minor #20196 [SecurityBundle] Cache contexts per request in FirewallM…

…ap (chalasr)

This PR was merged into the 3.2-dev branch.

Discussion
----------

[SecurityBundle] Cache contexts per request in FirewallMap

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #19819 (comment)
| License       | MIT
| Doc PR        | n/a

From @HeahDude in #19819 (comment), I propose to store and retrieve `Context` objects per `Request` using `SplObjectStorage`.

At the moment, contexts are consumed by the `Symfony\Components\Security\Http\Firewall` class only, but they could be indirectly by end users if #19490 and/or #19819 come to be merged.

Commits
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ffacec1 [SecurityBundle] Cache contexts per request in FirewallMap

src/Symfony/Bundle/SecurityBundle/Security/FirewallMap.php

@@ -26,18 +26,24 @@ class FirewallMap implements FirewallMapInterface
 {
     protected $container;
     protected $map;
+    private $contexts;
 
     public function __construct(ContainerInterface $container, array $map)
     {
         $this->container = $container;
         $this->map = $map;
+        $this->contexts = new \SplObjectStorage();
     }
 
     public function getListeners(Request $request)
     {
+        if ($this->contexts->contains($request)) {
+            return $this->contexts[$request];
+        }
+
         foreach ($this->map as $contextId => $requestMatcher) {
             if (null === $requestMatcher || $requestMatcher->matches($request)) {
-                return $this->container->get($contextId)->getContext();
+                return $this->contexts[$request] = $this->container->get($contextId)->getContext();
             }
         }