Thread sync problem

  • Thread starter Thread starter Gordon Knote
  • Start date Start date
G

Gordon Knote

Hi

I'm currently writing a VB.NET service that uses external
Dlls, like this:

Private Declare Function ReadSettings Lib "mydll.dll" ()

Now, how can I protect this function (ReadSettings) from
being called more then once a time?
I tried to use

System.Threading.Monitor.Enter(ReadSettings)
ReadSettings()
System.Threading.Monitor.Exit(ReadSettings)

but this caused a reference null exception. So, can
anyone tell me how I can protect external functions?


Thanks
Gordon
 
Gordon said:
Hi

I'm currently writing a VB.NET service that uses external
Dlls, like this:

Private Declare Function ReadSettings Lib "mydll.dll" ()

Now, how can I protect this function (ReadSettings) from
being called more then once a time?
I tried to use

System.Threading.Monitor.Enter(ReadSettings)
ReadSettings()
System.Threading.Monitor.Exit(ReadSettings)

but this caused a reference null exception. So, can
anyone tell me how I can protect external functions?


Thanks
Gordon
Click to expand...

You need to use an object in your Monitor.Enter. So you would do
something like this...

Public Class Resource

Private Object lockObject = New Object()


Public Function ThisIsTheFunction() As Integer
Try
Monitor.Enter(lockObject)
ReadSettings()
Catch (Exception ex)
' Handle your exceptions
Finally
Monitor.Exit(lockObject)
End Try
End Function

End Class

You can also use SyncLock as well. It is really just a shorthand for
using the Monitor object and the Try/Catch/Finally stuff ;)

HTH,
Tom Shelton
 
You can also use SyncLock as well. It is really just a shorthand for
using the Monitor object and the Try/Catch/Finally stuff ;)
Click to expand...

Which would become...

' ///
Public Class Resource

Private lockObject As New Object

Public Function ThisIsTheFunction() As Integer

SyncLock lockObject
ReadSettings()
End SyncLock

End Function

End Class
' ///

--
HTH,
-- Tom Spink, Über Geek

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