potiuk commented on code in PR #37058: URL: https://github.com/apache/airflow/pull/37058#discussion_r1468907283
########## airflow/io/xcom.py: ########## @@ -0,0 +1,111 @@ +# 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. +from __future__ import annotations + +import json +import sys +import uuid +from typing import TYPE_CHECKING, Any, TypeVar +from urllib.parse import urlsplit + +from airflow.configuration import conf +from airflow.io.path import ObjectStoragePath +from airflow.models.xcom import BaseXCom +from airflow.utils.json import XComDecoder, XComEncoder + +if TYPE_CHECKING: + from sqlalchemy.orm import Session + + from airflow.models import XCom + +T = TypeVar("T") + + +class XComObjectStoreBackend(BaseXCom): + """XCom backend that stores data in an object store.""" + + path = conf.get("core", "xcom_objectstore_path", fallback="") + + @staticmethod + def _get_key(data: str) -> str: + path = conf.get("core", "xcom_objectstore_path", fallback="") + p = ObjectStoragePath(path) + + url = urlsplit(data) + if url.scheme: + k = ObjectStoragePath(data) + + if k.is_relative_to(p) is False: + raise ValueError(f"Invalid key: {data}") + else: + return data.replace(path, "", 1).lstrip("/") + + raise ValueError(f"Not a valid url: {data}") + + @staticmethod + def serialize_value( + value: T, + *, + key: str | None = None, + task_id: str | None = None, + dag_id: str | None = None, + run_id: str | None = None, + map_index: int | None = None, + ) -> bytes | str: + s_val = json.dumps(value, cls=XComEncoder).encode("utf-8") + path = conf.get("core", "xcom_objectstore_path", fallback="") + compression = conf.get("core", "xcom_objectstore_compression", fallback=None) + threshold = conf.getint("core", "xcom_objectstore_threshold", fallback=-1) + + if path and -1 < threshold < sys.getsizeof(value): + p = ObjectStoragePath(path) / f"{run_id}/{task_id}/{str(uuid.uuid4())}" + + if not p.exists(): + p.parent.mkdir(parents=True, exist_ok=True) + + with p.open("wb", compression=compression) as f: + f.write(s_val) + + return BaseXCom.serialize_value(str(p)) + else: + return s_val + + @staticmethod + def deserialize_value( + result: XCom, + ) -> Any: + data = BaseXCom.deserialize_value(result) + path = conf.get("core", "xcom_objectstore_path", fallback="") + try: + p = ObjectStoragePath(path) / XComObjectStoreBackend._get_key(data) Review Comment: There are two potential problems here: 1) there is quite an extra overhead for small values here - where retrieving of small value always involves extra storage call that could be avoided 2) there is a potential (small probablitly of course) - that there will be a storage object created externally and it might wreak havoc Maybe another option would be to add a bool field in the Xcom table to distinquish local/remote? Mostly because of 1). I think it would be a way more performant approach for a number of cases. We've already had precedents with secret backends where reaching out to remote before checking things in the DB caused a lot of cost and network overhead. I think we should learn from that. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
