Merge pull request #37 from iricigor/LockFile

added lock file

Author: iricigor

PSAptGetUpdate.psm1

@@ -47,4 +47,6 @@ if ($V) {
     Write-Host "'Get-Command -Module $ModName | Get-Help | Select Name, Synopsis' for explanation on all commands`n"
 }
 
+# initial actions
+if (Test-Path $TP.LockFile) {Remove-Item $TP.LockFile -Force}
 Update-PSRepositoryCache

Private/Config.ps1

@@ -20,6 +20,7 @@ $Script:Config = New-Object PSObject -Property @{
 
     # General names
     IndexFile = 'PSGalleryIndex.zip'
+    LockFile = 'psaptgetupdate.lock'
 
     # Config file names
     ModulesCache = 'Modules.Cache'
@@ -38,6 +39,7 @@ $Script:TP = New-Object PSObject -Property @{
     Modules  = Join-Path $Config.TempPath $Config.ModulesCache
     Scripts  = Join-Path $Config.TempPath $Config.ScriptsCache
     Commands = Join-Path $Config.TempPath $Config.CommandsCache
+    LockFile = Join-Path $Config.TempPath $Config.LockFile
 }
 
 # IndexPath File Locations, used like $IP.Modules

Public/Update-ModuleFromCache.ps1

@@ -26,6 +26,7 @@ function Update-ModuleFromCache {
             Write-Log -Message "Reading list of all modules from the system"
             $SearchAll = $true
             $AllModules = Get-Module -ListAvailable -Verbose:$false | where {$_.RepositorySourceLocation.Host -eq 'www.powershellgallery.com'}
+            # We do not use Get-InstalledModule although it returns smaller number of modules, because we do not spend much time on search anyway
             $ModuleName = $AllModules.Name | Select -Unique
         }
         foreach ($M1 in $ModuleName) {

Public/Update-PSRepositoryCache.ps1

@@ -11,6 +11,7 @@ function Update-PSRepositoryCache {
     # function begin phase
     $FunctionName = $MyInvocation.MyCommand.Name
     Write-Log -Message "$FunctionName starting" -TimeStampFormat 'G'
+    $LockFileCreated = $false # not yet
 
 
     #
@@ -24,43 +25,59 @@ function Update-PSRepositoryCache {
 
     if ($Age -lt 10) {
         Write-Log -Message "Skipping download, as index file is $Age seconds old"    
+    } elseif (Test-Path $TP.LockFile) {
+        Write-Log -Message "Skipping download as another process has lock file $($TP.LockFile)" -Verbosity Warning
     } else {
 
         #
         # get a index.zip file to $TP.Index
         #
 
-        CreateTempFolder
-        Write-Log -Message "Downloading index from the Internet"
-        # temporary remove ProgressBar, https://stackoverflow.com/questions/28682642/powershell-why-is-using-invoke-webrequest-much-slower-than-a-browser-download
-        $OldProgressPreference = $ProgressPreference
-        $ProgressPreference = 'SilentlyContinue'
-        $Response = Invoke-WebRequest -Uri 'https://psgallery.blob.core.windows.net/index/PSGalleryIndex.zip' -Verbose:$false -OutFile $TP.Index -PassThru
-        $ProgressPreference = $OldProgressPreference
         try {
-            [string]$AgeString = [int](((Get-Date)-[datetime]($Response.Headers.'Last-Modified')).TotalMinutes)
+
+            CreateTempFolder
+            Write-Log -Message "Creating lock file $($TP.LockFile)"
+            New-Item $TP.LockFile -ItemType File -Force -ErrorAction Stop | Out-Null
+            $LockFileCreated = $true
+            Write-Log -Message "Downloading index from the Internet"
+            # temporary remove ProgressBar, https://stackoverflow.com/questions/28682642/powershell-why-is-using-invoke-webrequest-much-slower-than-a-browser-download
+            $OldProgressPreference = $ProgressPreference
+            $ProgressPreference = 'SilentlyContinue'
+            $Response = Invoke-WebRequest -Uri 'https://psgallery.blob.core.windows.net/index/PSGalleryIndex.zip' -Verbose:$false -OutFile $TP.Index -PassThru
+            $ProgressPreference = $OldProgressPreference
+            try {
+                [string]$AgeString = [int](((Get-Date)-[datetime]($Response.Headers.'Last-Modified')).TotalMinutes)
+            } catch {
+                $AgeString = 'unknown'
+            }
+            Write-Log -Message "Downloading completed, index file is $(size $TP.Index)MB large and $AgeString minutes old"
+
+
+            #
+            # unzip index.zip
+            #
+
+            Write-Log -Message "Expanding archive to $($Config.IndexPath)"
+            Microsoft.PowerShell.Archive\Expand-Archive $TP.Index -DestinationPath $Config.IndexPath -Force
+            Write-Log -Message "Expanded total $((Get-ChildItem $Config.IndexPath).Count) files" # FIXME: This lists also old files from folder
+
+            #
+            # Touch one file to prevent too fast/double updates
+            #
+            
+            (Get-Item $IP.Commands).LastWriteTime = Get-Date
+
+            # the end
+            
+            RemoveTempFolder
         } catch {
-            $AgeString = 'unknown'
+            Write-Log -Message "Cache update failed: $_"
+        } finally {
+            if ($LockFileCreated -and (Test-Path $TP.LockFile)) {
+                Remove-Item $TP.LockFile -Force
+            }
         }
-        Write-Log -Message "Downloading completed, index file is $(size $TP.Index)MB large and $AgeString minutes old"
-
-
-        #
-        # unzip index.zip
-        #
-
-        Write-Log -Message "Expanding archive to $($Config.IndexPath)"
-        Microsoft.PowerShell.Archive\Expand-Archive $TP.Index -DestinationPath $Config.IndexPath -Force
-        Write-Log -Message "expanded total $((Get-ChildItem $Config.IndexPath).Count) files" # FIXME: This lists also old files from folder
-
-        #
-        # Touch one file to prevent too fast/double updates
-        #
-        
-        (Get-Item $IP.Commands).LastWriteTime = Get-Date
 
-        # the end
-        RemoveTempFolder
 
     }