Add (forward-compatible) change to annotated steps of target-arm builder to support sharding

tools/bots/cross-vm.py

 #!/usr/bin/python
 # Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 import os
 import re
 import sys
 
 import bot
 
 GCS_BUCKET = 'gs://dart-cross-compiled-binaries'
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
 sys.path.append(os.path.join(SCRIPT_DIR, '..'))
 
 import utils
 
 CROSS_VM = r'cross-(arm)-vm-linux-(release)'
-TARGET_VM = r'target-(arm)-vm-linux-(release)'
+TARGET_VM = r'target-(arm)-vm-linux-(([0-9]+)-([0-9]+))?(release)'
 GSUTIL = utils.GetBuildbotGSUtilPath()
 
 def run(args):
   print 'Running: %s' % (' '.join(args))
   sys.stdout.flush()
   bot.RunProcess(args)
 
 def tarball_name(arch, mode, revision):
   return 'cross_build_%s_%s_%s.tar.bz2' % (arch, mode, revision)
 
@@ skipping 28 matching lines @@
       with bot.BuildStep('tests'):
         print "Please see the target device for results."
         print "We no longer record/replay tests."
     else:
       raise Exception("Invalid annotated steps run")
   finally:
     for path in temporary_files:
       if os.path.exists(path):
         os.remove(path)
 
-def target_builder(arch, mode):
+def target_builder(arch, mode, total_shards, shard_index):
   test_py = os.path.join('tools', 'test.py')
   test_args = [sys.executable, test_py, '--progress=line', '--report',
                '--time', '--compiler=none', '--runtime=vm', '--write-debug-log',
                '--write-test-outcome-log', '--mode=' + mode, '--arch=' + arch,
                '--exclude-suite=pkg']
+  if total_shards and shard_index:
+    test_args.append('--shards=%s' % total_shards)
+    test_args.append('--shard=%s' % shard_index)
 
   revision = os.environ['BUILDBOT_GOT_REVISION']
   tarball = tarball_name(arch, mode, revision)
   temporary_files = [tarball]
   bot.Clobber()
   try:
     with bot.BuildStep('Fetch build tarball'):
       run([GSUTIL, 'cp', "%s/%s" % (GCS_BUCKET, tarball), tarball])
 
     with bot.BuildStep('Unpack build tarball'):
@@ skipping 15 matching lines @@
   name, is_buildbot = bot.GetBotName()
 
   cross_vm_pattern_match = re.match(CROSS_VM, name)
   target_vm_pattern_match = re.match(TARGET_VM, name)
   if cross_vm_pattern_match:
     arch = cross_vm_pattern_match.group(1)
     mode = cross_vm_pattern_match.group(2)
     cross_compiling_builder(arch, mode)
   elif target_vm_pattern_match:
     arch = target_vm_pattern_match.group(1)
-    mode = target_vm_pattern_match.group(2)
-    target_builder(arch, mode)
+    mode = target_vm_pattern_match.group(5)
+    shard_index = target_vm_pattern_match.group(3)
+    total_shards = target_vm_pattern_match.group(4)
+    target_builder(arch, mode, total_shards, shard_index)
   else:
     raise Exception("Unknown builder name %s" % name)
 
 if __name__ == '__main__':
   try:
     sys.exit(main())
   except OSError as e:
     sys.exit(e.errno)