->print();
225 model_print("(Not set)\n");
231 /* Don't print invalid bugs */
232 if (printbugs && execution->have_bug_reports()) {
238 execution->print_summary();
242 * Queries the model-checker for more executions to explore and, if one
243 * exists, resets the model-checker state to execute a new execution.
245 * @return If there are more executions to explore, return true. Otherwise,
248 bool ModelChecker::next_execution()
251 /* Is this execution a feasible execution that's worth bug-checking? */
252 bool complete = execution->isfeasibleprefix() &&
253 (execution->is_complete_execution() ||
254 execution->have_bug_reports());
256 /* End-of-execution bug checks */
258 if (execution->is_deadlocked())
259 assert_bug("Deadlock detected");
262 run_trace_analyses();
267 if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
268 print_execution(complete);
270 clear_program_output();
278 reset_to_initial_state();
279 node_stack->full_reset();
284 earliest_diverge = NULL;
289 // diverge = execution->get_next_backtrack();
290 if (diverge == NULL) {
292 reset_to_initial_state();
293 model_print("Does not diverge\n");
298 model_print("Next execution will diverge at:\n");
304 if (params.maxexecutions != 0 && stats.num_complete >= params.maxexecutions)
307 reset_to_initial_state();
313 /** @brief Run trace analyses on complete trace */
314 void ModelChecker::run_trace_analyses() {
315 for (unsigned int i = 0; i < trace_analyses.size(); i++)
316 trace_analyses[i]->analyze(execution->get_action_trace());
320 * @brief Get a Thread reference by its ID
321 * @param tid The Thread's ID
322 * @return A Thread reference
324 Thread * ModelChecker::get_thread(thread_id_t tid) const
326 return execution->get_thread(tid);
330 * @brief Get a reference to the Thread in which a ModelAction was executed
331 * @param act The ModelAction
332 * @return A Thread reference
334 Thread * ModelChecker::get_thread(const ModelAction *act) const
336 return execution->get_thread(act);
340 * Switch from a model-checker context to a user-thread context. This is the
341 * complement of ModelChecker::switch_to_master and must be called from the
342 * model-checker context
344 * @param thread The user-thread to switch to
346 void ModelChecker::switch_from_master(Thread *thread)
348 scheduler->set_current_thread(thread);
349 Thread::swap(&system_context, thread);
353 * Switch from a user-context to the "master thread" context (a.k.a. system
354 * context). This switch is made with the intention of exploring a particular
355 * model-checking action (described by a ModelAction object). Must be called
356 * from a user-thread context.
358 * @param act The current action that will be explored. May be NULL only if
359 * trace is exiting via an assertion (see ModelExecution::set_assert and
360 * ModelExecution::has_asserted).
361 * @return Return the value returned by the current action
363 uint64_t ModelChecker::switch_to_master(ModelAction *act)
366 Thread *old = thread_current();
367 scheduler->set_current_thread(NULL);
368 ASSERT(!old->get_pending());
370 if (inspect_plugin != NULL) {
371 inspect_plugin->inspectModelAction(act);
373 old->set_pending(act);
374 if (Thread::swap(old, &system_context) < 0) {
375 perror("swap threads");
378 return old->get_return_value();
381 /** Wrapper to run the user's main function, with appropriate arguments */
382 void user_main_wrapper(void *)
384 user_main(model->params.argc, model->params.argv);
387 bool ModelChecker::should_terminate_execution()
389 /* Infeasible -> don't take any more steps */
390 if (execution->is_infeasible())
392 else if (execution->isfeasibleprefix() && execution->have_bug_reports()) {
393 execution->set_assert();
397 if (execution->too_many_steps())
402 /** @brief Exit ModelChecker upon returning to the run loop of the
404 void ModelChecker::exit_model_checker()
409 /** @brief Restart ModelChecker upon returning to the run loop of the
411 void ModelChecker::restart()
416 void ModelChecker::do_restart()
418 restart_flag = false;
420 earliest_diverge = NULL;
421 reset_to_initial_state();
422 node_stack->full_reset();
423 memset(&stats,0,sizeof(struct execution_stats));
424 execution_number = 1;
427 /** @brief Run ModelChecker for the user program */
428 void ModelChecker::run()
434 Thread *t = new Thread(execution->get_next_id(), &user_thread, &user_main_wrapper, NULL, NULL); // L: user_main_wrapper passes the user program
435 execution->add_thread(t);
438 * Stash next pending action(s) for thread(s). There
439 * should only need to stash one thread's action--the
440 * thread which just took a step--plus the first step
441 * for any newly-created thread
444 for (unsigned int i = 0; i < get_num_threads(); i++) {
445 thread_id_t tid = int_to_id(i);
446 Thread *thr = get_thread(tid);
447 if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) {
448 switch_from_master(thr); // L: context swapped, and action type of thr changed.
449 if (thr->is_waiting_on(thr))
450 assert_bug("Deadlock detected (thread %u)", i);
454 /* Don't schedule threads which should be disabled */
455 for (unsigned int i = 0; i < get_num_threads(); i++) {
456 Thread *th = get_thread(int_to_id(i));
457 ModelAction *act = th->get_pending();
458 if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
459 scheduler->sleep(th);
463 for (unsigned int i = 1; i < get_num_threads(); i++) {
464 Thread *th = get_thread(int_to_id(i));
465 ModelAction *act = th->get_pending();
466 if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ){
467 if (act->is_write()){
468 std::memory_order order = act->get_mo();
469 if (order == std::memory_order_relaxed || \
470 order == std::memory_order_release) {
474 } else if (act->get_type() == THREAD_CREATE || \
475 act->get_type() == PTHREAD_CREATE || \
476 act->get_type() == THREAD_START || \
477 act->get_type() == THREAD_FINISH) {
484 /* Catch assertions from prior take_step or from
485 * between-ModelAction bugs (e.g., data races) */
487 if (execution->has_asserted())
490 t = get_next_thread();
491 if (!t || t->is_model_thread())
494 /* Consume the next action for a Thread */
495 ModelAction *curr = t->get_pending();
496 t->set_pending(NULL);
497 t = execution->take_step(curr);
498 } while (!should_terminate_execution());
500 has_next = next_execution();
502 } while (i<2); // while (has_next);
504 execution->fixup_release_sequences();
506 model_print("******* Model-checking complete: *******\n");
509 /* Have the trace analyses dump their output. */
510 for (unsigned int i = 0; i < trace_analyses.size(); i++)
511 trace_analyses[i]->finish();