[telemetry] Implement first version of timeline based measurement

tools/perf/measurements/timeline_based_measurement.py

+# Copyright 2014 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.
+
+from metrics import timeline as timeline_module
+from metrics import timeline_interaction_record as tir_module
+from telemetry.page import page_measurement
+from telemetry.core.timeline import model as model_module
+
+
+
+# TimelineBasedMeasurement considers all instrumentation as producing a single
+# timeline. But, depending on the amount of instrumentation that is enabled,
+# overhead increases. The user of the measurement must therefore chose between
+# a few levels of instrumentation.
+NO_OVERHEAD_LEVEL = 'no-overhead'
+MINIMAL_OVERHEAD_LEVEL = 'minimal-overhead'
+DEBUG_OVERHEAD_LEVEL = 'debug-overhead'
+
+ALL_OVERHEAD_LEVELS = [
+  NO_OVERHEAD_LEVEL,
+  MINIMAL_OVERHEAD_LEVEL,
+  DEBUG_OVERHEAD_LEVEL
+]
+
+
+class _TimelineBasedMetrics(object):
+  def __init__(self, model, renderer_thread):
+    self._model = model
+    self._renderer_thread = renderer_thread
+
+  def FindTimelineInteractionRecords(self):
+    # TODO(nduca): Add support for page-load interaction record.
+    return [tir_module.TimelineInteractionRecord(event) for
+            event in self._renderer_thread.IterAllAsyncSlices()
+            if tir_module.IsTimelineInteractionRecord(event.name)]
+
+  def CreateMetricsForTimelineInteractionRecord(self, interaction):
+    res = []
+    if interaction.is_smooth:
+      pass # TODO(nduca): res.append smoothness metric instance.
+    return res
+
+  def AddResults(self, results):
+    interactions = self.FindTimelineInteractionRecords()
+    if len(interactions) == 0:
+      raise Exception('Expected at least one Interaction on the page')
+    for interaction in interactions:
+      metrics = self.CreateMetricsForTimelineInteractionRecord(interaction)
+      for m in metrics:
+        m.AddResults(self._model, self._renderer_thread,
+                     interaction, results)
+
+
+class TimelineBasedMeasurement(page_measurement.PageMeasurement):
+  """A timeline measurement shifts the burden of what metrics to collect onto
+  the page under test, or the pageset running that page. Instead of the
+  measurement having a fixed set of values it collects about the page, the page
+  being tested issues a set of standard calls to the user timing API specifying
+  time spans of interest during which interactions are running, and for each, a
+  standardized set of flags describing the work being done in that time range.
+  This measurement object then collects a trace alongside these interaction
+  records, and passes the recorded timeline to different TimelineBasedMetrics
+  based on those flags.

[nednguyen, 2014/03/04 15:38:47]

Add examples of the interaction marker that the page need to make here or make a
reference to timeline_interaction_record_unittest.py?

+
+  """
+  def __init__(self):
+    super(TimelineBasedMeasurement, self).__init__('smoothness')
+
+  def AddCommandLineOptions(self, parser):
+    parser.add_option(
+        '--overhead-level', type='choice',
+        choices=ALL_OVERHEAD_LEVELS,
+        default=NO_OVERHEAD_LEVEL,
+        help='How much overhead to incur during the measurement.')
+
+  def CanRunForPage(self, page):
+    return hasattr(page, 'smoothness')
+
+  def WillNavigateToPage(self, page, tab):
+    if not tab.browser.supports_tracing:
+      raise Exception('Not supported')
+    assert self.options.overhead_level in ALL_OVERHEAD_LEVELS
+    if self.options.overhead_level == NO_OVERHEAD_LEVEL:
+      categories = timeline_module.MINIMAL_TRACE_CATEGORIES
+    elif self.options.overhead_level == \
+        MINIMAL_OVERHEAD_LEVEL:
+      categories = ''
+    else:
+      categories = '*,disabled-by-default-cc.debug'
+    tab.browser.StartTracing(categories)
+
+  def MeasurePage(self, page, tab, results):
+    """ Collect all possible metrics and added them to results. """
+    trace_result = tab.browser.StopTracing()
+    model = model_module.TimelineModel(trace_result)
+    renderer_thread = model.GetRendererThreadFromTab(tab)
+    meta_metrics = _TimelineBasedMetrics(model, renderer_thread)
+    meta_metrics.AddResults(results)