Enable windows builds back

Now we run a pre-commit hook that tries to kill any process that locked
a file in target directory.

Updated timeout interval on windows from 120 to 90 minutes.

Fixes #243

containers/agent-windows-buildkite/Dockerfile

@@ -4,5 +4,8 @@
 ARG agent_windows_version=latest
 FROM gcr.io/llvm-premerge-checks/agent-windows-vs2019:${agent_windows_version}
 
+RUN choco install -y handle --checksum 524E61547C8E26608CDA1B11B6E9471616CCCC48530F6E7EC9131EABF839357E
 COPY start_agent.ps1 C:\scripts\
+COPY pre-checkout.bat c:\buildkite-agent\hooks\
+COPY unlock_path.ps1 c:\scripts
 CMD "powershell C:\scripts\start_agent.ps1"

containers/agent-windows-buildkite/pre-checkout.bat

@@ -0,0 +1,2 @@
+handle -nobanner %BUILDKITE_BUILD_CHECKOUT_PATH%
+powershell c:\scripts\unlock_path.ps1 %BUILDKITE_BUILD_CHECKOUT_PATH%

containers/agent-windows-buildkite/unlock_path.ps1

@@ -0,0 +1,34 @@
+# Based ob https://dandraka.com/2019/08/13/find-and-kill-processes-that-lock-a-file-or-directory/
+$path = $args[0]
+$handleOutput = & handle -a $path
+
+if ($handleOutput -match "no matching handles found") {
+    Write-Host "Nothing to kill, exiting"
+    exit
+}
+
+$pidList = New-Object System.Collections.ArrayList
+$lines = $handleOutput -split "`n"
+foreach($line in $lines) {
+  # sample line:
+  # chrome.exe         pid: 11392  type: File           5BC: C:\Windows\Fonts\timesbd.ttf
+  # regex to get pid and process name: (.*)\b(?:.*)(?:pid: )(\d*)
+  $matches = $null
+  $line -match "(.*)\b(?:.*)(?:pid: )(\d*)" | Out-Null
+  if (-not $matches) { continue }
+  if ($matches.Count -eq 0) { continue }
+  $pidName = $matches[1]
+  $pidStr = $matches[2]
+  if ($pidList -notcontains $pidStr) {
+    Write-Host "Will kill process $pidStr $pidName"
+    $pidList.Add($pidStr) | Out-Null
+  }
+}
+
+foreach($pidStr in $pidList) {
+    $pidInt = [int]::Parse($pidStr)
+    Stop-Process -Id $pidInt -Force
+    Write-Host "Killed process $pidInt"
+}
+
+Write-Host "Finished"

scripts/steps.py

@@ -91,8 +91,6 @@ def generic_linux(projects: str, check_diff: bool) -> List:
 
 
 def generic_windows(projects: str) -> List:
-    # TODO: windows builds are temporary disabled #243
-    return []
     if os.getenv('ph_skip_windows') is not None:
         return []
     scripts_refspec = os.getenv("ph_scripts_refspec", "master")
@@ -138,7 +136,7 @@ def generic_windows(projects: str) -> List:
         ],
         'artifact_paths': ['artifacts/**/*', '*_result.json'],
         'agents': win_agents,
-        'timeout_in_minutes': 120,
+        'timeout_in_minutes': 90,
         'retry': {'automatic': [
             {'exit_status': -1, 'limit': 2},  # Agent lost
             {'exit_status': 255, 'limit': 2},  # Forced agent shutdown