Add script to rebaseline benches from codereview trybot results

tools/gen_bench_expectations_from_codereview.py

Index: tools/gen_bench_expectations_from_codereview.py
diff --git a/tools/gen_bench_expectations_from_codereview.py b/tools/gen_bench_expectations_from_codereview.py
new file mode 100644
index 0000000000000000000000000000000000000000..cc28996fbe036e832321c3b440a591f39878bec9
--- /dev/null
+++ b/tools/gen_bench_expectations_from_codereview.py
@@ -0,0 +1,154 @@
+#!/usr/bin/python
+
+# Copyright (c) 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.
+
+
+"""Generate new bench expectations from results of trybots on a code review."""
+
+
+import collections
+import compare_codereview
+import os
+import re
+import shutil
+import subprocess
+import sys
+
+
+BENCH_DATA_URL = 'gs://chromium-skia-gm/perfdata/%s/%s/*'
+CHECKOUT_PATH = os.path.realpath(os.path.join(
+    os.path.dirname(os.path.abspath(__file__)), os.pardir))
+TMP_BENCH_DATA_DIR = os.path.join(CHECKOUT_PATH, '.bench_data')
+
+
+def find_all_builds(codereview_url):
+  """Finds and returns information about trybot runs for a code review.
+
+  Args:
+    codereview_url: URL of the codereview in question.
+
+  Returns:
+      List of NamedTuples: (builder_name, build_number, is_finished)
+  """
+  results = compare_codereview.CodeReviewHTMLParser().parse(codereview_url)
+  TryBuild = collections.namedtuple(
+      'TryBuild', ['builder_name', 'build_number', 'is_finished'])
+  try_builds = []
+
+  for builder, data in results.iteritems():
+    if builder.startswith('Perf'):
+      try_builds.append(TryBuild(builder, data.url.split('/')[-1],
+                                 data.status != 'pending'))
+  return try_builds
+
+
+def get_bench_data(builder, build_num, dest_dir):
+  """Download the bench data for the given builder at the given build_num.
+
+  Args:
+      builder: string; name of the builder.
+      build_num: string; build number.
+      dest_dir: string; destination directory for the bench data.
+  """
+  url = BENCH_DATA_URL % (builder, build_num)
+  subprocess.check_call(['gsutil', 'cp', '-R', url, dest_dir],
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+
+
+def find_revision_from_downloaded_data(dest_dir):
+  """Finds the revision at which the downloaded data was generated.
+
+  Args:
+      dest_dir: string; directory holding the downloaded data.
+
+  Returns:
+      The revision (git commit hash) at which the downloaded data was
+      generated, or None if no revision can be found.
+  """
+  for data_file in os.listdir(dest_dir):
+    match = re.match('bench_(?P<revision>[0-9a-fA-F]{2,40})_data.*', data_file)
+    if match:
+      return match.group('revision')
+  return None
+
+
+class TrybotNotFinishedError(Exception):
+  pass
+
+
+def gen_bench_expectations_from_codereview(codereview_url,
+                                           error_on_unfinished=True):
+  """Generate bench expectations from a code review.
+
+  Scans the given code review for Perf trybot runs. Downloads the results of
+  finished trybots and uses them to generate new expectations for their
+  waterfall counterparts.
+
+  Args:
+      url: string; URL of the code review.
+      error_on_unfinished: bool; throw an error if any trybot has not finished.
+  """
+  try_builds = find_all_builds(codereview_url)
+
+  # Verify that all trybots have finished running.
+  if error_on_unfinished:
+    for try_build in try_builds:
+      if not try_build.is_finished:
+        raise TrybotNotFinishedError('%s: #%s is not finished.' % (
+                                         try_build.builder_name,
+                                         try_build.build_number))
+  failed_data_pull = []
+  failed_gen_expectations = []
+
+  if os.path.isdir(TMP_BENCH_DATA_DIR):
+    shutil.rmtree(TMP_BENCH_DATA_DIR)
+
+  for try_build in try_builds:
+    try_builder = try_build.builder_name
+    builder = try_builder.replace('-Trybot', '')
+
+    # Download the data.
+    dest_dir = os.path.join(TMP_BENCH_DATA_DIR, builder)
+    os.makedirs(dest_dir)
+    try:
+      get_bench_data(try_builder, try_build.build_number, dest_dir)
+    except subprocess.CalledProcessError:
+      failed_data_pull.append(try_builder)
+      continue
+
+    # Find the revision at which the data was generated.
+    revision = find_revision_from_downloaded_data(dest_dir)
+    if not revision:
+      # If we can't find a revision, then something is wrong with the data we
+      # downloaded. Skip this builder.
+      failed_data_pull.append(try_builder)
+      continue
+
+    # Generate new expectations.
+    output_file = os.path.join(CHECKOUT_PATH, 'expectations', 'bench',
+                               'bench_expectations_%s.txt' % builder)
+    try:
+      subprocess.check_call(['python',
+                             os.path.join(CHECKOUT_PATH, 'bench',
+                                          'gen_bench_expectations.py'),
+                             '-b', builder, '-o', output_file,
+                             '-d', dest_dir, '-r', revision])
+    except subprocess.CalledProcessError:
+      failed_gen_expectations.append(builder)
+
+  failure = ''
+  if failed_data_pull:
+    failure += 'Failed to load data for: %s\n\n' % ','.join(failed_data_pull)
+  if failed_gen_expectations:
+    failure += 'Failed to generate expectations for: %s\n\n' % ','.join(
+        failed_gen_expectations)
+  if failure:
+    raise Exception(failure)
+
+
+if __name__ == '__main__':
+  gen_bench_expectations_from_codereview(sys.argv[1])
+