scheduler

scheduler_vanilla.js

app.get('/home', prioritize(prioritizer, responder));

var queues = [];

function flush() {
  if (!flush.polling) {
    flush.polling = setInterval(function() {
      var x;
      for (var i = 0; i < queues.length; i++) {
        for (var j = 0; j < queues[i].length; j++) {
          if (x = queues[i].shift()) {
            x();
            break;
          }
        }
        if (x) {
          break;
        }
      }
    }, 0);
  }
}

function done(req, resp, priority, action) {
  queues[priority].queue.push(function() {
    action(req, resp);
  });
  flush();
}

function prioritizer(req) {
  
  for (var i = 0; i < queues.length; i++) {
    if (queues[i].heuristic()) {
      return i;
    }
  }
  
  return priorities.length;
}

function prioritize(prioritizer, action) {
  
  queues.push({
    "heuristic": function() {
      return req.xhr
    },
    "queue": []
  });
  
  queues.push({
    "heuristic": function() {
      return true;
    },
    "queue": []
  });
  
  return function(req, res) {
    done(req, resp, prioritizer(req), action);
  };
}

function responder(req, res){
  var body = 'Homepage';
  res.setHeader('Content-Type', 'text/plain');
  res.setHeader('Content-Length', body.length);
  res.end(body);
}