From d6f23893b5735500095bc65743a51d84a1d2adc5 Mon Sep 17 00:00:00 2001
From: Baptiste Langlade <baptouuuu@gmail.com>
Date: Sat, 26 Oct 2024 14:53:08 +0200
Subject: [PATCH] use static closures to avoid capturing $this to avoid
 circular references

---
 CHANGELOG.md                   |  6 +++++
 src/Application/Async/Http.php | 46 ++++++++++++++++++++++++----------
 src/Application/Cli.php        | 19 +++++++++-----
 src/Application/Http.php       | 24 +++++++++++-------
 src/Http/Router.php            |  3 ++-
 src/Middleware/LoadDotEnv.php  | 10 +++++---
 6 files changed, 75 insertions(+), 33 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a6906d4..c77b8a4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased]
+
+### Changed
+
+- Use `static` closures as much as possible to reduce the probability of creating circular references by capturing `$this` as it can lead to memory root buffer exhaustion.
+
 ## 2.2.0 - 2024-03-24
 
 ### Added
diff --git a/src/Application/Async/Http.php b/src/Application/Async/Http.php
index 583bc73..135e0b7 100644
--- a/src/Application/Async/Http.php
+++ b/src/Application/Async/Http.php
@@ -100,10 +100,12 @@ public static function of(OperatingSystem $os): self
      */
     public function mapEnvironment(callable $map): self
     {
+        $previous = $this->map;
+
         return new self(
             $this->os,
-            function(OperatingSystem $os, Environment $env) use ($map): array {
-                [$os, $env] = ($this->map)($os, $env);
+            static function(OperatingSystem $os, Environment $env) use ($previous, $map): array {
+                [$os, $env] = $previous($os, $env);
                 $env = $map($env, $os);
 
                 return [$os, $env];
@@ -120,10 +122,12 @@ function(OperatingSystem $os, Environment $env) use ($map): array {
      */
     public function mapOperatingSystem(callable $map): self
     {
+        $previous = $this->map;
+
         return new self(
             $this->os,
-            function(OperatingSystem $os, Environment $env) use ($map): array {
-                [$os, $env] = ($this->map)($os, $env);
+            static function(OperatingSystem $os, Environment $env) use ($previous, $map): array {
+                [$os, $env] = $previous($os, $env);
                 $os = $map($os, $env);
 
                 return [$os, $env];
@@ -140,10 +144,12 @@ function(OperatingSystem $os, Environment $env) use ($map): array {
      */
     public function service(string|Service $name, callable $definition): self
     {
+        $container = $this->container;
+
         return new self(
             $this->os,
             $this->map,
-            fn(OperatingSystem $os, Environment $env) => ($this->container)($os, $env)->add(
+            static fn(OperatingSystem $os, Environment $env) => $container($os, $env)->add(
                 $name,
                 static fn($service) => $definition($service, $os, $env),
             ),
@@ -207,18 +213,20 @@ public function appendRoutes(callable $append): self
      */
     public function mapRequestHandler(callable $map): self
     {
+        $previous = $this->mapRequestHandler;
+
         return new self(
             $this->os,
             $this->map,
             $this->container,
             $this->routes,
-            fn(
+            static fn(
                 RequestHandler $handler,
                 Container $container,
                 OperatingSystem $os,
                 Environment $env,
             ) => $map(
-                ($this->mapRequestHandler)($handler, $container, $os, $env),
+                $previous($handler, $container, $os, $env),
                 $container,
                 $os,
                 $env,
@@ -244,13 +252,25 @@ public function notFoundRequestHandler(callable $handle): self
 
     public function run($input)
     {
+        $map = $this->map;
+        $container = $this->container;
+        $routes = $this->routes;
+        $notFound = $this->notFound;
+        $mapRequestHandler = $this->mapRequestHandler;
+
         $run = Commands::of(Serve::of(
             $this->os,
-            function(ServerRequest $request, OperatingSystem $os): Response {
+            static function(ServerRequest $request, OperatingSystem $os) use (
+                $map,
+                $container,
+                $routes,
+                $notFound,
+                $mapRequestHandler,
+            ): Response {
                 $env = Environment::http($request->environment());
-                [$os, $env] = ($this->map)($os, $env);
-                $container = ($this->container)($os, $env)->build();
-                $routes = Sequence::lazyStartingWith($this->routes)
+                [$os, $env] = $map($os, $env);
+                $container = $container($os, $env)->build();
+                $routes = Sequence::lazyStartingWith($routes)
                     ->flatMap(static fn($routes) => $routes)
                     ->map(static fn($provide) => $provide(
                         Routes::lazy(),
@@ -261,7 +281,7 @@ function(ServerRequest $request, OperatingSystem $os): Response {
                     ->flatMap(static fn($routes) => $routes->toSequence());
                 $router = new Router(
                     $routes,
-                    $this->notFound->map(
+                    $notFound->map(
                         static fn($handle) => static fn(ServerRequest $request) => $handle(
                             $request,
                             $container,
@@ -270,7 +290,7 @@ function(ServerRequest $request, OperatingSystem $os): Response {
                         ),
                     ),
                 );
-                $handle = ($this->mapRequestHandler)($router, $container, $os, $env);
+                $handle = $mapRequestHandler($router, $container, $os, $env);
 
                 return $handle($request);
             },
diff --git a/src/Application/Cli.php b/src/Application/Cli.php
index f2b1825..31c5254 100644
--- a/src/Application/Cli.php
+++ b/src/Application/Cli.php
@@ -109,10 +109,12 @@ public function mapOperatingSystem(callable $map): self
      */
     public function service(string|Service $name, callable $definition): self
     {
+        $container = $this->container;
+
         return new self(
             $this->os,
             $this->env,
-            fn(OperatingSystem $os, Environment $env) => ($this->container)($os, $env)->add(
+            static fn(OperatingSystem $os, Environment $env) => $container($os, $env)->add(
                 $name,
                 static fn($service) => $definition($service, $os, $env),
             ),
@@ -144,18 +146,20 @@ public function command(callable $command): self
      */
     public function mapCommand(callable $map): self
     {
+        $previous = $this->mapCommand;
+
         return new self(
             $this->os,
             $this->env,
             $this->container,
             $this->commands,
-            fn(
+            static fn(
                 Command $command,
                 Container $service,
                 OperatingSystem $os,
                 Environment $env,
             ) => $map(
-                ($this->mapCommand)($command, $service, $os, $env),
+                $previous($command, $service, $os, $env),
                 $service,
                 $os,
                 $env,
@@ -198,11 +202,14 @@ public function notFoundRequestHandler(callable $handle): self
     public function run($input)
     {
         $container = ($this->container)($this->os, $this->env)->build();
-        $mapCommand = fn(Command $command): Command => ($this->mapCommand)(
+        $mapCommand = $this->mapCommand;
+        $os = $this->os;
+        $env = $this->env;
+        $mapCommand = static fn(Command $command): Command => $mapCommand(
             $command,
             $container,
-            $this->os,
-            $this->env,
+            $os,
+            $env,
         );
         $commands = $this->commands->map(static fn($service) => new Defer(
             $service,
diff --git a/src/Application/Http.php b/src/Application/Http.php
index 3a2f86f..8596160 100644
--- a/src/Application/Http.php
+++ b/src/Application/Http.php
@@ -121,10 +121,12 @@ public function mapOperatingSystem(callable $map): self
      */
     public function service(string|Service $name, callable $definition): self
     {
+        $container = $this->container;
+
         return new self(
             $this->os,
             $this->env,
-            fn(OperatingSystem $os, Environment $env) => ($this->container)($os, $env)->add(
+            static fn(OperatingSystem $os, Environment $env) => $container($os, $env)->add(
                 $name,
                 static fn($service) => $definition($service, $os, $env),
             ),
@@ -188,18 +190,20 @@ public function appendRoutes(callable $append): self
      */
     public function mapRequestHandler(callable $map): self
     {
+        $previous = $this->mapRequestHandler;
+
         return new self(
             $this->os,
             $this->env,
             $this->container,
             $this->routes,
-            fn(
+            static fn(
                 RequestHandler $handler,
                 Container $container,
                 OperatingSystem $os,
                 Environment $env,
             ) => $map(
-                ($this->mapRequestHandler)($handler, $container, $os, $env),
+                $previous($handler, $container, $os, $env),
                 $container,
                 $os,
                 $env,
@@ -226,23 +230,25 @@ public function notFoundRequestHandler(callable $handle): self
     public function run($input)
     {
         $container = ($this->container)($this->os, $this->env)->build();
+        $os = $this->os;
+        $env = $this->env;
         $routes = Sequence::lazyStartingWith($this->routes)
             ->flatMap(static fn($routes) => $routes)
-            ->map(fn($provide) => $provide(
+            ->map(static fn($provide) => $provide(
                 Routes::lazy(),
                 $container,
-                $this->os,
-                $this->env,
+                $os,
+                $env,
             ))
             ->flatMap(static fn($routes) => $routes->toSequence());
         $router = new Router(
             $routes,
             $this->notFound->map(
-                fn($handle) => fn(ServerRequest $request) => $handle(
+                static fn($handle) => static fn(ServerRequest $request) => $handle(
                     $request,
                     $container,
-                    $this->os,
-                    $this->env,
+                    $os,
+                    $env,
                 ),
             ),
         );
diff --git a/src/Http/Router.php b/src/Http/Router.php
index b624605..55904ea 100644
--- a/src/Http/Router.php
+++ b/src/Http/Router.php
@@ -41,10 +41,11 @@ public function __construct(Sequence $routes, Maybe $notFound)
     public function __invoke(ServerRequest $request): Response
     {
         $match = new RequestMatcher($this->routes);
+        $notFound = $this->notFound;
 
         return $match($request)
             ->map(static fn($route) => $route->respondTo(...))
-            ->otherwise(fn() => $this->notFound)
+            ->otherwise(static fn() => $notFound)
             ->match(
                 static fn($handle) => $handle($request),
                 static fn() => Response::of(
diff --git a/src/Middleware/LoadDotEnv.php b/src/Middleware/LoadDotEnv.php
index de41b43..15e8389 100644
--- a/src/Middleware/LoadDotEnv.php
+++ b/src/Middleware/LoadDotEnv.php
@@ -30,14 +30,16 @@ private function __construct(Path $folder)
 
     public function __invoke(Application $app): Application
     {
+        $folder = $this->folder;
+
         return $app->mapEnvironment(
-            fn($env, $os) => $os
+            static fn($env, $os) => $os
                 ->filesystem()
-                ->mount($this->folder)
+                ->mount($folder)
                 ->get(Name::of('.env'))
                 ->keep(Instance::of(File::class))
                 ->match(
-                    fn($file) => $this->add($env, $file),
+                    static fn($file) => self::add($env, $file),
                     static fn() => $env,
                 ),
         );
@@ -48,7 +50,7 @@ public static function at(Path $folder): self
         return new self($folder);
     }
 
-    private function add(Environment $env, File $file): Environment
+    private static function add(Environment $env, File $file): Environment
     {
         /** @psalm-suppress InvalidArgument Due to the empty sequence in the flatMap */
         return $file