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