3 * StatusNet - the distributed open-source microblogging tool
4 * Copyright (C) 2011, StatusNet, Inc.
10 * This program is free software: you can redistribute it and/or modify
11 * it under the terms of the GNU Affero General Public License as published by
12 * the Free Software Foundation, either version 3 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU Affero General Public License for more details.
20 * You should have received a copy of the GNU Affero General Public License
21 * along with this program. If not, see <http://www.gnu.org/licenses/>.
25 * @author Evan Prodromou <evan@status.net>
26 * @copyright 2011 StatusNet, Inc.
27 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
28 * @link http://status.net/
31 if (!defined('STATUSNET')) {
32 // This check helps protect against security problems;
33 // your code file can't be executed directly from the web.
38 * Class for notice streams
42 * @author Evan Prodromou <evan@status.net>
43 * @copyright 2011 StatusNet, Inc.
44 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
45 * @link http://status.net/
48 class CachingNoticeStream extends NoticeStream
50 const CACHE_WINDOW = 200;
52 public $stream = null;
53 public $cachekey = null;
55 function __construct($stream, $cachekey)
57 $this->stream = $stream;
58 $this->cachekey = $cachekey;
61 function getNoticeIds($offset, $limit, $sinceId, $maxId)
63 $cache = Cache::instance();
65 // We cache self::CACHE_WINDOW elements at the tip of the stream.
66 // If the cache won't be hit, just generate directly.
69 $sinceId != 0 || $maxId != 0 ||
71 ($offset + $limit) > self::CACHE_WINDOW) {
72 return $this->stream->getNoticeIds($offset, $limit, $sinceId, $maxId);
75 // Check the cache to see if we have the stream.
77 $idkey = Cache::key($this->cachekey);
79 $idstr = $cache->get($idkey);
81 if ($idstr !== false) {
83 $window = explode(',', $idstr);
84 $ids = array_slice($window, $offset, $limit);
88 // Check the cache to see if we have a "last-known-good" version.
89 // The actual cache gets blown away when new notices are added, but
90 // the "last" value holds a lot of info. We might need to only generate
91 // a few at the "tip", which can bound our queries and save lots
94 $laststr = $cache->get($idkey.';last');
96 if ($laststr !== false) {
97 $window = explode(',', $laststr);
98 $last_id = $window[0];
99 $new_ids = $this->stream->getNoticeIds(0, self::CACHE_WINDOW, $last_id, 0);
101 $new_window = array_merge($new_ids, $window);
103 $new_windowstr = implode(',', $new_window);
105 $result = $cache->set($idkey, $new_windowstr);
106 $result = $cache->set($idkey . ';last', $new_windowstr);
108 $ids = array_slice($new_window, $offset, $limit);
113 // No cache hits :( Generate directly and stick the results
114 // into the cache. Note we generate the full cache window.
116 $window = $this->stream->getNoticeIds(0, self::CACHE_WINDOW, 0, 0);
118 $windowstr = implode(',', $window);
120 $result = $cache->set($idkey, $windowstr);
121 $result = $cache->set($idkey . ';last', $windowstr);
123 // Return just the slice that was requested
125 $ids = array_slice($window, $offset, $limit);