Bnaya Eshet

Async and AggregateException

Async and AggregateException this post is a complementary to Eran Stiller's post . I was reading Eran Stiller's post about exception handling using async methods and I want to add a few side notes. 1) the exception handling behavior decisions is well documented in this post (by the TPL team), it decided after they had consider different options. 2) I was suggesting that compiler will check whether the a catch of AggregateException is implemented and if so to avoid the unwrapping behavior...

Tpl Dataflow walkthrough - Part 5

Tpl Dataflow walkthrough - Part 5 this post is a complete walkthrough of a web crawler sample that was build purely by using Tpl Dataflow . it was built on .NET 4.5 / C# 5 (on a virtual machine using VS 11 ). I will analyze each part of this sample, both by discussing the Dataflow blocks and the patterns in used. the sample code is available in here (it is a VS 11 project). during the walkthrough you will see the following Tpl Dataflow blocks: TransformBlock TransformManyBlock ActionBlock BroadcastBlock...

async / await, some reasoning

async / await, some reasoning this post will try to make some reasoning about the .NET 4.5 / C#5 await keyword. I will begin with a quiz. how long will it take to the following method to produce the 42 value? Code Snippet async Task < int > Execute() { await Task .Delay(1000); await Task .Delay(1000); return 42; } you should remember that conceptually the await keyword will translate to a continuation . the above code can be compare to the following TPL 4 code snippet: Code Snippet Task <...

Using async / await

Using async / await this post will discuss parallel disposal. whenever we want to dispose a parallel execution upon completion we can't use the convenient using keyword. for example, the following code may be dispose the command before completion: Very bad Code Snippet using ( var conn = new SqlConnection (CONN_STR)) using ( var cmd = new SqlCommand ( "Select * from Employee" , conn)) { conn.Open(); cmd.BeginExecuteReader(ar => { int affected = cmd.EndExecuteNonQuery(ar); }); } the...

async \ await and Exception Handling

async \ await and Exception Handling this post will discuss how async / await is handling exceptions . as we mention in previous post , about the async / await concept, await is all about continuation . before .NET 4.5 parallel execution exceptions has to be handle in separate of the synchronic handling. for example: handling ThreadPool execution: Code Snippet void Foo() { try { Console .WriteLine( "Synchronic" ); ThreadPool .QueueUserWorkItem(state => { try { Console .WriteLine( "Parallel"...

the concept of async \ await

the concept of async \ await in this post I will survey the new .NET 4.5 / C# 5 concept of async / await. I will focus on how to understand what is really happens behind the new async / await syntax. What's it all about? the new async / await syntax is using the C# syntactic compiler to generate async operation from code that is looking very much like a synchronous code. but before we start we should discus the new C# 5  syntax. the syntax include 2 keywords: async - which is only a marker...