103 lines
4.0 KiB
Python
103 lines
4.0 KiB
Python
import asyncio
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from asyncio import Task
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from typing import Optional, cast
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from django.conf import settings
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from .autoupdate import get_autoupdate_data
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from .cache import element_cache
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from .websocket import ChangeIdTooHighException, ProtocollAsyncJsonWebsocketConsumer
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AUTOUPDATE_DELAY = getattr(settings, "AUTOUPDATE_DELAY", None)
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class ConsumerAutoupdateStrategy:
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def __init__(self, consumer: ProtocollAsyncJsonWebsocketConsumer) -> None:
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self.consumer = consumer
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# client_change_id = None: unknown -> set on first autoupdate or request_change_id
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# client_change_id is int: the change_id, the client knows about, so the next
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# update must be from client_change_id+1 .. <next clange_id>
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self.client_change_id: Optional[int] = None
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self.next_send_time = None
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self.timer_task_handle: Optional[Task[None]] = None
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self.lock = asyncio.Lock()
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async def request_change_id(
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self, change_id: int, in_response: Optional[str] = None
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) -> None:
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"""
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The change id is not inclusive, so the client is on change_id and wants
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data from change_id+1 .. now
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"""
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# This resets the server side tracking of the client's change id.
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async with self.lock:
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await self.stop_timer()
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max_change_id = await element_cache.get_current_change_id()
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self.client_change_id = change_id
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if self.client_change_id == max_change_id:
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# The client is up-to-date, so nothing will be done
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return None
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if self.client_change_id > max_change_id:
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message = (
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f"Requested change_id {self.client_change_id} is higher than the "
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+ f"highest change_id {max_change_id}."
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)
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raise ChangeIdTooHighException(message, in_response=in_response)
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await self.send_autoupdate(in_response=in_response)
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async def new_change_id(self, change_id: int) -> None:
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async with self.lock:
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if self.client_change_id is None:
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# The -1 is to send this autoupdate as the first one to he client.
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# Remember: the client_change_id is the change_id the client knows about
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self.client_change_id = change_id - 1
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if AUTOUPDATE_DELAY is None: # feature deactivated, send directly
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await self.send_autoupdate()
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elif self.timer_task_handle is None:
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await self.start_timer()
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async def get_running_loop(self) -> asyncio.AbstractEventLoop:
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if hasattr(asyncio, "get_running_loop"):
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return asyncio.get_running_loop() # type: ignore
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else:
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return asyncio.get_event_loop()
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async def start_timer(self) -> None:
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loop = await self.get_running_loop()
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self.timer_task_handle = loop.create_task(self.timer_task())
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async def stop_timer(self) -> None:
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if self.timer_task_handle is not None:
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self.timer_task_handle.cancel()
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self.timer_task_handle = None
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async def timer_task(self) -> None:
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try:
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await asyncio.sleep(AUTOUPDATE_DELAY)
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except asyncio.CancelledError:
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return
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async with self.lock:
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await self.send_autoupdate()
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self.timer_task_handle = None
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async def send_autoupdate(self, in_response: Optional[str] = None) -> None:
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# here, 1 is added to the change_id, because the client_change_id is the id the client
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# *knows* about -> the client needs client_change_id+1 since get_autoupdate_data is
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# inclusive [change_id .. max_change_id].
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max_change_id, autoupdate = await get_autoupdate_data(
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cast(int, self.client_change_id) + 1, self.consumer.user_id
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)
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if autoupdate is not None:
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self.client_change_id = max_change_id
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# It will be send, so we can set the client_change_id
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await self.consumer.send_json(
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type="autoupdate", content=autoupdate, in_response=in_response
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)
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