Problems doing asynch operations in C# using Mutex.
- by firoso
I've tried this MANY ways, here is the current iteration. I think I've just implemented this all wrong. What I'm trying to accomplish is to treat this Asynch result in such a way that until it returns AND I finish with my add-thumbnail call, I will not request another call to imageProvider.BeginGetImage.
To Clarify, my question is two-fold. Why does what I'm doing never seem to halt at my Mutex.WaitOne() call, and what is the proper way to handle this scenario?
/// <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.
}
}
}
