SMS optimisations

After RX of an SMPP Submit, send the SMS we just received.

Previously, after we have stored the new SMS in the db, we then
signalled the queue to run, but this is not good enough.

The queue may not pick up this new SMS on the next run,
if there are sufficient older messages in the queue. So let's
specifically send the message that was just submitted.

when fetching from the DB, Prioritise SMS with least number of delivery attempts

Try to send ALL pending SMS for subscriber in sub_ready_for_sms() callback

Change-Id: I9af51ef0d9c2e6c5acc5128efd6195df881b680c

include/osmocom/msc/signal.h

@@ -86,4 +86,6 @@ struct sms_signal_data {
 	struct gsm_sms *sms;
 	/* true when paging was successful */
 	bool paging_result;
+	/* the id of the last inserted SMS */
+	unsigned long long id;
 };

src/libmsc/db.c

@@ -282,7 +282,7 @@ static const char *stmt_sql[] = {
 		" WHERE sent IS NULL"
 		" AND dest_addr = $dest_addr"
 		" AND deliver_attempts <= $attempts"
-		" ORDER BY id LIMIT 1",
+		" ORDER BY deliver_attempts, id LIMIT 1",
 	[DB_STMT_SMS_GET_NEXT_UNSENT_RR_MSISDN] =
 		"SELECT " SEL_COLUMNS " FROM SMS"
 		" WHERE sent IS NULL"

src/libmsc/gsm_04_11.c

@@ -119,6 +119,7 @@ static void send_signal(int sig_no,
 	struct sms_signal_data sig;
 	sig.trans = trans;
 	sig.sms = sms;
+	sig.id = sms->id;
 	sig.paging_result = paging_result;
 	osmo_signal_dispatch(SS_SMS, sig_no, &sig);
 }

src/libmsc/sms_queue.c

@@ -547,6 +547,8 @@ static int sub_ready_for_sm(struct gsm_network *net, struct vlr_subscr *vsub)
 		return -1;
 
 	_gsm411_send_sms(net, vsub, sms);
+	if (!sms_subscriber_is_pending(net->sms_queue, vsub))
+		sms_send_next(vsub);
 	return 0;
 }
 
@@ -572,10 +574,46 @@ static int sms_sms_cb(unsigned int subsys, unsigned int signal,
 	struct sms_signal_data *sig_sms = signal_data;
 	struct gsm_sms_pending *pending;
 	struct vlr_subscr *vsub;
+	struct gsm_sms *sms;
 
 	/* We got a new SMS and maybe should launch the queue again. */
-	if (signal == S_SMS_SUBMITTED || signal == S_SMS_SMMA) {
-		/* TODO: For SMMA we might want to re-use the radio connection. */
+	if (signal == S_SMS_SUBMITTED) {
+		if (sig_sms->id) {
+			LOGP(DLSMS, LOGL_INFO, "Got Signal for new Sms Submitted with ID [%llu]\n",
+			     sig_sms->id);
+			sms = db_sms_get(network, sig_sms->id);
+			if (!sms)
+				return -1;
+			if (!sms->receiver || !sms->receiver->lu_complete) {
+				LOGP(DLSMS, LOGL_DEBUG,
+				     "Subscriber %s%s is not attached, skipping SMS.\n",
+				     sms->receiver ? "" : "MSISDN-",
+				     sms->receiver ? vlr_subscr_msisdn_or_name(sms->receiver) : sms->dst.addr);
+				return -1;
+			}
+
+			/* Check somehow it's not already in the pending list */
+			if (sms_queue_sms_is_pending(smq, sms->id)) {
+				sms_free(sms);
+				return 0;
+			}
+			/* Or that this sub is not already pending */
+			if (sms_subscriber_is_pending(smq, sms->receiver)) {
+				sms_free(sms);
+				return 0;
+			}
+			/* Now add this SMS to the Queue for immediate sending. */
+			pending = sms_pending_from(smq, sms);
+			sms_free(sms);
+			/* Schedule the timer to send this SMS */
+			sms_pending_resend(pending);
+			return 0;
+		}
+	}
+
+	if (signal == S_SMS_SMMA) {
+		/* TODO: For SMMA we might want to re-use the radio connection.
+		 */
 		sms_queue_trigger(smq);
 		return 0;
 	}

src/libsmpputil/smpp_msc.c

@@ -306,6 +306,8 @@ int handle_smpp_submit(struct smpp_esme *esme, struct submit_sm_t *submit,
 	case 1: /* datagram */
 	case 3: /* store-and-forward */
 		rc = db_sms_store(sms);
+		memset(&sig, 0, sizeof(sig));
+		sig.id = sms->id;
 		sms_free(sms);
 		sms = NULL;
 		if (rc < 0) {
@@ -317,7 +319,6 @@ int handle_smpp_submit(struct smpp_esme *esme, struct submit_sm_t *submit,
 		strcpy((char *)submit_r->message_id, "msg_id_not_implemented");
 		LOGP(DLSMS, LOGL_INFO, "SMPP SUBMIT-SM: Stored in DB\n");
 
-		memset(&sig, 0, sizeof(sig));
 		osmo_signal_dispatch(SS_SMS, S_SMS_SUBMITTED, &sig);
 		rc = 0;
 		break;