mirror of
https://github.com/yeicor-3d/yet-another-cad-viewer.git
synced 2025-12-19 14:14:13 +01:00
61 lines
2.2 KiB
Python
61 lines
2.2 KiB
Python
import asyncio
|
|
from typing import List, TypeVar, \
|
|
Generic, AsyncGenerator
|
|
|
|
from mylogger import logger
|
|
|
|
T = TypeVar('T')
|
|
|
|
|
|
class BufferedPubSub(Generic[T]):
|
|
"""A simple implementation of publish-subscribe pattern using asyncio and buffering all previous events"""
|
|
|
|
_buffer: List[T]
|
|
_subscribers: List[asyncio.Queue[T]]
|
|
_lock = asyncio.Lock()
|
|
max_buffer_size = 1000
|
|
|
|
def __init__(self):
|
|
self._buffer = []
|
|
self._subscribers = []
|
|
|
|
def publish_nowait(self, event: T):
|
|
"""Publishes an event without blocking (synchronous API does not require locking)"""
|
|
self._buffer.append(event)
|
|
if len(self._buffer) > self.max_buffer_size:
|
|
self._buffer.pop(0)
|
|
for q in self._subscribers:
|
|
q.put_nowait(event)
|
|
|
|
async def _subscribe(self, include_buffered: bool = True, include_future: bool = True) -> asyncio.Queue[T]:
|
|
"""Subscribes to events"""
|
|
q = asyncio.Queue()
|
|
async with self._lock:
|
|
self._subscribers.append(q)
|
|
logger.debug(f"Subscribed to %s (%d subscribers)", self, len(self._subscribers))
|
|
if include_buffered:
|
|
for event in self._buffer:
|
|
await q.put(event)
|
|
if not include_future:
|
|
await q.put(None)
|
|
return q
|
|
|
|
async def _unsubscribe(self, q: asyncio.Queue[T]):
|
|
"""Unsubscribes from events"""
|
|
async with self._lock:
|
|
self._subscribers.remove(q)
|
|
logger.debug(f"Unsubscribed from %s (%d subscribers)", self, len(self._subscribers))
|
|
|
|
async def subscribe(self, include_buffered: bool = True, include_future: bool = True) -> AsyncGenerator[T, None]:
|
|
"""Subscribes to events as an async generator that yields events and automatically unsubscribes"""
|
|
q = await self._subscribe(include_buffered, include_future)
|
|
try:
|
|
while True:
|
|
v = await q.get()
|
|
# include_future is incompatible with None values as they are used to signal the end of the stream
|
|
if v is None and not include_future:
|
|
break
|
|
yield v
|
|
finally: # When aclose() is called
|
|
await self._unsubscribe(q)
|