joshooaj / bgprocess Goto Github PK

The method of monitoring StandardOutput and StandardError in this module is to read the streams from a separate runspace where, if the read operation blocks, it doesn't have to impact the user's shell.

Another option for reading from these streams is to use 'Register-ObjectEvent' to subscribe to the OutputDataReceived and ErrorDataReceived events.

This could simplify the module a bit, but it looks like the event only fires when a newline is encountered. This means that when an application prompts for input, typically you wouldn't receive the prompt until you blindly write to StandardInput and cause the application to write a newline.

The events also exclusively send string data, so if I want to add binary support to the module the event handlers wouldn't be an option.

Because of these two issues, I'm leaning towards avoiding the event handlers entirely. The only true advantage of using them was being able to interleave stdout and stderr messages accurately, but this can be done in the current implementation with some smarter processing anyway.

Currently, all of the StandardError content is returned, followed by all of the StandardOutput content, each as individual strings.

This means the output order is not being preserved, and we can't tell how much time passed between two lines of output.

Instead of returning strings, Read-BGProces could return a rich object similar to BGProcessRecord...

enum StdIOStream {
    StandardOutput
    StandardError
    StandardInput
}

class BGProcessRecord {
    [int]         $PID
    [datetime]    $Timestamp
    [StdIOStream] $Stream
    [string]      $Content
}