Fix DateTime comparison in PSAdapter cache code

powershell-adapter/Tests/powershellgroup.resource.tests.ps1

@@ -280,4 +280,31 @@ Describe 'PowerShell adapter resource tests' {
 
         $env:TestClassResourceResultCount = $null
     }
+
+    It 'Verify that there are no cache rebuilds for several sequential executions' {
+
+        # remove cache file
+        $cacheFilePath = if ($IsWindows) {
+            # PS 6+ on Windows
+            Join-Path $env:LocalAppData "dsc\PSAdapterCache.json"
+        } else {
+            # either WinPS or PS 6+ on Linux/Mac
+            if ($PSVersionTable.PSVersion.Major -le 5) {
+                Join-Path $env:LocalAppData "dsc\WindowsPSAdapterCache.json"
+            } else {
+                Join-Path $env:HOME ".dsc" "PSAdapterCache.json"
+            }
+        }
+        Remove-Item -Force -Path $cacheFilePath -ErrorAction Ignore
+
+        # first execution should build the cache
+        dsc -l trace resource list -a Microsoft.DSC/PowerShell 2> $TestDrive/tracing.txt
+        "$TestDrive/tracing.txt" | Should -FileContentMatchExactly 'Constructing Get-DscResource cache'
+
+        # next executions following shortly after should Not rebuild the cache
+        1..3 | %{
+            dsc -l trace resource list -a Microsoft.DSC/PowerShell 2> $TestDrive/tracing.txt
+            "$TestDrive/tracing.txt" | Should -Not -FileContentMatchExactly 'Constructing Get-DscResource cache'
+        }
+    }
 }

powershell-adapter/Tests/win_powershellgroup.tests.ps1

@@ -70,4 +70,21 @@ Describe 'WindowsPowerShell adapter resource tests' {
       $res = $r | ConvertFrom-Json
       $res.results[0].result.actualState.result[0].properties.DestinationPath | Should -Be "$testFile"
     }
+
+    It 'Verify that there are no cache rebuilds for several sequential executions' -Skip:(!$IsWindows) {
+
+        # remove cache file
+        $cacheFilePath = Join-Path $env:LocalAppData "dsc\WindowsPSAdapterCache.json"
+        Remove-Item -Force -Path $cacheFilePath -ErrorAction Ignore
+
+        # first execution should build the cache
+        dsc -l trace resource list -a Microsoft.Windows/WindowsPowerShell 2> $TestDrive/tracing.txt
+        "$TestDrive/tracing.txt" | Should -FileContentMatchExactly 'Constructing Get-DscResource cache'
+
+        # next executions following shortly after should Not rebuild the cache
+        1..3 | %{
+            dsc -l trace resource list -a Microsoft.Windows/WindowsPowerShell 2> $TestDrive/tracing.txt
+            "$TestDrive/tracing.txt" | Should -Not -FileContentMatchExactly 'Constructing Get-DscResource cache'
+        }
+    }
 }

powershell-adapter/psDscAdapter/psDscAdapter.psm1

@@ -264,12 +264,19 @@ function Invoke-DscCacheRefresh {
                 "Checking cache for stale entries" | Write-DscTrace
 
                 foreach ($cacheEntry in $dscResourceCacheEntries) {
-                    #"Checking cache entry '$($cacheEntry.Type) $($cacheEntry.LastWriteTimes)'" | Write-DscTrace -Operation Trace
 
                     $cacheEntry.LastWriteTimes.PSObject.Properties | ForEach-Object {
 
                         if (Test-Path $_.Name) {
-                            if (-not ((Get-Item $_.Name).LastWriteTime.Equals([DateTime]$_.Value)))
+                            $file_LastWriteTime = (Get-Item $_.Name).LastWriteTime
+                            # Truncate DateTime to seconds
+                            $file_LastWriteTime = $file_LastWriteTime.AddTicks( - ($file_LastWriteTime.Ticks % [TimeSpan]::TicksPerSecond));
+
+                            $cache_LastWriteTime = [DateTime]$_.Value
+                            # Truncate DateTime to seconds
+                            $cache_LastWriteTime = $cache_LastWriteTime.AddTicks( - ($cache_LastWriteTime.Ticks % [TimeSpan]::TicksPerSecond));
+
+                            if (-not ($file_LastWriteTime.Equals($cache_LastWriteTime)))
                             {
                                 "Detected stale cache entry '$($_.Name)'" | Write-DscTrace
                                 $refreshCache = $true

powershell-adapter/psDscAdapter/win_psDscAdapter.psm1

@@ -86,12 +86,19 @@ function Invoke-DscCacheRefresh {
                 "Checking cache for stale entries" | Write-DscTrace
 
                 foreach ($cacheEntry in $dscResourceCacheEntries) {
-                    #"Checking cache entry '$($cacheEntry.Type) $($cacheEntry.LastWriteTimes)'" | Write-DscTrace -Operation Trace
 
                     $cacheEntry.LastWriteTimes.PSObject.Properties | ForEach-Object {
 
                         if (Test-Path $_.Name) {
-                            if (-not ((Get-Item $_.Name).LastWriteTime.Equals([DateTime]$_.Value)))
+                            $file_LastWriteTime = (Get-Item $_.Name).LastWriteTimeUtc
+                            # Truncate DateTime to seconds
+                            $file_LastWriteTime = $file_LastWriteTime.AddTicks( - ($file_LastWriteTime.Ticks % [TimeSpan]::TicksPerSecond));
+
+                            $cache_LastWriteTime = [DateTime]$_.Value
+                            # Truncate DateTime to seconds
+                            $cache_LastWriteTime = $cache_LastWriteTime.AddTicks( - ($cache_LastWriteTime.Ticks % [TimeSpan]::TicksPerSecond));
+
+                            if (-not ($file_LastWriteTime.Equals($cache_LastWriteTime)))
                             {
                                 "Detected stale cache entry '$($_.Name)'" | Write-DscTrace
                                 $refreshCache = $true