From 59aaf50bde2347f826259a1951a5af4bfca060e0 Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Mon, 12 Mar 2012 16:06:14 -0700
Subject: [PATCH] move 'current thread' details

The low level details regarding the 'current thread' should be encapsulated in
the scheduler (i.e., 'get_current_thread()'). So we move the 'current' variable
to scheduler.c.
---
 libthreads.c | 14 ++++++--------
 schedule.c   | 23 ++++++++++++++++-------
 schedule.h   |  2 --
 3 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/libthreads.c b/libthreads.c
index 3697c08..c164d67 100644
--- a/libthreads.c
+++ b/libthreads.c
@@ -10,7 +10,7 @@
 
 #define STACK_SIZE (1024 * 1024)
 
-static struct thread *current, *main_thread;
+static struct thread *main_thread;
 
 static void *stack_allocate(size_t size)
 {
@@ -62,10 +62,9 @@ int thread_yield(void)
 	struct thread *old, *next;
 
 	DBG();
-	old = current;
+	old = thread_current();
 	model->scheduler->add_thread(old);
 	next = model->scheduler->next_thread();
-	current = next;
 	DEBUG("(%d, %d)\n", old->index, next->index);
 	return thread_swap(old, next);
 }
@@ -79,15 +78,14 @@ static void thread_dispose(struct thread *t)
 
 static void thread_wait_finish(void)
 {
-	struct thread *next;
+	struct thread *curr, *next;
 
 	DBG();
 
 	do {
-		if (current)
-			thread_dispose(current);
+		if ((curr = thread_current()))
+			thread_dispose(curr);
 		next = model->scheduler->next_thread();
-		current = next;
 	} while (next && !thread_swap(main_thread, next));
 }
 
@@ -122,7 +120,7 @@ void thread_join(struct thread *t)
 
 struct thread *thread_current(void)
 {
-	return current;
+	return model->scheduler->get_current_thread();
 }
 
 int main()
diff --git a/schedule.c b/schedule.c
index 4ac8b49..c8f54e8 100644
--- a/schedule.c
+++ b/schedule.c
@@ -15,6 +15,7 @@ struct thread_list_node {
 
 struct thread_list_node *head, *tail;
 struct thread_list_node nodes[NUM_LIST_NODES];
+struct thread *current;
 
 static void enqueue_thread(struct thread *t)
 {
@@ -35,7 +36,7 @@ static void enqueue_thread(struct thread *t)
 	tail = node;
 }
 
-struct thread *dequeue_thread(void)
+static struct thread *dequeue_thread(void)
 {
 	struct thread *pop;
 
@@ -48,30 +49,38 @@ struct thread *dequeue_thread(void)
 		tail = NULL;
 	head = head->next;
 
+	/* Set new current thread */
+	current = pop;
+
 	return pop;
 }
 
-void schedule_add_thread(struct thread *t)
+static void default_add_thread(struct thread *t)
 {
 	DEBUG("thread %d\n", t->index);
 	enqueue_thread(t);
 }
 
-struct thread *schedule_choose_next(void)
+static struct thread *default_choose_next(void)
 {
 	return dequeue_thread();
 }
 
+static struct thread *default_thread_current(void)
+{
+	return current;
+}
+
 void scheduler_init(struct model_checker *mod)
 {
 	struct scheduler *sched;
 
-	/* Initialize FCFS scheduler */
+	/* Initialize default scheduler */
 	sched = malloc(sizeof(*sched));
 	sched->init = NULL;
 	sched->exit = NULL;
-	sched->add_thread = schedule_add_thread;
-	sched->next_thread = schedule_choose_next;
-	sched->get_current_thread = thread_current;
+	sched->add_thread = default_add_thread;
+	sched->next_thread = default_choose_next;
+	sched->get_current_thread = default_thread_current;
 	mod->scheduler = sched;
 }
diff --git a/schedule.h b/schedule.h
index 360b390..bae8c1f 100644
--- a/schedule.h
+++ b/schedule.h
@@ -15,7 +15,5 @@ struct scheduler {
 };
 
 void scheduler_init(struct model_checker *mod);
-void schedule_add_thread(struct thread *t);
-struct thread *schedule_choose_next(void);
 
 #endif /* __SCHEDULE_H__ */
-- 
2.34.1