minor #33725 [HttpFoundation] optimize normalization of headers (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
----------

[HttpFoundation] optimize normalization of headers

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

I was experimenting with using maps to bypass calls to normalization functions, but that didn't lead to any significant perf improvement.

I still found this, the new call is twice as fast :)

Commits
-------

9c676d37a0 [HttpFoundation] optimize normalization of headers

src/Symfony/Component/HttpFoundation/HeaderBag.php

@@ -18,6 +18,9 @@ namespace Symfony\Component\HttpFoundation;
  */
 class HeaderBag implements \IteratorAggregate, \Countable
 {
+    protected const UPPER = '_ABCDEFGHIJKLMNOPQRSTUVWXYZ';
+    protected const LOWER = '-abcdefghijklmnopqrstuvwxyz';
+
     protected $headers = [];
     protected $cacheControl = [];
 
@@ -62,9 +65,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
     public function all(/*string $key = null*/)
     {
         if (1 <= \func_num_args() && null !== $key = func_get_arg(0)) {
-            $key = str_replace('_', '-', strtolower($key));
+            return $this->headers[strtr($key, self::UPPER, self::LOWER)] ?? [];
-
-            return $this->headers[$key] ?? [];
         }
 
         return $this->headers;
@@ -138,7 +139,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
      */
     public function set($key, $values, $replace = true)
     {
-        $key = str_replace('_', '-', strtolower($key));
+        $key = strtr($key, self::UPPER, self::LOWER);
 
         if (\is_array($values)) {
             $values = array_values($values);
@@ -170,7 +171,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
      */
     public function has($key)
     {
-        return \array_key_exists(str_replace('_', '-', strtolower($key)), $this->all());
+        return \array_key_exists(strtr($key, self::UPPER, self::LOWER), $this->all());
     }
 
     /**
@@ -193,7 +194,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
      */
     public function remove($key)
     {
-        $key = str_replace('_', '-', strtolower($key));
+        $key = strtr($key, self::UPPER, self::LOWER);
 
         unset($this->headers[$key]);
 

src/Symfony/Component/HttpFoundation/Request.php

@@ -541,7 +541,7 @@ class Request
 
         foreach ($this->headers->all() as $key => $value) {
             $key = strtoupper(str_replace('-', '_', $key));
-            if (\in_array($key, ['CONTENT_TYPE', 'CONTENT_LENGTH'])) {
+            if (\in_array($key, ['CONTENT_TYPE', 'CONTENT_LENGTH', 'CONTENT_MD5'], true)) {
                 $_SERVER[$key] = implode(', ', $value);
             } else {
                 $_SERVER['HTTP_'.$key] = implode(', ', $value);

src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php

@@ -51,7 +51,7 @@ class ResponseHeaderBag extends HeaderBag
     {
         $headers = [];
         foreach ($this->all() as $name => $value) {
-            $headers[isset($this->headerNames[$name]) ? $this->headerNames[$name] : $name] = $value;
+            $headers[$this->headerNames[$name] ?? $name] = $value;
         }
 
         return $headers;
@@ -95,7 +95,7 @@ class ResponseHeaderBag extends HeaderBag
         $headers = parent::all();
 
         if (1 <= \func_num_args() && null !== $key = func_get_arg(0)) {
-            $key = str_replace('_', '-', strtolower($key));
+            $key = strtr($key, self::UPPER, self::LOWER);
 
             return 'set-cookie' !== $key ? $headers[$key] ?? [] : array_map('strval', $this->getCookies());
         }
@@ -112,7 +112,7 @@ class ResponseHeaderBag extends HeaderBag
      */
     public function set($key, $values, $replace = true)
     {
-        $uniqueKey = str_replace('_', '-', strtolower($key));
+        $uniqueKey = strtr($key, self::UPPER, self::LOWER);
 
         if ('set-cookie' === $uniqueKey) {
             if ($replace) {
@@ -143,7 +143,7 @@ class ResponseHeaderBag extends HeaderBag
      */
     public function remove($key)
     {
-        $uniqueKey = str_replace('_', '-', strtolower($key));
+        $uniqueKey = strtr($key, self::UPPER, self::LOWER);
         unset($this->headerNames[$uniqueKey]);
 
         if ('set-cookie' === $uniqueKey) {

src/Symfony/Component/HttpFoundation/ServerBag.php

@@ -28,13 +28,10 @@ class ServerBag extends ParameterBag
     public function getHeaders()
     {
         $headers = [];
-        $contentHeaders = ['CONTENT_LENGTH' => true, 'CONTENT_MD5' => true, 'CONTENT_TYPE' => true];
         foreach ($this->parameters as $key => $value) {
             if (0 === strpos($key, 'HTTP_')) {
                 $headers[substr($key, 5)] = $value;
-            }
+            } elseif (\in_array($key, ['CONTENT_TYPE', 'CONTENT_LENGTH', 'CONTENT_MD5'], true)) {
-            // CONTENT_* are not prefixed with HTTP_
-            elseif (isset($contentHeaders[$key])) {
                 $headers[$key] = $value;
             }
         }