Refactor stages 1, 2 and test_api overhaul.

scripts/slave/recipe_modules/auto_bisect/bisector.py

Index: scripts/slave/recipe_modules/auto_bisect/bisector.py
diff --git a/scripts/slave/recipe_modules/auto_bisect/bisector.py b/scripts/slave/recipe_modules/auto_bisect/bisector.py
index cd46eb187fbc2b818e67509b6c6a9350f9519313..1abaaa0b57599a965125f61c95eb1281db5b5676 100644
--- a/scripts/slave/recipe_modules/auto_bisect/bisector.py
+++ b/scripts/slave/recipe_modules/auto_bisect/bisector.py
@@ -46,14 +46,7 @@ DEFAULT_SEARCH_RANGE_PERCENTAGE = 0.25
 
 # How long to re-test the initial good-bad range for until significant
 # difference is established.
-REGRESSION_CHECK_TIMEOUT = 20 * 60 * 60  # 20 hours. A build times out after 24.
-# If we reach this number of samples on the reference range and have not
-# achieved statistical significance, bail.
-MAX_REQUIRED_SAMPLES = 15
-
-# Significance level to use for determining difference between revisions via
-# hypothesis testing.
-SIGNIFICANCE_LEVEL = 0.01
+REGRESSION_CHECK_TIMEOUT = 2 * 60 * 60
 
 _FAILED_INITIAL_CONFIDENCE_ABORT_REASON = (
     'The metric values for the initial "good" and "bad" revisions '
@@ -155,7 +148,9 @@ class Bisector(object):
       commit_position = self._api.m.commit_position.construct(
           branch='refs/heads/master', value=rev)
       try:
-        return self._api.m.crrev.to_commit_hash(commit_position)
+        return self._api.m.crrev.to_commit_hash(
+            commit_position,
+            step_test_data=lambda: self.api._test_data['hash_cp_map'][rev])
       except self.api.m.step.StepFailure:  # pragma: no cover
         self.surface_result('BAD_REV')
         raise
@@ -167,37 +162,37 @@ class Bisector(object):
   def _is_sha1(s):
     return bool(re.match('^[0-9A-Fa-f]{40}$', s))
 
-  def significantly_different(
-      self, list_a, list_b,
-      significance_level=SIGNIFICANCE_LEVEL):  # pragma: no cover
-    """Uses an external script to run hypothesis testing with scipy.
-
-    The reason why we need an external script is that scipy is not available to
-    the default python installed in all platforms. We instead rely on an
-    anaconda environment to provide those packages.
-
-    Args:
-      list_a, list_b: Two lists representing samples to be compared.
-      significance_level: Self-describing. As a decimal fraction.
-
+  def compare_revisions(self, revision_a, revision_b):
+    """
     Returns:

[prasadv, 2016/09/09 18:52:30]

I think it is better to have a consistent datatype value to return. 
In this case if there might be a confusion to evaluate False and None.
May be we should use some kind of enum here.

Same for the "needMoreData"

[RobertoCN, 2016/09/13 22:11:40]

Done.

-      A boolean indicating whether the null hypothesis ~(that the lists are
-      samples from the same population) can be rejected at the specified
-      significance level.
+      True if the samples are significantly different.
+      None if there is not enough data to tell.
+      False if there's enough data but still can't tell the samples apart.
     """
-    step_result = self.api.m.python(
-        'Checking sample difference',
-        self.api.resource('significantly_different.py'),
-        [json.dumps(list_a), json.dumps(list_b), str(significance_level)],
-        stdout=self.api.m.json.output())
-    results = step_result.stdout
-    if results is None:
-      assert self.dummy_builds
-      return True
-    significantly_different = results['significantly_different']
-    step_result.presentation.logs[str(significantly_different)] = [
-        'See json.output for details']
-    return significantly_different
+    output_format = 'chartjson'
+    values_a = revision_a.chartjson_paths
+    values_b = revision_b.chartjson_paths
+    if revision_a.valueset_paths and revision_b.valueset_paths:
+      output_format = 'valueset'
+
+    result = self.api.stat_compare(
+        values_a,
+        values_b,
+        self.bisect_config['metric'],
+        output_format=output_format,
+        step_test_data=lambda: self.api.test_api.compare_samples_data(
+            self.api._test_data.get('revision_data'), revision_a, revision_b))
+
+    revision_a.debug_values = result['sample_a']['debug_values']
+    revision_b.debug_values = result['sample_b']['debug_values']
+    revision_a.mean = result['sample_a']['mean']
+    revision_b.mean = result['sample_b']['mean']
+    revision_a.std_dev = result['sample_a']['std_dev']
+    revision_b.std_dev = result['sample_b']['std_dev']
+
+    if result['result'] == 'needMoreData':
+      return None
+    return bool(result['result'])
 
   def config_step(self):
     """Yields a step that prints the bisect config."""
@@ -235,8 +230,8 @@ class Bisector(object):
     return self._api
 
   def compute_relative_change(self):
-    old_value = float(self.good_rev.mean_value)
-    new_value = float(self.bad_rev.mean_value)
+    old_value = float(self.good_rev.mean or 0)
+    new_value = float(self.bad_rev.mean or 0)
 
     if new_value and not old_value:  # pragma: no cover
       self.relative_change = ZERO_TO_NON_ZERO
@@ -273,8 +268,10 @@ class Bisector(object):
     stdin = self.api.m.raw_io.input(file_contents)
     stdout = self.api.m.raw_io.output()
     step_name = 'Hashing modified DEPS file with revision ' + commit_hash
-    step_result = self.api.m.git(*cmd, cwd=cwd, stdin=stdin, stdout=stdout,
-                                 name=step_name)
+    step_result = self.api.m.git(
+        *cmd, cwd=cwd, stdin=stdin, stdout=stdout, name=step_name,
+        step_test_data=lambda:
+            self.api.m.raw_io.test_api.stream_output(commit_hash))
     hash_string = step_result.stdout.splitlines()[0]
     try:
       if hash_string:
@@ -309,7 +306,9 @@ class Bisector(object):
     cmd = cmd.split(' ')
     stdout = self.api.m.raw_io.output()
     step_name = 'Generating patch for %s to %s' % (git_object_a, deps_rev)
-    step_result = self.api.m.git(*cmd, cwd=cwd, stdout=stdout, name=step_name)
+    step_result = self.api.m.git(
+        *cmd, cwd=cwd, stdout=stdout, name=step_name,
+        step_test_data=lambda: self.api._test_data['diff_patch'])
     patch_text = step_result.stdout
     src_string = 'IAMSRC:' + git_object_a
     dst_string = 'IAMDST:' + git_object_b
@@ -372,18 +371,21 @@ class Bisector(object):
     with self.api.m.step.nest('Expanding revision range'):
       good_hash = self.good_rev.commit_hash
       bad_hash = self.bad_rev.commit_hash
+      depot = self.good_rev.depot_name
       step_name = 'for revisions %s:%s' % (good_hash, bad_hash)
       revisions = self._revision_range(
           start=good_hash,
           end=bad_hash,
           depot_name=self.base_depot,
           step_name=step_name,
-          exclude_end=True)
+          exclude_end=True,
+          step_test_data=lambda: self.api._test_data['revision_list'][depot]
+      )
       self.revisions = [self.good_rev] + revisions + [self.bad_rev]
       self._update_revision_list_indexes()
 
   def _revision_range(self, start, end, depot_name, base_revision=None,
-                      step_name=None, exclude_end=False):
+                      step_name=None, exclude_end=False, **kwargs):
     """Returns a list of RevisionState objects between |start| and |end|.
 
     When expanding the initial revision range we want to exclude the last
@@ -412,7 +414,7 @@ class Bisector(object):
           step_name,
           self.api.resource('fetch_intervening_revisions.py'),
           [start, end, depot_config.DEPOT_DEPS_NAME[depot_name]['url']],
-          stdout=self.api.m.json.output())
+          stdout=self.api.m.json.output(), **kwargs)
     except self.api.m.step.StepFailure:  # pragma: no cover
       self.surface_result('BAD_REV')
       raise
@@ -521,7 +523,9 @@ class Bisector(object):
                 end=dep_revision_max,
                 depot_name=depot_name,
                 base_revision=min_revision,
-                step_name=step_name)
+                step_name=step_name,
+                step_test_data=lambda:
+                    self.api._test_data['revision_list'][depot_name])
             new_revisions = self.revisions[:max_revision.list_index]
             new_revisions += rev_list
             new_revisions += self.revisions[max_revision.list_index:]
@@ -558,8 +562,8 @@ class Bisector(object):
       True if the check passes (i.e. no problem), False if the change is not
       a regression according to the improvement direction.
     """
-    good = self.good_rev.mean_value
-    bad = self.bad_rev.mean_value
+    good = self.good_rev.mean
+    bad = self.bad_rev.mean
 
     if self.is_return_code_mode():
       return True
@@ -594,32 +598,32 @@ class Bisector(object):
     other in a statistically significant manner. False if such difference could
     not be established in the time or sample size allowed.
     """
-    if self.test_type == 'return_code':
+    if self.is_return_code_mode():
       return (self.good_rev.overall_return_code !=
               self.bad_rev.overall_return_code)
 
     if self.bypass_stats_check:
-      dummy_result = self.good_rev.values != self.bad_rev.values
+      self.compare_revisions(self.good_rev, self.bad_rev)
+      dummy_result = self.good_rev.mean != self.bad_rev.mean
       if not dummy_result:
         self._set_insufficient_confidence_warning()
       return dummy_result
 
+    # TODO(robertocn): This step should not be necessary in some cases.
     with self.api.m.step.nest('Re-testing reference range'):
       expiration_time = time.time() + REGRESSION_CHECK_TIMEOUT
       while time.time() < expiration_time:
-        if len(self.good_rev.values) >= 5 and len(self.bad_rev.values) >= 5:
-          if self.significantly_different(self.good_rev.values,
-                                          self.bad_rev.values):
+        if (self.good_rev.test_run_count >= 5
+            and self.bad_rev.test_run_count >= 5):
+          if self.compare_revisions(self.good_rev, self.bad_rev):
             return True
-        if len(self.good_rev.values) == len(self.bad_rev.values):
+        if self.good_rev.test_run_count == self.bad_rev.test_run_count:
           revision_to_retest = self.last_tested_revision
         else:
           revision_to_retest = min(self.good_rev, self.bad_rev,
-                                   key=lambda x: len(x.values))
-        if len(revision_to_retest.values) < MAX_REQUIRED_SAMPLES:
-          revision_to_retest.retest()
-        else:
-          break
+                                   key=lambda x: x.test_run_count)
+        revision_to_retest._do_test()
+
       self._set_insufficient_confidence_warning()
       return False
 
@@ -641,14 +645,18 @@ class Bisector(object):
     result = 'bisector.lkgr: %r\n' % self.lkgr
     result += 'bisector.fkbr: %r\n\n' % self.fkbr
     result += self._revision_value_table()
-    if (self.lkgr and self.lkgr.values and self.fkbr and self.fkbr.values):
-      result += '\n' + self._t_test_results()
+    if (self.lkgr and self.lkgr.test_run_count and self.fkbr and
+        self.fkbr.test_run_count):
+      result += '\n' + '\n'.join([
+          'LKGR values: %r' % list(self.lkgr.debug_values),
+          'FKBR values: %r' % list(self.fkbr.debug_values),
+      ])
     return result
 
   def _revision_value_table(self):
     """Returns a string table showing revisions and their values."""
     header = [['Revision', 'Values']]
-    rows = [[r.revision_string(), str(r.values)] for r in self.revisions]
+    rows = [[r.revision_string(), str(r.debug_values)] for r in self.revisions]
     return self._pretty_table(header + rows)
 
   def _pretty_table(self, data):
@@ -657,20 +665,6 @@ class Bisector(object):
       results.append('%-15s' * len(row) % tuple(row))
     return '\n'.join(results)
 
-  def _t_test_results(self):
-    """Returns a string showing t-test results for lkgr and fkbr."""
-    t, df, p = self.api.m.math_utils.welchs_t_test(
-        self.lkgr.values, self.fkbr.values)
-    lines = [
-        'LKGR values: %r' % self.lkgr.values,
-        'FKBR values: %r' % self.fkbr.values,
-        't-statistic: %r' % t,
-        'deg. of freedom:  %r' % df,
-        'p-value: %r' % p,
-        'Confidence score: %r' % (100 * (1 - p))
-    ]
-    return '\n'.join(lines)
-
   def print_result_debug_info(self):
     """Prints extra debug info at the end of the bisect process."""
     lines = self._results_debug_message().splitlines()
@@ -695,7 +689,7 @@ class Bisector(object):
     candidate_range = [revision for revision in
                        self.revisions[self.lkgr.list_index + 1:
                                       self.fkbr.list_index]
-                       if not revision.tested and not revision.failed]
+                       if not revision.failed]
     if len(candidate_range) == 1:
       return candidate_range[0]
     if len(candidate_range) == 0:
@@ -738,7 +732,7 @@ class Bisector(object):
     does not contain a DEPS change.
     """
     if (revision.bad and revision.previous_revision and
-        revision.previous_revision.good):  # pragma: no cover
+        revision.previous_revision.good):
       if revision.deps_change() and self._expand_deps_revisions(revision):
         return False
       self.culprit = revision
@@ -750,32 +744,9 @@ class Bisector(object):
         return False
       self.culprit = revision.next_revision
       return True
-    return False
-
-  def wait_for_all(self, revision_list):
-    """Waits for all revisions in list to finish."""
-    for r in revision_list:
-      self.wait_for(r)
-
-  def wait_for(self, revision, nest_check=True):
-    """Waits for the revision to finish its job."""
-    if nest_check and not self.flags.get(
-        'do_not_nest_wait_for_revision'):  # pragma: no cover
-      with self.api.m.step.nest('Waiting for ' + revision.revision_string()):
-        return self.wait_for(revision, nest_check=False)
-    while True:
-      revision.update_status()
-      if revision.in_progress:
-        self.api.m.python.inline(
-            'sleeping',
-            """
-            import sys
-            import time
-            time.sleep(20*60)
-            sys.exit(0)
-            """)
-      else:
-        break
+    # We'll never get here because revision adjacency is checked before this
+    # function is called.
+    assert False  # pragma: no cover
 
   def _update_candidate_range(self):
     """Updates lkgr and fkbr (last known good/first known bad) revisions.
@@ -783,7 +754,7 @@ class Bisector(object):
     lkgr and fkbr are 'pointers' to the appropriate RevisionState objects in
     bisectors.revisions."""
     for r in self.revisions:
-      if r.tested:
+      if r.test_run_count:
         if r.good:
           self.lkgr = r
         elif r.bad:
@@ -821,7 +792,7 @@ class Bisector(object):
 
     # TODO(prasadv): Refactor this code to remove hard coded values and use
     # target_bit from the bot config. crbug.com/640287
-    if 'android' in bot_name:
+    if 'android' in bot_name:  # pragma: no cover
       if any(b in bot_name for b in ['arm64', 'nexus9', 'nexus5X']):
         return 'android_arm64_perf_bisect_builder'
       return 'android_perf_bisect_builder'
@@ -851,7 +822,7 @@ class Bisector(object):
 
     # TODO(prasadv): Refactor this code to remove hard coded values and use
     # target_bit from the bot config. crbug.com/640287
-    if 'android' in bot_name:
+    if 'android' in bot_name: #pragma: no cover
       if any(b in bot_name for b in ['arm64', 'nexus9', 'nexus5X']):
         return 'gs://chrome-perf/Android arm64 Builder/full-build-linux_'
       return 'gs://chrome-perf/Android Builder/full-build-linux_'
@@ -876,7 +847,7 @@ class Bisector(object):
 
   def is_return_code_mode(self):
     """Checks whether this is a bisect on the test's exit code."""
-    return self.bisect_config.get('test_type') == 'return_code'
+    return self.test_type == 'return_code'
 
   def surface_result(self, result_string):
     assert result_string in VALID_RESULT_CODES
@@ -891,10 +862,6 @@ class Bisector(object):
   def get_result(self):
     """Returns the results as a jsonable object."""
     config = self.bisect_config
-    results_confidence = 0
-    if self.culprit:
-      results_confidence = self.api.m.math_utils.confidence_score(
-          self.lkgr.values, self.fkbr.values)
 
     if self.failed:
       status = 'failed'
@@ -916,9 +883,8 @@ class Bisector(object):
         'bisect_bot': self.get_perf_tester_name(),
         'command': config['command'],
         'test_type': config['test_type'],
-        'metric': config['metric'],
+        'metric': config.get('metric'),
         'change': self.relative_change,
-        'score': results_confidence,
         'good_revision': self.good_rev.commit_hash,
         'bad_revision': self.bad_rev.commit_hash,
         'warnings': self.warnings,
@@ -950,14 +916,14 @@ class Bisector(object):
   def _revision_data(self):
     revision_rows = []
     for r in self.revisions:
-      if r.tested or r.aborted:
+      if r.test_run_count:
         revision_rows.append({
             'depot_name': r.depot_name,
             'commit_hash': r.commit_hash,
             'revision_string': r.revision_string(),
-            'mean_value': r.mean_value,
+            'mean_value': r.mean,
             'std_dev': r.std_dev,
-            'values': r.values,
+            'values': r.debug_values,
             'result': 'good' if r.good else 'bad' if r.bad else 'unknown',
         })
     return revision_rows