[telemetry] Add Html2OutputFormatter for generating results2.html

telemetry/telemetry/value/scalar.py

Index: telemetry/telemetry/value/scalar.py
diff --git a/telemetry/telemetry/value/scalar.py b/telemetry/telemetry/value/scalar.py
index 2789b81319e9224333c4178683afc3b23dceebec..9b31e719e0c9eb3e384786cfb73fb1498a66151b 100644
--- a/telemetry/telemetry/value/scalar.py
+++ b/telemetry/telemetry/value/scalar.py
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import math
 import numbers
 
 from telemetry import value as value_module
@@ -68,7 +69,17 @@ class ScalarValue(summarizable.SummarizableValue):
 
   def AsDict(self):
     d = super(ScalarValue, self).AsDict()
-    d['value'] = self.value
+
+    # Infinity and NaN are left out of JSON for security reasons that do not

[eakuefner, 2016/05/19 17:30:56]

In Telemetry, we don't support string-valued scalars like this, and this is
likely to cause 400s on the dashboard. Instead you set value to None and set
none_value_reason to something like 'Value was inf/-inf/nan'.

This is, as I understand apocryphally, based on a mishearing of "NaN" once upon
a time as "None", so now this value system has these "NoneValues" when really we
should have just developed a scheme for handling nan/inf like you propose now.

Sigh.

[eakuefner, 2016/05/19 17:33:04]

Sorry, to be even more clear, I mean that you should probably delete this code
in light of the hack that I'm asking you to introduce in FromDict.

+    # apply to our use cases.
+    if self.value == float('inf'):
+      d['value'] = 'Infinity'
+    elif self.value == -float('inf'):
+      d['value'] = '-Infinity'
+    elif math.isnan(self.value):
+      d['value'] = 'NaN'
+    else:
+      d['value'] = self.value
 
     if self.none_value_reason is not None:
       d['none_value_reason'] = self.none_value_reason
@@ -78,7 +89,17 @@ class ScalarValue(summarizable.SummarizableValue):
   @staticmethod
   def FromDict(value_dict, page_dict):
     kwargs = value_module.Value.GetConstructorKwArgs(value_dict, page_dict)
-    kwargs['value'] = value_dict['value']
+
+    # Infinity and NaN are left out of JSON for security reasons that do not

[eakuefner, 2016/05/19 17:30:56]

Here I'd write an additional comment that says 'TBMv2 metrics can emit these
strings to describe infinity and nan' to show that this is a hack to accommodate
tbmv2.

[eakuefner, 2016/05/19 17:32:09]

And to be clear, I'm not married to the wording; please feel free to innovate on
grammar and spelling.

+    # apply to our use cases.
+    if value_dict['value'] == 'Infinity':

[eakuefner, 2016/05/19 17:30:56]

And flatten all these cases to this block:

if ...:
  kwargs['value'] = None
  kwargs['none_value_reason'] = 'Value was ' + value_dict['value']

+      kwargs['value'] = float('inf')
+    elif value_dict['value'] == '-Infinity':
+      kwargs['value'] = -float('inf')
+    elif value_dict['value'] == 'NaN':
+      kwargs['value'] = float('nan')
+    else:
+      kwargs['value'] = value_dict['value']
 
     if 'improvement_direction' in value_dict:
       kwargs['improvement_direction'] = value_dict['improvement_direction']