Powershell Custom Cmdlet - Call WriteObject in Background Thread

Question

Calling the WriteObject Method from a background thread is not possible!

Is there a possibility, to invoke/dispatch this method in the main thread of the powershell (like in WPF)?

Code sample:

protected override void ProcessRecord()
{
    base.ProcessRecord();
    ...
    Service.StartReading(filter, list => { WriteObject(list, true); } );
}

EDIT:

Any solution, workaround or quick fix?

thx, Mathias

Answer 1

I found a solution, which solves my problem.

1. created a ConcurrentQueue

   ConcurrentQueue<LogEntryInfoBase> logEntryQueue = 
           new ConcurrentQueue<LogEntryInfoBase>();
   

2. start a background thread to enqueue items to the ConcurrentQueue

   Task.Factory.StartNew(() => Service.StartReading(
           filter, EnqueueLogEntryInfoBases));
   

3. meanwhile, try to dequeue from this queue in the main thread

   for ( ; ; )
   {
       LogEntryInfoBase logEntry = null;
       logEntryQueue.TryDequeue(out logEntry);
       if (logEntry != null)
       {
           WriteObject(logEntry);
       }
       Thread.Sleep(100);
   }
   

From my point of view, this solution/fix is ugly, but it works for my current issue.

Answer 2

I was stuck on pretty much the same issue. In my opinion we can improve the solution by adding a sleep in the infinite loop. Of course we will need to have a global reference to our main thread and the background thread will need to call interrupt as soon as an item is added in queue.