[GitHub] [airflow] yuqian90 commented on a change in pull request #10153: [AIP-34] Alternative proposal: Add TaskGroup as a DAG construction helper and UI concept with example

[GitBox <gi...@apache.org>]

yuqian90 commented on a change in pull request #10153:
URL: https://github.com/apache/airflow/pull/10153#discussion_r469280080



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File path: airflow/utils/task_group.py
##########
@@ -0,0 +1,233 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+"""
+TaskGroup
+"""
+
+from typing import List, Optional
+
+
+class TaskGroup:
+    """
+    A collection of tasks. Tasks within the TaskGroup have their task_id prefixed with the
+    group_id of the TaskGroup. When set_downstream() or set_upstream() are called on the
+    TaskGroup, it is applied across all tasks within the group if necessary.
+    """
+    def __init__(self, group_id, parent_group=None):
+        if group_id is None:
+            # This creates a root TaskGroup.
+            self.parent_group = None
+        else:
+            if not isinstance(group_id, str):
+                raise ValueError("group_id must be str")
+            if not group_id:
+                raise ValueError("group_id must not be empty")
+            self.parent_group = parent_group or TaskGroupContext.get_current_task_group()
+
+        self._group_id = group_id
+        if self.parent_group:
+            self.parent_group.add(self)
+        self.children = {}
+
+    @classmethod
+    def create_root(cls):
+        """
+        Create a root TaskGroup with no group_id or parent.
+        """
+        return cls(group_id=None)
+
+    @property
+    def is_root(self):
+        """
+        Returns True if this TaskGroup is the root TaskGroup. Otherwise False
+        """
+        return not self.parent_group
+
+    def __iter__(self):
+        for child in self.children.values():
+            if isinstance(child, TaskGroup):
+                for inner_task in child:
+                    yield inner_task
+            else:
+                yield child
+
+    def add(self, task):
+        """
+        Add a task to this TaskGroup.
+        """
+        if task.label in self.children:
+            raise ValueError(f"Duplicate label {task.label} in {self.group_id}")
+        self.children[task.label] = task
+
+    @property
+    def label(self):
+        """
+        group_id excluding parent's group_id.
+        """
+        return self._group_id
+
+    @property
+    def group_id(self):
+        """
+        group_id is prefixed with parent group_id if applicable.
+        """
+        if not self.group_ids:
+            return None
+
+        return ".".join(self.group_ids)
+
+    @property
+    def group_ids(self):
+        """
+        Returns all the group_id of nested TaskGroups as a list, starting from the top.
+        """
+        return list(self._group_ids())[1:]
+
+    def _group_ids(self):
+        if self.parent_group:
+            for group_id in self.parent_group._group_ids():  # pylint: disable=protected-access
+                yield group_id
+
+        yield self._group_id
+
+    def set_downstream(self, task_or_task_list) -> None:

Review comment:
       Sure. will do.




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