Merge pull request #3 from johncoder/master

Adds support for batching requests.

index.js

@@ -4,22 +4,54 @@ var cachestore = new Eidetic({
   canPutWhenFull: true
 });
 
+var queues = {};
+
 module.exports.cacheSeconds = function(ttl) {
 
   return function(req, res, next) {
-
+    var self = this;
     var cache = cachestore.get(req.path);
+    //var send = res.send;
+    res.original_send = res.send;
 
+    // returns the value immediately
     if (cache) {
       res.send(cache);
-    } else {
-      var send = res.send;
-      res.send = function(string) {
+      return;
+    }
+
+    if (!queues[req.path]) {
+      queues[req.path] = [];
+    }
+
+    // first request will get rendered output
+    if (queues[req.path].length === 0
+      && queues[req.path].push(function noop(){})) {
+
+      res.send = function (string) {
         var body = string instanceof Buffer ? string.toString() : string;
         cachestore.put(req.url, body, ttl);
-        send.call(this, body);
+
+        // drain the queue so anyone else waiting for
+        // this value will get their responses.
+        var subscriber = null;
+        while (subscriber = queues[req.path].shift()) {
+          if (subscriber) {
+            process.nextTick(subscriber);
+          }
+        }
+        res.original_send(body);
       };
+
       next();
+    // subsequent requests will batch while the first computes
+    } else {
+      queues[req.path].push(function() {
+        var body = cachestore.get(req.path);
+        res.send(body);
+      });
     }
+
   }
+
 };