[telemetry] Add support for BenchmarkResults that vary from page to page

tools/telemetry/telemetry/csv_page_benchmark_results.py

Index: tools/telemetry/telemetry/csv_page_benchmark_results.py
diff --git a/tools/telemetry/telemetry/csv_page_benchmark_results.py b/tools/telemetry/telemetry/csv_page_benchmark_results.py
new file mode 100644
index 0000000000000000000000000000000000000000..3a9995e344b3278d8e596701270e0c461245f416
--- /dev/null
+++ b/tools/telemetry/telemetry/csv_page_benchmark_results.py
@@ -0,0 +1,79 @@
+# Copyright (c) 2012 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 telemetry.page_benchmark_results import PageBenchmarkResults
+
+class CsvPageBenchmarkResults(PageBenchmarkResults):
+  def __init__(self, results_writer, output_after_every_page):
+    super(CsvPageBenchmarkResults, self).__init__()
+    self._results_writer = results_writer
+    self._did_output_header = False
+    self._header_names_written_to_writer = None
+    self._output_after_every_page = output_after_every_page
+
+  def DidMeasurePage(self):
+    assert self.values_for_current_page, 'Failed to call WillMeasurePage'
+    if not self._output_after_every_page:
+      super(CsvPageBenchmarkResults, self).DidMeasurePage()
+      return
+
+    if not self._did_output_header:
+      self._OutputHeader()
+    else:
+      self._ValidateOutputNamesForCurrentPage()
+
+    self._OutputValuesForPage(self.values_for_current_page)
+
+    super(CsvPageBenchmarkResults, self).DidMeasurePage()
+
+  def PrintSummary(self, trace_tag):
+    if not self._output_after_every_page:
+      self._OutputHeader()
+      for page_values in self.all_values_for_all_pages:
+        self._OutputValuesForPage(page_values)
+
+    super(CsvPageBenchmarkResults, self).PrintSummary(trace_tag)
+
+  def _ValidateOutputNamesForCurrentPage(self):
+    assert self._did_output_header
+    current_page_measurement_names = \
+        self.values_for_current_page.measurement_names
+    if self._header_names_written_to_writer == current_page_measurement_names:
+      return
+    assert False, """To use CsvPageBenchmarkResults, you must add the same
+result names for every page. In this case, first page output:
+%s
+
+Thus, all subsequent pages must output this as well. Instead, the current page
+output:
+%s
+
+Change your test to produce the same thing each time, or modify
+MultiPageBenchmark.results_are_the_same_on_every_page to return False.
+""" % (repr(self._header_names_written_to_writer),
+       repr(current_page_measurement_names))
+
+  def _OutputHeader(self):
+    assert not self._did_output_header
+    all_measurement_names = list(
+      self.all_measurements_that_have_been_seen.keys())
+    all_measurement_names.sort()
+    self._did_output_header = True
+    self._header_names_written_to_writer = list(all_measurement_names)
+
+    row = ['url']
+    for measurement_name in all_measurement_names:
+      measurement_data = \
+          self.all_measurements_that_have_been_seen[measurement_name]
+      row.append('%s (%s)' % (measurement_name, measurement_data['units']))
+    self._results_writer.writerow(row)
+
+  def _OutputValuesForPage(self, page_values):
+    row = [page_values.page.url]
+    for measurement_name in self._header_names_written_to_writer:
+      value = page_values.FindValueByMeasurementName(measurement_name)
+      if value:
+        row.append('%s' % value.output_value)
+      else:
+        row.append('-')
+    self._results_writer.writerow(row)