dispatcher: add option to retain existing latency stats when reloadin…

…g destinations

- also retain when adding/removing individual destinations via RPC

src/modules/dispatcher/dispatch.c

@@ -109,6 +109,7 @@ static int *_ds_ping_active = NULL;
 extern int ds_force_dst;
 extern str ds_event_callback;
 extern int ds_ping_latency_stats;
+extern int ds_retain_latency_stats;
 extern float ds_latency_estimator_alpha;
 extern int ds_attrs_none;
 extern param_t *ds_db_extra_attrs_list;
@@ -543,7 +544,7 @@ ds_dest_t *pack_dest(str iuri, int flags, int priority, str *attrs, int dload)
  *
  */
 int add_dest2list(int id, str uri, int flags, int priority, str *attrs,
-		int list_idx, int *setn, int dload)
+		int list_idx, int *setn, int dload, ds_latency_stats_t *latency_stats)
 {
 	ds_dest_t *dp = NULL;
 	ds_set_t *sp = NULL;
@@ -554,6 +555,17 @@ int add_dest2list(int id, str uri, int flags, int priority, str *attrs,
 	if(!dp)
 		goto err;
 
+	if(latency_stats != NULL) {
+		dp->latency_stats.stdev = latency_stats->stdev;
+		dp->latency_stats.m2 = latency_stats->m2;
+		dp->latency_stats.max = latency_stats->max;
+		dp->latency_stats.min = latency_stats->min;
+		dp->latency_stats.average = latency_stats->average;
+		dp->latency_stats.estimate = latency_stats->estimate;
+		dp->latency_stats.count = latency_stats->count;
+		dp->latency_stats.timeout = latency_stats->timeout;
+	}
+
 	sp = ds_avl_insert(&ds_lists[list_idx], id, setn);
 	if(!sp) {
 		LM_ERR("no more memory.\n");
@@ -811,6 +823,7 @@ int ds_load_list(char *lfile)
 	int id, setn, flags, priority;
 	str uri;
 	str attrs;
+	ds_latency_stats_t *latency_stats;
 
 	if((*ds_crt_idx) != (*ds_next_idx)) {
 		LM_WARN("load command already generated, aborting reload...\n");
@@ -906,8 +919,12 @@ int ds_load_list(char *lfile)
 		attrs.len = p - attrs.s;
 
 	add_destination:
-		if(add_dest2list(
-				   id, uri, flags, priority, &attrs, *ds_next_idx, &setn, 0)
+		latency_stats = NULL;
+		if(ds_ping_latency_stats && ds_retain_latency_stats) {
+			latency_stats = latency_stats_find(id, &uri);
+		}
+		if(add_dest2list(id, uri, flags, priority, &attrs, *ds_next_idx, &setn,
+				   0, latency_stats)
 				!= 0) {
 			LM_WARN("unable to add destination %.*s to set %d -- skipping\n",
 					uri.len, uri.s, id);
@@ -1054,6 +1071,7 @@ int ds_load_db(void)
 	int plen;
 #define DS_ATTRS_MAXSIZE 1024
 	char ds_attrs_buf[DS_ATTRS_MAXSIZE];
+	ds_latency_stats_t *latency_stats;
 
 	query_cols[0] = &ds_set_id_col;
 	query_cols[1] = &ds_dest_uri_col;
@@ -1161,8 +1179,12 @@ int ds_load_db(void)
 		}
 		LM_DBG("attributes string: [%.*s]\n", attrs.len,
 				(attrs.s) ? attrs.s : "");
-		if(add_dest2list(
-				   id, uri, flags, priority, &attrs, *ds_next_idx, &setn, 0)
+		latency_stats = NULL;
+		if(ds_ping_latency_stats && ds_retain_latency_stats) {
+			latency_stats = latency_stats_find(id, &uri);
+		}
+		if(add_dest2list(id, uri, flags, priority, &attrs, *ds_next_idx, &setn,
+				   0, latency_stats)
 				!= 0) {
 			dest_errs++;
 			LM_WARN("unable to add destination %.*s to set %d -- skipping\n",
@@ -2649,7 +2671,8 @@ void ds_add_dest_cb(ds_set_t *node, int i, void *arg)
 
 	if(add_dest2list(node->id, node->dlist[i].uri, node->dlist[i].flags,
 			   node->dlist[i].priority, &node->dlist[i].attrs.body,
-			   *ds_next_idx, &setn, node->dlist[i].dload)
+			   *ds_next_idx, &setn, node->dlist[i].dload,
+			   &node->dlist[i].latency_stats)
 			!= 0) {
 		LM_WARN("failed to add destination in group %d - %.*s\n", node->id,
 				node->dlist[i].uri.len, node->dlist[i].uri.s);
@@ -2671,8 +2694,8 @@ int ds_add_dst(int group, str *address, int flags, int priority, str *attrs)
 	ds_iter_set(_ds_list, &ds_add_dest_cb, NULL);
 
 	// add new destination
-	if(add_dest2list(
-			   group, *address, flags, priority, attrs, *ds_next_idx, &setn, 0)
+	if(add_dest2list(group, *address, flags, priority, attrs, *ds_next_idx,
+			   &setn, 0, NULL)
 			!= 0) {
 		LM_WARN("unable to add destination %.*s to set %d", address->len,
 				address->s, group);
@@ -2712,7 +2735,8 @@ void ds_filter_dest_cb(ds_set_t *node, int i, void *arg)
 
 	if(add_dest2list(node->id, node->dlist[i].uri, node->dlist[i].flags,
 			   node->dlist[i].priority, &node->dlist[i].attrs.body,
-			   *ds_next_idx, filter_arg->setn, node->dlist[i].dload)
+			   *ds_next_idx, filter_arg->setn, node->dlist[i].dload,
+			   &node->dlist[i].latency_stats)
 			!= 0) {
 		LM_WARN("failed to add destination in group %d - %.*s\n", node->id,
 				node->dlist[i].uri.len, node->dlist[i].uri.s);
@@ -2825,6 +2849,36 @@ void latency_stats_init(
 	latency_stats->count = count;
 }
 
+ds_latency_stats_t *latency_stats_find(int group, str *address)
+{
+
+	int i = 0;
+	ds_set_t *idx = NULL;
+
+	if(_ds_list == NULL || _ds_list_nr <= 0) {
+		LM_DBG("the list is null\n");
+		return NULL;
+	}
+
+	/* get the index of the set */
+	if(ds_get_index(group, *ds_crt_idx, &idx) != 0) {
+		LM_DBG("destination set [%d] not found\n", group);
+		return NULL;
+	}
+
+	while(i < idx->nr) {
+		if(idx->dlist[i].uri.len == address->len
+				&& strncasecmp(idx->dlist[i].uri.s, address->s, address->len)
+						   == 0) {
+			/* destination address found - copy current stats */
+			return &idx->dlist[i].latency_stats;
+		}
+		i++;
+	}
+
+	return NULL;
+}
+
 #define _VOR1(v) ((v) ? (v) : 1)
 
 static inline void latency_stats_update(
@@ -2946,6 +3000,14 @@ int ds_update_latency(int group, str *address, int code)
 			}
 			if(code == 408 && latency_stats->timeout < UINT32_MAX)
 				latency_stats->timeout++;
+
+			if(latency_stats->start.tv_sec == 0
+					&& latency_stats->start.tv_usec == 0) {
+				/* If we don't have a start time, we can't calculate latency */
+				i++;
+				continue;
+			}
+
 			gettimeofday(&now, NULL);
 			latency_ms = (now.tv_sec - latency_stats->start.tv_sec) * 1000
 						 + (now.tv_usec - latency_stats->start.tv_usec) / 1000;

src/modules/dispatcher/dispatch.h

@@ -218,6 +218,7 @@ typedef struct _ds_latency_stats {
 } ds_latency_stats_t;
 
 void latency_stats_init(ds_latency_stats_t *latency_stats, int latency, int count);
+ds_latency_stats_t *latency_stats_find(int group, str *address);
 
 typedef struct _ds_dest {
 	str uri;          /*!< address/uri */

src/modules/dispatcher/dispatcher.c

@@ -101,6 +101,7 @@ str ds_ping_method = str_init("OPTIONS");
 str ds_ping_from   = str_init("sip:dispatcher@localhost");
 static int ds_ping_interval = 0;
 int ds_ping_latency_stats = 0;
+int ds_retain_latency_stats = 0;
 int ds_latency_estimator_alpha_i = 900;
 float ds_latency_estimator_alpha = 0.9f;
 int ds_probing_mode = DS_PROBE_NONE;
@@ -283,6 +284,7 @@ static param_export_t params[]={
 	{"ds_ping_from",       PARAM_STR, &ds_ping_from},
 	{"ds_ping_interval",   INT_PARAM, &ds_ping_interval},
 	{"ds_ping_latency_stats", INT_PARAM, &ds_ping_latency_stats},
+	{"ds_retain_latency_stats", INT_PARAM, &ds_retain_latency_stats},
 	{"ds_latency_estimator_alpha", INT_PARAM, &ds_latency_estimator_alpha_i},
 	{"ds_ping_reply_codes", PARAM_STR, &ds_ping_reply_codes_str},
 	{"ds_probing_mode",    INT_PARAM, &ds_probing_mode},

src/modules/dispatcher/doc/dispatcher_admin.xml

@@ -756,6 +756,38 @@ modparam("dispatcher", "ds_ping_latency_stats", 1)
 </programlisting>
 		</example>
 	</section>
+
+
+	<section id="dispatcher.p.ds_retain_latency_stats">
+		<title><varname>ds_retain_latency_stats</varname> (int)</title>
+		<para>
+		Retain latency stats for existing destinations when reloading from file or database.
+		</para>
+
+		<itemizedlist>
+		<listitem>
+			<para>If set to 0, stats for all destinations will be reset on reload.</para>
+		</listitem>
+		<listitem>
+			<para>If set to 1, stats for existing destinations will persist across reloads.
+			</para>
+		</listitem>
+		</itemizedlist>
+		<para>
+		<emphasis>
+			Default value is <quote>0</quote>.
+		</emphasis>
+		</para>
+		<example>
+		<title>Set the <quote>ds_retain_latency_stats</quote> parameter</title>
+<programlisting format="linespecific">
+...
+modparam("dispatcher", "ds_retain_latency_stats", 1)
+...
+</programlisting>
+		</example>
+	</section>
+
 	<section id="dispatcher.p.ds_latency_estimator_alpha">
 		<title><varname>ds_latency_estimator_alpha</varname> (int)</title>
 		<para>