WIP to improve Telemetry logging

telemetry/telemetry/internal/story_runner.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.
 
 import logging
 import optparse
 import os
 import sys
 import time
 
 import py_utils
 from py_utils import cloud_storage  # pylint: disable=import-error
 
 from telemetry.core import exceptions
 from telemetry import decorators
 from telemetry.internal.actions import page_action
 from telemetry.internal.browser import browser_finder
 from telemetry.internal.results import results_options
 from telemetry.internal.util import exception_formatter
+from telemetry.internal.util import log_stream
 from telemetry import page
 from telemetry.page import legacy_page_test
 from telemetry import story as story_module
 from telemetry.util import wpr_modes
 from telemetry.value import failure
 from telemetry.value import skip
 from telemetry.value import scalar
 from telemetry.web_perf import story_test
 from tracing.value import histogram
 from tracing.value.diagnostics import reserved_infos
@@ skipping 51 matching lines @@
 def _GenerateTagMapFromStorySet(stories):
   tagmap = histogram.TagMap({})
   for s in stories:
     for t in s.tags:
       tagmap.AddTagAndStoryDisplayName(t, s.name)
   return tagmap
 
 
 def _RunStoryAndProcessErrorIfNeeded(story, results, state, test):
   def ProcessError(description=None):
+    # Flush all the existing log upon failure.
+    log_stream.FlushLogStream(sys.stdout)
+
     state.DumpStateUponFailure(story, results)
     # Note: adding the FailureValue to the results object also normally
     # cause the progress_reporter to log it in the output.
     results.AddValue(failure.FailureValue(story, sys.exc_info(), description))
   try:
     if isinstance(test, story_test.StoryTest):
       test.WillRunStory(state.platform)
     state.WillRunStory(story)
     if not state.CanRunStory(story):
       results.AddValue(skip.SkipValue(
@@ skipping 71 matching lines @@
   # Effective max failures gives priority to command-line flag value.
   effective_max_failures = finder_options.max_failures
   if effective_max_failures is None:
     effective_max_failures = max_failures
 
   state = None
   device_info_diags = {}
   try:
     for storyset_repeat_counter in xrange(finder_options.pageset_repeat):
       for story in stories:
+        log_stream.TruncateLogStream()
         if not state:
           # Construct shared state by using a copy of finder_options. Shared
           # state may update the finder_options. If we tear down the shared
           # state after this story run, we want to construct the shared
           # state for the next story from the original finder_options.
           state = story_set.shared_state_class(
               test, finder_options.Copy(), story_set)
 
         results.WillRunPage(story, storyset_repeat_counter)
 
@@ skipping 266 matching lines @@
       reserved_infos.OS_VERSIONS.name: state.platform.GetOSVersionName(),
   }
 
   device_info_diangostics = {}
 
   for name, value in device_info_data.iteritems():
     if not value:
       continue
     device_info_diangostics[name] = histogram.GenericSet([value])
   return device_info_diangostics