minix/lib/libmthread/queue.c
Thomas Veerman a7072a5e1c Revamp the mthread library and update test59
Before, the 'main thread' of a process was never taken into account anywhere in
the library, causing mutexes not to work properly (and consequently, neither
did the condition variables). For example, if the 'main thread' (that is, the
thread which is started at the beginning of a process; not a spawned thread by
the library) would lock a mutex, it wasn't actually locked.
2010-09-30 13:44:13 +00:00

128 lines
3.4 KiB
C

#include <minix/mthread.h>
#include "global.h"
#include "proto.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.
*/
mthread_tcb_t *last;
if (!isokthreadid(thread))
mthread_panic("Can't append invalid thread ID to a queue");
last = mthread_find_tcb(thread);
if (mthread_queue_isempty(queue)) {
queue->head = queue->tail = last;
} else {
queue->tail->m_next = last;
queue->tail = last; /* 'last' 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 = NULL;
}
/*===========================================================================*
* mthread_queue_isempty *
*===========================================================================*/
PUBLIC int mthread_queue_isempty(queue)
mthread_queue_t *queue;
{
return(queue->head == NULL);
}
/*===========================================================================*
* mthread_dump_queue *
*===========================================================================*/
PUBLIC void mthread_dump_queue(queue)
mthread_queue_t *queue;
{
int threshold, count = 0;
mthread_tcb_t *t;
mthread_thread_t tid;
threshold = no_threads;
#ifdef MDEBUG
printf("Dumping queue: ");
#endif
if(queue->head != NULL) {
t = queue->head;
if (t == &mainthread) tid = MAIN_THREAD;
else tid = t->m_tid;
#ifdef MDEBUG
printf("%d ", tid);
#endif
count++;
t = t->m_next;
while (t != NULL) {
if (t == &mainthread) tid = MAIN_THREAD;
else tid = t->m_tid;
#ifdef MDEBUG
printf("%d ", tid);
#endif
t = 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;
mthread_tcb_t *tcb;
/* Calculate thread id from queue head */
if (queue->head == NULL) thread = NO_THREAD;
else if (queue->head == &mainthread) thread = MAIN_THREAD;
else thread = (queue->head->m_tid);
if (thread != NO_THREAD) { /* i.e., this queue is not empty */
tcb = queue->head;
if (queue->head == queue->tail) {
/* Queue holds only one thread */
queue->head = queue->tail = NULL; /* So mark thread empty */
} else {
/* Second thread in line is the new first */
queue->head = queue->head->m_next;
}
tcb->m_next = NULL; /* This thread is no longer part of a queue */
}
return(thread);
}