NOT FOR SUBMIT: telemetry use counter measurement

tools/perf/metrics/usecounter.py

+# Copyright 2016 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 json
+
+from telemetry.value import histogram_util
+from telemetry.value import list_of_scalar_values
+from telemetry.value import scalar
+
+from metrics import Metric
+
+class UseCounterMetric(Metric):
+  """UseCounterMetric trackers whether specific blink UseCounters were hit
+  """
+
+  HISTOGRAM_NAME = 'WebCore.UseCounter_TEST.Features'
+
+  PAGE_VISITS_BUCKET = 52
+
+  LIMITED_BUCKETS_MODE = False
+
+  # If the above is true, then use only the features specified here.
+  # Telemetry doesn't appear to have any way of passing options into
+  # a benchmark from the command line.
+  BUCKET_VALUES = [
+    0,     # PageDestruction
+    52,    # PageVisits
+    343,   # EventSrcElement
+    677,   # XMLHttpRequestAsynchronous (a popular JS metric as a control)
+    1075,  # V8SloppyMode
+    1076,  # V8StrictMode
+    1077,  # V8StrongMode
+#    967,   # AddEventListenerThirdArgumentIsObject
+#    968,   # RemoveEventListenerThirdArgumentIsObject
+#    1279,  # AddEventListenerFourArguments
+#    1280,  # RemoveEventListenerFourArguments
+    575,  # WindowPostMessageWithLegacyTargetOriginArgument
+  ]
+
+  @classmethod
+  def CustomizeBrowserOptions(cls, options):
+    options.AppendExtraBrowserArgs(['--enable-stats-collection-bindings'])
+
+  def __init__(self):
+    super(UseCounterMetric, self).__init__()
+    self._histogram_start = ""
+
+  def Start(self, page, tab):
+    self._histogram_start = histogram_util.GetHistogram(
+        histogram_util.RENDERER_HISTOGRAM,
+        UseCounterMetric.HISTOGRAM_NAME,
+        tab)
+
+  def AddResults(self, tab, results):
+    """Adds the number of times the specified metrics were hit
+    Should be 0 or 1 if UseCounter and the user story are functioning correctly.
+    """
+
+    histogram = histogram_util.GetHistogram(
+        histogram_util.RENDERER_HISTOGRAM,
+        UseCounterMetric.HISTOGRAM_NAME,
+        tab)
+
+    # Determine if the renderer has been restarted as a result of the
+    # navigation. Normally checking the 'pid' should be sufficient, but the fix
+    # for crbug.com/666912 may not be in the build under test, and besides it
+    # may be possible (if unlikely) for a unique process ID to get recycled.
+    # So also check for a decrease in the histogram.
+    start_parsed = json.loads(self._histogram_start)
+    end_parsed = json.loads(histogram)
+    if start_parsed:
+        start_page_visits = sum(b['count'] for b in start_parsed['buckets']
+            if b['low'] == UseCounterMetric.PAGE_VISITS_BUCKET)
+    else:
+        start_page_visits = 0
+    end_page_visits = sum(b['count'] for b in end_parsed['buckets']
+        if b['low'] == UseCounterMetric.PAGE_VISITS_BUCKET)
+
+    if (not start_parsed or
+          start_parsed['pid'] != end_parsed['pid'] or
+          start_parsed['sum'] > end_parsed['sum'] or
+          start_page_visits > end_page_visits):
+        # Just use the raw ending histogram
+        histogram_delta = histogram
+    else:
+        # Use the difference between the start and end histograms
+        histogram_delta = histogram_util.SubtractHistogram(histogram,
+            self._histogram_start)
+
+    buckets = histogram_util.GetHistogramBucketsFromJson(histogram_delta)
+
+    if UseCounterMetric.LIMITED_BUCKETS_MODE:
+        for bucketValue in UseCounterMetric.BUCKET_VALUES:
+            useCount = sum(bucket['count'] for bucket in buckets
+                                             if bucket['low'] == bucketValue)
+            results.AddValue(scalar.ScalarValue(results.current_page,
+                'Feature' + str(bucketValue), 'count', useCount))
+
+    else:
+        results.AddValue(list_of_scalar_values.ListOfScalarValues(
+            results.current_page, 'features', 'list-of-ids',
+            [b['low'] for b in buckets]))
+