earliest_diverge=diverge;
Node *nextnode = next->get_node();
+ Node *prevnode = nextnode->get_parent();
+ scheduler->update_sleep_set(prevnode);
+
/* Reached divergence point */
if (nextnode->increment_promise()) {
/* The next node will try to satisfy a different set of promises. */
node_stack->pop_restofstack(2);
} else {
/* Make a different thread execute for next step */
- Node *node = nextnode->get_parent();
- tid = node->get_next_backtrack();
+ scheduler->add_sleep(thread_map->get(id_to_int(next->get_tid())));
+ tid = prevnode->get_next_backtrack();
+ /* Make sure the backtracked thread isn't sleeping. */
+ scheduler->remove_sleep(thread_map->get(id_to_int(tid)));
node_stack->pop_restofstack(1);
if (diverge==earliest_diverge) {
- earliest_diverge=node->get_action();
+ earliest_diverge=prevnode->get_action();
}
}
+ /* The correct sleep set is in the parent node. */
+ execute_sleep_set();
+
DEBUG("*** Divergence point ***\n");
diverge = NULL;
return thread_map->get(id_to_int(tid));
}
+/**
+ * We need to know what the next actions of all threads in the sleep
+ * set will be. This method computes them and stores the actions at
+ * the corresponding thread object's pending action.
+ */
+
+void ModelChecker::execute_sleep_set() {
+ for(unsigned int i=0;i<get_num_threads();i++) {
+ thread_id_t tid=int_to_id(i);
+ Thread *thr=get_thread(tid);
+ if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
+ thr->set_state(THREAD_RUNNING);
+ scheduler->next_thread(thr);
+ Thread::swap(&system_context, thr);
+ thr->set_pending(priv->current_action);
+ }
+ }
+ priv->current_action = NULL;
+}
+
+void ModelChecker::wake_up_sleeping_actions(ModelAction * curr) {
+ for(unsigned int i=0;i<get_num_threads();i++) {
+ thread_id_t tid=int_to_id(i);
+ Thread *thr=get_thread(tid);
+ if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
+ ModelAction *pending_act=thr->get_pending();
+ if (pending_act->could_synchronize_with(curr)) {
+ //Remove this thread from sleep set
+ scheduler->remove_sleep(thr);
+ }
+ }
+ }
+}
+
/**
* Queries the model-checker for more executions to explore and, if one
* exists, resets the model-checker state to execute a new execution.
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
- if (act->is_synchronizing(prev))
+ if (prev->could_synchronize_with(act))
return prev;
}
break;
return NULL;
}
-/** This method find backtracking points where we should try to
+/** This method finds backtracking points where we should try to
* reorder the parameter ModelAction against.
*
* @param the ModelAction to find backtracking points for.
for(int i = low_tid; i < high_tid; i++) {
thread_id_t tid = int_to_id(i);
+
if (!node->is_enabled(tid))
continue;
-
+
/* Check if this has been explored already */
if (node->has_been_explored(tid))
continue;
if (unfair)
continue;
}
-
/* Cache the latest backtracking point */
if (!priv->next_backtrack || *prev > *priv->next_backtrack)
priv->next_backtrack = prev;
Thread * ModelChecker::check_current_action(ModelAction *curr)
{
ASSERT(curr);
-
bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
if (!check_action_enabled(curr)) {
return get_next_thread(NULL);
}
+ wake_up_sleeping_actions(curr);
+
ModelAction *newcurr = initialize_curr_action(curr);
+
/* Add the action to lists before any other model-checking tasks */
if (!second_part_of_rmw)
add_action_to_lists(newcurr);
/* Initialize work_queue with the "current action" work */
work_queue_t work_queue(1, CheckCurrWorkEntry(curr));
-
while (!work_queue.empty()) {
WorkQueueEntry work = work_queue.front();
work_queue.pop_front();
}
check_curr_backtracking(curr);
-
set_backtracking(curr);
-
return get_next_thread(curr);
}
}
added = true;
break;
- } else if (act->is_read() && !act->is_synchronizing(curr) &&
+ } else if (act->is_read() && !act->could_synchronize_with(curr) &&
!act->same_thread(curr)) {
/* We have an action that:
(1) did not happen before us
* @todo Finish lazy updating, when promises are fulfilled in the future
* @param rf The action that might be part of a release sequence. Must be a
* write.
- * @param release_heads A pass-by-reference style return parameter. After
+ * @param release_heads A pass-by-reference style return parameter. After
* execution of this function, release_heads will contain the heads of all the
- * relevant release sequences, if any exists
+ * relevant release sequences, if any exists with certainty
+ * @param pending A pass-by-reference style return parameter which is only used
+ * when returning false (i.e., uncertain). Returns most information regarding
+ * an uncertain release sequence, including any write operations that might
+ * break the sequence.
* @return true, if the ModelChecker is certain that release_heads is complete;
* false otherwise
*/
-bool ModelChecker::release_seq_heads(const ModelAction *rf, rel_heads_list_t *release_heads) const
+bool ModelChecker::release_seq_heads(const ModelAction *rf,
+ rel_heads_list_t *release_heads,
+ struct release_seq *pending) const
{
/* Only check for release sequences if there are no cycles */
if (mo_graph->checkForCycles())
};
if (!rf) {
/* read from future: need to settle this later */
+ pending->rf = NULL;
return false; /* incomplete */
}
ASSERT(rf->same_thread(release));
+ pending->writes.clear();
+
bool certain = true;
for (unsigned int i = 0; i < thrd_lists->size(); i++) {
if (id_to_int(rf->get_tid()) == (int)i)
/* release --mo-> act --mo--> rf */
return true; /* complete */
}
+ /* act may break release sequence */
+ pending->writes.push_back(act);
certain = false;
}
if (!future_ordered)
- return false; /* This thread is uncertain */
+ certain = false; /* This thread is uncertain */
}
- if (certain)
+ if (certain) {
release_heads->push_back(release);
+ pending->writes.clear();
+ } else {
+ pending->release = release;
+ pending->rf = rf;
+ }
return certain;
}
struct release_seq *sequence = (struct release_seq *)snapshot_calloc(1, sizeof(struct release_seq));
sequence->acquire = act;
- if (!release_seq_heads(rf, release_heads)) {
+ if (!release_seq_heads(rf, release_heads, sequence)) {
/* add act to 'lazy checking' list */
pending_rel_seqs->push_back(sequence);
} else {
const ModelAction *rf = act->get_reads_from();
rel_heads_list_t release_heads;
bool complete;
- complete = release_seq_heads(rf, &release_heads);
+ complete = release_seq_heads(rf, &release_heads, pending);
for (unsigned int i = 0; i < release_heads.size(); i++) {
if (!act->has_synchronized_with(release_heads[i])) {
if (act->synchronize_with(release_heads[i]))
} else
promise_index++;
}
+
+ //Check whether reading these writes has made threads unable to
+ //resolve promises
+
for(unsigned int i=0;i<threads_to_check.size();i++)
mo_check_promises(threads_to_check[i], write);
const ModelAction *act = promise->get_action();
if (!act->happens_before(curr) &&
act->is_read() &&
- !act->is_synchronizing(curr) &&
+ !act->could_synchronize_with(curr) &&
!act->same_thread(curr) &&
promise->get_value() == curr->get_value()) {
curr->get_node()->set_promise(i);
}
}
-/** Checks promises in response to change in ClockVector Threads. */
+/** Checks promises in response to addition to modification order for threads.
+ * Definitions:
+ * pthread is the thread that performed the read that created the promise
+ *
+ * pread is the read that created the promise
+ *
+ * pwrite is either the first write to same location as pread by
+ * pthread that is sequenced after pread or the value read by the
+ * first read to the same lcoation as pread by pthread that is
+ * sequenced after pread..
+ *
+ * 1. If tid=pthread, then we check what other threads are reachable
+ * through the mode order starting with pwrite. Those threads cannot
+ * perform a write that will resolve the promise due to modification
+ * order constraints.
+ *
+ * 2. If the tid is not pthread, we check whether pwrite can reach the
+ * action write through the modification order. If so, that thread
+ * cannot perform a future write that will resolve the promise due to
+ * modificatin order constraints.
+ *
+ * @parem tid The thread that either read from the model action
+ * write, or actually did the model action write.
+ *
+ * @parem write The ModelAction representing the relevant write.
+ */
+
void ModelChecker::mo_check_promises(thread_id_t tid, const ModelAction *write) {
void * location = write->get_location();
for (unsigned int i = 0; i < promises->size(); i++) {
if ( act->get_location() != location )
continue;
- if ( act->get_tid()==tid) {
+ //same thread as the promise
+ if ( act->get_tid()==tid ) {
+
+ //do we have a pwrite for the promise, if not, set it
if (promise->get_write() == NULL ) {
promise->set_write(write);
}
projects / model-checker.git / blobdiff