@Override
        public boolean handleMessage(Message message) {
            if (MSG_COMPLETE == message.what || MSG_EXCEPTION == message.what) {
                EngineJob job = (EngineJob) message.obj;
                if (MSG_COMPLETE == message.what) {
                    job.handleResultOnMainThread();
                } else {
                    job.handleExceptionOnMainThread();
                }
                return true;
            }

            return false;
        }
A class that manages a load by adding and removing callbacks for for the load and notifying callbacks when the
load completes.
core/src/main/java/com/bumptech/glide/load/engine/EngineJob.java