44bcc942b8
Rearchitect (again!) notice stream code to delegate different functionality up and down the stack. Now, different classes implement NoticeStream.
130 lines
4.0 KiB
PHP
130 lines
4.0 KiB
PHP
<?php
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/**
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* StatusNet - the distributed open-source microblogging tool
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* Copyright (C) 2011, StatusNet, Inc.
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*
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* A stream of notices
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*
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* PHP version 5
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @category Stream
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* @package StatusNet
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* @author Evan Prodromou <evan@status.net>
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* @copyright 2011 StatusNet, Inc.
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
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* @link http://status.net/
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*/
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if (!defined('STATUSNET')) {
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// This check helps protect against security problems;
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// your code file can't be executed directly from the web.
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exit(1);
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}
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/**
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* Class for notice streams
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*
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* @category Stream
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* @package StatusNet
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* @author Evan Prodromou <evan@status.net>
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* @copyright 2011 StatusNet, Inc.
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
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* @link http://status.net/
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*/
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class CachingNoticeStream extends NoticeStream
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{
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const CACHE_WINDOW = 200;
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public $stream = null;
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public $cachekey = null;
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function __construct($stream, $cachekey)
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{
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$this->stream = $stream;
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$this->cachekey = $cachekey;
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}
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function getNoticeIds($offset=0, $limit=20, $sinceId=0, $maxId=0)
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{
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$cache = Cache::instance();
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// We cache self::CACHE_WINDOW elements at the tip of the stream.
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// If the cache won't be hit, just generate directly.
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if (empty($cache) ||
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$sinceId != 0 || $maxId != 0 ||
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is_null($limit) ||
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($offset + $limit) > self::CACHE_WINDOW) {
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return $this->stream->getNoticeIds($offset, $limit, $sinceId, $maxId);
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}
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// Check the cache to see if we have the stream.
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$idkey = Cache::key($this->cachekey);
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$idstr = $cache->get($idkey);
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if ($idstr !== false) {
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// Cache hit! Woohoo!
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$window = explode(',', $idstr);
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$ids = array_slice($window, $offset, $limit);
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return $ids;
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}
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// Check the cache to see if we have a "last-known-good" version.
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// The actual cache gets blown away when new notices are added, but
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// the "last" value holds a lot of info. We might need to only generate
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// a few at the "tip", which can bound our queries and save lots
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// of time.
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$laststr = $cache->get($idkey.';last');
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if ($laststr !== false) {
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$window = explode(',', $laststr);
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$last_id = $window[0];
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$new_ids = $this->stream->getNoticeIds(0, self::CACHE_WINDOW, $last_id, 0);
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$new_window = array_merge($new_ids, $window);
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$new_windowstr = implode(',', $new_window);
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$result = $cache->set($idkey, $new_windowstr);
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$result = $cache->set($idkey . ';last', $new_windowstr);
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$ids = array_slice($new_window, $offset, $limit);
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return $ids;
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}
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// No cache hits :( Generate directly and stick the results
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// into the cache. Note we generate the full cache window.
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$window = $this->stream->getNoticeIds(0, self::CACHE_WINDOW, 0, 0);
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$windowstr = implode(',', $window);
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$result = $cache->set($idkey, $windowstr);
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$result = $cache->set($idkey . ';last', $windowstr);
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// Return just the slice that was requested
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$ids = array_slice($window, $offset, $limit);
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return $ids;
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}
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}
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