<?php /** * StatusNet - the distributed open-source microblogging tool * Copyright (C) 2011, StatusNet, Inc. * * A stream of notices * * PHP version 5 * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. * * @category Stream * @package StatusNet * @author Evan Prodromou <evan@status.net> * @copyright 2011 StatusNet, Inc. * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0 * @link http://status.net/ */ if (!defined('STATUSNET')) { // This check helps protect against security problems; // your code file can't be executed directly from the web. exit(1); } /** * Class for notice streams * * @category Stream * @package StatusNet * @author Evan Prodromou <evan@status.net> * @copyright 2011 StatusNet, Inc. * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0 * @link http://status.net/ */ class CachingNoticeStream extends NoticeStream { const CACHE_WINDOW = 200; public $stream = null; public $cachekey = null; public $useLast = true; function __construct($stream, $cachekey, $useLast = true) { $this->stream = $stream; $this->cachekey = $cachekey; $this->useLast = $useLast; } function getNoticeIds($offset, $limit, $sinceId, $maxId) { $cache = Cache::instance(); // We cache self::CACHE_WINDOW elements at the tip of the stream. // If the cache won't be hit, just generate directly. if (empty($cache) || $sinceId != 0 || $maxId != 0 || is_null($limit) || ($offset + $limit) > self::CACHE_WINDOW) { return $this->stream->getNoticeIds($offset, $limit, $sinceId, $maxId); } // Check the cache to see if we have the stream. $idkey = Cache::key($this->cachekey); $idstr = $cache->get($idkey); if ($idstr !== false) { // Cache hit! Woohoo! $window = explode(',', $idstr); $ids = array_slice($window, $offset, $limit); return $ids; } if ($this->useLast) { // Check the cache to see if we have a "last-known-good" version. // The actual cache gets blown away when new notices are added, but // the "last" value holds a lot of info. We might need to only generate // a few at the "tip", which can bound our queries and save lots // of time. $laststr = $cache->get($idkey.';last'); if ($laststr !== false) { $window = explode(',', $laststr); $last_id = $window[0]; $new_ids = $this->stream->getNoticeIds(0, self::CACHE_WINDOW, $last_id, 0); $new_window = array_merge($new_ids, $window); $new_windowstr = implode(',', $new_window); $result = $cache->set($idkey, $new_windowstr); $result = $cache->set($idkey . ';last', $new_windowstr); $ids = array_slice($new_window, $offset, $limit); return $ids; } } // No cache hits :( Generate directly and stick the results // into the cache. Note we generate the full cache window. $window = $this->stream->getNoticeIds(0, self::CACHE_WINDOW, 0, 0); $windowstr = implode(',', $window); $result = $cache->set($idkey, $windowstr); if ($this->useLast) { $result = $cache->set($idkey . ';last', $windowstr); } // Return just the slice that was requested $ids = array_slice($window, $offset, $limit); return $ids; } }