Add concept of bot config and test spec database (BotConfigAndTestDB).

scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py

Index: scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
diff --git a/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py b/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
new file mode 100644
index 0000000000000000000000000000000000000000..c90aa3612e68646aacf4c4551bde6277f9741f0a
--- /dev/null
+++ b/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
@@ -0,0 +1,51 @@
+# 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.
+
+class BotConfigAndTestDB(object):
+  """An immutable database of bot configurations and test specifications.
+  Holds the data for potentially multiple waterfalls (masternames). Most
+  queries against this database are made with (mastername, buildername)
+  pairs.
+  """
+
+  def __init__(self):
+    # Indexed by mastername. Each entry contains a master_dict and a
+    # test_spec.
+    self._db = {}
+
+  def _add_master_dict_and_test_spec(self, mastername, master_dict, test_spec):
+    """Only used during construction in chromium_tests.prepare_checkout. Do not
+    call this externally.
+    """
+    # TODO(kbr): currently the master_dicts that are created by
+    # get_master_dict_with_dynamic_tests are over-specialized to a
+    # particular builder -- the "enable_swarming" flag paradoxically comes
+    # from that builder, rather than from each individual builder and/or
+    # the parent builder. This needs to be fixed so that there's exactly
+    # one master_dict per waterfall.
+    assert mastername not in self._db, (
+        'Illegal attempt to add multiple master dictionaries for waterfall %s' %
+        (mastername))
+    self._db[mastername] = { 'master_dict': master_dict,
+                             'test_spec': test_spec }
+
+  def get_bot_config(self, mastername, buildername):
+    return self._db[mastername]['master_dict'].get('builders', {}).get(
+        buildername)
+
+  def get_master_settings(self, mastername):
+    return self._db[mastername]['master_dict'].get('settings', {})
+
+  def bot_configs_matching_parent_buildername(
+      self, mastername, parent_buildername):
+    """A generator of all the (buildername, bot_config) tuples whose
+    parent_buildername is the passed one on the given master.
+    """
+    for buildername, bot_config in self._db[mastername]['master_dict'].get(
+        'builders', {}).iteritems():
+      if bot_config.get('parent_buildername') == parent_buildername:
+        yield buildername, bot_config
+
+  def get_test_spec(self, mastername, buildername):
+    return self._db[mastername]['test_spec'].get(buildername, {})