Prototype of build orchestrator

The code assumes a different source structure. It requires updating
the path configurations.

Bug: 230448564
Test: N/A
Change-Id: I38bf181eecdd291712212ba8ee6d61b85c3fbb07

orchestrator/demo/hierarchy.py

@@ -0,0 +1,79 @@
+# Copyright (C) 2022 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import os
+import yaml
+
+
+def parse_hierarchy(build_top):
+  """Parse build hierarchy file from given build top directory, and returns a dict from child targets to parent targets.
+
+  Example of hierarchy file:
+  ==========
+  aosp_arm64:
+  - armv8
+  - aosp_cf_arm64_phone
+
+  armv8:
+  - aosp_oriole
+  - aosp_sunfish
+
+  aosp_oriole:
+  - oriole
+
+  aosp_sunfish:
+  - sunfish
+
+  oriole:
+  # leaf
+
+  sunfish:
+  # leaf
+  ==========
+
+  If we parse this yaml, we get a dict looking like:
+
+  {
+      "sunfish": "aosp_sunfish",
+      "oriole": "aosp_oriole",
+      "aosp_oriole": "armv8",
+      "aosp_sunfish": "armv8",
+      "armv8": "aosp_arm64",
+      "aosp_cf_arm64_phone": "aosp_arm64",
+      "aosp_arm64": None, # no parent
+  }
+  """
+  metadata_path = os.path.join(build_top, 'tools', 'build', 'hierarchy.yaml')
+  if not os.path.isfile(metadata_path):
+    raise RuntimeError("target metadata file %s doesn't exist" % metadata_path)
+
+  with open(metadata_path, 'r') as f:
+    hierarchy_yaml = yaml.load(f, Loader=yaml.SafeLoader)
+
+  hierarchy_map = dict()
+
+  for parent_target, child_targets in hierarchy_yaml.items():
+    if not child_targets:
+      # leaf
+      continue
+    for child_target in child_targets:
+      hierarchy_map[child_target] = parent_target
+
+  for parent_target in hierarchy_yaml:
+    # targets with no parent
+    if parent_target not in hierarchy_map:
+      hierarchy_map[parent_target] = None
+
+  return hierarchy_map