verctor error middleware

lib/cartodb/controllers/layergroup.js

@@ -7,6 +7,7 @@ var BaseController = require('./base');
 var cors = require('../middleware/cors');
 var userMiddleware = require('../middleware/user');
 var allowQueryParams = require('../middleware/allow-query-params');
+var vectorError = require('../middleware/vector-error');
 
 var DataviewBackend = require('../backends/dataview');
 var AnalysisStatusBackend = require('../backends/analysis-status');
@@ -57,7 +58,8 @@ LayergroupController.prototype.register = function(app) {
         cors(),
         userMiddleware,
         this.prepareContext,
-        this.tile.bind(this)
+        this.tile.bind(this),
+        vectorError()
     );
 
     app.get(
@@ -65,7 +67,8 @@ LayergroupController.prototype.register = function(app) {
         cors(),
         userMiddleware,
         this.prepareContext,
-        this.tile.bind(this)
+        this.tile.bind(this),
+        vectorError()
     );
 
     app.get(
@@ -74,7 +77,8 @@ LayergroupController.prototype.register = function(app) {
         userMiddleware,
         validateLayerRouteMiddleware,
         this.prepareContext,
-        this.layer.bind(this)
+        this.layer.bind(this),
+        vectorError()
     );
 
     app.get(

lib/cartodb/middleware/vector-error.js

@@ -0,0 +1,30 @@
+const fs = require('fs');
+
+const timeoutErrorVectorTile = fs.readFileSync(__dirname + '/../../../assets/render-timeout-fallback.mvt', {encoding: null});
+
+module.exports = function vectorError() {
+    return function vectorErrorMiddleware(err, req, res, next) {
+        if(req.params.format === 'mvt') {
+
+            if (isTimeoutError(err)) {
+                res.set('Content-Type', 'application/x-protobuf');
+                return res.status(429).send(timeoutErrorVectorTile);
+            }
+        }
+
+        next(err);
+    }
+}
+
+
+function isRenderTimeoutError (err) {
+    return err.message === 'Render timed out';
+}
+
+function isDatasourceTimeoutError (err) {
+    return err.message && err.message.match(/canceling statement due to statement timeout/i);
+}
+
+function isTimeoutError (err) {
+    return isRenderTimeoutError(err) || isDatasourceTimeoutError(err);
+}