Question

I am currently facing an issue, I have a method that I run which queries specific ports of a server and writes the results to a text file called temp.txt. Temp.txt should never have any duplicate data in – the file should be clear before the method begins, although sometimes I find that the previous instance of the method is still running (as its asynchronous) and I often get duplicate data since the other method is still writing to the file / performing the queries.

Code Snippet:

            StreamWriter sw = File.AppendText("temp");
            sw.WriteLine("Check1=Success");
            sw.Close();

Answer 1

You can implement some sort of lock

Lock ensures that one thread does not enter a critical section of
code while another thread is in the critical section. If another
thread attempts to enter a locked code, it will wait, block, until the
object is released.

  class OnlyOneCallerAllowed
    {     
       private static readonly object locker = new object();        
        public static void OnlyOneMethodCanWrite()
        {
           lock (locker)
            {
             using(StreamWriter sw = File.AppendText("temp"))
             {
               sw.WriteLine("Check1=Success");
             }

         }
     }