stats_manager: more informative nan summary output

Now for the formatted output string, if any value a domain is NaN,
the domains gets tagged with a * and a help text gets added at the end
of the summary to highlight this issue.

CQ-DEPEND=CL:1140025

BRANCH=None
BUG=chromium:806146, chromium:760267
TEST=unit tests added & pass

Change-Id: I30791053bb1645065fa2bfd8305cc840a4a88031
Signed-off-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1140032
Reviewed-by: Mengqi Guo <mqg@chromium.org>

2 files changed, 39 insertions, 1 deletions

diff --git a/extra/usb_power/stats_manager.py b/extra/usb_power/stats_manager.py
index 66dd915a86..2d864e5cc0 100644
--- a/extra/usb_power/stats_manager.py
+++ b/extra/usb_power/stats_manager.py
@@ -15,6 +15,8 @@ import os
 import numpy
 
 STATS_PREFIX = '@@'
+NAN_TAG = '*'
+NAN_DESCRIPTION = '%s domains contain NaN samples' % NAN_TAG
 
 LONG_UNIT = {
     '': 'N/A',
@@ -68,6 +70,8 @@ class StatsManager(object):
     _order: list of formatting order for domains. Domains not listed are
             displayed in sorted order
     _hide_domains: collection of domains to hide when formatting summary string
+    _accept_nan: flag to indicate if NaN samples are acceptable
+    _nan_domains: set to keep track of which domains contain NaN samples
     _summary: dict of stats per domain (key): min, max, count, mean, stddev
     _logger = StatsManager logger
 
@@ -86,8 +90,9 @@ class StatsManager(object):
     self._smid = smid
     self._order = order
     self._hide_domains = hide_domains
-    self._summary = {}
     self._accept_nan = accept_nan
+    self._nan_domains = set()
+    self._summary = {}
     self._logger = logging.getLogger('StatsManager')
 
   def AddSample(self, domain, sample):
@@ -110,6 +115,8 @@ class StatsManager(object):
     if not self._accept_nan and math.isnan(sample):
       raise StatsManagerError('accept_nan is false. Cannot add NaN sample.')
     self._data[domain].append(sample)
+    if math.isnan(sample):
+      self._nan_domains.add(domain)
 
   def SetUnit(self, domain, unit):
     """Set the unit for a domain.
@@ -160,10 +167,14 @@ class StatsManager(object):
     display_order = [key for key in self._order if key in domains_to_display]
     domains_to_display -= set(display_order)
     display_order.extend(sorted(domains_to_display))
+    nan_in_output = False
     for domain in display_order:
       stats = self._summary[domain]
       if not domain.endswith(self._unit[domain]):
         domain = '%s_%s' % (domain, self._unit[domain])
+      if domain in self._nan_domains:
+        domain = '%s%s' % (domain, NAN_TAG)
+        nan_in_output = True
       row = [domain]
       row.append(str(stats['count']))
       for entry in headers[2:]:
@@ -181,6 +192,8 @@ class StatsManager(object):
       for i in range(len(row)):
         formatted_row += row[i].rjust(max_col_width[i] + 2)
       formatted_lines.append(formatted_row)
+    if nan_in_output:
+      formatted_lines.append('%s %s' % (prefix, NAN_DESCRIPTION))
 
     if self._title:
       line_length = len(formatted_lines[0])
diff --git a/extra/usb_power/stats_manager_unittest.py b/extra/usb_power/stats_manager_unittest.py
index ed0b424944..9d0d708af0 100644
--- a/extra/usb_power/stats_manager_unittest.py
+++ b/extra/usb_power/stats_manager_unittest.py
@@ -173,6 +173,31 @@ class TestStatsManager(unittest.TestCase):
     for fname in files:
       self.assertTrue(os.path.basename(fname).startswith(identifier))
 
+  def test_SummaryToStringNaNHelp(self):
+    """NaN containing row gets tagged with *, help banner gets added."""
+    help_banner_exp = '%s %s' % (stats_manager.STATS_PREFIX,
+                                 stats_manager.NAN_DESCRIPTION)
+    nan_domain = 'A-domain'
+    nan_domain_exp = '%s%s' % (nan_domain, stats_manager.NAN_TAG)
+    # NaN helper banner is added when a NaN domain is found & domain gets tagged
+    data = stats_manager.StatsManager()
+    data.AddSample(nan_domain, float('NaN'))
+    data.AddSample(nan_domain, 17)
+    data.AddSample('B-domain', 17)
+    data.CalculateStats()
+    summarystr = data.SummaryToString()
+    self.assertIn(help_banner_exp, summarystr)
+    self.assertIn(nan_domain_exp, summarystr)
+    # NaN helper banner is not added when no NaN domain output, no tagging
+    data = stats_manager.StatsManager()
+    # nan_domain in this scenario does not contain any NaN
+    data.AddSample(nan_domain, 19)
+    data.AddSample('B-domain', 17)
+    data.CalculateStats()
+    summarystr = data.SummaryToString()
+    self.assertNotIn(help_banner_exp, summarystr)
+    self.assertNotIn(nan_domain_exp, summarystr)
+
   def test_SummaryToStringTitle(self):
     """Title shows up in SummaryToString if title specified."""
     title = 'titulo'