add cache to /api/v1/tariffs and i/o-bound operations (sync read from file) which locked async event loop has moved to asyncio thread

routers/tariffs.py

@@ -1,9 +1,15 @@
-from fastapi import APIRouter, Request
-import aiofiles
+from fastapi import APIRouter
+from functools import lru_cache
+import json
+import asyncio
 
 router = APIRouter(prefix='/api/v1', tags=['tariffs'])
 
+@lru_cache(maxsize=1)
+def get_tariffs_sync():
+    with open('data/tariffs.json', 'r', encoding='utf-8') as f:
+        return json.load(f)
+
 @router.get('/tariffs')
-async def get_tariffs(request: Request):
-    async with aiofiles.open('data/tariffs.json', 'r', encoding='utf-8') as file:
-        return await file.read()
+async def get_tariffs():
+    return await asyncio.to_thread(get_tariffs_sync)