209 lines
6.9 KiB
Python
209 lines
6.9 KiB
Python
import json
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import threading
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from collections import defaultdict
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from contextlib import contextmanager
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from typing import Any, Dict, Iterable, Iterator, List, Optional
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from asgiref.sync import async_to_sync
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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 .stream import stream
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from .timing import Timing
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from .utils import get_model_from_collection_string
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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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"""
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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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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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self._disable_history = False
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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 disable_history(self) -> None:
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self._disable_history = True
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def done(self) -> Optional[int]:
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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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Returns the change id, if there are autoupdate elements. Otherwise none.
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"""
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if not self.autoupdate_elements:
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return None
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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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if not self._disable_history:
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save_history(self.element_iterator)
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# Update cache and send autoupdate using async code.
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change_id = async_to_sync(self.dispatch_autoupdate)()
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return change_id
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@property
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def element_iterator(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 get_data_for_cache(self) -> Dict[str, Optional[Dict[str, Any]]]:
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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.element_iterator:
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element_id = get_element_id(element["collection_string"], element["id"])
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cache_elements[element_id] = element.get("full_data")
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return cache_elements
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async def dispatch_autoupdate(self) -> int:
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"""
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Async helper function to update cache and send autoupdate.
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Return the change_id
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"""
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# Update cache
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cache_elements = await self.get_data_for_cache()
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change_id = await element_cache.change_elements(cache_elements)
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# Send autoupdate
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autoupdate_payload = {"elements": cache_elements, "change_id": change_id}
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await stream.send("autoupdate", autoupdate_payload)
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return change_id
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@contextmanager
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def autoupdate_bundle() -> Iterator[AutoupdateBundle]:
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bundle = _autoupdate_bundle.get(threading.get_ident())
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autodone = False
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if bundle is None:
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bundle = AutoupdateBundle()
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autodone = True
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yield bundle
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if autodone:
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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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timing = Timing("request")
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response = self.get_response(request)
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timing()
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status_ok = response.status_code >= 200 and response.status_code < 300
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status_redirect = response.status_code >= 300 and response.status_code < 400
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# rewrite the response by adding the autoupdate on any success-case (2xx status)
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bundle: AutoupdateBundle = _autoupdate_bundle.pop(thread_id)
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if status_ok or status_redirect:
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change_id = bundle.done()
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# inject the change id, if there was an autoupdate and the response status is
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# ok (and not redirect; redirects do not have a useful content)
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if change_id is not None and status_ok:
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# Inject the autoupdate in the response.
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# The complete response body will be overwritten!
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content = {"change_id": change_id, "data": response.data}
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# Note: autoupdate may be none on skipped ones (which should not happen
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# since the user has made the request....)
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response.content = json.dumps(content)
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timing(True)
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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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