X-Git-Url: http://plrg.eecs.uci.edu/git/?p=c11tester.git;a=blobdiff_plain;f=model.cc;h=64c1daa5d8f2b52aa561b50cbd2a07a65853ec84;hp=6732c265e9534a426a0aed9391303a2754faeda6;hb=f05f7c754e5d8c7b1152ab2004761fc50a0596a8;hpb=85fac9c01a7269fe0a879f97155f9c5976672606

diff --git a/model.cc b/model.cc
index 6732c265..64c1daa5 100644
--- a/model.cc
+++ b/model.cc
@@ -86,19 +86,19 @@ void ModelChecker::reset_to_initial_state()
 	snapshotObject->backTrackBeforeStep(0);
 }
 
-/** @returns a thread ID for a new Thread */
+/** @return a thread ID for a new Thread */
 thread_id_t ModelChecker::get_next_id()
 {
 	return priv->next_thread_id++;
 }
 
-/** @returns the number of user threads created during this execution */
+/** @return the number of user threads created during this execution */
 int ModelChecker::get_num_threads()
 {
 	return priv->next_thread_id;
 }
 
-/** @returns a sequence number for a new ModelAction */
+/** @return a sequence number for a new ModelAction */
 modelclock_t ModelChecker::get_next_seq_num()
 {
 	return ++priv->used_sequence_numbers;
@@ -200,9 +200,10 @@ bool ModelChecker::next_execution()
 
 ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
 {
-	action_type type = act->get_type();
-
-	if (type==ATOMIC_READ||type==ATOMIC_WRITE||type==ATOMIC_RMW) {
+	switch (act->get_type()) {
+	case ATOMIC_READ:
+	case ATOMIC_WRITE:
+	case ATOMIC_RMW: {
 		/* linear search: from most recent to oldest */
 		action_list_t *list = obj_map->get_safe_ptr(act->get_location());
 		action_list_t::reverse_iterator rit;
@@ -211,59 +212,84 @@ ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
 			if (act->is_synchronizing(prev))
 				return prev;
 		}
-	} else if (type==ATOMIC_LOCK||type==ATOMIC_TRYLOCK) {
+		break;
+	}
+	case ATOMIC_LOCK:
+	case ATOMIC_TRYLOCK: {
 		/* linear search: from most recent to oldest */
 		action_list_t *list = obj_map->get_safe_ptr(act->get_location());
 		action_list_t::reverse_iterator rit;
 		for (rit = list->rbegin(); rit != list->rend(); rit++) {
 			ModelAction *prev = *rit;
-			if (prev->is_success_lock())
+			if (act->is_conflicting_lock(prev))
 				return prev;
 		}
-	} else if (type==ATOMIC_UNLOCK) {
+		break;
+	}
+	case ATOMIC_UNLOCK: {
 		/* linear search: from most recent to oldest */
 		action_list_t *list = obj_map->get_safe_ptr(act->get_location());
 		action_list_t::reverse_iterator rit;
 		for (rit = list->rbegin(); rit != list->rend(); rit++) {
 			ModelAction *prev = *rit;
-			if (prev->is_failed_trylock())
+			if (!act->same_thread(prev)&&prev->is_failed_trylock())
 				return prev;
 		}
+		break;
+	}
+	default:
+		break;
 	}
 	return NULL;
 }
 
+/** This method find backtracking points where we should try to
+ * reorder the parameter ModelAction against.
+ *
+ * @param the ModelAction to find backtracking points for.
+ */
+
+
 void ModelChecker::set_backtracking(ModelAction *act)
 {
-	ModelAction *prev;
-	Node *node;
 	Thread *t = get_thread(act);
-
-	prev = get_last_conflict(act);
+	ModelAction * prev = get_last_conflict(act);
 	if (prev == NULL)
 		return;
 
-	node = prev->get_node()->get_parent();
+	Node * node = prev->get_node()->get_parent();
 
-	while (!node->is_enabled(t))
-		t = t->get_parent();
+	int low_tid, high_tid;
+	if (node->is_enabled(t)) {
+		low_tid = id_to_int(act->get_tid());
+		high_tid = low_tid+1;
+	} else {
+		low_tid = 0;
+		high_tid = get_num_threads();
+	}
 
-	/* Check if this has been explored already */
-	if (node->has_been_explored(t->get_id()))
-		return;
+	for(int i = low_tid; i < high_tid; i++) {
+		thread_id_t tid = int_to_id(i);
+		if (!node->is_enabled(tid))
+			continue;
 
-	/* Cache the latest backtracking point */
-	if (!priv->next_backtrack || *prev > *priv->next_backtrack)
-		priv->next_backtrack = prev;
+		/* Check if this has been explored already */
+		if (node->has_been_explored(tid))
+			continue;
 
-	/* If this is a new backtracking point, mark the tree */
-	if (!node->set_backtrack(t->get_id()))
-		return;
-	DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
-			prev->get_tid(), t->get_id());
-	if (DBG_ENABLED()) {
-		prev->print();
-		act->print();
+		/* Cache the latest backtracking point */
+		if (!priv->next_backtrack || *prev > *priv->next_backtrack)
+			priv->next_backtrack = prev;
+
+		/* If this is a new backtracking point, mark the tree */
+		if (!node->set_backtrack(tid))
+			continue;
+		DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
+					prev->get_tid(), t->get_id());
+		if (DBG_ENABLED()) {
+			prev->print();
+			act->print();
+		}
 	}
 }
 
@@ -325,36 +351,54 @@ bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw)
 	}
 }
 
+/**
+ * Processes a lock, trylock, or unlock model action.  @param curr is
+ * the read model action to process.
+ *
+ * The try lock operation checks whether the lock is taken.  If not,
+ * it falls to the normal lock operation case.  If so, it returns
+ * fail.
+ *
+ * The lock operation has already been checked that it is enabled, so
+ * it just grabs the lock and synchronizes with the previous unlock.
+ *
+ * The unlock operation has to re-enable all of the threads that are
+ * waiting on the lock.
+ */
 void ModelChecker::process_mutex(ModelAction *curr) {
-	std::mutex * mutex=(std::mutex *) curr->get_location();
-	struct std::mutex_state * state=mutex->get_state();
-	switch(curr->get_type()) {
+	std::mutex *mutex = (std::mutex *)curr->get_location();
+	struct std::mutex_state *state = mutex->get_state();
+	switch (curr->get_type()) {
 	case ATOMIC_TRYLOCK: {
-		bool success=!state->islocked;
+		bool success = !state->islocked;
 		curr->set_try_lock(success);
-		if (!success)
+		if (!success) {
+			get_thread(curr)->set_return_value(0);
 			break;
+		}
+		get_thread(curr)->set_return_value(1);
 	}
 		//otherwise fall into the lock case
 	case ATOMIC_LOCK: {
-		if (curr->get_cv()->getClock(state->alloc_tid)<=state->alloc_clock) {
+		if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock) {
 			printf("Lock access before initialization\n");
 			set_assert();
 		}
-		state->islocked=true;
-		ModelAction *unlock=get_last_unlock(curr);
+		state->islocked = true;
+		ModelAction *unlock = get_last_unlock(curr);
 		//synchronize with the previous unlock statement
-		curr->synchronize_with(unlock);
+		if (unlock != NULL)
+			curr->synchronize_with(unlock);
 		break;
 	}
 	case ATOMIC_UNLOCK: {
 		//unlock the lock
-		state->islocked=false;
+		state->islocked = false;
 		//wake up the other threads
-		action_list_t * waiters = lock_waiters_map->get_safe_ptr(curr->get_location());
+		action_list_t *waiters = lock_waiters_map->get_safe_ptr(curr->get_location());
 		//activate all the waiting threads
-		for(action_list_t::iterator rit = waiters->begin(); rit!=waiters->end(); rit++) {
-			add_thread(get_thread((*rit)->get_tid()));
+		for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
+			scheduler->add_thread(get_thread((*rit)->get_tid()));
 		}
 		waiters->clear();
 		break;
@@ -364,7 +408,6 @@ void ModelChecker::process_mutex(ModelAction *curr) {
 	}
 }
 
-
 /**
  * Process a write ModelAction
  * @param curr The ModelAction to process
@@ -376,7 +419,7 @@ bool ModelChecker::process_write(ModelAction *curr)
 	bool updated_promises = resolve_promises(curr);
 
 	if (promises->size() == 0) {
-		for (unsigned int i = 0; i<futurevalues->size(); i++) {
+		for (unsigned int i = 0; i < futurevalues->size(); i++) {
 			struct PendingFutureValue pfv = (*futurevalues)[i];
 			if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) &&
 					(!priv->next_backtrack || *pfv.act > *priv->next_backtrack))
@@ -418,7 +461,9 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr)
 		if (curr->is_rmwr())
 			newcurr->copy_typeandorder(curr);
 
-		ASSERT(curr->get_location()==newcurr->get_location());
+		ASSERT(curr->get_location() == newcurr->get_location());
+		newcurr->copy_from_new(curr);
+
 		/* Discard duplicate ModelAction; use action from NodeStack */
 		delete curr;
 
@@ -438,9 +483,17 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr)
 	return newcurr;
 }
 
+/**
+ * This method checks whether a model action is enabled at the given point.
+ * At this point, it checks whether a lock operation would be successful at this point.
+ * If not, it puts the thread in a waiter list.
+ * @param curr is the ModelAction to check whether it is enabled.
+ * @return a bool that indicates whether the action is enabled.
+ */
+
 bool ModelChecker::check_action_enabled(ModelAction *curr) {
 	if (curr->is_lock()) {
-		std::mutex * lock=(std::mutex *) curr->get_location();
+		std::mutex * lock = (std::mutex *)curr->get_location();
 		struct std::mutex_state * state = lock->get_state();
 		if (state->islocked) {
 			//Stick the action in the appropriate waiting queue
@@ -473,8 +526,8 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
 	if (!check_action_enabled(curr)) {
 		//we'll make the execution look like we chose to run this action
 		//much later...when a lock is actually available to relese
-		remove_thread(get_current_thread());
 		get_current_thread()->set_pending(curr);
+		remove_thread(get_current_thread());
 		return get_next_thread(NULL);
 	}
 
@@ -543,7 +596,7 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
 			if (act->is_write() && process_write(act))
 				updated = true;
 
-			if (act->is_mutex_op()) 
+			if (act->is_mutex_op())
 				process_mutex(act);
 
 			if (updated)
@@ -621,18 +674,18 @@ bool ModelChecker::promises_expired() {
 	return false;
 }
 
-/** @returns whether the current partial trace must be a prefix of a
+/** @return whether the current partial trace must be a prefix of a
  * feasible trace. */
 bool ModelChecker::isfeasibleprefix() {
 	return promises->size() == 0 && *lazy_sync_size == 0;
 }
 
-/** @returns whether the current partial trace is feasible. */
+/** @return whether the current partial trace is feasible. */
 bool ModelChecker::isfeasible() {
 	return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW();
 }
 
-/** @returns whether the current partial trace is feasible other than
+/** @return whether the current partial trace is feasible other than
  * multiple RMW reading from the same store. */
 bool ModelChecker::isfeasibleotherthanRMW() {
 	if (DBG_ENABLED()) {
@@ -764,7 +817,7 @@ void ModelChecker::check_recency(ModelAction *curr) {
 
 /**
  * Updates the mo_graph with the constraints imposed from the current
- * read.  
+ * read.
  *
  * Basic idea is the following: Go through each other thread and find
  * the lastest action that happened before our read.  Two cases:
@@ -823,7 +876,7 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf
  *  promises.  The basic problem is that actions that occur after the
  *  read curr could not property add items to the modification order
  *  for our read.
- *  
+ *
  *  So for each thread, we find the earliest item that happens after
  *  the read curr.  This is the item we have to fix up with additional
  *  constraints.  If that action is write, we add a MO edge between
@@ -959,7 +1012,7 @@ bool ModelChecker::w_modification_order(ModelAction *curr)
 				 */
 				if (thin_air_constraint_may_allow(curr, act)) {
 					if (isfeasible() ||
-							(curr->is_rmw() && act->is_rmw() && curr->get_reads_from()==act->get_reads_from() && isfeasibleotherthanRMW())) {
+							(curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && isfeasibleotherthanRMW())) {
 						struct PendingFutureValue pfv = {curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act};
 						futurevalues->push_back(pfv);
 					}
@@ -983,7 +1036,7 @@ bool ModelChecker::thin_air_constraint_may_allow(const ModelAction * writer, con
 		return true;
 
 	for (const ModelAction *search = writer->get_reads_from(); search != NULL; search = search->get_reads_from()) {
-		if (search==reader)
+		if (search == reader)
 			return false;
 		if (search->get_tid() == reader->get_tid() &&
 				search->happens_before(reader))
@@ -1070,10 +1123,12 @@ bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *rel
 		 * the release seq? */
 		bool future_ordered = false;
 
+		ModelAction *last = get_last_action(int_to_id(i));
+		if (last && rf->happens_before(last))
+			future_ordered = true;
+
 		for (rit = list->rbegin(); rit != list->rend(); rit++) {
 			const ModelAction *act = *rit;
-			if (!act->is_write())
-				continue;
 			/* Reach synchronization -> this thread is complete */
 			if (act->happens_before(release))
 				break;
@@ -1082,6 +1137,10 @@ bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *rel
 				continue;
 			}
 
+			/* Only writes can break release sequences */
+			if (!act->is_write())
+				continue;
+
 			/* Check modification order */
 			if (mo_graph->checkReachable(rf, act)) {
 				/* rf --mo--> act */
@@ -1222,10 +1281,15 @@ void ModelChecker::add_action_to_lists(ModelAction *act)
 	(*thrd_last_action)[tid] = act;
 }
 
-ModelAction * ModelChecker::get_last_action(thread_id_t tid)
+/**
+ * @brief Get the last action performed by a particular Thread
+ * @param tid The thread ID of the Thread in question
+ * @return The last action in the thread
+ */
+ModelAction * ModelChecker::get_last_action(thread_id_t tid) const
 {
-	int threadid=id_to_int(tid);
-	if (threadid<(int)thrd_last_action->size())
+	int threadid = id_to_int(tid);
+	if (threadid < (int)thrd_last_action->size())
 		return (*thrd_last_action)[id_to_int(tid)];
 	else
 		return NULL;
@@ -1239,7 +1303,7 @@ ModelAction * ModelChecker::get_last_action(thread_id_t tid)
  * check
  * @return The last seq_cst write
  */
-ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr)
+ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) const
 {
 	void *location = curr->get_location();
 	action_list_t *list = obj_map->get_safe_ptr(location);
@@ -1251,11 +1315,19 @@ ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr)
 	return NULL;
 }
 
-ModelAction * ModelChecker::get_last_unlock(ModelAction *curr)
+/**
+ * Gets the last unlock operation performed on a particular mutex (i.e., memory
+ * location). This function identifies the mutex according to the current
+ * action, which is presumed to perform on the same mutex.
+ * @param curr The current ModelAction; also denotes the object location to
+ * check
+ * @return The last unlock operation
+ */
+ModelAction * ModelChecker::get_last_unlock(ModelAction *curr) const
 {
 	void *location = curr->get_location();
 	action_list_t *list = obj_map->get_safe_ptr(location);
-	/* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */
+	/* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */
 	action_list_t::reverse_iterator rit;
 	for (rit = list->rbegin(); rit != list->rend(); rit++)
 		if ((*rit)->is_unlock())
@@ -1392,7 +1464,7 @@ void ModelChecker::build_reads_from_past(ModelAction *curr)
 				continue;
 
 			/* Don't consider more than one seq_cst write if we are a seq_cst read. */
-			if (!curr->is_seqcst()|| (!act->is_seqcst() && (last_seq_cst==NULL||!act->happens_before(last_seq_cst))) || act == last_seq_cst) {
+			if (!curr->is_seqcst() || (!act->is_seqcst() && (last_seq_cst == NULL || !act->happens_before(last_seq_cst))) || act == last_seq_cst) {
 				DEBUG("Adding action to may_read_from:\n");
 				if (DBG_ENABLED()) {
 					act->print();
@@ -1448,7 +1520,7 @@ void ModelChecker::print_summary()
 #if SUPPORT_MOD_ORDER_DUMP
 	scheduler->print();
 	char buffername[100];
-	sprintf(buffername, "exec%u",num_executions);
+	sprintf(buffername, "exec%04u", num_executions);
 	mo_graph->dumpGraphToFile(buffername);
 #endif
 
@@ -1469,6 +1541,11 @@ void ModelChecker::add_thread(Thread *t)
 	scheduler->add_thread(t);
 }
 
+/**
+ * Removes a thread from the scheduler. 
+ * @param the thread to remove.
+ */
+
 void ModelChecker::remove_thread(Thread *t)
 {
 	scheduler->remove_thread(t);