Cache construction of middleware handlers (#9158)

(cherry picked from commit bf022b3)

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 lru_cache, partial, update_wrapper
 from typing import (
  TYPE_CHECKING,
  Any,
@@ -38,7 +38,7 @@
 from .http_parser import RawRequestMessage
 from .log import web_logger
 from .streams import StreamReader
-from .typedefs import Middleware
+from .typedefs import Handler, Middleware
 from .web_exceptions import NotAppKeyWarning
 from .web_log import AccessLogger
 from .web_middlewares import _fix_request_current_app
@@ -79,6 +79,17 @@
 _Resource = TypeVar("_Resource", bound=AbstractResource)
 
 
+@lru_cache(None)
+def _build_middlewares(
+ handler: Handler, apps: Tuple["Application", ...]
+) -> Callable[[Request], Awaitable[StreamResponse]]:
+ """Apply middlewares to handler."""
+ for app in apps:
+ for m, _ in app._middlewares_handlers: # type: ignore[union-attr]
+ handler = update_wrapper(partial(m, handler=handler), handler) # type: ignore[misc]
+ return handler
+
+
 class Application(MutableMapping[Union[str, AppKey[Any]], Any]):
  ATTRS = frozenset(
  [
@@ -89,6 +100,7 @@ class Application(MutableMapping[Union[str, AppKey[Any]], Any]):
  "_handler_args",
  "_middlewares",
  "_middlewares_handlers",
+ "_has_legacy_middlewares",
  "_run_middlewares",
  "_state",
  "_frozen",
@@ -143,6 +155,7 @@ def __init__(
  self._middlewares_handlers: _MiddlewaresHandlers = None
  # initialized on freezing
  self._run_middlewares: Optional[bool] = None
+ self._has_legacy_middlewares: bool = True
 
  self._state: Dict[Union[AppKey[Any], str], object] = {}
  self._frozen = False
@@ -228,6 +241,9 @@ 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]: ...
 
@@ -284,6 +300,9 @@ def pre_freeze(self) -> None:
  self._on_shutdown.freeze()
  self._on_cleanup.freeze()
  self._middlewares_handlers = tuple(self._prepare_middleware())
+ self._has_legacy_middlewares = any(
+ not new_style for _, new_style in self._middlewares_handlers
+ )
 
  # If current app and any subapp do not have middlewares avoid run all
  # of the code footprint that it implies, which have a middleware
@@ -525,14 +544,17 @@ async def _handle(self, request: Request) -> StreamResponse:
  handler = match_info.handler
 
  if self._run_middlewares:
- for app in match_info.apps[::-1]:
- for m, new_style in app._middlewares_handlers: # type: ignore[union-attr]
- if new_style:
- handler = update_wrapper(
- partial(m, handler=handler), handler # type: ignore[misc]
- )
- else:
- handler = await m(app, handler) # type: ignore[arg-type,assignment]
+ if not self._has_legacy_middlewares:
+ handler = _build_middlewares(handler, match_info.apps[::-1])
+ else:
+ for app in match_info.apps[::-1]:
+ for m, new_style in app._middlewares_handlers: # type: ignore[union-attr]
+ if new_style:
+ handler = update_wrapper(
+ partial(m, handler=handler), handler # type: ignore[misc]
+ )
+ else:
+ handler = await m(app, handler) # type: ignore[arg-type,assignment]
 
  resp = await handler(request)
 

tests/test_web_middleware.py

@@ -24,10 +24,13 @@ 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, aiohttp_client) -> None:
@@ -44,10 +47,13 @@ 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, aiohttp_client) -> None: