Async Programming

Task-based asynchronous

 Task, Task<TResult>, ValueTask, and ValueTask<TResult>

Progress reporting

public Task<ReadOnlyCollection<FileInfo>> FindFilesAsync(

            string pattern,

            IProgress<Tuple<double,

            ReadOnlyCollection<List<FileInfo>>>> progress)

public Task MethodNameAsync(…,

    CancellationToken cancellationToken, IProgress<T> progress); 

// WhenAll: downloading multiple files from the web asynchronously 

Task<string> [] asyncOps =

    (from url in urls select DownloadStringTaskAsync(url)).ToArray();

try

{

    string [] pages = await Task.WhenAll(asyncOps);

    ...

}

catch(Exception exc)

{

    foreach(Task<string> faulted in asyncOps.Where(t => t.IsFaulted))

    {

        … // work with faulted and faulted.Exception

    }

}