Make bot_update on win more resilient

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 447 matching lines @@
   else:
     ref = branch if branch.startswith('refs/') else 'origin/%s' % branch
     git('checkout', '--force', ref, cwd=folder_name)
 
 
 def is_broken_repo_dir(repo_dir):
   # Treat absence of 'config' as a signal of a partially deleted repo.
   return not path.exists(os.path.join(repo_dir, '.git', 'config'))
 
 
+def _maybe_break_locks(checkout_path):
+  """This removes all .lock files from this repo's .git directory.
+
+  In particular, this will cleanup index.lock files, as well as ref lock
+  files.
+  """
+  git_dir = os.path.join(checkout_path, '.git')
+  for dirpath, _, filenames in os.walk(git_dir):
+    for filename in filenames:
+      if filename.endswith('.lock'):
+        to_break = os.path.join(dirpath, filename)
+        print 'breaking lock: %s' % to_break
+        try:
+          os.remove(to_break)
+        except OSError as ex:
+          print 'FAILED to break lock: %s: %s' % (to_break, ex)
+          raise
+
+
 def git_checkout(solutions, revisions, shallow, refs, git_cache_dir):
   build_dir = os.getcwd()
   # Before we do anything, break all git_cache locks.
   if path.isdir(git_cache_dir):
     git('cache', 'unlock', '-vv', '--force', '--all',
         '--cache-dir', git_cache_dir)
     for item in os.listdir(git_cache_dir):
       filename = os.path.join(git_cache_dir, item)
       if item.endswith('.lock'):
         raise Exception('%s exists after cache unlock' % filename)
@@ skipping 33 matching lines @@
 
         if not path.isdir(sln_dir):
           git(*clone_cmd)
         else:
           git('remote', 'set-url', 'origin', mirror_dir, cwd=sln_dir)
           git('fetch', 'origin', cwd=sln_dir)
         for ref in refs:
           refspec = '%s:%s' % (ref, ref.lstrip('+'))
           git('fetch', 'origin', refspec, cwd=sln_dir)
 
+        # Windows sometimes has trouble deleting files.
+        # This can make git commands that rely on locks fail.
+        # Try a few times in case Windows has trouble again (and again).
+        if sys.platform.startswith('win'):
+          tries = 3
+          while tries:
+            try:
+              _maybe_break_locks(sln_dir)
+              break
+            except Exception:
+              tries -= 1
+
         revision = get_target_revision(name, url, revisions) or 'HEAD'
         force_revision(sln_dir, revision)
         done = True
       except SubprocessFailed as e:
         # Exited abnormally, theres probably something wrong.
         print 'Something failed: %s.' % str(e)
 
         if time.time() > deadline:
           overrun = time.time() - deadline
           print 'Ran %s seconds past deadline. Aborting.' % overrun
@@ skipping 565 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())