bug #20374 [FrameworkBundle] Improve performance of ControllerNameParser (enumag)

This PR was merged into the 2.7 branch.

Discussion
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[FrameworkBundle] Improve performance of ControllerNameParser

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Today I was searching for bottlenecks in my application using Blackfire. And among other things I found one in Symfony. Blackfire showed that `Symfony\Bundle\FrameworkBundle\Controller\ControllerNameParser::findAlternative()` was called almost 300 times which took 28 miliseconds.

It turns out that `Symfony\Bundle\FrameworkBundle\Routing\DelegatingLoader::load()` is calling `ControllerNameParser::parse()` without actually needing to do so because `$controller` is in the class::method notation already. `ControllerNameParser` threw an exception, DelegatingLoader caught and ignored it - that's ok. The problem is that generating the exception message took a lot of time because findAlternative is slow. In my case it called the levenshtein function over 5000 times which was completely useless because the exception is ignored anyway.

Commits
-------

cf333f3 [FrameworkBundle] Improve performance of ControllerNameParser

Author: nicolas-grekas

Controller/ControllerNameParser.php

@@ -46,11 +46,12 @@ public function __construct(KernelInterface $kernel)
      */
     public function parse($controller)
     {
-        $originalController = $controller;
-        if (3 !== count($parts = explode(':', $controller))) {
+        $parts = explode(':', $controller);
+        if (3 !== count($parts) || in_array('', $parts, true)) {
             throw new \InvalidArgumentException(sprintf('The "%s" controller is not a valid "a:b:c" controller string.', $controller));
         }
 
+        $originalController = $controller;
         list($bundle, $controller, $action) = $parts;
         $controller = str_replace('/', '\\', $controller);
         $bundles = array();

Routing/DelegatingLoader.php

@@ -21,7 +21,7 @@
  * DelegatingLoader delegates route loading to other loaders using a loader resolver.
  *
  * This implementation resolves the _controller attribute from the short notation
- * to the fully-qualified form (from a:b:c to class:method).
+ * to the fully-qualified form (from a:b:c to class::method).
  *
  * @author Fabien Potencier <fabien@symfony.com>
  */
@@ -85,15 +85,17 @@ public function load($resource, $type = null)
         $this->loading = false;
 
         foreach ($collection->all() as $route) {
-            if ($controller = $route->getDefault('_controller')) {
-                try {
-                    $controller = $this->parser->parse($controller);
-                } catch (\InvalidArgumentException $e) {
-                    // unable to optimize unknown notation
-                }
+            if (!$controller = $route->getDefault('_controller')) {
+                continue;
+            }
 
-                $route->setDefault('_controller', $controller);
+            try {
+                $controller = $this->parser->parse($controller);
+            } catch (\InvalidArgumentException $e) {
+                // unable to optimize unknown notation
             }
+
+            $route->setDefault('_controller', $controller);
         }
 
         return $collection;