From c15d6fb4d15ad37101ce34a88a2863897658a0d5 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Fri, 15 Nov 2024 08:47:24 -0600
Subject: [PATCH] Refactor Resource.resolve to avoid linear search of methods
 (#9899)

(cherry picked from commit 2249f2d59d30b7992e3a2ea25ab790c6f621b5cb)
---
 CHANGES/9899.misc.rst        |  1 +
 aiohttp/web_urldispatcher.py | 45 ++++++++++++++++--------------------
 2 files changed, 21 insertions(+), 25 deletions(-)
 create mode 100644 CHANGES/9899.misc.rst

diff --git a/CHANGES/9899.misc.rst b/CHANGES/9899.misc.rst
new file mode 100644
index 0000000000..53243495d3
--- /dev/null
+++ b/CHANGES/9899.misc.rst
@@ -0,0 +1 @@
+Improved performance of resolving resources when multiple methods are registered for the same route -- by :user:`bdraco`.
diff --git a/aiohttp/web_urldispatcher.py b/aiohttp/web_urldispatcher.py
index 5153e5b73b..03d7d7b15b 100644
--- a/aiohttp/web_urldispatcher.py
+++ b/aiohttp/web_urldispatcher.py
@@ -350,7 +350,9 @@ async def _default_expect_handler(request: Request) -> None:
 class Resource(AbstractResource):
     def __init__(self, *, name: Optional[str] = None) -> None:
         super().__init__(name=name)
-        self._routes: List[ResourceRoute] = []
+        self._routes: Dict[str, ResourceRoute] = {}
+        self._any_route: Optional[ResourceRoute] = None
+        self._allowed_methods: Set[str] = set()
 
     def add_route(
         self,
@@ -359,14 +361,12 @@ def add_route(
         *,
         expect_handler: Optional[_ExpectHandler] = None,
     ) -> "ResourceRoute":
-
-        for route_obj in self._routes:
-            if route_obj.method == method or route_obj.method == hdrs.METH_ANY:
-                raise RuntimeError(
-                    "Added route will never be executed, "
-                    "method {route.method} is already "
-                    "registered".format(route=route_obj)
-                )
+        if route := self._routes.get(method, self._any_route):
+            raise RuntimeError(
+                "Added route will never be executed, "
+                f"method {route.method} is already "
+                "registered"
+            )
 
         route_obj = ResourceRoute(method, handler, self, expect_handler=expect_handler)
         self.register_route(route_obj)
@@ -376,23 +376,18 @@ def register_route(self, route: "ResourceRoute") -> None:
         assert isinstance(
             route, ResourceRoute
         ), f"Instance of Route class is required, got {route!r}"
-        self._routes.append(route)
+        if route.method == hdrs.METH_ANY:
+            self._any_route = route
+        else:
+            self._allowed_methods.add(route.method)
+            self._routes[route.method] = route
 
     async def resolve(self, request: Request) -> _Resolve:
-        allowed_methods: Set[str] = set()
-
-        match_dict = self._match(request.rel_url.path_safe)
-        if match_dict is None:
-            return None, allowed_methods
-
-        for route_obj in self._routes:
-            route_method = route_obj.method
-            allowed_methods.add(route_method)
-
-            if route_method == request.method or route_method == hdrs.METH_ANY:
-                return (UrlMappingMatchInfo(match_dict, route_obj), allowed_methods)
-        else:
-            return None, allowed_methods
+        if (match_dict := self._match(request.rel_url.path_safe)) is None:
+            return None, set()
+        if route := self._routes.get(request.method, self._any_route):
+            return UrlMappingMatchInfo(match_dict, route), self._allowed_methods
+        return None, self._allowed_methods
 
     @abc.abstractmethod
     def _match(self, path: str) -> Optional[Dict[str, str]]:
@@ -402,7 +397,7 @@ def __len__(self) -> int:
         return len(self._routes)
 
     def __iter__(self) -> Iterator["ResourceRoute"]:
-        return iter(self._routes)
+        return iter(self._routes.values())
 
     # TODO: implement all abstract methods