extract surrogate key functionality to its own middleware

lib/cartodb/controllers/map.js

@@ -274,6 +274,7 @@ MapController.prototype.instantiateTemplate = function(req, res, prepareParamsFn
             res.locals.layergroup = layergroup;
             res.locals.template = mapConfigProvider.template;
             res.locals.context = mapConfigProvider.context;
+            res.locals.templateName = mapConfigProvider.getTemplateName();
 
             const afterLayergroupCreate = self.afterLayergroupCreateBuilder({
                 useTemplateHash: true
@@ -289,8 +290,6 @@ MapController.prototype.instantiateTemplate = function(req, res, prepareParamsFn
 
             const { layergroup } = res.locals;
 
-            self.surrogateKeysCache.tag(res, new NamedMapsCacheEntry(cdbuser, mapConfigProvider.getTemplateName()));
-
             res.status(200);
 
             if (req.query && req.query.callback) {
@@ -360,6 +359,10 @@ MapController.prototype.afterLayergroupCreateBuilder = function (options = {}) {
                 assert.ifError(err);
                 self.setTurboCartoMetadataToLayergroup(req, res, this);
             },
+            function setSurrogateKeyHeader (err) {
+                assert.ifError(err);
+                self.setSurrogateKeyHeader(req, res, this);
+            },
             function finish(err) {
                 callback(err);
             }
@@ -431,15 +434,11 @@ MapController.prototype.getAffectedTables = function (req, res, callback) {
 };
 
 MapController.prototype.setCacheChannel = function (req, res, callback) {
-    const self = this;
     const { affectedTables } = res.locals;
 
     if (req.method === 'GET') {
         res.set('Last-Modified', (new Date()).toUTCString());
         res.set('X-Cache-Channel', affectedTables.getCacheChannel());
-        if (affectedTables.tables && affectedTables.tables.length > 0) {
-            self.surrogateKeysCache.tag(res, affectedTables);
-        }
     }
 
     callback();
@@ -547,6 +546,20 @@ function addContextMetadata(layergroup, mapConfig, context) {
     }
 }
 
+MapController.prototype.setSurrogateKeyHeader = function (req, res, callback) {
+    const { affectedTables, user, templateName } = res.locals;
+
+    if (req.method === 'GET' && affectedTables.tables && affectedTables.tables.length > 0) {
+        this.surrogateKeysCache.tag(res, affectedTables);
+    }
+
+    if (templateName) {
+        this.surrogateKeysCache.tag(res, new NamedMapsCacheEntry(user, templateName));
+    }
+
+    callback();
+};
+
 function getLastUpdatedTime(analysesResults, lastUpdateTime) {
     if (!Array.isArray(analysesResults)) {
         return lastUpdateTime;