Re-land: Add multi results in legacy perf dashboard script.

Currently when the script reads multiple results it overrites the
current result with last value read. It does not compute a mean
or standard deviation.

This change updates the script to keep a list of values. It then
computes a mean and standard deviation from the list.

The first attempt at fixing this returned a list of values. This
was incorrect. Also includes a comment an assert to prevent this.

Bug: 900677
Change-Id: Ided17ea36478128e003e6d9317ca5fb15128415a
Reviewed-on: https://chromium-review.googlesource.com/c/1341211
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#609342}

tools/perf/generate_legacy_perf_dashboard_json.py

@@ -73,11 +73,12 @@ class LegacyResultsProcessor(object):
 
     def __init__(self):
       self.important = False
-      self.value = 0.0
+      self.values = []
+      self.mean = 0.0
       self.stddev = 0.0
 
     def __str__(self):
-      result = _FormatHumanReadable(self.value)
+      result = _FormatHumanReadable(self.mean)
       if self.stddev:
         result += '+/-%s' % _FormatHumanReadable(self.stddev)
       return result
@@ -100,7 +101,7 @@ class LegacyResultsProcessor(object):
       """Returns a dictionary mapping trace names to [value, stddev]."""
       traces_dict = {}
       for name, trace in self.traces.items():
-        traces_dict[name] = [str(trace.value), str(trace.stddev)]
+        traces_dict[name] = [str(trace.mean), str(trace.stddev)]
       return traces_dict
 
 
@@ -141,37 +142,43 @@ class LegacyResultsProcessor(object):
     graph = self._graphs.get(graph_name, self.Graph())
     graph.units = (match_dict['UNITS'] or '').strip()
     trace = graph.traces.get(trace_name, self.Trace())
-    trace.value = match_dict['VALUE']
+    value = match_dict['VALUE']
     trace.important = match_dict['IMPORTANT'] or False
 
     # Compute the mean and standard deviation for a list or a histogram,
     # or the numerical value of a scalar value.
-    if trace.value.startswith('['):
+    if value.startswith('['):
       try:
-        value_list = [float(x) for x in trace.value.strip('[],').split(',')]
+        value_list = [float(x) for x in value.strip('[],').split(',')]
       except ValueError:
         # Report, but ignore, corrupted data lines. (Lines that are so badly
         # broken that they don't even match the RESULTS_REGEX won't be
         # detected.)
-        logging.warning("Bad test output: '%s'" % trace.value.strip())
+        logging.warning("Bad test output: '%s'" % value.strip())
         return
-      trace.value, trace.stddev, filedata = self._CalculateStatistics(
-          value_list, trace_name)
+      trace.values += value_list
+      trace.mean, trace.stddev, filedata = self._CalculateStatistics(
+        trace.values, trace_name)
       assert filedata is not None
       for filename in filedata:
         self._PrependLog(filename, filedata[filename])
-    elif trace.value.startswith('{'):
-      stripped = trace.value.strip('{},')
+    elif value.startswith('{'):
+      stripped = value.strip('{},')
       try:
-        trace.value, trace.stddev = [float(x) for x in stripped.split(',')]
+        trace.mean, trace.stddev = [float(x) for x in stripped.split(',')]
       except ValueError:
-        logging.warning("Bad test output: '%s'" % trace.value.strip())
+        logging.warning("Bad test output: '%s'" % value.strip())
         return
     else:
       try:
-        trace.value = float(trace.value)
+        trace.values.append(float(value))
+        trace.mean, trace.stddev, filedata = self._CalculateStatistics(
+          trace.values, trace_name)
+        assert filedata is not None
+        for filename in filedata:
+          self._PrependLog(filename, filedata[filename])
       except ValueError:
-        logging.warning("Bad test output: '%s'" % trace.value.strip())
+        logging.warning("Bad test output: '%s'" % value.strip())
         return
 
     graph.traces[trace_name] = trace
@@ -183,8 +190,14 @@ class LegacyResultsProcessor(object):
     """
     charts = {}
     for graph_name, graph in self._graphs.iteritems():
+      traces = graph.BuildTracesDict()
+
+      # Traces should contain exactly two elements: [mean, stddev].
+      for _, trace in traces.iteritems():
+        assert len(trace) == 2
+
       graph_dict = collections.OrderedDict([
-        ('traces', graph.BuildTracesDict()),
+        ('traces', traces),
         ('units', str(graph.units)),
       ])
 

tools/perf/testdata/artificial_graph-summary.dat

-{"traces": {"trace_with_one_sample": ["177.0", "0.0"], "trace_with_one_sample_comma": ["177.0", "0.0"], "trace_with_three_samples": ["140.0", "43.2049379894"], "trace_with_three_samples_comma": ["140.0", "43.2049379894"]}, "units": "you-nits"}
+{"units": "you-nits", "traces": {"trace_with_three_samples": ["140.0", "43.2049379894"], "trace_with_multiple_samples": ["250.0", "111.803398875"], "trace_with_one_sample_comma": ["177.0", "0.0"], "trace_with_one_sample": ["177.0", "0.0"], "trace_with_three_samples_comma": ["140.0", "43.2049379894"]}}
\ No newline at end of file

tools/perf/testdata/graphing_processor.log

@@ -47,3 +47,10 @@ RESULT artificial_graph: trace_with_one_sample= [177.0] you-nits
 RESULT artificial_graph: trace_with_one_sample_comma= [177.0,] you-nits
 RESULT artificial_graph: trace_with_three_samples= [100.0,120.0,200.0] you-nits
 RESULT artificial_graph: trace_with_three_samples_comma= [100.0,120.0,200.0,] you-nits
+
+# Artificial log output to test multiple results with the same name
+
+RESULT artificial_graph: trace_with_multiple_samples= 100 you-nits
+RESULT artificial_graph: trace_with_multiple_samples= 200 you-nits
+RESULT artificial_graph: trace_with_multiple_samples= 300 you-nits
+RESULT artificial_graph: trace_with_multiple_samples= 400 you-nits