<?php

/**
 * Memcache CacheResource
 *
 * CacheResource Implementation based on the KeyValueStore API to use
 * memcache as the storage resource for Smarty's output caching.
 *
 * Note that memcache has a limitation of 256 characters per cache-key.
 * To avoid complications all cache-keys are translated to a sha1 hash.
 *
 * @package CacheResource-examples
 * @author Rodney Rehm
 */
class Smarty_CacheResource_Memcache extends Smarty_CacheResource_KeyValueStore {
    /**
     * memcache instance
     * @var Memcache
     */
    protected $memcache = null;
    
    public function __construct()
    {
        $this->memcache = new Memcache();
        $this->memcache->addServer( '127.0.0.1', 11211 );
    }
    
    /**
     * Read values for a set of keys from cache
     *
     * @param array $keys list of keys to fetch
     * @return array list of values with the given keys used as indexes
     * @return boolean true on success, false on failure
     */
    protected function read(array $keys)
    {
        $_keys = $lookup = array();
        foreach ($keys as $k) {
            $_k = sha1($k);
            $_keys[] = $_k;
            $lookup[$_k] = $k;
        }
        $_res = array();
        $res = $this->memcache->get($_keys);
        foreach ($res as $k => $v) {
            $_res[$lookup[$k]] = $v;
        }
        return $_res;
    }
    
    /**
     * Save values for a set of keys to cache
     *
     * @param array $keys list of values to save
     * @param int $expire expiration time
     * @return boolean true on success, false on failure
     */
    protected function write(array $keys, $expire=null)
    {
        foreach ($keys as $k => $v) {
            $k = sha1($k);
            $this->memcache->set($k, $v, 0, $expire);
        }
        return true;
    }

    /**
     * Remove values from cache
     *
     * @param array $keys list of keys to delete
     * @return boolean true on success, false on failure
     */
    protected function delete(array $keys)
    {
        foreach ($keys as $k) {
            $k = sha1($k);
            $this->memcache->delete($k);
        }
        return true;
    }

    /**
     * Remove *all* values from cache
     *
     * @return boolean true on success, false on failure
     */
    protected function purge()
    {
        return $this->memcache->flush();
    }
}