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use backoff retry for queues #47

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113 changes: 35 additions & 78 deletions src/libparodus_queues.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,6 @@ typedef struct queue {
unsigned max_msgs;
int msg_count;
pthread_mutex_t mutex;
pthread_cond_t not_empty_cond;
pthread_cond_t not_full_cond;
void **msg_array;
int head_index;
int tail_index;
Expand Down Expand Up @@ -75,34 +73,11 @@ int libpd_qcreate (libpd_mq_t *mq, const char *queue_name,
return LIBPD_QERR_CREATE_MUTEX;
}

err = pthread_cond_init (&newq->not_empty_cond, NULL);
if (err != 0) {
*exterr = err;
libpd_log_err (LEVEL_ERROR, err, ("Error creating not_empty_cond for queue %s\n",
queue_name));
pthread_mutex_destroy (&newq->mutex);
free (newq);
return LIBPD_QERR_CREATE_NECOND;
}

err = pthread_cond_init (&newq->not_full_cond, NULL);
if (err != 0) {
*exterr = err;
libpd_log_err (LEVEL_ERROR, err, ("Error creating not_full_cond for queue %s\n",
queue_name));
pthread_mutex_destroy (&newq->mutex);
pthread_cond_destroy (&newq->not_empty_cond);
free (newq);
return LIBPD_QERR_CREATE_NFCOND;
}

newq->msg_array = malloc (array_size);
if (NULL == newq->msg_array) {
libpd_log (LEVEL_ERROR, ("Unable to allocate memory(2) for queue %s\n",
queue_name));
pthread_mutex_destroy (&newq->mutex);
pthread_cond_destroy (&newq->not_empty_cond);
pthread_cond_destroy (&newq->not_full_cond);
free (newq);
return LIBPD_QERR_CREATE_ALLOC_2;
}
Expand Down Expand Up @@ -160,95 +135,77 @@ int libpd_qdestroy (libpd_mq_t *mq, free_msg_func_t *free_msg_func)
}
}
free (q->msg_array);
pthread_cond_destroy (&q->not_empty_cond);
pthread_cond_destroy (&q->not_full_cond);
pthread_mutex_unlock (&q->mutex);
pthread_mutex_destroy (&q->mutex);
free (q);
*mq = NULL;
return 0;
}

void backoff (unsigned *current_wait)
{
unsigned current = *current_wait;
if (current == 0)
current = 10;
else if (current == 10)
current = 20;
else if (current == 20)
current = 50;
else if (current == 50)
current = 100;
else if (current == 100)
current = 200;
else
current = 500;
delay_ms (current);
*current_wait = current;
}

int libpd_qsend (libpd_mq_t mq, void *msg, unsigned timeout_ms, int *exterr)
{
queue_t *q = (queue_t*) mq;
struct timespec ts;
int rtn;
unsigned current_wait = 0;
unsigned total_wait = 0;

*exterr = 0;
if (NULL == mq)
return LIBPD_QERR_SEND_NULL;
pthread_mutex_lock (&q->mutex);
while (true) {
pthread_mutex_lock (&q->mutex);
if (enqueue_msg (q, msg))
break;
rtn = get_expire_time (timeout_ms, &ts);
if (rtn != 0) {
*exterr = rtn;
libpd_log_err (LEVEL_ERROR, rtn,
("gettimeofday error waiting to send queue\n"));
pthread_mutex_unlock (&q->mutex);
return LIBPD_QERR_SEND_EXPTIME;
}
rtn = pthread_cond_timedwait (&q->not_full_cond, &q->mutex, &ts);
if (rtn != 0) {
if (rtn == ETIMEDOUT) {
pthread_mutex_unlock (&q->mutex);
return 1;
}
*exterr = rtn;
libpd_log_err (LEVEL_ERROR, rtn,
("pthread_cond_timedwait error waiting for not_full_cond\n"));
pthread_mutex_unlock (&q->mutex);
return LIBPD_QERR_SEND_CONDWAIT;
}
pthread_mutex_unlock (&q->mutex);
if (total_wait >= timeout_ms)
return 1;
backoff (&current_wait);
total_wait += current_wait;
}
if (q->msg_count == 1)
pthread_cond_signal (&q->not_empty_cond);
pthread_mutex_unlock (&q->mutex);
return 0;
}

int libpd_qreceive (libpd_mq_t mq, void **msg, unsigned timeout_ms, int *exterr)
{
queue_t *q = (queue_t*) mq;
struct timespec ts;
unsigned current_wait = 0;
unsigned total_wait = 0;
void *msg__;
int rtn;

*exterr = 0;
if (NULL == mq)
return LIBPD_QERR_RCV_NULL;
pthread_mutex_lock (&q->mutex);
while (true) {
pthread_mutex_lock (&q->mutex);
msg__ = dequeue_msg (q);
pthread_mutex_unlock (&q->mutex);
if (NULL != msg__)
break;
rtn = get_expire_time (timeout_ms, &ts);
if (rtn != 0) {
*exterr = rtn;
libpd_log_err (LEVEL_ERROR, rtn,
("gettimeofday error waiting to receive on queue\n"));
pthread_mutex_unlock (&q->mutex);
return LIBPD_QERR_RCV_EXPTIME;
}
rtn = pthread_cond_timedwait (&q->not_empty_cond, &q->mutex, &ts);
if (rtn != 0) {
if (rtn == ETIMEDOUT) {
pthread_mutex_unlock (&q->mutex);
return 1;
}
*exterr = rtn;
libpd_log_err (LEVEL_ERROR, rtn,
("pthread_cond_timedwait error waiting for not_empty_cond\n"));
pthread_mutex_unlock (&q->mutex);
return LIBPD_QERR_RCV_CONDWAIT;
}
if (total_wait >= timeout_ms)
return 1;
backoff (&current_wait);
total_wait += current_wait;
}
*msg = msg__;
if ((q->msg_count+1) == (int)q->max_msgs)
pthread_cond_signal (&q->not_full_cond);
pthread_mutex_unlock (&q->mutex);
return 0;
}