bug #35015 [Config] fix perf of glob discovery when GLOB_BRACE is not…

… available (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
----------

[Config] fix perf of glob discovery when GLOB_BRACE is not available

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #35009
| License       | MIT
| Doc PR        | -

This PR implements a fast fallback implementation of GLOB_BRACE for musl-based libc, as found on Alpine. It is *not* a feature-complete fallback implementation. Implementing one would be [much more involving](https://github.com/zendframework/zend-stdlib/blob/master/src/Glob.php). But the provided implementation is good enough in practice IMHO, and the slow path is still used when not-covered glob patterns are used.

Here is the comparison:
![image](https://user-images.githubusercontent.com/243674/71022909-eb9f7000-2101-11ea-99f5-eab0286c77a3.png)

![image](https://user-images.githubusercontent.com/243674/71022899-e4786200-2101-11ea-8663-80c1674602db.png)

Commits
-------

8af6d86 [Config] improve perf of glob discovery when GLOB_BRACE is not available

src/Symfony/Component/Config/Resource/GlobResource.php

@@ -31,6 +31,7 @@ class GlobResource implements \IteratorAggregate, SelfCheckingResourceInterface
     private $hash;
     private $forExclusion;
     private $excludedPrefixes;
+    private $globBrace;
 
     /**
      * @param string $prefix    A directory prefix
@@ -47,6 +48,7 @@ public function __construct(string $prefix, string $pattern, bool $recursive, bo
         $this->recursive = $recursive;
         $this->forExclusion = $forExclusion;
         $this->excludedPrefixes = $excludedPrefixes;
+        $this->globBrace = \defined('GLOB_BRACE') ? GLOB_BRACE : 0;
 
         if (false === $this->prefix) {
             throw new \InvalidArgumentException(sprintf('The path "%s" does not exist.', $prefix));
@@ -101,9 +103,20 @@ public function getIterator()
             return;
         }
         $prefix = str_replace('\\', '/', $this->prefix);
+        $paths = null;
+
+        if (0 !== strpos($this->prefix, 'phar://') && false === strpos($this->pattern, '/**/')) {
+            if ($this->globBrace || false === strpos($this->pattern, '{')) {
+                $paths = glob($this->prefix.$this->pattern, GLOB_NOSORT | $this->globBrace);
+            } elseif (false === strpos($this->pattern, '\\') || !preg_match('/\\\\[,{}]/', $this->pattern)) {
+                foreach ($this->expandGlob($this->pattern) as $p) {
+                    $paths[] = glob($this->prefix.$p, GLOB_NOSORT);
+                }
+                $paths = array_merge(...$paths);
+            }
+        }
 
-        if (0 !== strpos($this->prefix, 'phar://') && false === strpos($this->pattern, '/**/') && (\defined('GLOB_BRACE') || false === strpos($this->pattern, '{'))) {
-            $paths = glob($this->prefix.$this->pattern, GLOB_NOSORT | (\defined('GLOB_BRACE') ? GLOB_BRACE : 0));
+        if (null !== $paths) {
             sort($paths);
             foreach ($paths as $path) {
                 if ($this->excludedPrefixes) {
@@ -187,4 +200,34 @@ private function computeHash(): string
 
         return hash_final($hash);
     }
+
+    private function expandGlob(string $pattern): array
+    {
+        $segments = preg_split('/\{([^{}]*+)\}/', $pattern, -1, PREG_SPLIT_DELIM_CAPTURE);
+        $paths = [$segments[0]];
+        $patterns = [];
+
+        for ($i = 1; $i < \count($segments); $i += 2) {
+            $patterns = [];
+
+            foreach (explode(',', $segments[$i]) as $s) {
+                foreach ($paths as $p) {
+                    $patterns[] = $p.$s.$segments[1 + $i];
+                }
+            }
+
+            $paths = $patterns;
+        }
+
+        $j = 0;
+        foreach ($patterns as $i => $p) {
+            if (false !== strpos($p, '{')) {
+                $p = $this->expandGlob($p);
+                array_splice($paths, $i + $j, 1, $p);
+                $j += \count($p) - 1;
+            }
+        }
+
+        return $paths;
+    }
 }

src/Symfony/Component/Config/Tests/Resource/GlobResourceTest.php

@@ -165,4 +165,33 @@ public function testIsFreshRecursiveDetectsNewFile()
         touch($dir.'/Resource/TmpGlob');
         $this->assertFalse($resource->isFresh(0));
     }
+
+    public function testBraceFallback()
+    {
+        $dir = \dirname(__DIR__).\DIRECTORY_SEPARATOR.'Fixtures';
+        $resource = new GlobResource($dir, '/*{/*/*.txt,.x{m,n}l}', true);
+
+        $p = new \ReflectionProperty($resource, 'globBrace');
+        $p->setAccessible(true);
+        $p->setValue($resource, 0);
+
+        $expected = [
+            $dir.'/Exclude/ExcludeToo/AnotheExcludedFile.txt',
+            $dir.'/foo.xml',
+        ];
+
+        $this->assertSame($expected, array_keys(iterator_to_array($resource)));
+    }
+
+    public function testUnbalancedBraceFallback()
+    {
+        $dir = \dirname(__DIR__).\DIRECTORY_SEPARATOR.'Fixtures';
+        $resource = new GlobResource($dir, '/*{/*/*.txt,.x{m,nl}', true);
+
+        $p = new \ReflectionProperty($resource, 'globBrace');
+        $p->setAccessible(true);
+        $p->setValue($resource, 0);
+
+        $this->assertSame([], array_keys(iterator_to_array($resource)));
+    }
 }