This backburner extension on the Ember run loop provides an API for attaching a callback to the end of any run loop that utilizes a certain queue.

backburner-events-ext.js

/*
Usage:

BackburnerEvents.on('afterRender', () => {
  // called after any run loop that utilizes the afterRender queue
});

*/

import Ember from "ember";

let BackburnerEvents = Ember.Object.createWithMixins(Ember.Evented);

let backburner = Ember.run.backburner;

let oldOnBegin = backburner.options.onBegin;
let oldOnEnd = backburner.options.onEnd;

function forEachQueue(runloop, func) {
  let queues = runloop.queues;
  let keys = Object.keys(queues);

  for (let i = 0; i < keys.length; i++) {
    let queueName = keys[i];
    let queue = queues[queueName];
    func.call(this, queue, queueName);
  }
}

// At the start of every run loop, go through every queue
// and override queue.push to set a flag on that queue.
// This gives us a flag that is true whenever the queue
// was actually utilized during the runloop
backburner.options.onBegin = function(runloop) {
  forEachQueue(runloop, queue => {
    let oldPush = queue._queue.push;

    queue._queue.push = function() {
      queue.wasFired = true;
      queue._queue.push = oldPush;
      return oldPush.apply(this, arguments);
    };
  });
  oldOnBegin.apply(this, arguments);
};

// When the run loop completes, check each flag to see
// that particular queue was used. If so, fire the
// appropriate event.
backburner.options.onEnd = function(runloop) {
  forEachQueue(runloop, (queue, queueName) => {
    if (queue.wasFired) {
      BackburnerEvents.trigger(queueName);
    }
  });
  oldOnEnd.apply(this, arguments);
};

export default BackburnerEvents;