在Powershell Cmdlet中处理同步的最佳方法

Question

As an experiment, I have been writing a cmdlet in C# which makes use of a SystemFileWatcher. As you know, the SystemFileWatcher will call a delegate when a changed event occurs. I would like to send messages back to the user from the delegate. Specifically, I would like to call WriteProgress.

Unfortunately, WriteProgress and, indeed, all other Write* methods will throw an exception if called from a thread other than the "pipeline thread". Further, Powershell doesn't seem to provide a SynchronizationContext, so I'm not sure how to marshal my delgates back to the correct thread.

It seems to me that, since Powershell requires GUI actions to execute on a particular thread, the framework should provide a way to marshal back to that thread. What am I missing? Is there an easier way to synchronize threads in my cmdlets? Is there a reason Powershell opted to use the ThreadPool based SynchronizationContext despite its Write* commands requiring the equivalent of a GUI thread?

Many thanks!

Answer 1

I've had some luck in setting System.Management.Automation.Runspaces.Runspace.DefaultRunspace before my PS code runs. (I did this for Powershell running as a WCF server).

Suggest you look at this blog , which shows setting the DefaultRunspace from C# before invoking a PS script, which is where I got the idea for my WCF server.