OpenSlides/openslides/utils/autoupdate.py

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import json
import time
import warnings
from collections import defaultdict
from typing import Any, Dict, Generator, Iterable, List, Tuple, Union
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from channels import Channel, Group
from channels.asgi import get_channel_layer
from channels.auth import channel_session_user, channel_session_user_from_http
from django.apps import apps
from django.core.exceptions import ObjectDoesNotExist
from django.db import transaction
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from django.db.models import Model
from ..core.config import config
from ..core.models import Projector
from .auth import anonymous_is_enabled, has_perm, user_to_collection_user
from .cache import restricted_data_cache, websocket_user_cache
from .collection import AutoupdateFormat # noqa
from .collection import (
ChannelMessageFormat,
Collection,
CollectionElement,
format_for_autoupdate,
from_channel_message,
to_channel_message,
)
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def send_or_wait(send_func: Any, *args: Any, **kwargs: Any) -> None:
"""
Wrapper for channels' send() method.
If the method send() raises ChannelFull exception the worker waits for 20
milliseconds and tries again. After 5 secondes it gives up, drops the
channel message and writes a warning to stderr.
Django channels' consumer atomicity feature is disabled.
"""
kwargs['immediately'] = True
for i in range(250):
try:
send_func(*args, **kwargs)
except get_channel_layer().ChannelFull:
time.sleep(0.02)
else:
break
else:
warnings.warn(
'Channel layer is full. Channel message dropped.',
RuntimeWarning
)
@channel_session_user_from_http
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def ws_add_site(message: Any) -> None:
"""
Adds the websocket connection to a group specific to the connecting user.
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The group with the name 'user-None' stands for all anonymous users.
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Send all "startup-data" through the connection.
"""
if not anonymous_is_enabled() and not message.user.id:
send_or_wait(message.reply_channel.send, {'accept': False})
return
Group('site').add(message.reply_channel)
message.channel_session['user_id'] = message.user.id
# Saves the reply channel to the user. Uses 0 for anonymous users.
websocket_user_cache.add(message.user.id or 0, message.reply_channel.name)
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# Open the websocket connection.
send_or_wait(message.reply_channel.send, {'accept': True})
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# Collect all elements that shoud be send to the client when the websocket
# connection is established.
user = user_to_collection_user(message.user.id)
user_id = user.id if user is not None else 0
if restricted_data_cache.exists_for_user(user_id):
output = restricted_data_cache.get_data(user_id)
else:
output = []
for collection in get_startup_collections():
access_permissions = collection.get_access_permissions()
restricted_data = access_permissions.get_restricted_data(collection.get_full_data(), user)
for data in restricted_data:
if data is None:
# We do not want to send 'deleted' objects on startup.
# That's why we skip such data.
continue
formatted_data = format_for_autoupdate(
collection_string=collection.collection_string,
id=data['id'],
action='changed',
data=data)
output.append(formatted_data)
# Cache restricted data for user
restricted_data_cache.add_element(
user_id,
collection.collection_string,
data['id'],
formatted_data)
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# Send all data.
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if output:
send_or_wait(message.reply_channel.send, {'text': json.dumps(output)})
@channel_session_user
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def ws_disconnect_site(message: Any) -> None:
"""
This function is called, when a client on the site disconnects.
"""
Group('site').discard(message.reply_channel)
websocket_user_cache.remove(message.user.id or 0, message.reply_channel.name)
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@channel_session_user
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def ws_receive_site(message: Any) -> None:
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"""
This function is called if a message from a client comes in. The message
should be a list. Every item is broadcasted to the given users (or all
users if no user list is given) if it is a notify element.
The server adds the sender's user id (0 for anonymous) and reply
channel name so that a receiver client may reply to the sender or to all
sender's instances.
"""
try:
incomming = json.loads(message.content['text'])
except ValueError:
# Message content is invalid. Just do nothing.
pass
else:
if isinstance(incomming, list):
# Parse all items
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receivers_users = defaultdict(list) # type: Dict[int, List[Any]]
receivers_reply_channels = defaultdict(list) # type: Dict[str, List[Any]]
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items_for_all = []
for item in incomming:
if item.get('collection') == 'notify':
use_receivers_dict = False
item['senderReplyChannelName'] = message.reply_channel.name
item['senderUserId'] = message.user.id or 0
# Force the params to be a dict
if not isinstance(item.get('params'), dict):
item['params'] = {}
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users = item.get('users')
if isinstance(users, list):
# Send this item only to all reply channels of some site users.
for user_id in users:
receivers_users[user_id].append(item)
use_receivers_dict = True
reply_channels = item.get('replyChannels')
if isinstance(reply_channels, list):
# Send this item only to some reply channels.
for reply_channel_name in reply_channels:
receivers_reply_channels[reply_channel_name].append(item)
use_receivers_dict = True
if not use_receivers_dict:
# Send this item to all reply channels.
items_for_all.append(item)
# Send all items
for user_id, channel_names in websocket_user_cache.get_all().items():
output = receivers_users[user_id]
if len(output) > 0:
for channel_name in channel_names:
send_or_wait(Channel(channel_name).send, {'text': json.dumps(output)})
for channel_name, output in receivers_reply_channels.items():
if len(output) > 0:
send_or_wait(Channel(channel_name).send, {'text': json.dumps(output)})
if len(items_for_all) > 0:
send_or_wait(Group('site').send, {'text': json.dumps(items_for_all)})
@channel_session_user_from_http
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def ws_add_projector(message: Any, projector_id: int) -> None:
"""
Adds the websocket connection to a group specific to the projector with the given id.
Also sends all data that are shown on the projector.
"""
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user = user_to_collection_user(message.user.id)
if not has_perm(user, 'core.can_see_projector'):
send_or_wait(message.reply_channel.send, {'text': 'No permissions to see this projector.'})
else:
try:
projector = Projector.objects.get(pk=projector_id)
except Projector.DoesNotExist:
send_or_wait(message.reply_channel.send, {'text': 'The projector {} does not exist.'.format(projector_id)})
else:
# At first, the client is added to the projector group, so it is
# informed if the data change.
Group('projector-{}'.format(projector_id)).add(message.reply_channel)
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# Then it is also added to the global projector group which is
# used for broadcasting data.
Group('projector-all').add(message.reply_channel)
# Now check whether broadcast is active at the moment. If yes,
# change the local projector variable.
if config['projector_broadcast'] > 0:
projector = Projector.objects.get(pk=config['projector_broadcast'])
# Collect all elements that are on the projector.
output = [] # type: List[AutoupdateFormat]
for requirement in projector.get_all_requirements():
required_collection_element = CollectionElement.from_instance(requirement)
output.append(required_collection_element.as_autoupdate_for_projector())
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# Collect all config elements.
config_collection = Collection(config.get_collection_string())
projector_data = (config_collection.get_access_permissions()
.get_projector_data(config_collection.get_full_data()))
for data in projector_data:
output.append(format_for_autoupdate(
config_collection.collection_string,
data['id'],
'changed',
data))
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# Collect the projector instance.
collection_element = CollectionElement.from_instance(projector)
output.append(collection_element.as_autoupdate_for_projector())
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# Send all the data that were only collected before.
send_or_wait(message.reply_channel.send, {'text': json.dumps(output)})
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def ws_disconnect_projector(message: Any, projector_id: int) -> None:
"""
This function is called, when a client on the projector disconnects.
"""
Group('projector-{}'.format(projector_id)).discard(message.reply_channel)
def send_data(message: ChannelMessageFormat) -> None:
"""
Informs all site users and projector clients about changed data.
"""
collection_elements = from_channel_message(message)
# Send data to site users.
for user_id, channel_names in websocket_user_cache.get_all().items():
if not user_id:
# Anonymous user
user = None
else:
try:
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user = user_to_collection_user(user_id)
except ObjectDoesNotExist:
# The user does not exist. Skip him/her.
continue
output = []
for collection_element in collection_elements:
formatted_data = collection_element.as_autoupdate_for_user(user)
if formatted_data['action'] == 'changed':
restricted_data_cache.add_element(
user_id or 0,
collection_element.collection_string,
collection_element.id,
formatted_data)
else:
restricted_data_cache.del_element(
user_id or 0,
collection_element.collection_string,
collection_element.id)
output.append(formatted_data)
for channel_name in channel_names:
send_or_wait(Channel(channel_name).send, {'text': json.dumps(output)})
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# Check whether broadcast is active at the moment and set the local
# projector queryset.
if config['projector_broadcast'] > 0:
queryset = Projector.objects.filter(pk=config['projector_broadcast'])
else:
queryset = Projector.objects.all()
# Loop over all projectors and send data that they need.
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for projector in queryset:
output = []
for collection_element in collection_elements:
if collection_element.is_deleted():
output.append(collection_element.as_autoupdate_for_projector())
else:
for element in projector.get_collection_elements_required_for_this(collection_element):
output.append(element.as_autoupdate_for_projector())
if output:
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if config['projector_broadcast'] > 0:
send_or_wait(
Group('projector-all').send,
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{'text': json.dumps(output)})
else:
send_or_wait(
Group('projector-{}'.format(projector.pk)).send,
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{'text': json.dumps(output)})
def inform_changed_data(instances: Union[Iterable[Model], Model], information: Dict[str, Any]=None) -> None:
"""
Informs the autoupdate system and the caching system about the creation or
update of an element.
The argument instances can be one instance or an interable 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
# Generates an collection element list for the root_instances.
collection_elements = [] # type: List[CollectionElement]
for root_instance in root_instances:
collection_elements.append(
CollectionElement.from_instance(
root_instance,
information=information))
# If currently there is an open database transaction, then the
# send_autoupdate function is only called, when the transaction is
# commited. If there is currently no transaction, then the function
# is called immediately.
transaction.on_commit(lambda: send_autoupdate(collection_elements))
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def inform_deleted_data(elements: Iterable[Tuple[str, int]], information: Dict[str, Any]=None) -> None:
"""
Informs the autoupdate system and the caching system about the deletion of
elements.
The argument information is added to each collection element.
"""
# Go through each pair of collection_string and id and generate a collection
# element from it.
collection_elements = [] # type: List[CollectionElement]
for element in elements:
collection_elements.append(CollectionElement.from_values(
collection_string=element[0],
id=element[1],
deleted=True,
information=information))
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# If currently there is an open database transaction, then the
# send_autoupdate function is only called, when the transaction is
# commited. If there is currently no transaction, then the function
# is called immediately.
transaction.on_commit(lambda: send_autoupdate(collection_elements))
def inform_data_collection_element_list(collection_elements: List[CollectionElement],
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information: Dict[str, Any]=None) -> None:
"""
Informs the autoupdate system about some collection elements. This is
used just to send some data to all users.
"""
# If currently there is an open database transaction, then the
# send_autoupdate function is only called, when the transaction is
# commited. If there is currently no transaction, then the function
# is called immediately.
transaction.on_commit(lambda: send_autoupdate(collection_elements))
def send_autoupdate(collection_elements: List[CollectionElement]) -> None:
"""
Helper function, that sends collection_elements through a channel to the
autoupdate system.
Does nothing if collection_elements is empty.
"""
if collection_elements:
send_or_wait(
Channel('autoupdate.send_data').send,
to_channel_message(collection_elements))
def get_startup_collections() -> Generator[Collection, None, None]:
"""
Returns all Collections that should be send to the user at startup
"""
for app in apps.get_app_configs():
try:
# Get the method get_startup_elements() from an app.
# This method has to return an iterable of Collection objects.
get_startup_elements = app.get_startup_elements
except AttributeError:
# Skip apps that do not implement get_startup_elements.
continue
yield from get_startup_elements()