Question

我尝试了很多方法，这是当前的迭代。我想我刚刚实施了这一切都错了。我想要完成的是以这样的方式对待这个Asynch结果，直到它返回并且我完成了我的add-thumbnail调用，我不会再请求对imageProvider.BeginGetImage的调用。

要澄清，我的问题是双重的。为什么我正在做的事情似乎永远不会停止在我的Mutex.WaitOne（）调用上，以及处理这种情况的正确方法是什么？

        /// <summary>
        /// re-creates a list of thumbnails from a list of TreeElementViewModels (directories)
        /// </summary>
        /// <param name="list">the list of TreeElementViewModels to process</param>
        public void BeginLayout(List<AiTreeElementViewModel> list)
        {
            // *removed code for canceling and cleanup from previous calls*

            // Starts the processing of all folders in parallel.
            Task.Factory.StartNew(() =>
                {
                    thumbnailRequests = Parallel.ForEach<AiTreeElementViewModel>(list, options, ProcessFolder);
                });
        }

        /// <summary>
        /// Processes a folder for all of it's image paths and loads them from disk.
        /// </summary>
        /// <param name="element">the tree element to process</param>
        private void ProcessFolder(AiTreeElementViewModel element)
        {
            try
            {
                var images = ImageCrawler.GetImagePaths(element.Path);

                AsyncCallback callback = AddThumbnail;

                foreach (var image in images)
                {
                     Console.WriteLine("Attempting Enter");

                     synchMutex.WaitOne();     

                     Console.WriteLine("Entered");

                     var result = imageProvider.BeginGetImage(callback, image);
                }
            }
            catch (Exception exc)
            {
                Console.WriteLine(exc.ToString());
                // TODO: Do Something here.
            }
        }

        /// <summary>
        /// Adds a thumbnail to the Browser
        /// </summary>
        /// <param name="result">an async result used for retrieving state data from the load task.</param>
        private void AddThumbnail(IAsyncResult result)
        {
            lock (Thumbnails)
            {
                try
                {
                    Stream image = imageProvider.EndGetImage(result);
                    string filename = imageProvider.GetImageName(result);
                    string imagePath = imageProvider.GetImagePath(result);
                    var imageviewmodel = new AiImageThumbnailViewModel(image, filename, imagePath);
                    thumbnailHash[imagePath] = imageviewmodel;
                    HostInvoke(() => Thumbnails.Add(imageviewmodel));
                    UpdateChildZoom();
                    //synchMutex.ReleaseMutex();
                    Console.WriteLine("Exited");
                }
                catch (Exception exc)
                {
                    Console.WriteLine(exc.ToString());
                    // TODO: Do Something here.
                }
            }
        }

Answer 1

首先，

创建一个Task来执行Parallel.ForEach来运行一个调用委托的方法。

三级并行，其中1就足够了。

如果我读得正确，在委托内你想使用Mutex一次只运行一个实例。

你能指出你想要并行发生的行动吗？

使用Mutex在C＃中执行异步操作时出现问题

1 个答案: