bolkedebruin commented on code in PR #37058: URL: https://github.com/apache/airflow/pull/37058#discussion_r1476602650
########## airflow/providers/common/io/xcom/backend.py: ########## @@ -0,0 +1,166 @@ +# 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 uuid +from typing import TYPE_CHECKING, Any, TypeVar +from urllib.parse import urlsplit + +import fsspec.utils + +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") + +SECTION = "common.io" + + +def _is_relative_to(o: ObjectStoragePath, other: ObjectStoragePath) -> bool: + """This is a port of the pathlib.Path.is_relative_to method. It is not available in python 3.8.""" + if hasattr(o, "is_relative_to"): + return o.is_relative_to(other) + + try: + o.relative_to(other) + return True + except ValueError: + return False + + +def _get_compression_suffix(compression: str) -> str: + """This returns the compression suffix for the given compression. + + :raises ValueError: if the compression is not supported + """ + for suffix, c in fsspec.utils.compressions.items(): + if c == compression: + return suffix + + raise ValueError(f"Compression {compression} is not supported. Make sure it is installed.") + + +class XComObjectStoreBackend(BaseXCom): + """XCom backend that stores data in an object store or database depending on the size of the data. + + If the value is larger than the configured threshold, it will be stored in an object store. + Otherwise, it will be stored in the database. If it is stored in an object store, the path + to the object in the store will be returned and saved in the database (by BaseXCom). Otherwise, the value + itself will be returned and thus saved in the database. + """ + + @staticmethod + def _get_key(data: str) -> str: + """This gets the key from the url and normalizes it to be relative to the configured path. + + :raises ValueError: if the key is not relative to the configured path + :raises TypeError: if the url is not a valid url or cannot be split + """ + path = conf.get(SECTION, "xcom_objectstore_path", fallback="") + p = ObjectStoragePath(path) + + try: + url = urlsplit(data) + except AttributeError: + raise TypeError(f"Not a valid url: {data}") + + if url.scheme: + k = ObjectStoragePath(data) + + if _is_relative_to(k, 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(SECTION, "xcom_objectstore_path", fallback="") + compression = conf.get(SECTION, "xcom_objectstore_compression", fallback=None) + + if compression: + suffix = "." + _get_compression_suffix(compression) + else: + suffix = "" + + threshold = conf.getint(SECTION, "xcom_objectstore_threshold", fallback=-1) + + if path and -1 < threshold < len(s_val): + # safeguard against collisions + while True: + p = ObjectStoragePath(path) / f"{dag_id}/{run_id}/{task_id}/{str(uuid.uuid4())}{suffix}" + if not p.exists(): + break + + if not p.parent.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 Review Comment: Mmm no not really, as s_val will be equal to what BaseXCom.serializer spits out but probably should call it here and move s_val to the if block. update: which we cannot do as we need the len of the serialized value update: fixed. update: reverted this as we cannot use the same deserialize method from BaseXcom. 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