Source code for swh.core.api.serializers

# Copyright (C) 2015-2020  The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

import base64
import datetime
from enum import Enum
import json
import traceback
import types
from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
from uuid import UUID

import iso8601
import msgpack
from requests import Response

from swh.core.api.classes import PagedResult

[docs]def encode_datetime(dt: datetime.datetime) -> str: """Wrapper of datetime.datetime.isoformat() that forbids naive datetimes.""" if dt.tzinfo is None: raise TypeError("can not serialize naive 'datetime.datetime' object") return dt.isoformat()
def _encode_paged_result(obj: PagedResult) -> Dict[str, Any]: """Serialize PagedResult to a Dict.""" return { "results": obj.results, "next_page_token": obj.next_page_token, } def _decode_paged_result(obj: Dict[str, Any]) -> PagedResult: """Deserialize Dict into PagedResult""" return PagedResult(results=obj["results"], next_page_token=obj["next_page_token"],)
[docs]def exception_to_dict(exception: Exception) -> Dict[str, Any]: tb = traceback.format_exception(None, exception, exception.__traceback__) exc_type = type(exception) return { "type": exc_type.__name__, "module": exc_type.__module__, "args": exception.args, "message": str(exception), "traceback": tb, }
[docs]def dict_to_exception(exc_dict: Dict[str, Any]) -> Exception: temp = __import__(exc_dict["module"], fromlist=[exc_dict["type"]]) try: return getattr(temp, exc_dict["type"])(*exc_dict["args"]) except Exception: # custom Exception type cannot be rebuilt, fallback to base Exception type return Exception(exc_dict["message"])
[docs]def encode_timedelta(td: datetime.timedelta) -> Dict[str, int]: return { "days": td.days, "seconds": td.seconds, "microseconds": td.microseconds, }
ENCODERS: List[Tuple[type, str, Callable]] = [ (UUID, "uuid", str), (datetime.timedelta, "timedelta", encode_timedelta), (PagedResult, "paged_result", _encode_paged_result), (Exception, "exception", exception_to_dict), ] JSON_ENCODERS: List[Tuple[type, str, Callable]] = [ (datetime.datetime, "datetime", encode_datetime), (bytes, "bytes", lambda o: base64.b85encode(o).decode("ascii")), ] DECODERS: Dict[str, Callable] = { "timedelta": lambda d: datetime.timedelta(**d), "uuid": UUID, "paged_result": _decode_paged_result, "exception": dict_to_exception, # for BW compat, to be moved in JSON_DECODERS ASAP "datetime": lambda d: iso8601.parse_date(d, default_timezone=None), } JSON_DECODERS: Dict[str, Callable] = { "bytes": base64.b85decode, }
[docs]def get_encoders( extra_encoders: Optional[List[Tuple[Type, str, Callable]]], with_json: bool = False ) -> List[Tuple[Type, str, Callable]]: encoders = ENCODERS if with_json: encoders = [*encoders, *JSON_ENCODERS] if extra_encoders: encoders = [*encoders, *extra_encoders] return encoders
[docs]def get_decoders( extra_decoders: Optional[Dict[str, Callable]], with_json: bool = False ) -> Dict[str, Callable]: decoders = DECODERS if with_json: decoders = {**decoders, **JSON_DECODERS} if extra_decoders is not None: decoders = {**decoders, **extra_decoders} return decoders
[docs]class MsgpackExtTypeCodes(Enum): LONG_INT = 1 LONG_NEG_INT = 2
[docs]def encode_data_client(data: Any, extra_encoders=None) -> bytes: try: return msgpack_dumps(data, extra_encoders=extra_encoders) except OverflowError as e: raise ValueError("Limits were reached. Please, check your input.\n" + str(e))
[docs]def decode_response(response: Response, extra_decoders=None) -> Any: content_type = response.headers["content-type"] if content_type.startswith("application/x-msgpack"): r = msgpack_loads(response.content, extra_decoders=extra_decoders) elif content_type.startswith("application/json"): r = json_loads(response.text, extra_decoders=extra_decoders) elif content_type.startswith("text/"): r = response.text else: raise ValueError("Wrong content type `%s` for API response" % content_type) return r
[docs]class SWHJSONEncoder(json.JSONEncoder): """JSON encoder for data structures generated by Software Heritage. This JSON encoder extends the default Python JSON encoder and adds awareness for the following specific types: - bytes (get encoded as a Base85 string); - datetime.datetime (get encoded as an ISO8601 string). Non-standard types get encoded as a a dictionary with two keys: - swhtype with value 'bytes' or 'datetime'; - d containing the encoded value. SWHJSONEncoder also encodes arbitrary iterables as a list (allowing serialization of generators). Caveats: Limitations in the JSONEncoder extension mechanism prevent us from "escaping" dictionaries that only contain the swhtype and d keys, and therefore arbitrary data structures can't be round-tripped through SWHJSONEncoder and SWHJSONDecoder. """ def __init__(self, extra_encoders=None, **kwargs): super().__init__(**kwargs) self.encoders = get_encoders(extra_encoders, with_json=True)
[docs] def default(self, o: Any) -> Union[Dict[str, Union[Dict[str, int], str]], list]: for (type_, type_name, encoder) in self.encoders: if isinstance(o, type_): return { "swhtype": type_name, "d": encoder(o), } try: return super().default(o) except TypeError as e: try: iterable = iter(o) except TypeError: raise e from None else: return list(iterable)
[docs]class SWHJSONDecoder(json.JSONDecoder): """JSON decoder for data structures encoded with SWHJSONEncoder. This JSON decoder extends the default Python JSON decoder, allowing the decoding of: - bytes (encoded as a Base85 string); - datetime.datetime (encoded as an ISO8601 string). Non-standard types must be encoded as a a dictionary with exactly two keys: - swhtype with value 'bytes' or 'datetime'; - d containing the encoded value. To limit the impact our encoding, if the swhtype key doesn't contain a known value, the dictionary is decoded as-is. """ def __init__(self, extra_decoders=None, **kwargs): super().__init__(**kwargs) self.decoders = get_decoders(extra_decoders, with_json=True)
[docs] def decode_data(self, o: Any) -> Any: if isinstance(o, dict): if set(o.keys()) == {"d", "swhtype"}: if o["swhtype"] == "bytes": return base64.b85decode(o["d"]) decoder = self.decoders.get(o["swhtype"]) if decoder: return decoder(self.decode_data(o["d"])) return {key: self.decode_data(value) for key, value in o.items()} if isinstance(o, list): return [self.decode_data(value) for value in o] else: return o
[docs] def raw_decode(self, s: str, idx: int = 0) -> Tuple[Any, int]: data, index = super().raw_decode(s, idx) return self.decode_data(data), index
[docs]def json_dumps(data: Any, extra_encoders=None) -> str: return json.dumps(data, cls=SWHJSONEncoder, extra_encoders=extra_encoders)
[docs]def json_loads(data: str, extra_decoders=None) -> Any: return json.loads(data, cls=SWHJSONDecoder, extra_decoders=extra_decoders)
[docs]def msgpack_dumps(data: Any, extra_encoders=None) -> bytes: """Write data as a msgpack stream""" encoders = get_encoders(extra_encoders) def encode_types(obj): if isinstance(obj, int): # integer overflowed while packing. Handle it as an extended type if obj > 0: code = MsgpackExtTypeCodes.LONG_INT.value else: code = MsgpackExtTypeCodes.LONG_NEG_INT.value obj = -obj length, rem = divmod(obj.bit_length(), 8) if rem: length += 1 return msgpack.ExtType(code, int.to_bytes(obj, length, "big")) if isinstance(obj, types.GeneratorType): return list(obj) for (type_, type_name, encoder) in encoders: if isinstance(obj, type_): return { b"swhtype": type_name, b"d": encoder(obj), } return obj return msgpack.packb( data, use_bin_type=True, datetime=True, # encode datetime as msgpack.Timestamp default=encode_types, )
[docs]def msgpack_loads(data: bytes, extra_decoders=None) -> Any: """Read data as a msgpack stream. .. Caution:: This function is used by swh.journal to decode the contents of the journal. This function **must** be kept backwards-compatible. """ decoders = get_decoders(extra_decoders) def ext_hook(code, data): if code == MsgpackExtTypeCodes.LONG_INT.value: return int.from_bytes(data, "big") elif code == MsgpackExtTypeCodes.LONG_NEG_INT.value: return -int.from_bytes(data, "big") raise ValueError("Unknown msgpack extended code %s" % code) def decode_types(obj): # Support for current encodings if set(obj.keys()) == {b"d", b"swhtype"}: decoder = decoders.get(obj[b"swhtype"]) if decoder: return decoder(obj[b"d"]) # Fallthrough return obj try: try: return msgpack.unpackb( data, raw=False, object_hook=decode_types, ext_hook=ext_hook, strict_map_key=False, timestamp=3, # convert Timestamp in datetime objects (tz UTC) ) except TypeError: # msgpack < 0.6.0 return msgpack.unpackb( data, raw=False, object_hook=decode_types, ext_hook=ext_hook ) except TypeError: # msgpack < 0.5.2 return msgpack.unpackb( data, encoding="utf-8", object_hook=decode_types, ext_hook=ext_hook )