RaumfeldNET.ImageDataCache.requestImageFromUrl C# (CSharp) Метод

        public void requestImageFromUrl(String _imageUrl, delegate_OnReqestImageDone _sink)
        {
            try
            {

                // if image is already in cache, we immediately notify the sinks
                // otherwise start web request for url
                if (this.existsImage(_imageUrl))
                {
                    if (_sink != null) ((delegate_OnReqestImageDone)_sink)(_imageUrl);
                }
                else
                {
                    lock (imageUrlOnRequest)
                    {
                        if (!imageUrlOnRequest.ContainsKey(_imageUrl))
                        {
                            imageUrlOnRequest.Add(_imageUrl, new List<delegate_OnReqestImageDone>());
                            webRequestHelper.httpPostRequestAsync(_imageUrl, null, null, (response) => requestImageFromUrlSink(response, _sink, _imageUrl));
                        }
                        else
                        {
                            imageUrlOnRequest[_imageUrl].Add(_sink);
                        }
                    }
                }
            }
            catch (Exception e)
            {
                this.writeLog(LogType.Error, String.Format("Fehler bei 'requestImageFromUrl' für Url '{0}'", _imageUrl), e);
            }
        }