# version 1.0
# PowerShell script to detect loop delays as follows:
# - Soft failure if delay is between 9-12ms or >=20ms
# - Hard failure if delay is between 13-19ms, which stops WPR and exits the script.
#   (delays in this range are likely to be caused by the mysterious ~14ms idle periods that are being investigated)

# Raise script process priority to High
try {
    $currentProcess = [System.Diagnostics.Process]::GetCurrentProcess()
    $currentProcess.PriorityClass = [System.Diagnostics.ProcessPriorityClass]::High
    Write-Host "Process priority set to High."
}
catch {
    Write-Warning "Failed to set process priority to High: $_"
}


# Define P/Invoke for NtSetTimerResolution
Add-Type @"
using System;
using System.Runtime.InteropServices;
public class TimerResolution {
    [DllImport("ntdll.dll", SetLastError=true)]
    public static extern int NtSetTimerResolution(uint DesiredResolution, bool Set, out uint CurrentResolution);
}
"@

# Set system timer to 1ms resolution (10000 in 100ns units)
$currentResolution = 0
try {
    $timerResult = [TimerResolution]::NtSetTimerResolution(10000, $true, [ref]$currentResolution)
    if ($timerResult -ne 0) {
        Write-Warning "Failed to set timer resolution to 1ms (status: $timerResult). Continuing with default resolution."
    }
    else {
        Write-Host "Timer resolution set to 1ms (current: $($currentResolution/10000)ms)."
    }
}
catch {
    Write-Warning "Error setting timer resolution: $_ Continuing with default resolution."
}

# Counter for total iterations
$totalIterations = 0

# Main loop
try {
    while ($true) {
        $start = [System.Diagnostics.Stopwatch]::StartNew()
        # Precise sleep for 1ms
        [System.Threading.Thread]::Sleep(1)
        $elapsedMs = [math]::Round($start.Elapsed.TotalMilliseconds)
        $totalIterations++
        
        # Check delay categories
        if ($elapsedMs -ge 9 -and $elapsedMs -le 12 -or $elapsedMs -ge 20) {
            Write-Host "Soft failure: $elapsedMs ms"
        }
        elseif ($elapsedMs -ge 13 -and $elapsedMs -le 19) {
            Write-Host "Loop delay exceeded 10ms: $elapsedMs ms"
            
            # Spawn process to stop WPR
            try {
                Write-Host "Stopping WPR..."
                Start-Process -FilePath "wpr" -ArgumentList "-stop WPRRecording.etl" -NoNewWindow -Wait
                Write-Host "WPR stopped. ETL file saved to: WPRRecording.etl"
            }
            catch {
                Write-Error "Failed to stop WPR: $_"
            }
            
            # Exit the script
            Write-Host "Exiting script after $totalIterations iterations."
            exit
        }
        
    }
}
finally {
    # Restore default timer resolution
    try {
        $currentResolution = 0
        $timerResult = [TimerResolution]::NtSetTimerResolution(0, $false, [ref]$currentResolution)
        if ($timerResult -ne 0) {
            Write-Warning "Failed to restore default timer resolution (status: $timerResult)."
        }
        else {
            Write-Host "Timer resolution restored."
        }
    }
    catch {
        Write-Warning "Error restoring timer resolution: $_"
    }
}