git cl try: support multiple bots from different masters without specifying master.

git_cl.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 # Copyright (C) 2008 Evan Martin <martine@danga.com>
 
 """A git-command for integrating reviews on Rietveld and Gerrit."""
 
 from __future__ import print_function
@@ skipping 4665 matching lines @@
   """Fetches the tree status from a json url and returns the message
   with the reason for the tree to be opened or closed."""
   url = settings.GetTreeStatusUrl()
   json_url = urlparse.urljoin(url, '/current?format=json')
   connection = urllib2.urlopen(json_url)
   status = json.loads(connection.read())
   connection.close()
   return status['message']
 
 
-def GetBuilderMaster(bot_list):
-  """For a given builder, fetch the master from AE if available."""
+def GetBuilderMasters(bot_list):
+  """Returns a map of masters to builders for the given builders."""
   map_url = 'https://builders-map.appspot.com/'
   try:
-    master_map = json.load(urllib2.urlopen(map_url))
+    builders_map = json.load(urllib2.urlopen(map_url))
   except urllib2.URLError as e:
     return None, ('Failed to fetch builder-to-master map from %s. Error: %s.' %
                   (map_url, e))
   except ValueError as e:
     return None, ('Invalid json string from %s. Error: %s.' % (map_url, e))

[tandrii(chromium), 2016/10/23 17:00:02]

this Go-style error reporting makes me sad in Python every time i look :(

[qyearsley, 2016/10/24 21:33:39]

Yeah -- I guess another way to do it is to raise an Exception and return a
single value; although that's not necessarily much easier to read, and it's not
clear what Exception should be raised.

-  if not master_map:
+  if not builders_map:
     return None, 'Failed to build master map.'
 
-  result_master = ''
+  master_map = {}
   for bot in bot_list:
     builder = bot.split(':', 1)[0]
-    master_list = master_map.get(builder, [])
+    master_list = builders_map.get(builder, [])
     if not master_list:
       return None, ('No matching master for builder %s.' % builder)
     elif len(master_list) > 1:
-      return None, ('The builder name %s exists in multiple masters %s.' %
+      return None, ('The builder name %s exists in multiple  masters %s.' %
                     (builder, master_list))
     else:
-      cur_master = master_list[0]
-      if not result_master:
-        result_master = cur_master
-      elif result_master != cur_master:
-        return None, 'The builders do not belong to the same master.'
-  return result_master, None
+      master = master_list[0]
+      master_map.setdefault(master, [])
+      master_map[master].append(bot)
+
+  return master_map, None
 
 
 def CMDtree(parser, args):
   """Shows the status of the tree."""
   _, args = parser.parse_args(args)
   status = GetTreeStatus()
   if 'unset' == status:
     print('You must configure your tree status URL by running "git cl config".')
     return 2
 
@@ skipping 75 matching lines @@
   error_message = cl.CannotTriggerTryJobReason()
   if error_message:
     parser.error('Can\'t trigger try jobs: %s')
 
   if not options.name:
     options.name = cl.GetBranch()
 
   if options.bucket and options.master:
     parser.error('Only one of --bucket and --master may be used.')
 
-  if options.bot and not options.master and not options.bucket:
-    options.master, err_msg = GetBuilderMaster(options.bot)
-    if err_msg:
-      parser.error('Tryserver master cannot be found because: %s\n'
-                   'Please manually specify the tryserver master'
-                   ', e.g. "-m tryserver.chromium.linux".' % err_msg)
-
   def GetMasterMap():
     # Process --bot.
     if not options.bot:
       change = cl.GetChange(cl.GetCommonAncestorWithUpstream(), None)
 
       # Get try masters from PRESUBMIT.py files.
       masters = presubmit_support.DoGetTryMasters(
           change,
           change.LocalPaths(),
           settings.GetRoot(),
@@ skipping 36 matching lines @@
 
     # Return a master map with one master to be backwards compatible. The
     # master name defaults to an empty string, which will cause the master
     # not to be set on rietveld (deprecated).
     bucket = ''
     if options.master:
       # Add the "master." prefix to the master name to obtain the bucket name.
       bucket = _prefix_master(options.master)
     return {bucket: builders_and_tests}
 
-  if options.bucket:
+  if options.bot and not options.master and not options.bucket:
+    masters, err_msg = GetBuilderMasters(options.bot)
+    if err_msg:
+      parser.error('Try server masters cannot be found because: %s\n'
+                   'Please manually specify the try server masters'
+                   ', e.g. "-m tryserver.chromium.linux".' % err_msg)
+    buckets = {}
+    for master, builders in masters.iteritems():
+      buckets[_prefix_master(master)] = {b: [] for b in builders}
+  elif options.bucket:
     buckets = {options.bucket: {b: [] for b in options.bot}}
   else:
     buckets = GetMasterMap()
     if not buckets:
       # Default to triggering Dry Run (see http://crbug.com/625697).
       if options.verbose:
         print('git cl try with no bots now defaults to CQ Dry Run.')
       try:
         cl.SetCQState(_CQState.DRY_RUN)
         print('scheduled CQ Dry Run on %s' % cl.GetIssueURL())
@@ skipping 530 matching lines @@
 if __name__ == '__main__':
   # These affect sys.stdout so do it outside of main() to simplify mocks in
   # unit testing.
   fix_encoding.fix_encoding()
   setup_color.init()
   try:
     sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)