1 files changed, 71 insertions, 0 deletions
diff --git a/tools/edit_monitor/utils.py b/tools/edit_monitor/utils.py
new file mode 100644
index 0000000000..1a3275c6e2
--- /dev/null
+++ b/tools/edit_monitor/utils.py
@@ -0,0 +1,71 @@
+# Copyright 2024, 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 hashlib
+import logging
+import os
+
+
+def is_feature_enabled(
+    feature_name: str,
+    user_name: str,
+    enable_flag: str = None,
+    rollout_flag: str = None,
+) -> bool:
+  """Determine whether the given feature is enabled.
+
+  Whether a given feature is enabled or not depends on two flags: 1) the
+  enable_flag that explicitly enable/disable the feature and 2) the rollout_flag
+  that controls the rollout percentage.
+
+  Args:
+    feature_name: name of the feature.
+    user_name: system user name.
+    enable_flag: name of the env var that enables/disables the feature
+      explicitly.
+    rollout_flg: name of the env var that controls the rollout percentage, the
+      value stored in the env var should be an int between 0 and 100 string
+  """
+  if enable_flag:
+    if os.environ.get(enable_flag, "") == "false":
+      logging.info("feature: %s is disabled", feature_name)
+      return False
+
+    if os.environ.get(enable_flag, "") == "true":
+      logging.info("feature: %s is enabled", feature_name)
+      return True
+
+  if not rollout_flag:
+    return True
+
+  hash_object = hashlib.sha256()
+  hash_object.update((user_name + feature_name).encode("utf-8"))
+  hash_number = int(hash_object.hexdigest(), 16) % 100
+
+  roll_out_percentage = os.environ.get(rollout_flag, "0")
+  try:
+    percentage = int(roll_out_percentage)
+    if percentage < 0 or percentage > 100:
+      logging.warning(
+          "Rollout percentage: %s out of range, disable the feature.",
+          roll_out_percentage,
+      )
+      return False
+    return hash_number < percentage
+  except ValueError:
+    logging.warning(
+        "Invalid rollout percentage: %s, disable the feature.",
+        roll_out_percentage,
+    )
+    return False