fixes the ui dashboard statistics in cluster environment (#6917)

CHANGELOG

@@ -1,6 +1,10 @@
 devel
 -----
 
+* The single database or single coordinator statistics in a cluster
+  environment within the Web UI sometimes got called way too often.
+  This caused artifacts in the graphs, which is now fixed.
+
 * An aardvark statistics route could not collect and sum up the statistics of
   all coordinators if one of them was ahead and had more results than the others
 

js/apps/system/_admin/aardvark/APP/frontend/js/views/dashboardView.js

@@ -759,7 +759,7 @@
           self.history[self.server][figure] = [];
 
           for (i = 0; i < d.times.length; ++i) {
-            self.mergeDygraphHistory(d, i, true);
+            self.mergeDygraphHistory(d, i);
           }
         }
       );
@@ -1069,6 +1069,12 @@
       );
     },
 
+    clearInterval: function () {
+      if (this.timer) {
+        clearInterval(this.timer);
+      }
+    },
+
     resize: function () {
       if (!this.isUpdating) {
         return;

js/apps/system/_admin/aardvark/APP/frontend/js/views/nodeView.js

@@ -71,7 +71,10 @@
       if (this.coordinator) {
         dashboard = this.coordinator.get('name');
         // coordinator
-        this.dashboards[this.coordinator.get('name')] = new window.DashboardView({
+        if (this.dashboards[dashboard]) {
+          this.dashboards[dashboard].clearInterval();
+        }
+        this.dashboards[dashboard] = new window.DashboardView({
           dygraphConfig: window.dygraphConfig,
           database: window.App.arangoDatabase,
           serverToShow: {
@@ -85,7 +88,10 @@
         // db server
         var attributes = this.dbServer.toJSON();
         dashboard = attributes.name;
-        this.dashboards[attributes.name] = new window.DashboardView({
+        if (this.dashboards[dashboard]) {
+          this.dashboards[dashboard].clearInterval();
+        }
+        this.dashboards[dashboard] = new window.DashboardView({
           dygraphConfig: null,
           database: window.App.arangoDatabase,
           serverToShow: {