minix/lib/libmthread/queue.c
2010-09-21 12:22:38 +00:00

105 lines
2.9 KiB
C

#include <minix/mthread.h>
#include "global.h"
/*===========================================================================*
* mthread_queue_add *
*===========================================================================*/
PUBLIC void mthread_queue_add(queue, thread)
mthread_queue_t *queue; /* Queue we want thread to append to */
mthread_thread_t thread;
{
/* Append a thread to the tail of the queue. As a process can be present on
* only one queue at the same time, we can use the threads array's 'next'
* pointer to point to the next thread on the queue.
*/
if (mthread_queue_isempty(queue)) {
queue->head = queue->tail = thread;
} else {
threads[queue->tail].m_next = thread;
queue->tail = thread; /* 'thread' is the new last in line */
}
}
/*===========================================================================*
* mthread_queue_init *
*===========================================================================*/
PUBLIC void mthread_queue_init(queue)
mthread_queue_t *queue; /* Queue that has to be initialized */
{
/* Initialize queue to a known state */
queue->head = queue->tail = NO_THREAD;
}
/*===========================================================================*
* mthread_queue_isempty *
*===========================================================================*/
PUBLIC int mthread_queue_isempty(queue)
mthread_queue_t *queue;
{
return(queue->head == NO_THREAD);
}
/*===========================================================================*
* mthread_dump_queue *
*===========================================================================*/
PUBLIC void mthread_dump_queue(queue)
mthread_queue_t *queue;
{
int threshold, count = 0;
mthread_thread_t t;
threshold = no_threads;
#ifdef MDEBUG
printf("Dumping queue: ");
#endif
if(queue->head != NO_THREAD) {
t = queue->head;
#ifdef MDEBUG
printf("%d ", t);
#endif
count++;
t = threads[t].m_next;
while (t != NO_THREAD) {
#ifdef MDEBUG
printf("%d ", t);
#endif
t = threads[t].m_next;
count++;
if (count > threshold) break;
}
} else {
#ifdef MDEBUG
printf("[empty]");
#endif
}
#ifdef MDEBUG
printf("\n");
#endif
}
/*===========================================================================*
* mthread_queue_remove *
*===========================================================================*/
PUBLIC mthread_thread_t mthread_queue_remove(queue)
mthread_queue_t *queue; /* Queue we want a thread from */
{
/* Get the first thread in this queue, if there is one. */
mthread_thread_t thread = queue->head;
if (thread != NO_THREAD) { /* i.e., this queue is not empty */
if (queue->head == queue->tail) /* Queue holds only one thread */
queue->head = queue->tail = NO_THREAD; /*So mark thread empty*/
else
/* Second thread in line is the new first */
queue->head = threads[thread].m_next;
}
return(thread);
}