From 38bc7d36149060c3f7df09928fe70f36c2c36b0c Mon Sep 17 00:00:00 2001
From: Azure SDK Bot <53356347+azure-sdk@users.noreply.github.com>
Date: Fri, 14 Jul 2023 17:19:25 -0700
Subject: [PATCH] Sync eng/common directory with azure-sdk-tools for PR 6521
 (#21180)

* Use System.Threading.Mutex to make threadsafe

* Rename test, add comments

---------

Co-authored-by: Mike Harder <mharder@microsoft.com>
---
 .../scripts/Helpers/PSModule-Helpers.ps1      | 71 ++++++++++++-------
 1 file changed, 45 insertions(+), 26 deletions(-)

diff --git a/eng/common/scripts/Helpers/PSModule-Helpers.ps1 b/eng/common/scripts/Helpers/PSModule-Helpers.ps1
index d9a5afaab1b3..bfca8a4154d8 100644
--- a/eng/common/scripts/Helpers/PSModule-Helpers.ps1
+++ b/eng/common/scripts/Helpers/PSModule-Helpers.ps1
@@ -47,6 +47,7 @@ function Update-PSModulePathForCI()
   }
 }
 
+# Manual test at eng/common-tests/psmodule-helpers/Install-Module-Parallel.ps1
 # If we want to use another default repository other then PSGallery we can update the default parameters
 function Install-ModuleIfNotInstalled()
 {
@@ -65,35 +66,53 @@ function Install-ModuleIfNotInstalled()
 
   if ($modules.Count -eq 0)
   {
-    $repositories = (Get-PSRepository).Where({ $_.SourceLocation -eq $repositoryUrl })
-    if ($repositories.Count -eq 0)
-    {
-      Register-PSRepository -Name $repositoryUrl -SourceLocation $repositoryUrl -InstallationPolicy Trusted
-      $repositories = (Get-PSRepository).Where({ $_.SourceLocation -eq $repositoryUrl })
-      if ($repositories.Count -eq 0) {
-        Write-Error "Failed to registory package repository $repositoryUrl."
-        return
+    # Use double-checked locking to avoid locking when module is already installed
+    $mutex = New-Object System.Threading.Mutex($false, "Install-ModuleIfNotInstalled")
+    $null = $mutex.WaitOne()
+
+    try {
+      # Check installed modules again after acquiring lock
+      $modules = (Get-Module -ListAvailable $moduleName)
+      if ($version -as [Version]) {
+        $modules = $modules.Where({ [Version]$_.Version -ge [Version]$version })
       }
-    }
-    $repository = $repositories[0]
-
-    if ($repository.InstallationPolicy -ne "Trusted") {
-      Set-PSRepository -Name $repository.Name -InstallationPolicy "Trusted"
-    }
 
-    Write-Host "Installing module $moduleName with min version $version from $repositoryUrl"
-    # Install under CurrentUser scope so that the end up under $CurrentUserModulePath for caching
-    Install-Module $moduleName -MinimumVersion $version -Repository $repository.Name -Scope CurrentUser -Force
-
-    # Ensure module installed
-    $modules = (Get-Module -ListAvailable $moduleName)
-    if ($version -as [Version]) {
-      $modules = $modules.Where({ [Version]$_.Version -ge [Version]$version })
+      if ($modules.Count -eq 0)
+      {
+        $repositories = (Get-PSRepository).Where({ $_.SourceLocation -eq $repositoryUrl })
+        if ($repositories.Count -eq 0)
+        {
+          Register-PSRepository -Name $repositoryUrl -SourceLocation $repositoryUrl -InstallationPolicy Trusted
+          $repositories = (Get-PSRepository).Where({ $_.SourceLocation -eq $repositoryUrl })
+          if ($repositories.Count -eq 0) {
+            Write-Error "Failed to register package repository $repositoryUrl."
+            return
+          }
+        }
+        $repository = $repositories[0]
+
+        if ($repository.InstallationPolicy -ne "Trusted") {
+          Set-PSRepository -Name $repository.Name -InstallationPolicy "Trusted"
+        }
+
+        Write-Host "Installing module $moduleName with min version $version from $repositoryUrl"
+        # Install under CurrentUser scope so that the end up under $CurrentUserModulePath for caching
+        Install-Module $moduleName -MinimumVersion $version -Repository $repository.Name -Scope CurrentUser -Force
+
+        # Ensure module installed
+        $modules = (Get-Module -ListAvailable $moduleName)
+        if ($version -as [Version]) {
+          $modules = $modules.Where({ [Version]$_.Version -ge [Version]$version })
+        }
+
+        if ($modules.Count -eq 0) {
+          Write-Error "Failed to install module $moduleName with version $version"
+          return
+        }
+      }
     }
-
-    if ($modules.Count -eq 0) {
-      Write-Error "Failed to install module $moduleName with version $version"
-      return
+    finally {
+      $mutex.ReleaseMutex()
     }
   }