Make build incremental

runtime/tools/create_snapshot_bin.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012, 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.
 
 """Script to create snapshot bin file."""
 
 import getopt
 import optparse
@@ skipping 34 matching lines @@
             "E.g.: --url_mapping=fileUri,/path/to/file.dart"))
   result.add_option("-v", "--verbose",
       help='Verbose output.',
       default=False, action="store_true")
   result.add_option("--target_os",
       action="store", type="string",
       help="Which os to run the executable on. Current choice is android")
   result.add_option("--abi",
       action="store", type="string",
       help="Desired ABI for android target OS. armeabi-v7a or x86")
+  result.add_option("--timestamp_file",
+      action="store", type="string",
+      help="Path to timestamp file that will be written",
+      default="")
   return result
 
 
 def ProcessOptions(options):
   if not options.executable:
     sys.stderr.write('--executable not specified\n')
     return False
   if not options.vm_output_bin:
     sys.stderr.write('--vm_output_bin not specified\n')
     return False
   if not options.output_bin:
     sys.stderr.write('--output_bin not specified\n')
     return False
   if options.abi and not options.target_os == 'android':
     sys.stderr.write('--abi requires --target_os android\n')
     return False
   return True
 
 
+def CreateTimestampFile(options):
+  if options.timestamp_file != '':
+    dir_name = os.path.dirname(options.timestamp_file)
+    if not os.path.exists(dir_name):
+      os.mkdir(dir_name)
+    open(options.timestamp_file, 'w').close()
+
+
 def Main():
   # Parse options.
   parser = BuildOptions()
   (options, args) = parser.parse_args()
   if not ProcessOptions(options):
     parser.print_help()
     return 1
 
   # If there are additional arguments, report error and exit.
   if args:
@@ skipping 22 matching lines @@
     script_args.append(options.script)
 
   # Construct command line to execute the snapshot generator binary and invoke.
   command = [ options.executable ] + script_args
   try:
     utils.RunCommand(command, outStream=sys.stderr, errStream=sys.stderr,
                      verbose=options.verbose, printErrorInfo=True)
   except Exception as e:
     return -1
 
+  # Success, update timestamp file.
+  CreateTimestampFile(options)
+
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(Main())