Powershell - Trying to streamline a Get-Service Command

Question

This is part of a larger script but, I feel like this part could be streamlined a bit. The code currently works but I feel like doing a Get-Process call twice is inefficient. Am I wrong?

# Variables:
$ServiceNames = @("HealthTLService","ThreatLockerService")

# Stop & disable some services - if they're running
ForEach ($Service in $ServiceNames) {
    Get-Service | Where-Object {($_.Name -eq $Service)} | Stop-Service -Force -ErrorAction SilentlyContinue -Verbose
    Get-Service | Where-Object {($_.Name -eq $Service)} | Set-Service -StartupType Disabled -ErrorAction SilentlyContinue -Verbose
}

Answer 1

doing a Get-Process call twice is inefficient ?

Well, sure, it's less efficient than doing it once. But there are other considerations. Often we care deeply about whether colleagues can quickly read and understand our code as a prelude to maintaining it. The OP code scores well on that metric, it is very clear.

You might choose to DRY it up slightly by defining a function for the {Get, Where} sequence. Clearly that wouldn't change the efficiency nor the elapsed time.

Almost equivalently we could follow your suggestion of defining a temp var which is sequentially fed to {Stop, Set}. This cuts lookup time in half.

But my chief concern is that we start out with an unqualified Get-Service, which seems to gather details on every service, follwed by filtering down to the service of interest. There is a perfectly good -Name option intended to accomplish exactly that. And accomplish it quickly. I would much rather do a \$O(1)\$ constant time lookup (or two of them!) than do even a single \$O(n)\$ operation that is linear in the amount of stuff installed on the given host. Some hosts accumulate quite a lot of stuff.

So I would say, do one or two lookups, it hardly matters as long as it happens "fast enough". But tell the tools you're working with about your true goal, rather than asking that they do a lot of busy work which will mostly be later discarded.