func handleDownloaderModify(ctxArg interface{}, objType string,
	key string, configArg interface{})  {
		log.Infof("handleDownloaderModify(%s)\n", key)
		ctx := ctxArg.(*downloaderContext)
		config := cast.CastDownloaderConfig(configArg)
		if config.Key() != key {
			log.Errorf("handleDownloaderModify key/UUID mismatch %s vs %s; ignored %+v\n",
				key, config.Key(), config)
			return
		}
		h, ok := handlerMap[config.Key()]
		if !ok {
			log.Fatalf("handleDownloaderModify called on config that does not exist")
		}
		h <- configArg
}
func handleDownloaderCreate(ctxArg interface{}, objType string,
	key string, configArg interface{})  {
		log.Infof("handleDownloaderModify(%s)\n", key)
		ctx := ctxArg.(*downloaderContext)
		config := cast.CastDownloaderConfig(configArg)
		if config.Key() != key {
			log.Errorf("handleDownloaderModify key/UUID mismatch %s vs %s; ignored %+v\n",
				key, config.Key(), config)
			return
		}
		h, ok := handlerMap[config.Key()]
		if ok {
			log.Fatalf("handleDownloaderCreate called on config that already exists")
		}
		h := make(chan interface{})
		handlerMap[config.Key()] = h
		go runHandler(ctx, objType, key, h)
		h <- configArg
}