Raise Exception instead of failure when some steps fail.

master/skia_master_scripts/skia_build_step.py

 # 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.
 
 """ Skia-specific subclass of BuildStep """
 
 
 from buildbot.status.logfile import STDOUT
 from master.log_parser import retcode_command
 import re
 
 
 class SkiaBuildStep(retcode_command.ReturnCodeCommand):
   """ BuildStep wrapper for Skia. Allows us to define properties of BuildSteps
   to be used by ShouldDoStep. This is necessary because the properties referred
   to by BuildStep.getProperty() are scoped for the entire duration of the build.
   """
   def __init__(self, is_upload_step=False, is_rebaseline_step=False,
-               get_props_from_stdout=None, **kwargs):
+               get_props_from_stdout=None, exception_on_failure=False,
+               **kwargs):
     """ Instantiates a new SkiaBuildStep.
 
     is_upload_step: boolean indicating whether this step should be skipped when
         the buildbot is not performing uploads.
     is_rebaseline_step: boolean indicating whether this step is required for
         rebaseline-only builds.
     get_props_from_stdout: optional dictionary. Keys are strings indicating
         build properties to set based on the output of this step. Values are
         strings containing regular expressions for parsing the property from
-        the output of the step. 
+        the output of the step.
+    exception_on_failure: boolean indicating whether to raise an exception if
+        this step fails. This causes the step to go purple instead of red, and
+        causes the build to stop. Should be used if the build step's failure is
+        typically transient or results from an infrastructure failure rather
+        than a code change.
     """
     self._is_upload_step = is_upload_step
     self._is_rebaseline_step = is_rebaseline_step
     self._get_props_from_stdout = get_props_from_stdout
+    self._exception_on_failure = exception_on_failure
 
     # self._changed_props will be a dictionary containing the build properties
     # which were updated by this BuildStep. Those properties will be displayed
     # in the label for this step.
     self._changed_props = None
 
     retcode_command.ReturnCodeCommand.__init__(self, **kwargs)
     self.name = ''.join(self.description)
 
   def IsUploadStep(self):
     return self._is_upload_step
 
   def IsRebaselineStep(self):
     return self._is_rebaseline_step
 
   def commandComplete(self, cmd):
     """ Override of BuildStep's commandComplete method which allows us to parse
     build properties from the output of this step. """
+    if cmd.rc and self._exception_on_failure:
+      raise Exception('Command marked exception_on_failure failed.')
     if self._get_props_from_stdout and cmd.rc == 0:
       log = cmd.logs['stdio']
       stdout = ''.join(log.getChunks([STDOUT], onlyText=True))
       self._changed_props = {}
       for prop, regex in self._get_props_from_stdout.iteritems():
         matches = re.search(regex, stdout)
         if not matches:
           raise Exception('Unable to parse %s from stdout.' % prop)
         groups = matches.groups()
         if len(groups) != 1:
@@ skipping 41 matching lines @@
   # If this step uploads results (and thus overwrites the most recently uploaded
   # results), only run it on scheduled builds (i.e. most recent revision) or if
   # the "force_upload" property was set.
   if step.IsUploadStep() and \
       not _HasProperty(step, 'scheduler') and \
       not _HasProperty(step, 'force_upload'):
     return False
 
   # Unless we have determined otherwise, run the step.
   return True