/** @brief Function to awaken all threads waiting on the
* condition variable
*
* Broadcast signal to wake all threads in the waiting list.
*
* @param *cv the cond variable that is being broadcasted
* @return Void.
*/
void
cond_broadcast (cond_t * cv)
{
cond_t *node_ptr = NULL;
assert (cv != NULL);
/* Lock the queue */
spin_lock_request (&cv->spinlock);
while (1) {
/* Wake up all the thread in the queue */
node_ptr = Q_GET_FRONT (&cv->waiting_list);
if (node_ptr == NULL) {
lprintf ("In cond_broadcast: no threads!");
break;
}else {
/* Remove node from waiting list */
Q_REMOVE (&cv->waiting_list, node_ptr, cond_link);
/* Make the thread runnable */
make_runnable (node_ptr->tid);
/* After move the node, free space */
free (node_ptr);
}
}
/* Unlock the thread */
spin_lock_release (&cv->spinlock);
return;
}
// need to have the sched lock
void wakeup_sleepers(void) {
struct timespec time;
clock_gettime(CLOCK_REALTIME, &time);
thread_t *t;
while ((t = Q_GET_FRONT(&state.sleep_queue)) &&
time_lt(t->sleep_event.u.wakeup, time)) {
Q_REMOVE(&state.sleep_queue, t, q_link);
Q_INSERT_TAIL(&state.sched_queue, t, q_link);
}
}
/** @brief Function to wake up a thread waiting on the conditon
* variable
*
* Wake the first thread in the waiting list of the condition
* variable.
*
* @param *cv the cond variable we are signaling
* @return void
*/
void
cond_signal (cond_t * cv)
{
assert (cv != NULL);
cond_t *node_ptr = NULL;
int tid = DEFAULT_TID;
/* Lock the queue */
spin_lock_request (&cv->spinlock);
/* Get the head node(thread) in the queue */
node_ptr = Q_GET_FRONT (&cv->waiting_list);
/* If there are no thread in the queue, unlock and return */
if (node_ptr == NULL) {
lprintf ("No blocked threads!");
spin_lock_release (&cv->spinlock);
return;
}
else {
/* If get, remove the first node from the queue */
Q_REMOVE (&cv->waiting_list, node_ptr, cond_link);
}
/* Got one waitting thread from the queue, unlock the queue */
tid = node_ptr->tid;
spin_lock_release (&cv->spinlock);
/* Make that thread runnable */
while (make_runnable (tid) < 0) {
yield (tid);
}
/* Free */
free (node_ptr);
return;
}