Add named map providers reporter to gather some stats

lib/cartodb/api/api-router.js

@@ -29,6 +29,7 @@ const VarnishHttpCacheBackend = require('../cache/backend/varnish_http');
 const FastlyCacheBackend = require('../cache/backend/fastly');
 const NamedMapProviderCache = require('../cache/named_map_provider_cache');
 const NamedMapsCacheEntry = require('../cache/model/named_maps_entry');
+const NamedMapProviderReporter = require('../stats/reporter/named-map-provider');
 
 const SqlWrapMapConfigAdapter = require('../models/mapconfig/adapter/sql-wrap-mapconfig-adapter');
 const MapConfigNamedLayersAdapter = require('../models/mapconfig/adapter/mapconfig-named-layers-adapter');
@@ -161,6 +162,13 @@ module.exports = class ApiRouter {
             layergroupAffectedTablesCache
         );
 
+        const namedMapProviderReporter = new NamedMapProviderReporter({
+            namedMapProviderCache,
+            intervalInMilliseconds: rendererCacheOpts.statsInterval
+        });
+
+        namedMapProviderReporter.start();
+
         const collaborators = {
             analysisStatusBackend,
             attributesBackend,

lib/cartodb/stats/reporter/named-map-provider.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const statKeyTemplate = ctx => `windshaft.named-map-provider-cache.${ctx.metric}`;
+
+module.exports = class NamedMapProviderReporter {
+    constructor ({ namedMapProviderCache, intervalInMilliseconds } = {}) {
+        this.namedMapProviderCache = namedMapProviderCache;
+        this.intervalInMilliseconds = intervalInMilliseconds;
+        this.intervalId = null;
+    }
+
+    start () {
+        const { providerCache: cache } = this.namedMapProviderCache;
+        const { statsClient: stats } = global;
+
+        this.intervalId = setInterval(() => {
+            stats.gauge(statKeyTemplate({ metric: 'named-map.count' }), cache.length);
+            const providers = cache.dump();
+
+            const namedMapIntantiations = providers.reduce((acc, { v: providers }) => {
+                acc += Object.keys(providers).length;
+                return acc;
+            }, 0);
+
+            stats.gauge(statKeyTemplate({ metric: 'named-map.intantiation.count' }), namedMapIntantiations);
+        }, this.intervalInMilliseconds);
+    }
+
+    stop () {
+        clearInterval(this.intervalId);
+        this.intervalId = null;
+    }
+};