[drouting] Improve probing by sending the probs outside locking

Collect the data under locking, move the OPTIONs probing outside the locking, to be sure that any potential blocking on SIP level sending is not leading to lock starvation.
Closes #2438

modules/drouting/drouting.c

@@ -844,12 +844,20 @@ static void dr_probing_callback( struct cell *t, int type,
 
 static void dr_prob_handler(unsigned int ticks, void* param)
 {
-	static char buff[1000] = {"sip:"};
+	struct gw_prob_pack {
+		/* IMPORTANT, this member must be the first, as we use its pointer
+		 * to free the whole structure here */
+		param_prob_callback_t params;
+
+		struct socket_info *sock;
+		str uri;
+
+		struct gw_prob_pack *next;
+	};
 	/* do probing */
 	pgw_t *dst;
-	param_prob_callback_t *params;
+	struct gw_prob_pack *pack, *pack_last, *pack_head;
 	dlg_t *dlg;
-	str uri;
 	int nodes_no, node_idx=-1;
 	unsigned int h;
 
@@ -875,6 +883,8 @@ static void dr_prob_handler(unsigned int ticks, void* param)
 		if (it->rdata==NULL)
 			return;
 
+		pack_last = pack_head = NULL;
+
 		lock_start_read( it->ref_lock );
 
 		/* go through all destinations */
@@ -905,45 +915,70 @@ static void dr_prob_handler(unsigned int ticks, void* param)
 					continue;
 			}
 
-			memcpy(buff + 4, dst->ip_str.s, dst->ip_str.len);
-			uri.s = buff;
-			uri.len = dst->ip_str.len + 4;
+			/* build its pack, so we can build and send the prob later */
+			pack = shm_malloc(sizeof(struct gw_prob_pack)+4+dst->ip_str.len);
+			if( params==0 ) {
+				LM_ERR("no more shm memory!\n");
+				/* send whatever probs we have so far */
+				break;
+			}
+
+			pack->uri.s = (char*)(pack+1);
+			memcpy(pack->uri.s, "sip:", 4);
+			memcpy(pack->uri.s+4, dst->ip_str.s, dst->ip_str.len);
+			pack->uri.len = dst->ip_str.len + 4;
+
+			pack->sock = dst->sock;
+
+			pack->params._id = dst->_id;
+			pack->params.current_partition = it;
+
+			if (pack_head==NULL) {
+				pack_head = pack_last = pack;
+			} else {
+				pack_last->next = pack;
+				pack_last = pack;
+			}
+		}
+
+		lock_stop_read( it->ref_lock );
+
+
+		/* now send all the probs, outside the lock */
+		for( pack = pack_head ; pack ; pack=pack->next ) {
 
 			/* Execute the Dialog using the "request"-Method of the
 			 * TM-Module.*/
-			if (dr_tmb.new_auto_dlg_uac(&dr_probe_from, &uri, NULL, NULL,
-			     dst->sock?dst->sock:dr_probe_sock, &dlg)!=0) {
+			if (dr_tmb.new_auto_dlg_uac(&dr_probe_from, &pack->uri,
+			  NULL, NULL,
+			  pack->sock?pack->sock:dr_probe_sock, &dlg)!=0) {
 				LM_ERR("failed to create new TM dlg\n");
 				continue;
 			}
 			dlg->state = DLG_CONFIRMED;
 
-			params = shm_malloc(sizeof(param_prob_callback_t));
-			if( params==0 ) {
-				LM_ERR("no more shm memory!\n");
-				return;
-			}
-			params->_id = dst->_id;
-			params->current_partition = it;
-
 			if (dr_tmb.t_request_within(&dr_probe_method, NULL, NULL, dlg,
-			dr_probing_callback, (void*)params, osips_shm_free)<0) {
+			dr_probing_callback, (void*)pack, osips_shm_free)<0) {
 				LM_ERR("unable to execute dialog, disabling destination...\n");
-				if ( (dst->flags&DR_DST_STAT_DSBL_FLAG)==0 ) {
+				lock_start_read( it->ref_lock );
+				dst = get_gw_by_internal_id( it->rdata->pgw_tree,
+					pack->params._id);
+				if ( dst && (dst->flags&DR_DST_STAT_DSBL_FLAG)==0 ) {
 					dst->flags |= DR_DST_STAT_DSBL_FLAG|DR_DST_STAT_DIRT_FLAG;
 					dr_gw_status_changed( it, dst,
 						MI_SSTR("failure to send probe"));
 				}
+				lock_stop_read( it->ref_lock );
 
-				shm_free(params);
+				shm_free(pack);
 			}
 			dr_tmb.free_dlg(dlg);
 
 		}
 
-		lock_stop_read( it->ref_lock );
 		it = it->next;
 	}
+	/* done with all partitions */
 }