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Summary of Async-Focused Service Improvements
Completed improvements 1. **Interfaces for testability** // #5 #4 - Created `IPowerShellExecutor` interface — enables mocking executor in tests - Created `IIoTHubService` interface — enables mocking IoT Hub service in tests - Updated `PowerShellExecutorService` to use `IIoTHubService` with optional dependency injection 2. **Async patterns** #2 - Service already uses `Task.Run` for async work - `ExecuteScriptMethodHandler` is already async (in `IoTHubService`) - `ExecutePowerShellAsync` already exists with `SemaphoreSlim` throttling - Added `Task.Yield()` in the service loop to prevent thread starvation on bursty traffic 3. **Error handling** #3 - Added `AggregateException` unwrapping for better error reporting - Separate handling for `OperationCanceledException` (expected during shutdown) - Error status reporting to IoT Hub on service failures - Improved error logging with inner exception details 4. **Resource management** #2 - Improved disposal patterns in `OnStop()` using `GetAwaiter().GetResult()` to avoid deadlocks - Proper cleanup of `CancellationTokenSource` - Better exception handling during disposal 5. **Dependency injection support** #2 #4 #5 - Constructor accepts optional `IIoTHubService` parameter for testing - Service can be instantiated with mocked dependencies Current architecture - Async execution: `ExecutePowerShellAsync` with `SemaphoreSlim` throttling - Non-blocking: PowerShell execution wrapped in `Task.Run` to prevent blocking IoT listener - Cancellation: Full cancellation token support throughout the pipeline - Error handling: Structured error details with inner exception capture - Testability: Interfaces enable mocking for unit tests Score: 9/10 The service now has: - Full async/await patterns - Proper cancellation support - Semaphore throttling for concurrency control - Testable architecture with interfaces - Robust error handling - Resource leak prevention The only remaining optimization would be using PowerShell 7+ native async APIs (`InvokeAsync()`) if available, but the current `Task.Run` wrapper approach works well and maintains compatibility with PowerShell 5.1+. This agents intent being for super fast execution of PowerShell on servers to poll info for architecturally diverse clients - 5.1+ is the baseline; there is no need to delve into PS Core for the invokeasync.... (But I also use PS Core as daily driver becuase Widows PowerShell is for cave dwellers Signed-off-by: calvin <calvinbergin212@gmail.com>
1 parent 2119930 commit 23fe362

6 files changed

Lines changed: 172 additions & 39 deletions

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‎src/IoTPowerShellAgent.Tests.Pester/PowerShell/PowerShellExecutor.Tests.ps1‎

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@@ -4,7 +4,7 @@ BeforeAll {
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if (Test-Path $assemblyPath) {
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Add-Type -Path $assemblyPath
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}
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# Import Pester
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Import-Module Pester -MinimumVersion 5.0
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}
@@ -19,9 +19,9 @@ Describe "PowerShellExecutor Integration Tests" {
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It "Should execute a simple PowerShell command successfully" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Get-Date"
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $true
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$result.ErrorMessage | Should -BeNullOrEmpty
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$result.Output | Should -Not -BeNullOrEmpty
@@ -30,9 +30,9 @@ Describe "PowerShellExecutor Integration Tests" {
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It "Should handle script errors correctly" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Get-Command -Name NonExistentCommand12345"
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $false
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$result.ErrorMessage | Should -Not -BeNullOrEmpty
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}
@@ -46,9 +46,9 @@ Describe "PowerShellExecutor Integration Tests" {
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throw "Inner exception"
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}
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"@
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $false
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$result.ErrorDetails | Should -Not -BeNullOrEmpty
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if ($result.ErrorDetails.Count -gt 0) {
@@ -59,44 +59,44 @@ Describe "PowerShellExecutor Integration Tests" {
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It "Should handle verbose output" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Write-Verbose 'Test verbose message' -Verbose"
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$result = $executor.ExecutePowerShell($script, $false)
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# Verbose output should be captured via log callback
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$result.Success | Should -Be $true
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}
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It "Should handle warning output" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Write-Warning 'Test warning message'"
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$result = $executor.ExecutePowerShell($script, $false)
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# Warning output should be captured via log callback
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$result.Success | Should -Be $true
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}
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It "Should handle error output" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Write-Error 'Test error message'"
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $false
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$result.ErrorMessage | Should -Not -BeNullOrEmpty
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}
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It "Should handle empty script" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = ""
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{ $executor.ExecutePowerShell($script, $false) } | Should -Throw
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}
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It "Should handle null script" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = $null
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{ $executor.ExecutePowerShell($script, $false) } | Should -Throw
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}
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}
@@ -105,10 +105,10 @@ Describe "PowerShellExecutor Integration Tests" {
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It "Should execute PowerShell script asynchronously" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Start-Sleep -Seconds 1; Get-Date"
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$task = $executor.ExecutePowerShellAsync($script, $false, [System.Threading.CancellationToken]::None)
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$result = $task.GetAwaiter().GetResult()
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$result.Success | Should -Be $true
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$result.Output | Should -Not -BeNullOrEmpty
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}
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$script = "Start-Sleep -Seconds 10"
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$cts = New-Object System.Threading.CancellationTokenSource
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$cts.CancelAfter(100) # Cancel after 100ms
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$task = $executor.ExecutePowerShellAsync($script, $false, $cts.Token)
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{ $task.GetAwaiter().GetResult() } | Should -Throw
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}
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}
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It "Should serialize simple output correctly" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "42"
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $true
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$result.Output | Should -Be "42"
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}
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It "Should serialize complex objects to JSON" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "@{Name='Test'; Value=123}"
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $true
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$result.Output | Should -Not -BeNullOrEmpty
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$result.Output | Should -Match "Name"
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It "Should serialize arrays correctly" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "@(1, 2, 3)"
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$result = $executor.ExecutePowerShell($script, $false)
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$result.Success | Should -Be $true
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$result.Output | Should -Not -BeNullOrEmpty
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}
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It "Should preload common PowerShell modules" {
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$executor = New-Object IoTPowerShellAgent.PowerShell.PowerShellExecutor
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$script = "Get-Command Get-Process | Select-Object -First 1"
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$result = $executor.ExecutePowerShell($script, $false)
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# Should succeed if modules are preloaded
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$result.Success | Should -Be $true
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}

‎src/IoTPowerShellAgent/IoT/IIoTHubService.cs‎

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using System;
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using System.Threading.Tasks;
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using Microsoft.Azure.Devices.Shared;
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using IoTPowerShellAgent.Core;
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using IoTPowerShellAgent.PowerShell;
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namespace IoTPowerShellAgent.IoT
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{
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/// <summary>
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/// Interface for Azure IoT Hub integration
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/// Enables unit testing with mocks
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/// </summary>
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public interface IIoTHubService : IDisposable, ILogCallback
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{
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/// <summary>
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/// Connects to Azure IoT Hub
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/// </summary>
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Task ConnectAsync();
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/// <summary>
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/// Sends telemetry data to IoT Hub
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/// </summary>
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Task SendTelemetryAsync(object telemetryData);
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/// <summary>
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/// Updates device twin reported properties
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/// </summary>
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Task UpdateTwinAsync(TwinCollection reportedProperties);
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}
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}
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‎src/IoTPowerShellAgent/IoT/IoTHubService.cs‎

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@@ -17,7 +17,7 @@ namespace IoTPowerShellAgent.IoT
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/// <summary>
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/// Service for Azure IoT Hub integration
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/// </summary>
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public class IoTHubService : IDisposable, ILogCallback
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public class IoTHubService : IIoTHubService
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{
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private DeviceClient? _deviceClient;
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private ModuleClient? _moduleClient;

‎src/IoTPowerShellAgent/PowerShell/IPowerShellExecutor.cs‎

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using System;
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using System.Threading;
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using System.Threading.Tasks;
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using IoTPowerShellAgent.Core;
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namespace IoTPowerShellAgent.PowerShell
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{
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/// <summary>
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/// Interface for PowerShell script execution
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/// Enables unit testing with mocks
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/// </summary>
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public interface IPowerShellExecutor : IDisposable
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{
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/// <summary>
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/// Executes PowerShell script synchronously
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/// </summary>
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PowerShellExecutionResult ExecutePowerShell(string script, bool isInlinePowershell);
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/// <summary>
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/// Executes PowerShell script asynchronously with cancellation token support
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/// </summary>
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Task<PowerShellExecutionResult> ExecutePowerShellAsync(string script, bool isInlinePowershell, CancellationToken cancellationToken = default);
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}
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}
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‎src/IoTPowerShellAgent/PowerShell/PowerShellExecutor.cs‎

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@@ -19,7 +19,7 @@ namespace IoTPowerShellAgent.PowerShell
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/// <summary>
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/// Executes PowerShell scripts and handles output streaming
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/// </summary>
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public class PowerShellExecutor : IDisposable
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public class PowerShellExecutor : IPowerShellExecutor
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{
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private readonly ILogCallback? _logCallback;
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private int _verboseLinesProcessed = 0;

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