OpenSlides/openslides/utils/autoupdate.py

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import threading
from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
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from asgiref.sync import async_to_sync
from channels.layers import get_channel_layer
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from django.db.models import Model
from .cache import element_cache, get_element_id
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from .collection import CollectionElement
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def inform_changed_data(instances: Union[Iterable[Model], Model]) -> None:
"""
Informs the autoupdate system and the caching system about the creation or
update of an element.
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The argument instances can be one instance or an iterable over instances.
"""
root_instances = set()
if not isinstance(instances, Iterable):
instances = (instances, )
for instance in instances:
try:
root_instances.add(instance.get_root_rest_element())
except AttributeError:
# Instance has no method get_root_rest_element. Just ignore it.
pass
collection_elements = {}
for root_instance in root_instances:
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collection_element = CollectionElement.from_instance(root_instance)
key = root_instance.get_collection_string() + str(root_instance.get_rest_pk())
collection_elements[key] = collection_element
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bundle = autoupdate_bundle.get(threading.get_ident())
if bundle is not None:
# Put all collection elements into the autoupdate_bundle.
bundle.update(collection_elements)
else:
# Send autoupdate directly
handle_collection_elements(collection_elements.values())
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def inform_deleted_data(elements: Iterable[Tuple[str, int]]) -> None:
"""
Informs the autoupdate system and the caching system about the deletion of
elements.
"""
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collection_elements: Dict[str, Any] = {}
for element in elements:
collection_element = CollectionElement.from_values(
collection_string=element[0],
id=element[1],
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deleted=True)
key = element[0] + str(element[1])
collection_elements[key] = collection_element
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bundle = autoupdate_bundle.get(threading.get_ident())
if bundle is not None:
# Put all collection elements into the autoupdate_bundle.
bundle.update(collection_elements)
else:
# Send autoupdate directly
handle_collection_elements(collection_elements.values())
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def inform_data_collection_element_list(collection_elements: List[CollectionElement]) -> None:
"""
Informs the autoupdate system about some collection elements. This is
used just to send some data to all users.
"""
elements = {}
for collection_element in collection_elements:
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key = collection_element.collection_string + str(collection_element.id)
elements[key] = collection_element
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bundle = autoupdate_bundle.get(threading.get_ident())
if bundle is not None:
# Put all collection elements into the autoupdate_bundle.
bundle.update(elements)
else:
# Send autoupdate directly
handle_collection_elements(elements.values())
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"""
Global container for autoupdate bundles
"""
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autoupdate_bundle: Dict[int, Dict[str, CollectionElement]] = {}
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class AutoupdateBundleMiddleware:
"""
Middleware to handle autoupdate bundling.
"""
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def __init__(self, get_response: Any) -> None:
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self.get_response = get_response
# One-time configuration and initialization.
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def __call__(self, request: Any) -> Any:
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thread_id = threading.get_ident()
autoupdate_bundle[thread_id] = {}
response = self.get_response(request)
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bundle: Dict[str, CollectionElement] = autoupdate_bundle.pop(thread_id)
handle_collection_elements(bundle.values())
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return response
def handle_collection_elements(collection_elements: Iterable[CollectionElement]) -> None:
"""
Helper function, that sends collection_elements through a channel to the
autoupdate system and updates the cache.
Does nothing if collection_elements is empty.
"""
async def update_cache(collection_elements: Iterable[CollectionElement]) -> int:
"""
Async helper function to update the cache.
Returns the change_id
"""
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cache_elements: Dict[str, Optional[Dict[str, Any]]] = {}
for element in collection_elements:
element_id = get_element_id(element.collection_string, element.id)
if element.is_deleted():
cache_elements[element_id] = None
else:
cache_elements[element_id] = element.get_full_data()
return await element_cache.change_elements(cache_elements)
async def async_handle_collection_elements(collection_elements: Iterable[CollectionElement]) -> None:
"""
Async helper function to update cache and send autoupdate.
"""
# Update cache
change_id = await update_cache(collection_elements)
# Send autoupdate
channel_layer = get_channel_layer()
await channel_layer.group_send(
"autoupdate",
{
"type": "send_data",
"change_id": change_id,
},
)
if collection_elements:
# TODO: Save histroy here using sync code
# Update cache and send autoupdate
async_to_sync(async_handle_collection_elements)(collection_elements)