Remove git lockfile flakiness on win (bot_update)

recipe_modules/bot_update/resources/bot_update.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # TODO(hinoka): Use logging.
 
 import cStringIO
 import codecs
 import copy
@@ skipping 304 matching lines @@
       print 'done'
 
 
 def gclient_configure(solutions, target_os, target_os_only, git_cache_dir):
   """Should do the same thing as gclient --spec='...'."""
   with codecs.open('.gclient', mode='w', encoding='utf-8') as f:
     f.write(get_gclient_spec(
         solutions, target_os, target_os_only, git_cache_dir))
 
 
-def gclient_sync(with_branch_heads, shallow):
+def gclient_sync(with_branch_heads, shallow, break_repo_locks):
   # We just need to allocate a filename.
   fd, gclient_output_file = tempfile.mkstemp(suffix='.json')
   os.close(fd)
   gclient_bin = 'gclient.bat' if sys.platform.startswith('win') else 'gclient'
   cmd = [gclient_bin, 'sync', '--verbose', '--reset', '--force',
          '--ignore_locks', '--output-json', gclient_output_file,
          '--nohooks', '--noprehooks', '--delete_unversioned_trees']
   if with_branch_heads:
     cmd += ['--with_branch_heads']
   if shallow:
     cmd += ['--shallow']
+  if break_repo_locks:
+    cmd += ['--break_repo_locks']
 
   try:
     call(*cmd, tries=1)
   except SubprocessFailed as e:
     # Throw a GclientSyncFailed exception so we can catch this independently.
     raise GclientSyncFailed(e.message, e.code, e.output)
   else:
     with open(gclient_output_file) as f:
       return json.load(f)
   finally:
@@ skipping 371 matching lines @@
                     patch_root, issue, patchset, rietveld_server, gerrit_repo,
                     gerrit_ref, gerrit_rebase_patch_ref, revision_mapping,
                     apply_issue_email_file, apply_issue_key_file,
                     apply_issue_oauth2_file, shallow, refs, git_cache_dir,
                     gerrit_reset):
   # Get a checkout of each solution, without DEPS or hooks.
   # Calling git directly because there is no way to run Gclient without
   # invoking DEPS.
   print 'Fetching Git checkout'
 
   git_ref = git_checkout(solutions, revisions, shallow, refs, git_cache_dir)

[ddoman1, 2016/10/25 19:08:55]

@katthomas,

The following log shows that git checkout failed at this due to a broken lock:
https://build.chromium.org/p/chromium.win/builders/Win%20x64%20Builder/builds...

Therefore, those locks need to be checked and removed before git_checkout().

 
   print '===Processing patch solutions==='
   already_patched = []
   patch_root = patch_root or ''
   applied_gerrit_patch = False
   print 'Patch root is %r' % patch_root
   for solution in solutions:
     print 'Processing solution %r' % solution['name']
     if (patch_root == solution['name'] or
         solution['name'].startswith(patch_root + '/')):
       relative_root = solution['name'][len(patch_root) + 1:]
       target = '/'.join([relative_root, 'DEPS']).lstrip('/')
       print '  relative root is %r, target is %r' % (relative_root, target)
       if issue:
         apply_rietveld_issue(issue, patchset, patch_root, rietveld_server,
                              revision_mapping, git_ref, apply_issue_email_file,
                              apply_issue_key_file, apply_issue_oauth2_file,
                              whitelist=[target])
         already_patched.append(target)
       elif gerrit_ref:
         apply_gerrit_ref(gerrit_repo, gerrit_ref, patch_root, gerrit_reset,
                          gerrit_rebase_patch_ref)
         applied_gerrit_patch = True
 
   # Ensure our build/ directory is set up with the correct .gclient file.
   gclient_configure(solutions, target_os, target_os_only, git_cache_dir)
 
+  # Windows sometimes has trouble deleting files. This can make git commands
+  # that rely on locks fail.
+  break_repo_locks = True if sys.platform.startswith('win') else False
   # Let gclient do the DEPS syncing.
   # The branch-head refspec is a special case because its possible Chrome
   # src, which contains the branch-head refspecs, is DEPSed in.
-  gclient_output = gclient_sync(BRANCH_HEADS_REFSPEC in refs, shallow)
+  gclient_output = gclient_sync(BRANCH_HEADS_REFSPEC in refs, shallow,
+                                break_repo_locks)
 
   # Now that gclient_sync has finished, we should revert any .DEPS.git so that
   # presubmit doesn't complain about it being modified.
   if git('ls-files', '.DEPS.git', cwd=first_sln).strip():
     git('checkout', 'HEAD', '--', '.DEPS.git', cwd=first_sln)
 
   # Finally, ensure that all DEPS are pinned to the correct revision.
   dir_names = [sln['name'] for sln in solutions]
   ensure_deps_revisions(gclient_output.get('solutions', {}),
                         dir_names, revisions)
@@ skipping 320 matching lines @@
     # download patch failure is still an infra problem.
     if e.code == 3:
       # Patch download problem.
       return 87
     # Genuine patch problem.
     return 88
 
 
 if __name__ == '__main__':
   sys.exit(main())