apcu_store - PHP code example

The PHP Function Apcu_Store

If you have PHP 4.7 or later installed on your web server, you'll already be using a caching solution for your PHP scripts. That's because PHP comes with a built-in, powerful opcode cache that works flawlessly and automatically, known as PHP OPcache. However, if you're working with an older version of PHP, or are hosting your site on a shared hosting platform, you might need to install the alternative PHP Cache User Cache (APCu) as an add-on to get the same userland shared memory caching functionality that OPcache offers.

The apcu_store function lets you store values identified by key in the APCu user cache. The cached value may be a simple string or a complex data structure that is serialized by APCu. A default duration in seconds before the cached item will expire is stored as well. The dependency of the item is stored as well, so that if it changes, the corresponding cached value will be invalidated when it's fetched via get() or getMultiple().

php_instructions

PHP scripts are written in human readable syntax but need to be converted to machine language instructions for execution by the server or central processing unit. This conversion takes up time, especially if there are many files in the script that need to be accessed. The file cache part of APCu stores the mappings between relative and absolute file paths beforehand so that the PHP engine doesn't spend much time resolving them.

Another common example is the need to sanitize HTML and other textual data for security reasons. Most PHP functions that operate on strings have an option to specify the character encoding used, and you should always use UTF-8. APCu has a function to do that called sanitizeData(), but this is slow for large strings, and you'd better have a caching solution in place.

apcu_store example

    public function save($data, $id, $tags = array(), $specificLifetime = false)
    {
        $lifetime = $this->getLifetime($specificLifetime);
        $result = apcu_store($id, array($data, time(), $lifetime), $lifetime);
        if (count($tags) > 0) {
            $this->_log(self::TAGS_UNSUPPORTED_BY_SAVE_OF_APCU_BACKEND);
        }
        return $result;
    }

    /** * Remove a cache record * * @param string $id cache id * @return boolean true if no problem */

/** * {@inheritdoc} */
  public function fetch(array $cids) {
    return apcu_fetch($cids);
  }

  /** * {@inheritdoc} */
  public function store($cid, $data) {
    apcu_store($cid, $data);
  }

  /** * {@inheritdoc} */
  public function delete($cid) {
    apcu_delete($cid);
  }

}

return true;
    }

    protected function doSave(array $values, int $lifetime): array|bool
    {
        if (null !== $this->marshaller && (!$values = $this->marshaller->marshall($values, $failed))) {
            return $failed;
        }

        try {
            if (false === $failures = apcu_store($values, null, $lifetime)) {
                $failures = $values;
            }

            return array_keys($failures);
        } catch (\Throwable $e) {
            if (1 === \count($values)) {
                // Workaround https://github.com/krakjoe/apcu/issues/170                 apcu_delete(array_key_first($values));
            }

            throw $e;
        }

$cache = new \stdClass();
    $cache->cid = $cid;
    $cache->created = round(microtime(TRUE), 3);
    $cache->expire = $expire;
    $cache->tags = implode(' ', $tags);
    $cache->checksum = $this->checksumProvider->getCurrentChecksum($tags);
    // APCu serializes/unserializes any structure itself.     $cache->serialized = 0;
    $cache->data = $data;

    // Expiration is handled by our own prepareItem(), not APCu.     apcu_store($this->getApcuKey($cid), $cache);
  }

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