split app from server, add toobusy

app.js

@@ -0,0 +1,24 @@
+
+var app = require('express')();
+
+/** ----------------------- middleware ----------------------- **/
+
+app.use( require('./middleware/toobusy') ); // should be first
+app.use( require('./middleware/headers') );
+app.use( require('./middleware/cors') );
+app.use( require('./middleware/jsonp') );
+
+/** ----------------------- routes ----------------------- **/
+
+// api root
+app.get( '/', require('./controller/index') );
+
+// suggest API
+app.get( '/suggest', require('./sanitiser/suggest'), require('./controller/suggest') );
+
+/** ----------------------- error middleware ----------------------- **/
+
+app.use( require('./middleware/404') );
+app.use( require('./middleware/500') );
+
+app.listen( process.env.PORT || 3100 );

index.js

@@ -1,23 +1,9 @@
 
-var app = require('express')();
+/** cluster webserver across all cores **/
 
-/** ----------------------- middleware ----------------------- **/
+var cluster = require('cluster'),
+    app = require('./app');
 
-app.use( require('./middleware/headers') );
-app.use( require('./middleware/cors') );
-app.use( require('./middleware/jsonp') );
-
-/** ----------------------- routes ----------------------- **/
-
-// api root
-app.get( '/', require('./controller/index') );
-
-// suggest API
-app.get( '/suggest', require('./sanitiser/suggest'), require('./controller/suggest') );
-
-/** ----------------------- error middleware ----------------------- **/
-
-app.use( require('./middleware/404') );
-app.use( require('./middleware/500') );
-
-app.listen( process.env.PORT || 3100 );
+cluster(app)
+  .use(cluster.stats())
+  .listen( process.env.PORT || 3100 );

middleware/toobusy.js

@@ -0,0 +1,19 @@
+
+// middleware which blocks requests when the eventloop is too busy
+var toobusy = require('toobusy');
+
+function middleware(req, res, next){
+  if( toobusy() ){
+    res.status(503); // Service Unavailable
+    return next('Server Overwhelmed');
+  }
+  return next();
+}
+
+// calling .shutdown allows your process to exit normally
+process.on('SIGINT', function() {
+  toobusy.shutdown();
+  process.exit();
+});
+
+module.exports = middleware;

package.json

@@ -33,7 +33,8 @@
   "dependencies": {
     "express": "^4.8.8",
     "geopipes-elasticsearch-backend": "0.0.7",
-    "pelias-esclient": "0.0.25"
+    "pelias-esclient": "0.0.25",
+    "toobusy": "^0.2.4"
   },
   "devDependencies": {
     "ciao": "^0.3.4",