model: pull scheduler's thread selection into get_next_thread()

The code makes more logical sense if ModelChecker::get_next_thread()
handles all of the thread selection decisions.

diff --git a/model.cc b/model.cc
index 70732868bd3114825f3ccc8c2db51bb57e339a92..2c0ec9bad9488ebafdc83351761bc24500f84016 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -211,11 +211,13 @@ Node * ModelChecker::get_curr_node() const
  * adjacency of read/write portions of a RMW action, force THREAD_CREATE to be
  * followed by a THREAD_START, or it can enforce execution replay/backtracking.
  * The model-checker may have no preference regarding the next thread (i.e.,
  * adjacency of read/write portions of a RMW action, force THREAD_CREATE to be
  * followed by a THREAD_START, or it can enforce execution replay/backtracking.
  * The model-checker may have no preference regarding the next thread (i.e.,

- * when exploring a new execution ordering), in which case this will return
- * NULL.
+ * when exploring a new execution ordering), in which case we defer to the
+ * scheduler.
+ *

  * @param curr The current ModelAction. This action might guide the choice of
  * next thread.
  * @param curr The current ModelAction. This action might guide the choice of
  * next thread.

- * @return The next thread to run. If the model-checker has no preference, NULL.
+ * @return The next chosen thread to run, if any exist. Or else if no threads
+ * remain to be executed, return NULL.

  */
 Thread * ModelChecker::get_next_thread(ModelAction *curr)
 {
  */
 Thread * ModelChecker::get_next_thread(ModelAction *curr)
 {


@@ -229,9 +231,12 @@ Thread * ModelChecker::get_next_thread(ModelAction *curr)
                        return curr->get_thread_operand();
        }
 
                        return curr->get_thread_operand();
        }
 

-       /* Have we completed exploring the preselected path? */
+       /*
+        * Have we completed exploring the preselected path? Then let the
+        * scheduler decide
+        */

        if (diverge == NULL)
        if (diverge == NULL)

-               return NULL;
+               return scheduler->select_next_thread();

 
        /* Else, we are trying to replay an execution */
        ModelAction *next = node_stack->get_next()->get_action();
 
        /* Else, we are trying to replay an execution */
        ModelAction *next = node_stack->get_next()->get_action();


@@ -2732,10 +2737,6 @@ Thread * ModelChecker::take_step(ModelAction *curr)
                scheduler->remove_thread(curr_thrd);
 
        Thread *next_thrd = get_next_thread(curr);
                scheduler->remove_thread(curr_thrd);
 
        Thread *next_thrd = get_next_thread(curr);

-       /* Only ask for the next thread from Scheduler if we haven't chosen one
-        * already */
-       if (!next_thrd)
-               next_thrd = scheduler->select_next_thread();

 
        DEBUG("(%d, %d)\n", curr_thrd ? id_to_int(curr_thrd->get_id()) : -1,
                        next_thrd ? id_to_int(next_thrd->get_id()) : -1);
 
        DEBUG("(%d, %d)\n", curr_thrd ? id_to_int(curr_thrd->get_id()) : -1,
                        next_thrd ? id_to_int(next_thrd->get_id()) : -1);