<?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() {

        $this->memcache->flush();

    }

}