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() :
25 /* Initialize default scheduler */
28 scheduler(new Scheduler()),
29 node_stack(new NodeStack()),
30 execution(new ModelExecution(this, scheduler, node_stack)),
35 memset(&stats,0,sizeof(struct execution_stats));
38 /** @brief Destructor */
39 ModelChecker::~ModelChecker()
45 /** Method to set parameters */
46 void ModelChecker::setParams(struct model_params params) {
47 this->params = params;
48 execution->setParams(¶ms);
52 * Restores user program to initial state and resets all model-checker data
55 void ModelChecker::reset_to_initial_state()
59 * FIXME: if we utilize partial rollback, we will need to free only
60 * those pending actions which were NOT pending before the rollback
63 for (unsigned int i = 0;i < get_num_threads();i++)
64 delete get_thread(int_to_id(i))->get_pending();
66 snapshot_backtrack_before(0);
69 /** @return the number of user threads created during this execution */
70 unsigned int ModelChecker::get_num_threads() const
72 return execution->get_num_threads();
76 * Must be called from user-thread context (e.g., through the global
77 * thread_current() interface)
79 * @return The currently executing Thread.
81 Thread * ModelChecker::get_current_thread() const
83 return scheduler->get_current_thread();
87 * @brief Choose the next thread to execute.
89 * This function chooses the next thread that should execute. It can enforce
90 * execution replay/backtracking or, if the model-checker has no preference
91 * regarding the next thread (i.e., when exploring a new execution ordering),
92 * we defer to the scheduler.
94 * @return The next chosen thread to run, if any exist. Or else if the current
95 * execution should terminate, return NULL.
97 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 * @brief Assert a bug in the executing program.
110 * Use this function to assert any sort of bug in the user program. If the
111 * current trace is feasible (actually, a prefix of some feasible execution),
112 * then this execution will be aborted, printing the appropriate message. If
113 * the current trace is not yet feasible, the error message will be stashed and
114 * printed if the execution ever becomes feasible.
116 * @param msg Descriptive message for the bug (do not include newline char)
117 * @return True if bug is immediately-feasible
119 bool ModelChecker::assert_bug(const char *msg, ...)
125 vsnprintf(str, sizeof(str), msg, ap);
128 return execution->assert_bug(str);
132 * @brief Assert a bug in the executing program, asserted by a user thread
133 * @see ModelChecker::assert_bug
134 * @param msg Descriptive message for the bug (do not include newline char)
136 void ModelChecker::assert_user_bug(const char *msg)
138 /* If feasible bug, bail out now */
140 switch_to_master(NULL);
143 /** @brief Print bug report listing for this execution (if any bugs exist) */
144 void ModelChecker::print_bugs() const
146 SnapVector<bug_message *> *bugs = execution->get_bugs();
148 model_print("Bug report: %zu bug%s detected\n",
150 bugs->size() > 1 ? "s" : "");
151 for (unsigned int i = 0;i < bugs->size();i++)
156 * @brief Record end-of-execution stats
158 * Must be run when exiting an execution. Records various stats.
159 * @see struct execution_stats
161 void ModelChecker::record_stats()
164 if (!execution->isfeasibleprefix())
165 stats.num_infeasible++;
166 else if (execution->have_bug_reports())
167 stats.num_buggy_executions++;
168 else if (execution->is_complete_execution())
169 stats.num_complete++;
171 stats.num_redundant++;
174 * @todo We can violate this ASSERT() when fairness/sleep sets
175 * conflict to cause an execution to terminate, e.g. with:
176 * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
178 //ASSERT(scheduler->all_threads_sleeping());
182 /** @brief Print execution stats */
183 void ModelChecker::print_stats() const
185 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
186 model_print("Number of redundant executions: %d\n", stats.num_redundant);
187 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
188 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
189 model_print("Total executions: %d\n", stats.num_total);
193 * @brief End-of-exeuction print
194 * @param printbugs Should any existing bugs be printed?
196 void ModelChecker::print_execution(bool printbugs) const
198 model_print("Program output from execution %d:\n",
199 get_execution_number());
200 print_program_output();
202 if (params.verbose >= 3) {
206 /* Don't print invalid bugs */
207 if (printbugs && execution->have_bug_reports()) {
213 execution->print_summary();
217 * Queries the model-checker for more executions to explore and, if one
218 * exists, resets the model-checker state to execute a new execution.
220 * @return If there are more executions to explore, return true. Otherwise,
223 bool ModelChecker::next_execution()
226 /* Is this execution a feasible execution that's worth bug-checking? */
227 bool complete = execution->isfeasibleprefix() &&
228 (execution->is_complete_execution() ||
229 execution->have_bug_reports());
231 /* End-of-execution bug checks */
233 if (execution->is_deadlocked())
234 assert_bug("Deadlock detected");
237 run_trace_analyses();
242 if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
243 print_execution(complete);
245 clear_program_output();
253 reset_to_initial_state();
257 /** @brief Run trace analyses on complete trace */
258 void ModelChecker::run_trace_analyses() {
259 for (unsigned int i = 0;i < trace_analyses.size();i++)
260 trace_analyses[i]->analyze(execution->get_action_trace());
264 * @brief Get a Thread reference by its ID
265 * @param tid The Thread's ID
266 * @return A Thread reference
268 Thread * ModelChecker::get_thread(thread_id_t tid) const
270 return execution->get_thread(tid);
274 * @brief Get a reference to the Thread in which a ModelAction was executed
275 * @param act The ModelAction
276 * @return A Thread reference
278 Thread * ModelChecker::get_thread(const ModelAction *act) const
280 return execution->get_thread(act);
284 * Switch from a model-checker context to a user-thread context. This is the
285 * complement of ModelChecker::switch_to_master and must be called from the
286 * model-checker context
288 * @param thread The user-thread to switch to
290 void ModelChecker::switch_from_master(Thread *thread)
292 scheduler->set_current_thread(thread);
293 Thread::swap(&system_context, thread);
297 * Switch from a user-context to the "master thread" context (a.k.a. system
298 * context). This switch is made with the intention of exploring a particular
299 * model-checking action (described by a ModelAction object). Must be called
300 * from a user-thread context.
302 * @param act The current action that will be explored. May be NULL only if
303 * trace is exiting via an assertion (see ModelExecution::set_assert and
304 * ModelExecution::has_asserted).
305 * @return Return the value returned by the current action
307 uint64_t ModelChecker::switch_to_master(ModelAction *act)
310 Thread *old = thread_current();
311 scheduler->set_current_thread(NULL);
312 ASSERT(!old->get_pending());
314 if (inspect_plugin != NULL) {
315 inspect_plugin->inspectModelAction(act);
317 old->set_pending(act);
318 if (Thread::swap(old, &system_context) < 0) {
319 perror("swap threads");
322 return old->get_return_value();
325 /** Wrapper to run the user's main function, with appropriate arguments */
326 void user_main_wrapper(void *)
328 user_main(model->params.argc, model->params.argv);
331 bool ModelChecker::should_terminate_execution()
333 /* Infeasible -> don't take any more steps */
334 if (execution->is_infeasible())
336 else if (execution->isfeasibleprefix() && execution->have_bug_reports()) {
337 execution->set_assert();
343 /** @brief Restart ModelChecker upon returning to the run loop of the
345 void ModelChecker::restart()
350 void ModelChecker::do_restart()
352 restart_flag = false;
353 reset_to_initial_state();
354 memset(&stats,0,sizeof(struct execution_stats));
355 execution_number = 1;
358 /** @brief Run ModelChecker for the user program */
359 void ModelChecker::run()
361 //Need to initial random number generator state to avoid resets on rollback
362 char random_state[256];
363 initstate(423121, random_state, sizeof(random_state));
365 for(int exec = 0;exec < params.maxexecutions;exec++) {
367 Thread *t = new Thread(execution->get_next_id(), &user_thread, &user_main_wrapper, NULL, NULL); // L: user_main_wrapper passes the user program
368 execution->add_thread(t);
369 //Need to seed random number generator, otherwise its state gets reset
372 * Stash next pending action(s) for thread(s). There
373 * should only need to stash one thread's action--the
374 * thread which just took a step--plus the first step
375 * for any newly-created thread
378 for (unsigned int i = 0;i < get_num_threads();i++) {
379 thread_id_t tid = int_to_id(i);
380 Thread *thr = get_thread(tid);
381 if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) {
382 switch_from_master(thr); // L: context swapped, and action type of thr changed.
383 if (thr->is_waiting_on(thr))
384 assert_bug("Deadlock detected (thread %u)", i);
388 /* Don't schedule threads which should be disabled */
389 for (unsigned int i = 0;i < get_num_threads();i++) {
390 Thread *th = get_thread(int_to_id(i));
391 ModelAction *act = th->get_pending();
392 if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
393 scheduler->sleep(th);
397 for (unsigned int i = 1;i < get_num_threads();i++) {
398 Thread *th = get_thread(int_to_id(i));
399 ModelAction *act = th->get_pending();
400 if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ) {
401 if (act->is_write()) {
402 std::memory_order order = act->get_mo();
403 if (order == std::memory_order_relaxed || \
404 order == std::memory_order_release) {
408 } else if (act->get_type() == THREAD_CREATE || \
409 act->get_type() == PTHREAD_CREATE || \
410 act->get_type() == THREAD_START || \
411 act->get_type() == THREAD_FINISH) {
418 /* Catch assertions from prior take_step or from
419 * between-ModelAction bugs (e.g., data races) */
421 if (execution->has_asserted())
424 t = get_next_thread();
425 if (!t || t->is_model_thread())
428 /* Consume the next action for a Thread */
429 ModelAction *curr = t->get_pending();
430 t->set_pending(NULL);
431 t = execution->take_step(curr);
432 } while (!should_terminate_execution());
434 //restore random number generator state after rollback
435 setstate(random_state);
438 model_print("******* Model-checking complete: *******\n");
441 /* Have the trace analyses dump their output. */
442 for (unsigned int i = 0;i < trace_analyses.size();i++)
443 trace_analyses[i]->finish();