Added support for improvement_direction to relevant values, which is propogated to chartjson.

tools/telemetry/telemetry/value/scalar.py

 # Copyright 2013 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.
 
 import numbers
 
 from telemetry import value as value_module
 from telemetry.value import list_of_scalar_values
 from telemetry.value import none_values
+from telemetry.value import summarizable
 
 
-class ScalarValue(value_module.Value):
+class ScalarValue(summarizable.SummarizableValue):
   def __init__(self, page, name, units, value, important=True,
-               description=None, none_value_reason=None):
+               description=None, none_value_reason=None,
+               improvement_direction=None):
     """A single value (float or integer) result from a test.
 
     A test that counts the number of DOM elements in a page might produce a
     scalar value:
        ScalarValue(page, 'num_dom_elements', 'count', num_elements)
     """
-    super(ScalarValue, self).__init__(page, name, units, important, description)
+    super(ScalarValue, self).__init__(
+        page, name, units, important, description, improvement_direction)
     assert value is None or isinstance(value, numbers.Number)
     none_values.ValidateNoneValueReason(value, none_value_reason)
     self.value = value
     self.none_value_reason = none_value_reason
 
   def __repr__(self):
     if self.page:
       page_name = self.page.url
     else:
       page_name = None
-    return 'ScalarValue(%s, %s, %s, %s, important=%s, description=%s)' % (
+    return ('ScalarValue(%s, %s, %s, %s, important=%s, description=%s, '
+            'improvement_direction=%s)') % (
       page_name,
       self.name,
       self.units,
       self.value,
       self.important,
-      self.description)
+      self.description,
+      self.improvement_direction)
 
   def GetBuildbotDataType(self, output_context):
     if self._IsImportantGivenOutputIntent(output_context):
       return 'default'
     return 'unimportant'
 
   def GetBuildbotValue(self):
     # Buildbot's print_perf_results method likes to get lists for all values,
     # even when they are scalar, so list-ize the return value.
     return [self.value]
@@ skipping 14 matching lines @@
 
     if self.none_value_reason is not None:
       d['none_value_reason'] = self.none_value_reason
 
     return d
 
   @staticmethod
   def FromDict(value_dict, page_dict):
     kwargs = value_module.Value.GetConstructorKwArgs(value_dict, page_dict)
     kwargs['value'] = value_dict['value']
+    kwargs['improvement_direction'] = value_dict['improvement_direction']
 
     if 'none_value_reason' in value_dict:
       kwargs['none_value_reason'] = value_dict['none_value_reason']
 
     return ScalarValue(**kwargs)
 
   @classmethod
   def MergeLikeValuesFromSamePage(cls, values):
     assert len(values) > 0
     v0 = values[0]
@@ skipping 10 matching lines @@
   @classmethod
   def _MergeLikeValues(cls, values, page, name):
     v0 = values[0]
     merged_value = [v.value for v in values]
     none_value_reason = None
     if None in merged_value:
       merged_value = None
       none_value_reason = none_values.MERGE_FAILURE_REASON
     return list_of_scalar_values.ListOfScalarValues(
         page, name, v0.units, merged_value, important=v0.important,
-        none_value_reason=none_value_reason)
+        none_value_reason=none_value_reason,
+        improvement_direction=v0.improvement_direction)

[nednguyen, 2015/01/08 18:07:41]

This is the ugliness that I mentioned. How do we guarantee that all values to be
merge have the same improvement_direction? :-(

It's fine if you want to punt this issue.

[qyearsley, 2015/01/27 00:50:46]

What does "like values" mean in this context? Maybe based on what's meant here,
it does make sense to assume that they'll all always have the same improvement
direction (e.g. if they all represent the same type of measurement?) If so, then
a comment could be added to explain this.