/* cf_queue_pop
* if ms_wait < 0, wait forever
* if ms_wait = 0, don't wait at all
* if ms_wait > 0, wait that number of ms
* */
int cf_queue_pop(cf_queue *q, void *buf, int ms_wait) {
if (NULL == q) {
cf_error("cf_queue_pop: try passing in a queue");
return(-1);
}
#ifdef EXTERNAL_LOCKS
if (ms_wait != CF_QUEUE_NOWAIT) { // this implementation won't wait
cf_error("cf_queue_pop: only nowait supported");
return(-1);
}
#endif // EXTERNAL_LOCKS
QUEUE_LOCK(q);
struct timespec tp;
if (ms_wait > 0) {
#ifdef OSX
uint64_t curms = cf_getms(); // using the cl generic functions defined in cf_clock.h. It is going to have slightly less resolution than the pure linux version
tp.tv_sec = (curms + ms_wait)/1000;
tp.tv_nsec = (ms_wait %1000) * 1000000;
#else // linux
clock_gettime( CLOCK_REALTIME, &tp);
tp.tv_sec += ms_wait / 1000;
tp.tv_nsec += (ms_wait % 1000) * 1000000;
if (tp.tv_nsec > 1000000000) {
tp.tv_nsec -= 1000000000;
tp.tv_sec++;
}
#endif
}
/* FIXME error checking */
/* Note that we apparently have to use a while() loop. Careful reading
* of the pthread_cond_signal() documentation says that AT LEAST ONE
* waiting thread will be awakened... */
if (q->threadsafe) {
#ifdef EXTERNAL_LOCKS
if (CF_Q_EMPTY(q)) {
QUEUE_UNLOCK(q);
return(CF_QUEUE_EMPTY);
}
#else
while (CF_Q_EMPTY(q)) {
if (CF_QUEUE_FOREVER == ms_wait) {
pthread_cond_wait(&q->CV, &q->LOCK);
}
else if (CF_QUEUE_NOWAIT == ms_wait) {
pthread_mutex_unlock(&q->LOCK);
return(CF_QUEUE_EMPTY);
}
else {
pthread_cond_timedwait(&q->CV, &q->LOCK, &tp);
if (CF_Q_EMPTY(q)) {
pthread_mutex_unlock(&q->LOCK);
return(CF_QUEUE_EMPTY);
}
}
}
#endif // EXTERNAL_LOCKS
} else if (CF_Q_EMPTY(q))
return(CF_QUEUE_EMPTY);
memcpy(buf, CF_Q_ELEM_PTR(q,q->read_offset), q->elementsz);
q->read_offset++;
// interesting idea - this probably keeps the cache fresher
// because the queue is fully empty just make it all zero
if (q->read_offset == q->write_offset) {
q->read_offset = q->write_offset = 0;
}
QUEUE_UNLOCK(q);
return(0);
}
/* cf_queue_pop
* if ms_wait < 0, wait forever
* if ms_wait = 0, don't wait at all
* if ms_wait > 0, wait that number of ms
* */
int
cf_queue_pop(cf_queue *q, void *buf, int ms_wait)
{
if (NULL == q)
return(-1);
/* FIXME error checking */
if (q->threadsafe && (0 != pthread_mutex_lock(&q->LOCK)))
return(-1);
struct timespec tp;
if (ms_wait > 0) {
clock_gettime( CLOCK_REALTIME, &tp);
tp.tv_sec += ms_wait / 1000;
tp.tv_nsec += (ms_wait % 1000) * 1000000;
if (tp.tv_nsec > 1000000000) {
tp.tv_nsec -= 1000000000;
tp.tv_sec++;
}
}
/* FIXME error checking */
/* Note that we apparently have to use a while() loop. Careful reading
* of the pthread_cond_signal() documentation says that AT LEAST ONE
* waiting thread will be awakened... */
if (q->threadsafe) {
while (CF_Q_EMPTY(q)) {
if (CF_QUEUE_FOREVER == ms_wait) {
pthread_cond_wait(&q->CV, &q->LOCK);
}
else if (CF_QUEUE_NOWAIT == ms_wait) {
pthread_mutex_unlock(&q->LOCK);
return(CF_QUEUE_EMPTY);
}
else {
pthread_cond_timedwait(&q->CV, &q->LOCK, &tp);
if (CF_Q_EMPTY(q)) {
pthread_mutex_unlock(&q->LOCK);
return(CF_QUEUE_EMPTY);
}
}
}
} else if (CF_Q_EMPTY(q))
return(CF_QUEUE_EMPTY);
memcpy(buf, CF_Q_ELEM_PTR(q,q->read_offset), q->elementsz);
q->read_offset++;
// interesting idea - this probably keeps the cache fresher
// because the queue is fully empty just make it all zero
if (q->read_offset == q->write_offset) {
q->read_offset = q->write_offset = 0;
}
/* FIXME blow a gasket */
if (q->threadsafe && (0 != pthread_mutex_unlock(&q->LOCK))) {
// cf_info(CF_QUEUE, "queue pop failed");
return(-1);
}
return(0);
}
