These are the database objects used while finding the regression range. 1/3

appengine/findit/model/base_swarming_task.py

+# Copyright 2016 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 collections import defaultdict
+
+from google.appengine.ext import ndb
+
+from model import analysis_status
+
+class BaseSwarmingTask(ndb.Model):
+  """Represents the progress of a general swarming task.
+  """
+  # The id of the Swarming task scheduled or running on Swarming Server.
+  task_id = ndb.StringProperty(indexed=True)
+
+  # A dict to keep track of running information for each test:
+  # number of total runs, number of each status (such as 'SUCCESS' or 'FAILED')
+  tests_statuses = ndb.JsonProperty(default={}, indexed=False, compressed=True)

[chanli, 2016/07/19 19:12:20]

This kind of default may lead to some unexpected problems. You can either
1. tests_statuses = ndb.JsonProperty(indexed=False, compressed=True) 
   so tests_statuses will default to None
Or

2. Initialize it to {} in constructor

I used approach 2 (see: https://codereview.chromium.org/2147713002/) but it's up
to you

[caiw, 2016/07/19 19:36:09]

I just removed it (approach 1).  I think it should be ok.

+
+  # The status of the swarming task.
+  status = ndb.IntegerProperty(
+      default=analysis_status.PENDING, indexed=False)
+
+  # The revision of the failed build.
+  build_revision = ndb.StringProperty(indexed=False)
+
+  # Time when the task is created.
+  created_time = ndb.DateTimeProperty(indexed=True)
+  # Time when the task is started.
+  started_time = ndb.DateTimeProperty(indexed=False)
+  # Time when the task is completed.
+  completed_time = ndb.DateTimeProperty(indexed=False)
+
+  # parameters need to be stored and analyzed later.
+  parameters = ndb.JsonProperty(default={}, indexed=False, compressed=True)