sms: Rewrite the queue to find SMS harder.

With the old code it was possible that we first saw SMS that
we have already in the queue. In that case we had free slots
available but have not filled them. With his new loop we try
harder to find SMS we can send, it attempts (and should work)
to detect a loop to break the loop before finding SMS to deliver.

1 files changed, 25 insertions, 3 deletions

diff --git a/openbsc/src/sms_queue.c b/openbsc/src/sms_queue.c
index e8e65846f..f6ac66090 100644
--- a/openbsc/src/sms_queue.c
+++ b/openbsc/src/sms_queue.c
@@ -217,11 +217,13 @@ static void sms_submit_pending(void *_data)
 {
 	struct gsm_sms_queue *smsq = _data;
 	int attempts = smsq->max_pending - smsq->pending;
-	int i;
+	int initialized = 0;
+	unsigned long long first_sub = 0;
+	int attempted = 0;
 
 	LOGP(DSMS, LOGL_NOTICE, "Attempting to send %d SMS\n", attempts);
 
-	for (i = 0; i < attempts; ++i) {
+	do {
 		struct gsm_sms_pending *pending;
 		struct gsm_sms *sms;
 
@@ -230,6 +232,23 @@ static void sms_submit_pending(void *_data)
 		if (!sms)
 			break;
 
+		/*
+		 * This code needs to detect a loop. It assumes that no SMS
+		 * will vanish during the time this is executed. We will remember
+		 * the id of the first GSM subscriber we see and then will
+		 * compare this. The Database code should make sure that we will
+		 * see all other subscribers first before seeing this one again.
+		 *
+		 * It is always scary to have an infinite loop like this.
+		 */
+		if (!initialized) {
+			first_sub = sms->receiver->id;
+			initialized = 1;
+		} else if (first_sub == sms->receiver->id) {
+			sms_free(sms);
+			break;
+		}
+
 		/* no need to send a pending sms */
 		if (sms_is_in_pending(smsq, sms)) {
 			LOGP(DSMS, LOGL_DEBUG,
@@ -254,10 +273,13 @@ static void sms_submit_pending(void *_data)
 			continue;
 		}
 
+		attempted += 1;
 		smsq->pending += 1;
 		llist_add(&pending->entry, &smsq->pending_sms);
 		gsm411_send_sms_subscr(sms->receiver, sms);
-	}
+	} while (attempted < attempts);
+
+	LOGP(DSMS, LOGL_DEBUG, "SMSqueue added %d messages\n", attempted);
 }
 
 /*