经过一段时间后从函数返回一个值？

Question

我有一个时间敏感的进程调用ASP.NET中的Web服务。如果Web服务运行时间超过N秒，我想从呼叫返回，以便时间敏感的操作可以继续。这是可能的，如果是这样的代码是什么？

Answer 1

有Web服务调用一个单独的线程其长期运行的一部分。然后等待，杀死它，如果花费太长时间，则保释。预先警告这可能会导致稀缺资源（例如，数据库连接等），但你也可以解决这个问题。

（遗憾的快速和肮脏的代码，它是演示，您应详细说明，并添加类型，web服务细节等）

dim ResultFromWorker as String 
dim DoneWorking as boolean 

sub GetWebServiceMagicNumber 
    DoneWorking = False 
    dim t as new thread = addressof (GetWebServiceMagicNumber_Worker) 
    t.start 
    dim count as integer = 0 
    while not DoneWorking and Count <100 
     count +=1 
     System.Threading.Thread.Sleep(100) ' Important to not kill CPU time 
    wend 
    if DoneWorking then 
     return ResultFromWorker 
    else 
     return "TimeOut" 
    EndIf 
end sub 

sub GetWebServiceMagicNumber_Worker 
    try 
     ResultFromWorker = SearchTheWholeWorldForTheAnswer() 
    catch ex1 as ThreadAbortException 
     ' ignore - My code caused this on purpose 
     ' calling thread should clean up scarce resources, this is borrowed time 
    catch ex2 as Exception 
     ResultFromWorker = "Error - " & ex.tostring 
    finally 
     DoneWorking=True 
    End Try 
end sub 

Answer 2

异步调用Web服务。

http://ondotnet.com/pub/a/dotnet/2005/08/01/async_webservices.html