ElggMemcache.php

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<?php
class ElggMemcache extends ElggSharedMemoryCache {
    private static $MINSERVERVERSION = '1.1.12';

    private $memcache;

    private $expires = 86400;

    private $version = 0;

    public function __construct($namespace = 'default') {
        global $CONFIG;

        $this->setNamespace($namespace);

        // Do we have memcache?
        if (!class_exists('Memcache')) {
            throw new ConfigurationException('PHP memcache module not installed, you must install php5-memcache');
        }

        // Create memcache object
        $this->memcache = new Memcache;

        // Now add servers
        if (!$CONFIG->memcache_servers) {
            throw new ConfigurationException('No memcache servers defined, please populate the $CONFIG->memcache_servers variable');
        }

        if (is_callable(array($this->memcache, 'addServer'))) {
            foreach ($CONFIG->memcache_servers as $server) {
                if (is_array($server)) {
                    $this->memcache->addServer(
                        $server[0],
                        isset($server[1]) ? $server[1] : 11211,
                        isset($server[2]) ? $server[2] : false,
                        isset($server[3]) ? $server[3] : 1,
                        isset($server[4]) ? $server[4] : 1,
                        isset($server[5]) ? $server[5] : 15,
                        isset($server[6]) ? $server[6] : true
                    );

                } else {
                    $this->memcache->addServer($server, 11211);
                }
            }
        } else {
            // don't use elgg_echo() here because most of the config hasn't been loaded yet
            // and it caches the language, which is hard coded in $CONFIG->language as en.
            // overriding it with real values later has no effect because it's already cached.
            elgg_log("This version of the PHP memcache API doesn't support multiple servers.", 'ERROR');

            $server = $CONFIG->memcache_servers[0];
            if (is_array($server)) {
                $this->memcache->connect($server[0], $server[1]);
            } else {
                $this->memcache->addServer($server, 11211);
            }
        }

        // Get version
        $this->version = $this->memcache->getVersion();
        if (version_compare($this->version, ElggMemcache::$MINSERVERVERSION, '<')) {
            $msg = vsprintf('Memcache needs at least version %s to run, you are running %s',
                array(ElggMemcache::$MINSERVERVERSION,
                $this->version
            ));

            throw new ConfigurationException($msg);
        }

        // Set some defaults
        if (isset($CONFIG->memcache_expires)) {
            $this->expires = $CONFIG->memcache_expires;
        }
    }

    public function setDefaultExpiry($expires = 0) {
        $this->expires = $expires;
    }

    private function makeMemcacheKey($key) {
        $prefix = $this->getNamespace() . ":";

        if (strlen($prefix . $key) > 250) {
            $key = md5($key);
        }

        return $prefix . $key;
    }

    public function save($key, $data, $expires = null) {
        $key = $this->makeMemcacheKey($key);

        if ($expires === null) {
            $expires = $this->expires;
        }

        $result = $this->memcache->set($key, $data, null, $expires);
        if ($result === false) {
            elgg_log("MEMCACHE: SAVE FAIL $key", 'ERROR');
        } else {
            elgg_log("MEMCACHE: SAVE SUCCESS $key", 'INFO');
        }

        return $result;
    }

    public function load($key, $offset = 0, $limit = null) {
        $key = $this->makeMemcacheKey($key);

        $result = $this->memcache->get($key);
        if ($result === false) {
            elgg_log("MEMCACHE: LOAD MISS $key", 'INFO');
        } else {
            elgg_log("MEMCACHE: LOAD HIT $key", 'INFO');
        }

        return $result;
    }

    public function delete($key) {
        $key = $this->makeMemcacheKey($key);

        return $this->memcache->delete($key, 0);
    }

    public function clear() {
        // DISABLE clearing for now - you must use delete on a specific key.
        return true;

        // @todo Namespaces as in #532
    }
}