MemoryBackend.php 5.16 KB
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<?php

namespace Drupal\Core\Cache;

/**
 * Defines a memory cache implementation.
 *
 * Stores cache items in memory using a PHP array.
 *
 * Should be used for unit tests and specialist use-cases only, does not
 * store cached items between requests.
 *
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 * The functions ::prepareItem()/::set() use unserialize()/serialize(). It
 * behaves as an external cache backend to avoid changing the cached data by
 * reference. In ::prepareItem(), the object is not modified by the call to
 * unserialize() because we make a clone of it.
 *
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 * @ingroup cache
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 */
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class MemoryBackend implements CacheBackendInterface, CacheTagsInvalidatorInterface {
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  /**
   * Array to store cache objects.
   */
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  protected $cache = [];
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  /**
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   * {@inheritdoc}
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   */
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  public function get($cid, $allow_invalid = FALSE) {
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    if (isset($this->cache[$cid])) {
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      return $this->prepareItem($this->cache[$cid], $allow_invalid);
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    }
    else {
      return FALSE;
    }
  }

  /**
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   * {@inheritdoc}
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   */
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  public function getMultiple(&$cids, $allow_invalid = FALSE) {
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    $ret = [];
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    $items = array_intersect_key($this->cache, array_flip($cids));

    foreach ($items as $item) {
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      $item = $this->prepareItem($item, $allow_invalid);
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      if ($item) {
        $ret[$item->cid] = $item;
      }
    }

    $cids = array_diff($cids, array_keys($ret));

    return $ret;
  }

  /**
   * Prepares a cached item.
   *
   * Checks that items are either permanent or did not expire, and returns data
   * as appropriate.
   *
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   * @param object $cache
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   *   An item loaded from cache_get() or cache_get_multiple().
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   * @param bool $allow_invalid
   *   (optional) If TRUE, cache items may be returned even if they have expired
   *   or been invalidated.
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   *
   * @return mixed
   *   The item with data as appropriate or FALSE if there is no
   *   valid item to load.
   */
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  protected function prepareItem($cache, $allow_invalid) {
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    if (!isset($cache->data)) {
      return FALSE;
    }
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    // The object passed into this function is the one stored in $this->cache.
    // We must clone it as part of the preparation step so that the actual
    // cache object is not affected by the unserialize() call or other
    // manipulations of the returned object.

    $prepared = clone $cache;
    $prepared->data = unserialize($prepared->data);
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    // Check expire time.
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    $prepared->valid = $prepared->expire == Cache::PERMANENT || $prepared->expire >= $this->getRequestTime();
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    if (!$allow_invalid && !$prepared->valid) {
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      return FALSE;
    }

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    return $prepared;
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  }

  /**
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   * {@inheritdoc}
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   */
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  public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
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    assert('\Drupal\Component\Assertion\Inspector::assertAllStrings($tags)', 'Cache Tags must be strings.');
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    $tags = array_unique($tags);
    // Sort the cache tags so that they are stored consistently in the database.
    sort($tags);
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    $this->cache[$cid] = (object) [
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      'cid' => $cid,
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      'data' => serialize($data),
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      'created' => $this->getRequestTime(),
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      'expire' => $expire,
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      'tags' => $tags,
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    ];
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  }

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  /**
   * {@inheritdoc}
   */
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  public function setMultiple(array $items = []) {
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    foreach ($items as $cid => $item) {
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      $this->set($cid, $item['data'], isset($item['expire']) ? $item['expire'] : CacheBackendInterface::CACHE_PERMANENT, isset($item['tags']) ? $item['tags'] : []);
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    }
  }

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  /**
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   * {@inheritdoc}
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   */
  public function delete($cid) {
    unset($this->cache[$cid]);
  }

  /**
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   * {@inheritdoc}
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   */
  public function deleteMultiple(array $cids) {
    $this->cache = array_diff_key($this->cache, array_flip($cids));
  }

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  /**
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   * {@inheritdoc}
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   */
  public function deleteAll() {
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    $this->cache = [];
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  }

  /**
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   * {@inheritdoc}
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   */
  public function invalidate($cid) {
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    if (isset($this->cache[$cid])) {
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      $this->cache[$cid]->expire = $this->getRequestTime() - 1;
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    }
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  }

  /**
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   * {@inheritdoc}
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   */
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  public function invalidateMultiple(array $cids) {
    foreach ($cids as $cid) {
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      if (isset($this->cache[$cid])) {
        $this->cache[$cid]->expire = $this->getRequestTime() - 1;
      }
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    }
  }

  /**
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   * {@inheritdoc}
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   */
  public function invalidateTags(array $tags) {
    foreach ($this->cache as $cid => $item) {
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      if (array_intersect($tags, $item->tags)) {
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        $this->cache[$cid]->expire = $this->getRequestTime() - 1;
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      }
    }
  }

  /**
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   * {@inheritdoc}
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   */
  public function invalidateAll() {
    foreach ($this->cache as $cid => $item) {
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      $this->cache[$cid]->expire = $this->getRequestTime() - 1;
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    }
  }

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  /**
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   * {@inheritdoc}
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   */
  public function garbageCollection() {
  }
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  /**
   * {@inheritdoc}
   */
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  public function removeBin() {
    $this->cache = [];
  }
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  /**
   * Wrapper method for REQUEST_TIME constant.
   *
   * @return int
   */
  protected function getRequestTime() {
    return defined('REQUEST_TIME') ? REQUEST_TIME : (int) $_SERVER['REQUEST_TIME'];
  }

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  /**
   * Prevents data stored in memory backends from being serialized.
   */
  public function __sleep() {
    return [];
  }

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  /**
   * Reset statically cached variables.
   *
   * This is only used by tests.
   */
  public function reset() {
    $this->cache = [];
  }

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}