rework routing

src/lib/queue.js

@@ -1,13 +1,19 @@
+/* Simple asynchronous queue.
+To make `get` blocking, we create a new promise and store its `resolve` function in `resolvers`.
+The next time an item is added to the queue, it will be resolved.
+*/
+
 export default function() {
     return {
         items: [],
 
-        resolvers: []
+        resolvers: [],
 
         put(item) {
             this.items.push(item);
-            if (resolvers.length > 0) {
-                resolvers.shift().resolve();
+            if (this.resolvers.length > 0) {
+                let resolver = this.resolvers.shift();
+                resolver();
             }
         },