265 lines
8.5 KiB
Python
265 lines
8.5 KiB
Python
import threading
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from collections import defaultdict
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from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
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from asgiref.sync import async_to_sync
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from channels.layers import get_channel_layer
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from django.db.models import Model
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from mypy_extensions import TypedDict
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from .cache import element_cache, get_element_id
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from .projector import get_projector_data
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from .utils import get_model_from_collection_string, is_iterable
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class AutoupdateElementBase(TypedDict):
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id: int
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collection_string: str
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class AutoupdateElement(AutoupdateElementBase, total=False):
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"""
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Data container to handle one root rest element for the autoupdate, history
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and caching process.
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The fields `id` and `collection_string` are required to identify the element. All
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other fields are optional:
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full_data: If a value is given (dict or None), it won't be loaded from the DB.
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If otherwise no value is given, the AutoupdateBundle will try to resolve the object
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from the DB and serialize it into the full_data.
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information and user_id: These fields are for the history indicating what and who
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made changes.
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disable_history: If this is True, the element (and the containing full_data) won't
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be saved into the history. Information and user_id is then irrelevant.
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no_delete_on_restriction is a flag, which is saved into the models in the cache
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as the _no_delete_on_restriction key. If this is true, there should neither be an
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entry for one specific model in the changed *nor the deleted* part of the
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autoupdate, if the model was restricted.
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"""
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information: List[str]
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user_id: Optional[int]
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disable_history: bool
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no_delete_on_restriction: bool
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full_data: Optional[Dict[str, Any]]
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class AutoupdateBundle:
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"""
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Collects changed elements via inform*_data. After the collecting-step is finished,
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the bundle releases all changes to the history and element cache via `.done()`.
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"""
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def __init__(self) -> None:
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self.autoupdate_elements: Dict[str, Dict[int, AutoupdateElement]] = defaultdict(
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dict
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)
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def add(self, elements: Iterable[AutoupdateElement]) -> None:
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""" Adds the elements to the bundle """
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for element in elements:
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self.autoupdate_elements[element["collection_string"]][
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element["id"]
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] = element
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def done(self) -> None:
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"""
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Finishes the bundle by resolving all missing data and passing it to
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the history and element cache.
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"""
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if not self.autoupdate_elements:
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return
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for collection, elements in self.autoupdate_elements.items():
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# Get all ids, that do not have a full_data key
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# (element["full_data"]=None will not be resolved again!)
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ids = [
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element["id"]
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for element in elements.values()
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if "full_data" not in element
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]
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if ids:
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# Get all missing models. If e.g. an id could not be found it
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# means, it was deleted. Since there is not full_data entry
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# for the element, the data will be interpreted as None, which
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# is correct for deleted elements.
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model_class = get_model_from_collection_string(collection)
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for full_data in model_class.get_elements(ids):
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elements[full_data["id"]]["full_data"] = full_data
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# Save histroy here using sync code.
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save_history(self.elements)
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# Update cache and send autoupdate using async code.
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async_to_sync(self.async_handle_collection_elements)()
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@property
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def elements(self) -> Iterable[AutoupdateElement]:
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""" Iterator for all elements in this bundle """
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for elements in self.autoupdate_elements.values():
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yield from elements.values()
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async def update_cache(self) -> int:
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"""
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Async helper function to update the cache.
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Returns the change_id
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"""
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cache_elements: Dict[str, Optional[Dict[str, Any]]] = {}
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for element in self.elements:
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element_id = get_element_id(element["collection_string"], element["id"])
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full_data = element.get("full_data")
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if full_data:
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full_data["_no_delete_on_restriction"] = element.get(
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"no_delete_on_restriction", False
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)
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cache_elements[element_id] = full_data
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return await element_cache.change_elements(cache_elements)
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async def async_handle_collection_elements(self) -> None:
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"""
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Async helper function to update cache and send autoupdate.
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"""
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# Update cache
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change_id = await self.update_cache()
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# Send autoupdate
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channel_layer = get_channel_layer()
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await channel_layer.group_send(
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"autoupdate", {"type": "send_data", "change_id": change_id}
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)
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projector_data = await get_projector_data()
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# Send projector
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channel_layer = get_channel_layer()
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await channel_layer.group_send(
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"projector",
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{
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"type": "projector_changed",
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"data": projector_data,
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"change_id": change_id,
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},
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)
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def inform_changed_data(
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instances: Union[Iterable[Model], Model],
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information: List[str] = None,
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user_id: Optional[int] = None,
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disable_history: bool = False,
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no_delete_on_restriction: bool = False,
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) -> None:
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"""
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Informs the autoupdate system and the caching system about the creation or
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update of an element.
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The argument instances can be one instance or an iterable over instances.
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History creation is enabled.
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"""
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if information is None:
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information = []
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if not is_iterable(instances):
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instances = (instances,)
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root_instances = set(instance.get_root_rest_element() for instance in instances)
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elements = [
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AutoupdateElement(
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id=root_instance.get_rest_pk(),
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collection_string=root_instance.get_collection_string(),
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disable_history=disable_history,
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information=information,
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user_id=user_id,
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no_delete_on_restriction=no_delete_on_restriction,
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)
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for root_instance in root_instances
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]
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inform_elements(elements)
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def inform_deleted_data(
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deleted_elements: Iterable[Tuple[str, int]],
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information: List[str] = None,
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user_id: Optional[int] = None,
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) -> None:
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"""
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Informs the autoupdate system and the caching system about the deletion of
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elements.
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History creation is enabled.
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"""
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if information is None:
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information = []
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elements = [
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AutoupdateElement(
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id=deleted_element[1],
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collection_string=deleted_element[0],
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full_data=None,
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information=information,
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user_id=user_id,
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)
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for deleted_element in deleted_elements
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]
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inform_elements(elements)
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def inform_elements(elements: Iterable[AutoupdateElement]) -> None:
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"""
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Informs the autoupdate system about some elements. This is used just to send
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some data to all users.
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If you want to save history information, user id or disable history you
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have to put information or flag inside the elements.
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"""
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bundle = autoupdate_bundle.get(threading.get_ident())
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if bundle is not None:
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# Put all elements into the autoupdate_bundle.
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bundle.add(elements)
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else:
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# Send autoupdate directly
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bundle = AutoupdateBundle()
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bundle.add(elements)
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bundle.done()
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"""
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Global container for autoupdate bundles
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"""
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autoupdate_bundle: Dict[int, AutoupdateBundle] = {}
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class AutoupdateBundleMiddleware:
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"""
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Middleware to handle autoupdate bundling.
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"""
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def __init__(self, get_response: Any) -> None:
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self.get_response = get_response
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# One-time configuration and initialization.
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def __call__(self, request: Any) -> Any:
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thread_id = threading.get_ident()
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autoupdate_bundle[thread_id] = AutoupdateBundle()
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response = self.get_response(request)
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bundle: AutoupdateBundle = autoupdate_bundle.pop(thread_id)
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bundle.done()
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return response
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def save_history(elements: Iterable[AutoupdateElement]) -> Iterable:
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"""
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Thin wrapper around the call of history saving manager method.
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This is separated to patch it during tests.
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"""
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from ..core.models import History
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return History.objects.add_elements(elements)
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