Fix race between data sync and data load

Be sure we trigger the startup cluster sync AFTER loading the data from DB.
Also, when receiving replicated data, be sure the data is actually loaded.
Closes #2581

modules/drouting/dr_clustering.c

@@ -160,7 +160,7 @@ static int gw_status_update(bin_packet_t *packet, int raise_event)
 	bin_pop_int(packet, &flags);
 
 	part = get_partition( &part_name );
-	if (part==NULL)
+	if (part==NULL || part->rdata==NULL)
 		return -1;
 
 	lock_start_read(part->ref_lock);
@@ -197,7 +197,7 @@ static int cr_status_update(bin_packet_t *packet)
 	bin_pop_int(packet, &flags);
 
 	part = get_partition( &part_name );
-	if (part==NULL)
+	if (part==NULL || part->rdata==NULL)
 		return -1;
 
 	lock_start_read(part->ref_lock);
@@ -377,8 +377,5 @@ int dr_init_cluster(void)
 		dr_cluster_shtag.len = 0;
 	}
 
-	if (dr_cluster_sync() < 0)
-		return -1;
-
 	return 0;
 }

modules/drouting/drouting.c

@@ -1930,6 +1930,9 @@ static int db_connect_head(struct head_db *x) {
 static void rpc_dr_reload_data(int sender_id, void *unused)
 {
 	dr_reload_data(1);
+
+	dr_cluster_sync();
+
 }