All Questions
67
questions
377
votes
3
answers
443k
views
Do you have to put Task.Run in a method to make it async?
I'm trying to understand async await in the simplest form. I want to create a very simple method that adds two numbers for the sake of this example, granted, it's no processing time at all, it's just ...
- 9,539
212
votes
4
answers
163k
views
Using 'async' in a console application in C# [duplicate]
I have this simple code:
public static async Task<int> SumTwoOperationsAsync()
{
var firstTask = GetOperationOneAsync();
var secondTask = GetOperationTwoAsync();
return await ...
- 147k
155
votes
2
answers
168k
views
How does Task<int> become an int?
We have this method:
async Task<int> AccessTheWebAsync()
{
HttpClient client = new HttpClient();
Task<string> getStringTask = client.GetStringAsync("http://msdn.microsoft.com");
...
- 5,741
69
votes
6
answers
11k
views
Why doesn't generic ICollection implement IReadOnlyCollection in .NET 4.5?
In .NET 4.5 / C# 5, IReadOnlyCollection<T> is declared with a Count property:
public interface IReadOnlyCollection<out T> : IEnumerable<T>, IEnumerable
{
int Count { get; }
}
I ...
- 13.3k
63
votes
1
answer
26k
views
What can I do in C# 5 with .Net 4.5 that I couldn't do in C# 4 with .Net 4? [closed]
I have Visual Studio 2012 RC installed on Windows 8 Release Preview and my question is are there any useful new features not related to Metro, or is Metro what seperates .Net 4 and .Net 4.5?
- 27.7k
61
votes
4
answers
34k
views
What are the differences between using ConfigureAwait(false) and Task.Run?
I understand that it's recommended to use ConfigureAwait(false) for awaits in library code so that subsequent code does not run in the caller's execution context, which could be a UI thread. I also ...
- 41.5k
50
votes
6
answers
32k
views
Task.Yield - real usages?
I've been reading about Task.Yield , And as a Javascript developer I can tell that's it's job is exactly the same as setTimeout(function (){...},0); in terms of letting the main single thread deal ...
- 147k
40
votes
1
answer
7k
views
Has foreach's use of variables been changed in C# 5?
In this answer https://stackoverflow.com/a/8649429/1497 Eric Lippert says that "FYI we are highly likely to fix this in the next version of C#; this is a major pain point for developers" with regards ...
- 5,122
28
votes
2
answers
22k
views
awaiting on an observable
So in the sad days of C# 4.0, I created the following "WorkflowExecutor" class that allowed asynchronous workflows in the GUI thread by hacking into IEnumerable's "yield return" continuations to wait ...
- 10.7k
23
votes
8
answers
30k
views
TcpListener: how to stop listening while awaiting AcceptTcpClientAsync()?
I don't know how to properly close a TcpListener while an async method await for incoming connections.
I found this code on SO, here the code :
public class Server
{
private TcpListener _Server;
...
- 1,146
20
votes
3
answers
6k
views
How to attach CancellationTokenSource to DownloadStringTaskAsync method and cancel the async call?
I an creating a sample example to call link using WebClient using async and await method now I want to attach cancel async call functionality also. But I am not able to get CancellationTokenSource ...
- 3,441
19
votes
5
answers
344
views
Is there an elegant LINQ solution for SomeButNotAll()?
Here is what I'm trying to do overall. Just to be clear, this isn't homework or for a contest or anything. Hopefully, I've made the wording clear enough:
Problem
Given a set of strings in the same ...
- 61.3k
18
votes
2
answers
12k
views
Building .NET 4.5 Projects with Nant
I'm curious if it's possible to use Nant to target the .NET 4.5 using the C# 5.0 compiler. As of right now, the latest version only states support for .NET 4.0.
I tried downloading the source and ...
- 47.2k
18
votes
1
answer
12k
views
Interface implementation with optional arguments
Take this interface:
interface ILogger
{
void Store(string payload);
}
And this class implementation of ILogger:
class Logger : ILogger
{
void Store(string payload, bool swallowException = ...
- 8,683
15
votes
4
answers
2k
views
Code Contracts + Async in .NET 4.5: "The method or operation is not implemented"
I receive the following compilation error from ccrewrite when using Code Contracts 1.4.51019.0 in VS2012 on Windows 7 x64: "The method or operation is not implemented."
It appears to be caused by a ...
- 6,521
13
votes
1
answer
5k
views
How to use a breakpoint after await in unit test?
I am surprised my breakpoint after awaiting an async method that is on a line that references the awaited Task<T> is never hit:
[Test]
public async void GetSomethingTest()
{
...
- 11.3k
13
votes
5
answers
6k
views
How can I start a Windows App Background Task immediately after registering it?
I am writing a Metro App that will only run on PCs (so there is no, or at least less, worry about the battery life). I need it to register and run a background task when the user clicks a button. It ...
- 5,620
11
votes
2
answers
6k
views
How do I convert this to an async task?
Given the following code...
static void DoSomething(int id) {
Thread.Sleep(50);
Console.WriteLine(@"DidSomething({0})", id);
}
I know I can convert this to an async task as follows...
...
- 6,103
10
votes
3
answers
8k
views
async - stay on the current thread?
I've read Eric lippert's article about async , and about confusions people had with async keyword. he said :
it (async) means “this method contains control flow that involves awaiting
...
- 147k
9
votes
1
answer
2k
views
c# 5 async as a sugar syntax (or not)?
So I was asking this question about async , and I thought that it it's just a sugar syntax for :
Task<..>...ContinueWith...
And finally inspect the Result property.
I even asked a question ...
- 147k
9
votes
2
answers
22k
views
.NET 4.5 forms app connecting to SQL Server 2012 fails: SSL Provider, error: 0
I have a problem connection to a SQL Server 2012 instance running on Windows Server 2012. I have a .NET 4.5 windows forms application installed on a client machine running Windows 7. The error I get ...
- 2,775
7
votes
2
answers
2k
views
async void event handlers - clarification?
I'm trying to understand the reason why is it bad to do: (notice, context here is asp.net, regardless the plain reason that async void can't be tracked)
public async void Page_Load(object sender, ...
- 147k
6
votes
2
answers
15k
views
C# 5.0 async await return a list
I'm learning about async/await, and ran into a situation where I need to call an async method
that should return an object or list of same object.
Is this the right way to implement ?
from AManager....
- 4,834
6
votes
2
answers
2k
views
What in the Rx Framework allows me to return an IObservable<T> while awaiting other methods during creation?
I've been working on creating an IObservable<T> implementation using the Reactive Extensions for Twitter's streaming APIs.
From a high level an HTTP request is sent and the connection is kept ...
- 74.1k
6
votes
4
answers
7k
views
Most efficient way of reading a BinaryFormatter serialized object from a NetworkStream?
I have an app that is sending serializable objects of varying sizes over a socket connection, and I'd like it to be as scalable as possible. There could also be dozens to even hundreds of connections.
...
- 108k
6
votes
1
answer
341
views
Why await both the asynchronous request and the reading of its contents?
Why is it necessary in .NET Web API to have a a method that reads the content of an HTTP response asynchronously, given that there is already a method to make the request asynchronously? Said another ...
- 7,875
6
votes
1
answer
2k
views
Why does cancellation block for so long when cancelling a lot of HTTP requests?
Background
I have some code that performs batch HTML page processing using content from one specific host. It tries to make a large number (~400) of simultaneous HTTP requests using HttpClient. I ...
- 41.5k
5
votes
2
answers
2k
views
RESTful authentication. Client-side, stateless unauthentication
I'm implementing a set of RESTful services for some developments and one of these is an authentication service.
This authentication service authenticates two kinds of identities:
Applications. ...
- 64.5k
5
votes
1
answer
1k
views
Easy Way to Perform C# Null Check in a Type Conversion
I am doing some quick type conversions in a project I am not that very familiar with.
They look similar to this:
var NewType = new
{
NewTypeId = old.SubType == null ? 0 : old.SubType.SubTypeId ?...
- 1,272
5
votes
2
answers
311
views
Cancelling all tasks when a new one is created
I have the following task that is run when the section item of a list box changes.
I am trying to cancel any task that are running when a user changes their selection and start a new task . I can ...
- 1,268
4
votes
4
answers
4k
views
What is the best way to return completed Task?
What is the best way to return a completed Task object?
It is possible to write Task.Delay(0), or Task.FromResult<bool>(true) whatever.
But what is the most efficient way?
- 1,140
4
votes
3
answers
3k
views
async await usages for CPU computing vs IO operation?
I already know that async-await keeps the thread context , also handle exception forwarding etc.(which helps a lot).
But consider the following example :
/*1*/ public async Task<int> ...
- 147k
4
votes
1
answer
2k
views
Cold Tasks and TaskExtensions.Unwrap
I've got a caching class that uses cold (unstarted) tasks to avoid running the expensive thing multiple times.
public class AsyncConcurrentDictionary<TKey, TValue> : System.Collections....
- 5,038
4
votes
3
answers
916
views
Why does MVC 4 dispose the controller when action await something?
Why is my controller being disposed after the await statement?
public async Task<ViewResult> MyAction()
{
await Task.Yield();
// controller disposed at this ...
- 24k
4
votes
0
answers
2k
views
How to await Tasks kicked off in Dispose
I have a general question about how to keep track of an asynchronous task that is started when an object is disposed in .Net. I have a class designed around Stephen Cleary's Dispose means cancel ...
- 275
3
votes
2
answers
5k
views
C# async awaitable clarification?
I've read here that :
Await examines that awaitable to see if it has already completed; if
the awaitable has already completed, then the method just continues
running (synchronously, just like ...
- 147k
3
votes
2
answers
2k
views
create an async method that wraps subscribe and publish on a bus
I have a kind of bus that implements this interface:
public interface IBus
{
void Publish<T>(T t);
void Subscribe<T>(Guid subscriptionId, Action<T> action);
void ...
- 353
3
votes
1
answer
4k
views
C#5 async method completed event.
I have an asynchronous method like this
public async void Method()
{
await // Long run method
}
When Im calling this method can I have a event when this Method completed?
public void CallMethod(...
- 2,868
3
votes
2
answers
1k
views
How to use async/await with a library that uses an event-based asynchronous pattern?
I use a library that has an asynchronous method called DoWork(...) that will raise a WorkDone event when the operation completes.
I would like to write a method that calls this library, but instead ...
- 19.5k
3
votes
1
answer
243
views
WEB API call stops working after introducing the "await" keyword
I have a simple web api method which retrieves a list of items from a database. When the method looks like this it works and the items are displayed in the UI:
[ActionName("GetServices")]
public ...
- 16.9k
2
votes
1
answer
4k
views
Getting deadlock when using ExecuteReaderAsync
I'm trying to use the async pattern to execute a SQL command and return a DataTable.
Can someone please advice how to solve this problem?
This is my code:
private static async Task<DataTable&...
- 1,449
2
votes
2
answers
341
views
Examples of solutions using C# 5 Caller Information
I am struggling to think of real-world usage of C# 5's Caller Information feature
In what scenarios do you need to know who called your method? What other usages does it have other than tracing and ...
- 12.8k
2
votes
1
answer
515
views
Overload resolution and async await
Below code gives error CS0121,
The call is ambiguous between the following methods or properties: 'RunTask(System.Func<System.Threading.Tasks.Task>)' and 'RunTask(System.Action)'
static ...
- 2,921
2
votes
1
answer
215
views
async ( with non-async) function control flow clarification?
( I've read a lot about async and I wonder what happens if there is a mix of async function call and non-async) and im talking about THREAD pov .
( I know that mix should not be done , but im asking ...
- 147k
2
votes
1
answer
1k
views
Windows Phone 8 MVVM with JSON Deserialization
(Need suggestion about scary code)
I am trying to bring about some elegance to my old Windows Phone app code by incorporating MVVM and a generalized DataService class for all View Models, to call ...
- 33.1k
2
votes
1
answer
638
views
ReactiveAsyncCommand missing in ReactiveUI 5.0.2
I just start learn ReactiveUI from https://github.com/reactiveui/ReactiveUI.Samples/blob/master/ReactiveUI_4Only.Samples.sln.
I download lastest version via nuget but I cant find class ...
- 81
2
votes
1
answer
417
views
How to improve throughput with FileStream in a single-threaded application
I am trying to get top I/O performance in a data streaming application with eight SSDs in RAID-5 (each SSD advertises and delivers 500 MB/sec reads).
I create FileStream with 64KB buffer and read ...
- 7,807
2
votes
1
answer
790
views
Unit testing async method: The remote hostanme could not be resolved
I am trying to test some async methods involving the HttpClient work with vs 2012 express for win 8 and it's test framework. No matter how I try I always get the same exception.
For example this test ...
- 445
2
votes
0
answers
315
views
Equivalence or conversion matrix between .NET 4.0 Async CTP terms and their .NET 4.5 analogs?
I am using Async CTP (Version 3) + SP1 to it for developing and testing in Visual Studio 2010 SP1 on Windows XP SP3 mainly because my clients (as well as I) are on Windows XP SP3. See related topics: ...
1
vote
1
answer
427
views
How to get data of the Task with await keyword?
I just need in main code get FlowDocument...
I do like this but no success
this.flowDoc = engine.CreateFlowDocument(contentItems); // Can't compile
public async Task<FlowDocument> ...
- 37k