+Thread *ModelChecker::schedule_next_thread()
+{
+ Thread *t;
+ if (nextThread == THREAD_ID_T_NONE)
+ return NULL;
+ t = thread_map[nextThread];
+ if (t == NULL)
+ DEBUG("*** error: thread not in thread_map: id = %d\n", nextThread);
+ return t;
+}
+
+/*
+ * get_next_replay_thread() - Choose the next thread in the replay sequence
+ *
+ * If we've reached the 'diverge' point, then we pick a thread from the
+ * backtracking set.
+ * Otherwise, we simply return the next thread in the sequence.
+ */
+thread_id_t ModelChecker::get_next_replay_thread()
+{
+ ModelAction *next;
+ thread_id_t tid;
+
+ next = exploring->get_state();
+
+ if (next == exploring->get_diverge()) {
+ TreeNode *node = next->get_node();
+
+ /* Reached divergence point; discard our current 'exploring' */
+ DEBUG("*** Discard 'Backtrack' object ***\n");
+ tid = node->getNextBacktrack();
+ delete exploring;
+ exploring = NULL;
+ } else {
+ tid = next->get_tid();
+ }
+ DEBUG("*** ModelChecker chose next thread = %d ***\n", tid);
+ return tid;
+}
+
+thread_id_t ModelChecker::advance_backtracking_state()
+{
+ /* Have we completed exploring the preselected path? */
+ if (exploring == NULL)
+ return THREAD_ID_T_NONE;
+
+ /* Else, we are trying to replay an execution */
+ exploring->advance_state();
+ if (exploring->get_state() == NULL)
+ DEBUG("*** error: reached end of backtrack trace\n");
+
+ return get_next_replay_thread();
+}
+