ElggMemcache.php

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<?php

class ElggMemcache extends \ElggSharedMemoryCache {

    private $ttl = 86400;

    private $stash_pool;

    public function __construct($namespace = 'default', \Stash\Pool $pool = null, $ttl = null) {
        parent::__construct();

        $this->setNamespace($namespace);

        if (!$pool) {
            $pool = _elgg_services()->memcacheStashPool;
            if (!$pool) {
                throw new \ConfigurationException('No memcache servers defined, please populate the $this->CONFIG->memcache_servers variable');
            }
        }
        $this->stash_pool = $pool;

        if ($ttl === null) {
            $ttl = _elgg_services()->config->get('memcache_expires');
        }
        if (isset($ttl)) {
            $this->ttl = $ttl;
        }
        
        // make sure memcache is reset
        _elgg_services()->events->registerHandler('cache:flush', 'system', array($this, 'clear'));
    }

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

    private function makeMemcacheKey($key) {
        // using stacks grouping http://www.stashphp.com/Grouping.html#stacks
        // this will allowing clearing the namespace later
        return "/{$this->getNamespace()}/$key";
    }

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

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

        $item = $this->stash_pool->getItem($key);

        $item->set($data);
        $item->expiresAfter($ttl);
        $result = $item->save();

        if ($result) {
            _elgg_services()->logger->info("MEMCACHE: SAVE SUCCESS $key");
        } else {
            _elgg_services()->logger->error("MEMCACHE: SAVE FAIL $key");
        }

        return $result;
    }

    public function load($key, $unused1 = 0, $unused2 = null) {
        $key = $this->makeMemcacheKey($key);

        $item = $this->stash_pool->getItem($key);

        $item->setInvalidationMethod(\Stash\Invalidation::NONE);
        $value = $item->get();

        if ($item->isMiss()) {
            _elgg_services()->logger->info("MEMCACHE: LOAD MISS $key");
            return false;
        }

        _elgg_services()->logger->info("MEMCACHE: LOAD HIT $key");

        return $value;
    }

    public function delete($key) {
        $key = $this->makeMemcacheKey($key);
        return $this->stash_pool->getItem($key)->clear();
    }

    public function clear() {
        // using stacks grouping http://www.stashphp.com/Grouping.html#stacks
        // this will clear all key keys beneath it
        return $this->stash_pool->getItem("/{$this->getNamespace()}")->clear();
    }
    
    public function setNamespace($namespace = "default") {
        $config_prefix = _elgg_services()->config->getVolatile('memcache_namespace_prefix');
        if ($config_prefix) {
            $namespace = $config_prefix . $namespace;
        }
        
        parent::setNamespace($namespace);
    }
}