Cache construction of middleware handlers

CHANGES/9158.misc.rst

@@ -0,0 +1,3 @@
+Significantly improved performance of middlewares -- by :user:`bdraco`.
+
+The construction of the middleware wrappers is now cached and is built once per handler instead of on every request.

aiohttp/web_app.py

@@ -1,7 +1,7 @@
 import asyncio
 import logging
 import warnings
-from functools import partial, update_wrapper
+from functools import cache, partial, update_wrapper
 from typing import (
  TYPE_CHECKING,
  Any,
@@ -16,6 +16,7 @@
  MutableMapping,
  Optional,
  Sequence,
+ Tuple,
  Type,
  TypeVar,
  Union,
@@ -30,7 +31,7 @@
 from . import hdrs
 from .helpers import AppKey
 from .log import web_logger
-from .typedefs import Middleware
+from .typedefs import Handler, Middleware
 from .web_exceptions import NotAppKeyWarning
 from .web_middlewares import _fix_request_current_app
 from .web_request import Request
@@ -69,6 +70,18 @@
 _Resource = TypeVar("_Resource", bound=AbstractResource)
 
 
+@cache
+def _build_middlewares(
+ handler: Handler, apps: Tuple["Application", ...]
+) -> Callable[[Request], Awaitable[StreamResponse]]:
+ """Apply middlewares to handler."""
+ for app in apps:
+ assert app.pre_frozen, "middleware handlers are not ready"
+ for m in app._middlewares_handlers:
+ handler = update_wrapper(partial(m, handler=handler), handler)
+ return handler
+
+
 @final
 class Application(MutableMapping[Union[str, AppKey[Any]], Any]):
  __slots__ = (
@@ -186,6 +199,9 @@ def __len__(self) -> int:
  def __iter__(self) -> Iterator[Union[str, AppKey[Any]]]:
  return iter(self._state)
 
+ def __hash__(self) -> int:
+ return id(self)
+
  @overload # type: ignore[override]
  def get(self, key: AppKey[_T], default: None = ...) -> Optional[_T]: ...
 
@@ -380,10 +396,7 @@ async def _handle(self, request: Request) -> StreamResponse:
  handler = match_info.handler
 
  if self._run_middlewares:
- for app in match_info.apps[::-1]:
- assert app.pre_frozen, "middleware handlers are not ready"
- for m in app._middlewares_handlers:
- handler = update_wrapper(partial(m, handler=handler), handler)
+ handler = _build_middlewares(handler, match_info.apps[::-1])
 
  resp = await handler(request)
 

tests/test_web_middleware.py

@@ -23,10 +23,13 @@ async def middleware(request, handler: Handler):
  app.middlewares.append(middleware)
  app.router.add_route("GET", "/", handler)
  client = await aiohttp_client(app)
- resp = await client.get("/")
- assert 201 == resp.status
- txt = await resp.text()
- assert "OK[MIDDLEWARE]" == txt
+
+ # Call twice to verify cache works
+ for _ in range(2):
+ resp = await client.get("/")
+ assert 201 == resp.status
+ txt = await resp.text()
+ assert "OK[MIDDLEWARE]" == txt
 
 
 async def test_middleware_handles_exception(loop: Any, aiohttp_client: Any) -> None:
@@ -42,10 +45,13 @@ async def middleware(request, handler: Handler):
  app.middlewares.append(middleware)
  app.router.add_route("GET", "/", handler)
  client = await aiohttp_client(app)
- resp = await client.get("/")
- assert 501 == resp.status
- txt = await resp.text()
- assert "Error text[MIDDLEWARE]" == txt
+
+ # Call twice to verify cache works
+ for _ in range(2):
+ resp = await client.get("/")
+ assert 501 == resp.status
+ txt = await resp.text()
+ assert "Error text[MIDDLEWARE]" == txt
 
 
 async def test_middleware_chain(loop: Any, aiohttp_client: Any) -> None: