From: Brian Norris <banorris@uci.edu>
Date: Sat, 10 Mar 2012 02:22:50 +0000 (-0800)
Subject: schedule: return next thread pointer directly
X-Git-Tag: pldi2013~603
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=01237c41090e450db348ef0045a3d3cfd23cd041;p=model-checker.git

schedule: return next thread pointer directly

It's better to just return a pointer to the 'next' thread, rather than
sending it through the argument list.
---

diff --git a/libthreads.c b/libthreads.c
index 2a4c51c..8bdd76e 100644
--- a/libthreads.c
+++ b/libthreads.c
@@ -61,7 +61,7 @@ static int thread_yield()
 	DBG();
 	old = current;
 	schedule_add_thread(old);
-	schedule_choose_next(&next);
+	next = schedule_choose_next();
 	current = next;
 	DEBUG("(%d, %d)\n", old->index, next->index);
 	return thread_swap(old, next);
@@ -83,7 +83,7 @@ static void thread_wait_finish()
 	do {
 		if (current)
 			thread_dispose(current);
-		schedule_choose_next(&next);
+		next = schedule_choose_next();
 		current = next;
 	} while (next && !thread_swap(main_thread, next));
 }
diff --git a/schedule.c b/schedule.c
index a06a5c4..d567dd7 100644
--- a/schedule.c
+++ b/schedule.c
@@ -32,18 +32,20 @@ static void enqueue_thread(struct thread *t)
 	tail = node;
 }
 
-static int dequeue_thread(struct thread **t)
+struct thread *dequeue_thread(void)
 {
-	if (!head) {
-		*t = NULL;
-		return -1;
-	}
-	*t = head->this;
+	struct thread *pop;
+
+	if (!head)
+		return NULL;
+
+	pop = head->this;
 	head->live = 0;
 	if (head == tail)
 		tail = NULL;
 	head = head->next;
-	return 0;
+
+	return pop;
 }
 
 void schedule_add_thread(struct thread *t)
@@ -52,7 +54,7 @@ void schedule_add_thread(struct thread *t)
 	enqueue_thread(t);
 }
 
-int schedule_choose_next(struct thread **t)
+struct thread *schedule_choose_next(void)
 {
-	return dequeue_thread(t);
+	return dequeue_thread();
 }
diff --git a/schedule.h b/schedule.h
index 801af0d..ac69fa1 100644
--- a/schedule.h
+++ b/schedule.h
@@ -4,6 +4,6 @@
 #include "libthreads.h"
 
 void schedule_add_thread(struct thread *t);
-int schedule_choose_next(struct thread **t);
+struct thread *schedule_choose_next(void);
 
 #endif /* __SCHEDULE_H__ */