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cache_middleware.py
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cache_middleware.py
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from __future__ import annotations
import re
from fastapi import Request
from starlette.concurrency import iterate_in_threadpool
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import Response
from starlette.responses import StreamingResponse
from app.config.base import settings
from app.wrappers.cache_wrappers import CacheUtils
class CacheMiddleware(BaseHTTPMiddleware):
def __init__(
self,
app,
cached_endpoints: list[str],
):
super().__init__(app)
self.cached_endpoints = cached_endpoints
def matches_any_path(self, path_url):
for end_point in self.cached_endpoints:
if end_point in path_url:
return True
return False
async def handle_max_age(self, max_age, response_body, key):
if max_age:
await CacheUtils.create_cache(response_body[0].decode(), key, max_age)
async def dispatch(self, request: Request, call_next) -> Response:
path_url = request.url.path
request_type = request.method
cache_control = request.headers.get("Cache-Control", None)
auth = request.headers.get("Authorization", "token public")
token = auth.split(" ")[1]
max_age = settings.CACHE_MAX_AGE
key = f"{path_url}_{token}"
matches = self.matches_any_path(path_url)
if request_type != "GET":
return await call_next(request)
stored_cache, expire = await CacheUtils.retrieve_cache(key)
res = stored_cache and cache_control != "no-cache"
if res:
headers = {"Cache-Control": f"max-age:{expire}"}
return StreamingResponse(iter([stored_cache]), media_type="application/json", headers=headers)
response: Response = await call_next(request)
response_body = [chunk async for chunk in response.body_iterator]
response.body_iterator = iterate_in_threadpool(iter(response_body))
if response.status_code == 200:
if cache_control == "no-store":
return response
if cache_control:
max_age_match = re.search(r"max-age=(\d+)", cache_control)
if max_age_match:
max_age = int(max_age_match.group(1))
await self.handle_max_age(max_age, response_body, key)
elif matches:
await CacheUtils.create_cache(response_body[0].decode(), key, max_age)
return response