From c8ee2170fdc39e8f6a02f5418adc5055508b9a05 Mon Sep 17 00:00:00 2001
From: mixologic <Mixologic@391689.no-reply.drupal.org>
Date: Wed, 30 Apr 2014 17:55:24 -0700
Subject: [PATCH] Reroll Merge with HEAD for 1807662

---
 core/core.services.yml                             |   2 +
 core/lib/Drupal/Core/Cache/ApcuBackend.php         | 380 +++++++++++++++++++++
 core/lib/Drupal/Core/Cache/ApcuBackendFactory.php  |  39 +++
 .../system/Tests/Cache/ApcuBackendUnitTest.php     |  56 +++
 4 files changed, 477 insertions(+)
 create mode 100644 core/lib/Drupal/Core/Cache/ApcuBackend.php
 create mode 100644 core/lib/Drupal/Core/Cache/ApcuBackendFactory.php
 create mode 100644 core/modules/system/lib/Drupal/system/Tests/Cache/ApcuBackendUnitTest.php

diff --git a/core/core.services.yml b/core/core.services.yml
index 19b0b72..703d255 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -25,6 +25,8 @@ services:
   cache.backend.database:
     class: Drupal\Core\Cache\DatabaseBackendFactory
     arguments: ['@database']
+  cache.backend.apcu:
+    class: Drupal\Core\Cache\ApcuBackendFactory
   cache.backend.php:
     class: Drupal\Core\Cache\PhpBackendFactory
   cache.bootstrap:
diff --git a/core/lib/Drupal/Core/Cache/ApcuBackend.php b/core/lib/Drupal/Core/Cache/ApcuBackend.php
new file mode 100644
index 0000000..f6de468
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/ApcuBackend.php
@@ -0,0 +1,380 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\ApcuBackend.
+ */
+
+namespace Drupal\Core\Cache;
+
+/**
+ * Stores cache items in the Alternative PHP Cache User Cache (APCu).
+ */
+class ApcuBackend implements CacheBackendInterface {
+
+  /**
+   * The name of the cache bin to use.
+   *
+   * @var string
+   */
+  protected $bin;
+
+  /**
+   * Prefix for all keys in the storage that belong to this site.
+   *
+   * @var string
+   */
+  protected $sitePrefix;
+
+  /**
+   * Prefix for all keys in this cache bin.
+   *
+   * Includes the site-specific prefix in $sitePrefix.
+   *
+   * @var string
+   */
+  protected $binPrefix;
+
+  /**
+   * Prefix for keys holding cache tags.
+   *
+   * Includes the site-specific prefix in $sitePrefix.
+   *
+   * @var string
+   */
+  protected $tagsPrefix;
+
+  /**
+   * A static cache of all tags checked during the request.
+   *
+   * @var array
+   */
+  protected static $tagCache = array();
+
+  /**
+   * Constructs a new ApcuBackend instance.
+   *
+   * @param string $bin
+   *   The name of the cache bin.
+   * @param string $site_prefix
+   *   The prefix to use for all keys in the storage that belong to this site.
+   */
+  public function __construct($bin, $site_prefix) {
+    $this->bin = $bin;
+    $this->sitePrefix = $site_prefix;
+    $this->binPrefix = $this->sitePrefix . '::' . $this->bin . '::';
+    $this->tagsPrefix = $this->sitePrefix . '::tags::';
+  }
+
+  /**
+   * Prepends the APC user variable prefix for this bin to a cache item ID.
+   *
+   * @param string $cid
+   *   The cache item ID to prefix.
+   *
+   * @return string
+   *   The APCu key for the cache item ID.
+   */
+  protected function getApcuKey($cid) {
+    return $this->binPrefix . $cid;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function get($cid, $allow_invalid = FALSE) {
+    $cache = apc_fetch($this->getApcuKey($cid));
+    return $this->prepareItem($cache, $allow_invalid);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMultiple(&$cids, $allow_invalid = FALSE) {
+    // Translate the requested cache item IDs to APCu keys.
+    $map = array();
+    foreach ($cids as $cid) {
+      $map[$this->getApcuKey($cid)] = $cid;
+    }
+
+    $result = apc_fetch(array_keys($map));
+    $cache = array();
+    foreach ($result as $key => $item) {
+      $item = $this->prepareItem($item, $allow_invalid);
+      if ($item) {
+        $cache[$map[$key]] = $item;
+      }
+    }
+    unset($result);
+
+    $cids = array_diff($cids, array_keys($cache));
+    return $cache;
+  }
+
+  /**
+   * Returns all cached items, optionally limited by a cache ID prefix.
+   *
+   * APCu is a memory cache, shared across all server processes. To prevent
+   * cache item clashes with other applications/installations, every cache item
+   * is prefixed with a unique string for this site. Therefore, functions like
+   * apc_clear_cache() cannot be used, and instead, a list of all cache items
+   * belonging to this application need to be retrieved through this method
+   * instead.
+   *
+   * @param string $prefix
+   *   (optional) A cache ID prefix to limit the result to.
+   *
+   * @return \APCIterator
+   *   An APCIterator containing matched items.
+   */
+  public function getAll($prefix = '') {
+    return new \APCIterator('user', '/^' . preg_quote($this->getApcuKey($prefix), '/') . '/');
+  }
+
+  /**
+   * Prepares a cached item.
+   *
+   * Checks that the item is either permanent or did not expire.
+   *
+   * @param \stdClass $cache
+   *   An item loaded from cache_get() or cache_get_multiple().
+   * @param bool $allow_invalid
+   *   If TRUE, a cache item may be returned even if it is expired or has been
+   *   invalidated. See ::get().
+   *
+   * @return mixed
+   *   The cache item or FALSE if the item expired.
+   */
+  protected function prepareItem($cache, $allow_invalid) {
+    if (!isset($cache->data)) {
+      return FALSE;
+    }
+
+    $cache->tags = $cache->tags ? explode(' ', $cache->tags) : array();
+    $checksum = $this->checksumTags($cache->tags);
+
+    // The cache data is invalid if any of its tags have been cleared since.
+    if (!$this->validTags($checksum, $cache->tags)) {
+      return FALSE;
+    }
+
+    // Check expire time.
+    $cache->valid = ($cache->expire == CacheBackendInterface::CACHE_PERMANENT) || ($cache->expire >= REQUEST_TIME);
+
+    // Check if invalidateTags() has been called with any of the entry's tags.
+    if ($cache->checksum != $checksum) {
+      $cache->valid = FALSE;
+    }
+
+    if (!$allow_invalid && !$cache->valid) {
+      return FALSE;
+    }
+
+    return $cache;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANENT, array $tags = array()) {
+    $cache = new \stdClass();
+    $cache->cid = $cid;
+    $cache->created = REQUEST_TIME;
+    $cache->expire = $expire;
+    $cache->tags = implode(' ', $this->flattenTags($tags));
+    $cache->checksum = $this->checksumTags($tags);
+
+    // APC serializes/unserializes any structure itself.
+    $cache->serialized = 0;
+    $cache->data = $data;
+
+    // apc_store()'s $ttl argument can be omitted but also set to 0 (zero),
+    // in which case the value will persist until it's removed from the cache or
+    // until the next cache clear, restart, etc. This is what we want to do
+    // when $expire equals CacheBackendInterface::CACHE_PERMANENT.
+    if ($expire === CacheBackendInterface::CACHE_PERMANENT) {
+      $expire = 0;
+    }
+    apc_store($this->getApcuKey($cid), $cache, $expire);
+  }
+
+  /**
+   * {@inheritdoc
+   */
+  public function setMultiple(array $items = array()) {
+    foreach ($items as $cid => $item) {
+      $this->set($cid, $item['data'], isset($item['expire']) ? $item['expire'] : CacheBackendInterface::CACHE_PERMANENT, isset($item['tags']) ? $item['tags'] : array());
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function delete($cid) {
+    apc_delete($this->getApcuKey($cid));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteMultiple(array $cids) {
+    apc_delete(array_map(array($this, 'getApcuKey'), $cids));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteAll() {
+    apc_delete(new \APCIterator('user', '/^' . preg_quote($this->binPrefix, '/') . '/'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function garbageCollection() {
+    // Any call to apc_fetch() causes APC to expunge expired items.
+    apc_fetch('');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function removeBin() {
+    $this->deleteAll();
+    apc_delete(new \APCIterator('user', '/^' . preg_quote($this->tagsPrefix, '/') . '/'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isEmpty() {
+    return $this->getAll()->getTotalCount() === 0;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidate($cid) {
+    $this->invalidateMultiple(array($cid));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateMultiple(array $cids) {
+    foreach ($this->getMultiple($cids) as $cache) {
+      $cache->expire = REQUEST_TIME - 1;
+      $this->set($cache->cid, $cache);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateAll() {
+    foreach ($this->getAll() as $data) {
+      $data['value']->expire = REQUEST_TIME - 1;
+      $this->set($data['key'], $data['value']);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteTags(array $tags) {
+    foreach ($this->flattenTags($tags) as $tag) {
+      apc_delete($this->tagsPrefix . $tag);
+      unset(static::$tagCache[$tag]);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateTags(array $tags) {
+    foreach ($this->flattenTags($tags) as $tag) {
+      unset(static::$tagCache[$tag]);
+      apc_inc($this->tagsPrefix . $tag, 1, $success);
+      if (!$success) {
+        apc_store($this->tagsPrefix . $tag, 1);
+      }
+    }
+  }
+
+  /**
+   * Compares two checksums of tags.
+   *
+   * Used to determine whether to serve a cached item or treat it as
+   * invalidated.
+   *
+   * @param int $checksum
+   *   The initial checksum to compare against.
+   * @param array $tags
+   *   An array of tags to calculate a checksum for.
+   *
+   * @return bool
+   *   TRUE if the checksums match, FALSE otherwise.
+   */
+  protected function validTags($checksum, array $tags) {
+    return $checksum == $this->checksumTags($tags);
+  }
+
+  /**
+   * Flattens a tags array into a numeric array suitable for string storage.
+   *
+   * @param array $tags
+   *   Associative array of tags to flatten.
+   *
+   * @return array
+   *   Indexed array of flattened tag identifiers.
+   */
+  protected function flattenTags(array $tags) {
+    if (isset($tags[0])) {
+      return $tags;
+    }
+
+    $flat_tags = array();
+    foreach ($tags as $namespace => $values) {
+      if (is_array($values)) {
+        foreach ($values as $value) {
+          $flat_tags[] = "$namespace:$value";
+        }
+      }
+      else {
+        $flat_tags[] = "$namespace:$values";
+      }
+    }
+    return $flat_tags;
+  }
+
+  /**
+   * Returns the sum total of validations for a given set of tags.
+   *
+   * @param array $tags
+   *   Associative array of tags.
+   *
+   * @return int
+   *   Sum of all invalidations.
+   */
+  protected function checksumTags(array $tags) {
+    $checksum = 0;
+    $query_tags = array();
+
+    foreach ($this->flattenTags($tags) as $tag) {
+      if (isset(static::$tagCache[$tag])) {
+        $checksum += static::$tagCache[$tag];
+      }
+      else {
+        $query_tags[] = $this->tagsPrefix . $tag;
+      }
+    }
+    if ($query_tags) {
+      $result = apc_fetch($query_tags);
+      static::$tagCache = array_merge(static::$tagCache, $result);
+      $checksum += array_sum($result);
+    }
+
+    return $checksum;
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Cache/ApcuBackendFactory.php b/core/lib/Drupal/Core/Cache/ApcuBackendFactory.php
new file mode 100644
index 0000000..6c6d4ba
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/ApcuBackendFactory.php
@@ -0,0 +1,39 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\ApcuBackendFactory.
+ */
+
+namespace Drupal\Core\Cache;
+
+class ApcuBackendFactory implements CacheFactoryInterface {
+
+  /**
+   * The site prefix string.
+   *
+   * @var string
+   */
+  protected $sitePrefix;
+
+  /**
+   * Constructs an ApcuBackendFactory object.
+   */
+  public function __construct() {
+    $this->sitePrefix = md5(DRUPAL_ROOT . '/' . conf_path());
+  }
+
+  /**
+   * Gets ApcuBackend for the specified cache bin.
+   *
+   * @param $bin
+   *   The cache bin for which the object is created.
+   *
+   * @return \Drupal\Core\Cache\ApcuBackend
+   *   The cache backend object for the specified cache bin.
+   */
+  public function get($bin) {
+    return new ApcuBackend($bin, $this->sitePrefix);
+  }
+
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/Cache/ApcuBackendUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Cache/ApcuBackendUnitTest.php
new file mode 100644
index 0000000..8da6243
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/Cache/ApcuBackendUnitTest.php
@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\system\Tests\Cache\ApcuBackendUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\ApcuBackend;
+
+/**
+ * Tests the APC cache backend.
+ *
+ * @todo APC still contains the following variables after each tearDown() of a
+ *   test method:
+ *   - cache::theme_registry:build:modules
+ *   - cache::theme_registry:stark
+ *   - tags::*
+ *   The first two are caused by CacheArray::__destruct() being invoked *after*
+ *   TestBase::tearDown() reset static caches.
+ *   Cache tag invalidation counters, however, are not flushed by design. It
+ *   might be possible to flush them in a tearDown() override method in this
+ *   class though.
+ */
+class ApcuBackendUnitTest extends GenericCacheBackendUnitTestBase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'APCu cache backend',
+      'description' => 'Tests the APCu cache backend.',
+      'group' => 'Cache',
+    );
+  }
+
+  protected function checkRequirements() {
+    $requirements = parent::checkRequirements();
+    if (!extension_loaded('apc')) {
+      $requirements[] = 'APC extension not found.';
+    }
+    else {
+      if (version_compare(phpversion('apc'), '3.1.1', '<')) {
+        $requirements[] = 'APC extension must be newer than 3.1.1 for APCIterator support.';
+      }
+      if (PHP_SAPI === 'cli' && !ini_get('apc.enable_cli')) {
+        $requirements[] = 'apc.enable_cli must be enabled to run this test.';
+      }
+    }
+    return $requirements;
+  }
+
+  protected function createCacheBackend($bin) {
+    return new ApcuBackend($bin, 'test');
+  }
+
+}
-- 
1.8.5.3