Initial Plast Track MVP

backend/app/services/realtime.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+import asyncio
+from collections.abc import Iterable
+
+from fastapi import WebSocket
+
+
+class RealtimeHub:
+    def __init__(self) -> None:
+        self._connections: set[WebSocket] = set()
+        self._loop: asyncio.AbstractEventLoop | None = None
+
+    def bind_loop(self, loop: asyncio.AbstractEventLoop) -> None:
+        self._loop = loop
+
+    async def connect(self, websocket: WebSocket) -> None:
+        await websocket.accept()
+        self._connections.add(websocket)
+
+    def disconnect(self, websocket: WebSocket) -> None:
+        self._connections.discard(websocket)
+
+    async def broadcast(self, payload: dict) -> None:
+        stale: list[WebSocket] = []
+        for websocket in self._connections:
+            try:
+                await websocket.send_json(payload)
+            except Exception:
+                stale.append(websocket)
+        for websocket in stale:
+            self._connections.discard(websocket)
+
+    def notify(self, payload: dict) -> None:
+        if self._loop is None:
+            return
+        asyncio.run_coroutine_threadsafe(self.broadcast(payload), self._loop)
+
+
+hub = RealtimeHub()