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https://gitlab.ub.uni-bielefeld.de/sfb1288inf/nopaque.git
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74 lines
2.5 KiB
Python
74 lines
2.5 KiB
Python
from flask import current_app, request
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from flask_login import current_user
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from . import db, socketio
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from .decorators import socketio_admin_required, socketio_login_required
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from .models import User
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import json
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import jsonpatch
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'''
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' A list containing session ids of connected Socket.IO sessions, to keep track
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' of all connected sessions, which is used to determine the runtimes of
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' associated background tasks.
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'''
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connected_sessions = []
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@socketio.on('connect')
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def connect():
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'''
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' The Socket.IO module creates a session id (sid) for each request.
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' On connect the sid is saved in the connected sessions list.
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'''
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connected_sessions.append(request.sid)
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@socketio.on('disconnect')
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def disconnect():
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'''
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' On disconnect the session id gets removed from the connected sessions
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' list.
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'''
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connected_sessions.remove(request.sid)
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@socketio.on('start_user_session')
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@socketio_login_required
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def start_user_session(user_id):
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if not (current_user.id == user_id or current_user.is_administrator):
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return
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socketio.start_background_task(user_session,
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current_app._get_current_object(),
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user_id, request.sid)
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def user_session(app, user_id, session_id):
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'''
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' Sends initial user data to the client. Afterwards it checks every 3s if
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' changes to the initial values appeared. If changes are detected, a
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' RFC 6902 compliant JSON patch gets send.
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'''
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init_event = 'user_{}_init'.format(user_id)
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patch_event = 'user_{}_patch'.format(user_id)
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with app.app_context():
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# Gather current values from database.
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user = User.query.get(user_id)
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user_dict = user.to_dict()
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# Send initial values to the client.
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socketio.emit(init_event, json.dumps(user_dict), room=session_id)
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while session_id in connected_sessions:
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# Get new values from the database
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db.session.refresh(user)
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new_user_dict = user.to_dict()
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# Compute JSON patches.
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user_patch = jsonpatch.JsonPatch.from_diff(user_dict,
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new_user_dict)
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# In case there are patches, send them to the client.
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if user_patch:
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socketio.emit(patch_event, user_patch.to_string(),
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room=session_id)
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# Set new values as references for the next iteration.
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user_dict = new_user_dict
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socketio.sleep(3)
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