fixed APCu dep version

This PR was merged into the 2.3 branch.

Discussion
----------

Fix performance (PHP5) and memory (PHP7) issues when using token_get_all

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #16868
| License       | MIT
| Doc PR        | -

Although it's not the case anymore on PHP 7, on PHP 5, `is_array` checks are much slower than `isset` checks.

Also from @peteward in #17384:
>  New PHP7 memory manager will not release small buckets to OS automatically in cases exposed by `token_get_all()`. This function call addition specifically for PHP7 will reclaim this memory to keep the footprint down of long processe

> See above ticket and suggested actions by PHP internals team for long-running tasks (https://bugs.php.net/70098) - I think `cache:clear/warmup` on a heavy app justifies this.

> We're running on cloud-based hosting platforms under memory limitations (Platform.sh). When memory is exceeded we're into swap and the cache clearing process goes from seconds to minutes for the initial deployment, which really slows our development workflow and also causes holding page delays.

Commits
-------

e555aad Add gc_mem_caches() call for PHP7 after itoken_get_all() as new memory manager will not release small buckets to OS automatically
d1f72d8 Fix perf and mem issue when using token_get_all

ApcClassLoader.php

@@ -67,8 +67,8 @@ class ApcClassLoader
      */
     public function __construct($prefix, $decorated)
     {
-        if (!extension_loaded('apc')) {
-            throw new \RuntimeException('Unable to use ApcClassLoader as APC is not enabled.');
+        if (!function_exists('apcu_fetch')) {
+            throw new \RuntimeException('Unable to use ApcClassLoader as APC is not installed.');
         }
 
         if (!method_exists($decorated, 'findFile')) {
@@ -122,8 +122,8 @@ class ApcClassLoader
      */
     public function findFile($class)
     {
-        if (false === $file = apc_fetch($this->prefix.$class)) {
-            apc_store($this->prefix.$class, $file = $this->decorated->findFile($class));
+        if (false === $file = apcu_fetch($this->prefix.$class)) {
+            apcu_store($this->prefix.$class, $file = $this->decorated->findFile($class));
         }
 
         return $file;

ApcUniversalClassLoader.php

@@ -71,7 +71,7 @@ class ApcUniversalClassLoader extends UniversalClassLoader
      */
     public function __construct($prefix)
     {
-        if (!extension_loaded('apc')) {
+        if (!function_exists('apcu_fetch')) {
             throw new \RuntimeException('Unable to use ApcUniversalClassLoader as APC is not enabled.');
         }
 
@@ -87,8 +87,8 @@ class ApcUniversalClassLoader extends UniversalClassLoader
      */
     public function findFile($class)
     {
-        if (false === $file = apc_fetch($this->prefix.$class)) {
-            apc_store($this->prefix.$class, $file = parent::findFile($class));
+        if (false === $file = apcu_fetch($this->prefix.$class)) {
+            apcu_store($this->prefix.$class, $file = parent::findFile($class));
         }
 
         return $file;

ClassCollectionLoader.php

@@ -149,8 +149,9 @@ class ClassCollectionLoader
         $inNamespace = false;
         $tokens = token_get_all($source);
 
-        for (reset($tokens); false !== $token = current($tokens); next($tokens)) {
-            if (is_string($token)) {
+        for ($i = 0; isset($tokens[$i]); ++$i) {
+            $token = $tokens[$i];
+            if (!isset($token[1]) || 'b"' === $token) {
                 $rawChunk .= $token;
             } elseif (in_array($token[0], array(T_COMMENT, T_DOC_COMMENT))) {
                 // strip comments
@@ -162,12 +163,12 @@ class ClassCollectionLoader
                 $rawChunk .= $token[1];
 
                 // namespace name and whitespaces
-                while (($t = next($tokens)) && is_array($t) && in_array($t[0], array(T_WHITESPACE, T_NS_SEPARATOR, T_STRING))) {
-                    $rawChunk .= $t[1];
+                while (isset($tokens[++$i][1]) && in_array($tokens[$i][0], array(T_WHITESPACE, T_NS_SEPARATOR, T_STRING))) {
+                    $rawChunk .= $tokens[$i][1];
                 }
-                if ('{' === $t) {
+                if ('{' === $tokens[$i]) {
                     $inNamespace = false;
-                    prev($tokens);
+                    --$i;
                 } else {
                     $rawChunk = rtrim($rawChunk)."\n{";
                     $inNamespace = true;
@@ -175,8 +176,8 @@ class ClassCollectionLoader
             } elseif (T_START_HEREDOC === $token[0]) {
                 $output .= self::compressCode($rawChunk).$token[1];
                 do {
-                    $token = next($tokens);
-                    $output .= is_string($token) ? $token : $token[1];
+                    $token = $tokens[++$i];
+                    $output .= isset($token[1]) && 'b"' !== $token ? $token[1] : $token;
                 } while ($token[0] !== T_END_HEREDOC);
                 $output .= "\n";
                 $rawChunk = '';
@@ -192,7 +193,15 @@ class ClassCollectionLoader
             $rawChunk .= "}\n";
         }
 
-        return $output.self::compressCode($rawChunk);
+        $output .= self::compressCode($rawChunk);
+
+        if (PHP_VERSION_ID >= 70000) {
+            // PHP 7 memory manager will not release after token_get_all(), see https://bugs.php.net/70098
+            unset($tokens, $rawChunk);
+            gc_mem_caches();
+        }
+
+        return $output;
     }
 
     /**

ClassMapGenerator.php

@@ -72,6 +72,11 @@ class ClassMapGenerator
 
             $classes = self::findClasses($path);
 
+            if (PHP_VERSION_ID >= 70000) {
+                // PHP 7 memory manager will not release after token_get_all(), see https://bugs.php.net/70098
+                gc_mem_caches();
+            }
+
             foreach ($classes as $class) {
                 $map[$class] = $path;
             }
@@ -95,10 +100,10 @@ class ClassMapGenerator
         $classes = array();
 
         $namespace = '';
-        for ($i = 0, $max = count($tokens); $i < $max; ++$i) {
+        for ($i = 0; isset($tokens[$i]); ++$i) {
             $token = $tokens[$i];
 
-            if (is_string($token)) {
+            if (!isset($token[1])) {
                 continue;
             }
 
@@ -108,9 +113,9 @@ class ClassMapGenerator
                 case T_NAMESPACE:
                     $namespace = '';
                     // If there is a namespace, extract it
-                    while (($t = $tokens[++$i]) && is_array($t)) {
-                        if (in_array($t[0], array(T_STRING, T_NS_SEPARATOR))) {
-                            $namespace .= $t[1];
+                    while (isset($tokens[++$i][1])) {
+                        if (in_array($tokens[$i][0], array(T_STRING, T_NS_SEPARATOR))) {
+                            $namespace .= $tokens[$i][1];
                         }
                     }
                     $namespace .= '\\';
@@ -121,7 +126,7 @@ class ClassMapGenerator
                     // Skip usage of ::class constant
                     $isClassConstant = false;
                     for ($j = $i - 1; $j > 0; --$j) {
-                        if (is_string($tokens[$j])) {
+                        if (!isset($tokens[$j][1])) {
                             break;
                         }
 
@@ -138,10 +143,11 @@ class ClassMapGenerator
                     }
 
                     // Find the classname
-                    while (($t = $tokens[++$i]) && is_array($t)) {
+                    while (isset($tokens[++$i][1])) {
+                        $t = $tokens[$i];
                         if (T_STRING === $t[0]) {
                             $class .= $t[1];
-                        } elseif ($class !== '' && T_WHITESPACE == $t[0]) {
+                        } elseif ('' !== $class && T_WHITESPACE === $t[0]) {
                             break;
                         }
                     }

Tests/ApcUniversalClassLoaderTest.php

@@ -13,15 +13,12 @@ namespace Symfony\Component\ClassLoader\Tests;
 
 use Symfony\Component\ClassLoader\ApcUniversalClassLoader;
 
-/**
- * @requires extension apc
- */
 class ApcUniversalClassLoaderTest extends \PHPUnit_Framework_TestCase
 {
     protected function setUp()
     {
         if (ini_get('apc.enabled') && ini_get('apc.enable_cli')) {
-            apc_clear_cache('user');
+            apcu_clear_cache();
         } else {
             $this->markTestSkipped('APC is not enabled.');
         }
@@ -30,7 +27,7 @@ class ApcUniversalClassLoaderTest extends \PHPUnit_Framework_TestCase
     protected function tearDown()
     {
         if (ini_get('apc.enabled') && ini_get('apc.enable_cli')) {
-            apc_clear_cache('user');
+            apcu_clear_cache();
         }
     }
 
@@ -39,7 +36,7 @@ class ApcUniversalClassLoaderTest extends \PHPUnit_Framework_TestCase
         $loader = new ApcUniversalClassLoader('test.prefix.');
         $loader->registerNamespace('Apc\Namespaced', __DIR__.DIRECTORY_SEPARATOR.'Fixtures');
 
-        $this->assertEquals($loader->findFile('\Apc\Namespaced\FooBar'), apc_fetch('test.prefix.\Apc\Namespaced\FooBar'), '__construct() takes a prefix as its first argument');
+        $this->assertEquals($loader->findFile('\Apc\Namespaced\FooBar'), apcu_fetch('test.prefix.\Apc\Namespaced\FooBar'), '__construct() takes a prefix as its first argument');
     }
 
    /**

composer.json

@@ -17,7 +17,8 @@
     ],
     "minimum-stability": "dev",
     "require": {
-        "php": ">=5.3.3"
+        "php": ">=5.3.3",
+        "symfony/polyfill-apcu": "~1.1"
     },
     "require-dev": {
         "symfony/finder": "~2.0,>=2.0.5"