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<?php
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;
/**
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* The cache tags checksum provider.
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*
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* @var \Drupal\Core\Cache\CacheTagsChecksumInterface
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*/
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protected $checksumProvider;
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/**
* 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.
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* @param \Drupal\Core\Cache\CacheTagsChecksumInterface $checksum_provider
* The cache tags checksum provider.
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*/
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public function __construct($bin, $site_prefix, CacheTagsChecksumInterface $checksum_provider) {
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$this->bin = $bin;
$this->sitePrefix = $site_prefix;
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$this->checksumProvider = $checksum_provider;
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$this->binPrefix = $this->sitePrefix . '::' . $this->bin . '::';
}
/**
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* Prepends the APCu user variable prefix for this bin to a cache item ID.
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*
* @param string $cid
* The cache item ID to prefix.
*
* @return string
* The APCu key for the cache item ID.
*/
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public function getApcuKey($cid) {
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return $this->binPrefix . $cid;
}
/**
* {@inheritdoc}
*/
public function get($cid, $allow_invalid = FALSE) {
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$cache = apcu_fetch($this->getApcuKey($cid));
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return $this->prepareItem($cache, $allow_invalid);
}
/**
* {@inheritdoc}
*/
public function getMultiple(&$cids, $allow_invalid = FALSE) {
// Translate the requested cache item IDs to APCu keys.
$map = [];
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foreach ($cids as $cid) {
$map[$this->getApcuKey($cid)] = $cid;
}
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$result = apcu_fetch(array_keys($map));
$cache = [];
if ($result) {
foreach ($result as $key => $item) {
$item = $this->prepareItem($item, $allow_invalid);
if ($item) {
$cache[$map[$key]] = $item;
}
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}
}
unset($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
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* apcu_clear_cache() cannot be used, and instead, a list of all cache items
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* belonging to this application need to be retrieved through this method
* instead.
*
* @param string $prefix
* (optional) A cache ID prefix to limit the result to.
*
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* @return \APCUIterator
* An APCUIterator containing matched items.
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*/
protected function getAll($prefix = '') {
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return $this->getIterator('/^' . preg_quote($this->getApcuKey($prefix), '/') . '/');
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}
/**
* 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) : [];
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// Check expire time.
$cache->valid = $cache->expire == Cache::PERMANENT || $cache->expire >= REQUEST_TIME;
// Check if invalidateTags() has been called with any of the entry's tags.
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if (!$this->checksumProvider->isValid($cache->checksum, $cache->tags)) {
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$cache->valid = FALSE;
}
if (!$allow_invalid && !$cache->valid) {
return FALSE;
}
return $cache;
}
/**
* {@inheritdoc}
*/
public function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANENT, array $tags = []) {
assert('\Drupal\Component\Assertion\Inspector::assertAllStrings($tags)', 'Cache tags must be strings.');
$tags = array_unique($tags);
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$cache = new \stdClass();
$cache->cid = $cid;
$cache->created = round(microtime(TRUE), 3);
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$cache->expire = $expire;
$cache->tags = implode(' ', $tags);
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$cache->checksum = $this->checksumProvider->getCurrentChecksum($tags);
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// APCu serializes/unserializes any structure itself.
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$cache->serialized = 0;
$cache->data = $data;
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// Expiration is handled by our own prepareItem(), not APCu.
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apcu_store($this->getApcuKey($cid), $cache);
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}
/**
* {@inheritdoc}
*/
public function setMultiple(array $items = []) {
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foreach ($items as $cid => $item) {
$this->set($cid, $item['data'], isset($item['expire']) ? $item['expire'] : CacheBackendInterface::CACHE_PERMANENT, isset($item['tags']) ? $item['tags'] : []);
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}
}
/**
* {@inheritdoc}
*/
public function delete($cid) {
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apcu_delete($this->getApcuKey($cid));
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}
/**
* {@inheritdoc}
*/
public function deleteMultiple(array $cids) {
apcu_delete(array_map([$this, 'getApcuKey'], $cids));
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}
/**
* {@inheritdoc}
*/
public function deleteAll() {
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apcu_delete($this->getIterator('/^' . preg_quote($this->binPrefix, '/') . '/'));
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}
/**
* {@inheritdoc}
*/
public function garbageCollection() {
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// APCu performs garbage collection automatically.
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}
/**
* {@inheritdoc}
*/
public function removeBin() {
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apcu_delete($this->getIterator('/^' . preg_quote($this->binPrefix, '/') . '/'));
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}
/**
* {@inheritdoc}
*/
public function invalidate($cid) {
$this->invalidateMultiple([$cid]);
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}
/**
* {@inheritdoc}
*/
public function invalidateMultiple(array $cids) {
foreach ($this->getMultiple($cids) as $cache) {
$this->set($cache->cid, $cache, REQUEST_TIME - 1);
}
}
/**
* {@inheritdoc}
*/
public function invalidateAll() {
foreach ($this->getAll() as $data) {
$cid = str_replace($this->binPrefix, '', $data['key']);
$this->set($cid, $data['value'], REQUEST_TIME - 1);
}
}
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/**
* Instantiates and returns the APCUIterator class.
*
* @param mixed $search
* A PCRE regular expression that matches against APC key names, either as a
* string for a single regular expression, or as an array of regular
* expressions. Or, optionally pass in NULL to skip the search.
* @param int $format
* The desired format, as configured with one or more of the APC_ITER_*
* constants.
* @param int $chunk_size
* The chunk size. Must be a value greater than 0. The default value is 100.
* @param int $list
* The type to list. Either pass in APC_LIST_ACTIVE or APC_LIST_DELETED.
*
* @return \APCUIterator
*/
protected function getIterator($search = NULL, $format = APC_ITER_ALL, $chunk_size = 100, $list = APC_LIST_ACTIVE) {
return new \APCUIterator($search, $format, $chunk_size, $list);
}