model: improve get_next_thread() comments

It's curious that get_next_thread() needs the current ModelAction as a
parameter. It helps to clarify that this argument is somwhat "optional."

diff --git a/model.cc b/model.cc
index 2c0ec9bad9488ebafdc83351761bc24500f84016..655c511db1b4fa1f282f6d8a770e29490f27d1d5 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -214,8 +214,9 @@ Node * ModelChecker::get_curr_node() const
  * 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 Optional: The current ModelAction. Only used if non-NULL and it
+ * might guide the choice of next thread (i.e., THREAD_CREATE should be
+ * followed by THREAD_START, or ATOMIC_RMWR followed by ATOMIC_{RMW,RMWC})
  * @return The next chosen thread to run, if any exist. Or else if no threads
  * remain to be executed, return NULL.
  */