The Tor Browser / file revision

 // 'timer' is global to avoid getting GCed which would cancel the timer

 var timer;

 const nsITimer = Components.interfaces.nsITimer;

 function attemptUnblock(s) {

   try {

     let blockedResponse = null;

     getObjectState("bug503481_" + s, function(x) {blockedResponse = x.wrappedJSObject.r});

     blockedResponse.finish();

     setObjectState("bug503481_" + s, null);

   } catch(e) {

     dump("unable to unblock " + s + "retrying in half a second\n");

     timer = Components.classes["@mozilla.org/timer;1"]

                       .createInstance(nsITimer);

     timer.initWithCallback(function () { attemptUnblock(s) }, 500, nsITimer.TYPE_ONE_SHOT);

   }

 }

 function handleRequest(request, response)

 {

   var query = {};

   request.queryString.split('&').forEach(function (val) {

     var [name, value] = val.split('=');

     query[name] = unescape(value);

   });

   dump("processing:" + request.queryString + "\n");

   if (query.unblock) {

     attemptUnblock(query.unblock);

   }

   if (query.blockOn) {

     response.processAsync();

     x = { r: response, QueryInterface: function(iid) { return this } };

     x.wrappedJSObject = x;

     setObjectState("bug503481_" + query.blockOn, x);

   }

   response.setHeader("Cache-Control", "no-cache", false);

   response.setHeader("Content-Type", "text/plain", false);

   response.write(query.body);

 }