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MemcachedBackend.php
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MemcachedBackend.php
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<?php
declare(strict_types=1);
namespace Neos\Cache\Backend;
/*
* This file is part of the Neos.Cache package.
*
* (c) Contributors of the Neos Project - www.neos.io
*
* This package is Open Source Software. For the full copyright and license
* information, please view the LICENSE file which was distributed with this
* source code.
*/
use Neos\Cache\Backend\AbstractBackend as IndependentAbstractBackend;
use Neos\Cache\EnvironmentConfiguration;
use Neos\Cache\Exception;
use Neos\Cache\Frontend\LowLevelFrontendInterface;
/**
* A caching backend which stores cache entries by using Memcache/Memcached.
*
* This backend uses the following types of cache keys:
* - tag_xxx
* xxx is tag name, value is array of associated identifiers identifier. This
* is "forward" tag index. It is mainly used for obtaining content by tag
* (get identifier by tag -> get content by identifier)
* - ident_xxx
* xxx is identifier, value is array of associated tags. This is "reverse" tag
* index. It provides quick access for all tags associated with this identifier
* and used when removing the identifier
* - tagIndex
* Value is a List of all tags (array)
*
* Each key is prepended with a prefix. By default prefix consists from two parts
* separated by underscore character and ends in yet another underscore character:
* - "Flow"
* - MD5 of script path and filename and SAPI name
* This prefix makes sure that keys from the different installations do not
* conflict.
*
* Note: When using the Memcache backend to store values of more than ~1 MB, the
* data will be split into chunks to make them fit into the caches limits.
*
* @api
*/
class MemcachedBackend extends IndependentAbstractBackend implements TaggableBackendInterface, PhpCapableBackendInterface
{
use RequireOnceFromValueTrait;
/**
* Max bucket size, (1024*1024)-42 bytes
* @var int
*/
const MAX_BUCKET_SIZE = 1048534;
/**
* Instance of the PHP Memcache/Memcached class
*
* @var \Memcache|\Memcached
*/
protected $memcache;
/**
* Array of Memcache server configurations
*
* @var array
*/
protected $servers = [];
/**
* Indicates whether the memcache uses compression or not (requires zlib),
* either 0 or MEMCACHE_COMPRESSED
*
* @var integer
*/
protected $flags;
/**
* A prefix to separate stored data from other data possible stored in the memcache
*
* @var string
*/
protected $identifierPrefix;
/**
* {@inheritdoc}
*/
public function __construct(EnvironmentConfiguration $environmentConfiguration, array $options = [])
{
if (!extension_loaded('memcache') && !extension_loaded('memcached')) {
throw new Exception('The PHP extension "memcache" or "memcached" must be installed and loaded in order to use the Memcache backend.', 1213987706);
}
parent::__construct($environmentConfiguration, $options);
if (!count($this->servers)) {
throw new Exception('No servers were given to Memcache', 1213115903);
}
}
/**
* Setter for servers to be used. Expects an array, the values are expected
* to be formatted like "<host>[:<port>]" or "unix://<path>"
*
* @param array $servers An array of servers to add.
* @return void
* @throws Exception
* @api
*/
protected function setServers(array $servers)
{
$this->servers = $servers;
if (!count($this->servers)) {
throw new Exception('No servers were given to Memcache', 1213115903);
}
$this->memcache = extension_loaded('memcached') ? new \MemCached() : new \Memcache();
$defaultPort = (int)ini_get('memcache.default_port') ?: 11211;
foreach ($this->servers as $server) {
$host = $server;
$port = 0;
if (strpos($server, 'tcp://') === 0) {
$port = $defaultPort;
$server = substr($server, 6);
}
if (strpos($server, ':') !== false) {
[$host, $portValue] = explode(':', $server, 2);
$port = (int)$portValue;
}
$this->memcache->addServer($host, $port);
}
}
/**
* Setter for compression flags bit
*
* @param boolean $useCompression
* @return void
* @api
*/
protected function setCompression(bool $useCompression)
{
if ($this->memcache instanceof \Memcached) {
$this->memcache->setOption(\Memcached::OPT_COMPRESSION, $useCompression);
return;
}
if ($useCompression === true) {
$this->flags ^= MEMCACHE_COMPRESSED;
} else {
$this->flags &= ~MEMCACHE_COMPRESSED;
}
}
/**
* Initializes the identifier prefix when setting the cache.
*
* @param LowLevelFrontendInterface $cache
* @return void
*/
public function setCache(LowLevelFrontendInterface $cache): void
{
parent::setCache($cache);
$pathHash = substr(md5($this->environmentConfiguration->getApplicationIdentifier() . $cache->getIdentifier()), 0, 12);
$this->identifierPrefix = 'Flow_' . $pathHash . '_';
}
/**
* Returns the internally used, prefixed entry identifier for the given public
* entry identifier.
*
* While Flow applications will mostly refer to the simple entry identifier, it
* may be necessary to know the actual identifier used by the cache backend
* in order to share cache entries with other applications. This method allows
* for retrieving it.
*
* @param string $entryIdentifier The short entry identifier, for example "NumberOfPostedArticles"
* @return string The prefixed identifier, for example "Flow694a5c7a43a4_NumberOfPostedArticles"
* @api
*/
public function getPrefixedIdentifier(string $entryIdentifier): string
{
return $this->identifierPrefix . $entryIdentifier;
}
/**
* Saves data in the cache.
*
* @param string $entryIdentifier An identifier for this specific cache entry
* @param string $data The data to be stored
* @param array $tags Tags to associate with this cache entry
* @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
* @return void
* @throws Exception if no cache frontend has been set.
* @throws \InvalidArgumentException if the identifier is not valid or the final memcached key is longer than 250 characters
* @api
*/
public function set(string $entryIdentifier, string $data, array $tags = [], int $lifetime = null): void
{
if (strlen($this->getPrefixedIdentifier($entryIdentifier)) > 250) {
throw new \InvalidArgumentException('Could not set value. Key more than 250 characters (' . $this->getPrefixedIdentifier($entryIdentifier) . ').', 1232969508);
}
if (!$this->cache instanceof LowLevelFrontendInterface) {
throw new Exception('No cache frontend has been set yet via setCache().', 1207149215);
}
$tags[] = '%MEMCACHEBE%' . $this->cacheIdentifier;
$expiration = $lifetime !== null ? $lifetime : $this->defaultLifetime;
// Memcache considers values over 2592000 sec (30 days) as UNIX timestamp
// thus $expiration should be converted from lifetime to UNIX timestamp
if ($expiration > 2592000) {
$expiration += time();
}
try {
if (strlen($data) > self::MAX_BUCKET_SIZE) {
$data = str_split($data, self::MAX_BUCKET_SIZE - 1024);
$success = true;
$chunkNumber = 1;
foreach ($data as $chunk) {
$success = $success && $this->setItem($this->getPrefixedIdentifier($entryIdentifier) . '_chunk_' . $chunkNumber, $chunk, $expiration);
$chunkNumber++;
}
$success = $success && $this->setItem($this->getPrefixedIdentifier($entryIdentifier), 'Flow*chunked:' . $chunkNumber, $expiration);
} else {
$success = $this->setItem($this->getPrefixedIdentifier($entryIdentifier), $data, $expiration);
}
if ($success === true) {
$this->removeIdentifierFromAllTags($entryIdentifier);
$this->addIdentifierToTags($entryIdentifier, $tags);
} else {
throw new Exception('Could not set value on memcache server.', 1275830266);
}
} catch (\Exception $exception) {
throw new Exception('Could not set value. ' . $exception->getMessage(), 1207208100);
}
}
/**
* Stores an item on the server
*
* @param string $key
* @param string $value
* @param integer $expiration
* @return boolean
*/
protected function setItem(string $key, string $value, int $expiration)
{
if ($this->memcache instanceof \Memcached) {
return $this->memcache->set($key, $value, $expiration);
}
return $this->memcache->set($key, $value, $this->flags, $expiration);
}
/**
* Loads data from the cache.
*
* @param string $entryIdentifier An identifier which describes the cache entry to load
* @return mixed The cache entry's content as a string or false if the cache entry could not be loaded
* @api
*/
public function get(string $entryIdentifier)
{
$value = $this->memcache->get($this->getPrefixedIdentifier($entryIdentifier));
if (is_string($value) && strpos($value, 'Flow*chunked:') === 0) {
[, $chunkCount] = explode(':', $value);
$value = '';
for ($chunkNumber = 1; $chunkNumber < $chunkCount; $chunkNumber++) {
$value .= $this->memcache->get($this->getPrefixedIdentifier($entryIdentifier) . '_chunk_' . $chunkNumber);
}
}
return $value;
}
/**
* Checks if a cache entry with the specified identifier exists.
*
* @param string $entryIdentifier An identifier specifying the cache entry
* @return boolean true if such an entry exists, false if not
* @api
*/
public function has(string $entryIdentifier): bool
{
return $this->memcache->get($this->getPrefixedIdentifier($entryIdentifier)) !== false;
}
/**
* Removes all cache entries matching the specified identifier.
* Usually this only affects one entry but if - for what reason ever -
* old entries for the identifier still exist, they are removed as well.
*
* @param string $entryIdentifier Specifies the cache entry to remove
* @return boolean true if (at least) an entry could be removed or false if no entry was found
* @api
*/
public function remove(string $entryIdentifier): bool
{
$this->removeIdentifierFromAllTags($entryIdentifier);
return $this->memcache->delete($this->getPrefixedIdentifier($entryIdentifier));
}
/**
* Finds and returns all cache entry identifiers which are tagged by the
* specified tag.
*
* @param string $tag The tag to search for
* @return string[] An array with identifiers of all matching entries. An empty array if no entries matched
* @api
*/
public function findIdentifiersByTag(string $tag): array
{
$identifiers = $this->memcache->get($this->identifierPrefix . 'tag_' . $tag);
if ($identifiers !== false) {
return (array) $identifiers;
}
return [];
}
/**
* Finds all tags for the given identifier. This function uses reverse tag
* index to search for tags.
*
* @param string $identifier Identifier to find tags by
* @return array Array with tags
*/
protected function findTagsByIdentifier(string $identifier): array
{
$tags = $this->memcache->get($this->identifierPrefix . 'ident_' . $identifier);
return ($tags === false ? [] : (array)$tags);
}
/**
* Removes all cache entries of this cache.
*
* @return void
* @throws Exception
* @api
*/
public function flush(): void
{
if (!$this->cache instanceof LowLevelFrontendInterface) {
throw new Exception('Yet no cache frontend has been set via setCache().', 1204111376);
}
$this->flushByTag('%MEMCACHEBE%' . $this->cacheIdentifier);
}
/**
* Removes all cache entries of this cache which are tagged by the specified tag.
*
* @param string $tag The tag the entries must have
* @return integer The number of entries which have been affected by this flush
* @api
*/
public function flushByTag(string $tag): int
{
$identifiers = $this->findIdentifiersByTag($tag);
foreach ($identifiers as $identifier) {
$this->remove($identifier);
}
return count($identifiers);
}
/**
* Removes all cache entries of this cache which are tagged by any of the specified tags.
*
* @api
*/
public function flushByTags(array $tags): int
{
$flushed = 0;
foreach ($tags as $tag) {
$flushed += $this->flushByTag($tag);
}
return $flushed;
}
/**
* Associates the identifier with the given tags
*
* @param string $entryIdentifier
* @param array $tags
* @return void
*/
protected function addIdentifierToTags(string $entryIdentifier, array $tags)
{
foreach ($tags as $tag) {
// Update tag-to-identifier index
$identifiers = $this->findIdentifiersByTag($tag);
if (array_search($entryIdentifier, $identifiers) === false) {
$identifiers[] = $entryIdentifier;
$this->memcache->set($this->identifierPrefix . 'tag_' . $tag, $identifiers);
}
// Update identifier-to-tag index
$existingTags = $this->findTagsByIdentifier($entryIdentifier);
if (array_search($tag, $existingTags) === false) {
$this->memcache->set($this->identifierPrefix . 'ident_' . $entryIdentifier, array_merge($existingTags, $tags));
}
}
}
/**
* Removes association of the identifier with the given tags
*
* @param string $entryIdentifier
* @return void
*/
protected function removeIdentifierFromAllTags(string $entryIdentifier)
{
// Get tags for this identifier
$tags = $this->findTagsByIdentifier($entryIdentifier);
// Deassociate tags with this identifier
foreach ($tags as $tag) {
$identifiers = $this->findIdentifiersByTag($tag);
// Formally array_search() below should never return false due to
// the behavior of findTagsByIdentifier(). But if reverse index is
// corrupted, we still can get 'false' from array_search(). This is
// not a problem because we are removing this identifier from
// anywhere.
if (($key = array_search($entryIdentifier, $identifiers)) !== false) {
unset($identifiers[$key]);
if (count($identifiers)) {
$this->memcache->set($this->identifierPrefix . 'tag_' . $tag, $identifiers);
} else {
$this->memcache->delete($this->identifierPrefix . 'tag_' . $tag);
}
}
}
// Clear reverse tag index for this identifier
$this->memcache->delete($this->identifierPrefix . 'ident_' . $entryIdentifier);
}
/**
* Does nothing, as memcache/memcached does GC itself
*
* @return void
* @api
*/
public function collectGarbage(): void
{
}
}