cache noticesWithFriends in memcached

noticesWithFriends is turning out to be one of our most expensive
queries. The join is costly, and this method is hit over and over and
over by desktop clients and other API users.

So, I've added a first pass at caching the results. I store a "window"
of notices -- equal to the first 3 pages of notices, plus one for
pagination -- in the memcached cache. If with-friends notices are
requests, I fetch the whole window out of the cache and grab the slice
requested. If the requested notices are outside the window, we just do
the query. If there's nothing in the cache, we request the window and
store it, then return a slice.

I had to add a NoticeWrapper class that works like DB_DataObject
(well, just the fetch() part...) but just holds an array of notices
instead of a DB cursor.

Finally, saving a new notice blows away the caches for subscribed users.

darcs-hash:20080915065616-84dde-1b1e814c2294498a10b763b779cbb62c3f96aa84.gz

1 files changed, 57 insertions, 0 deletions

diff --git a/lib/noticewrapper.php b/lib/noticewrapper.php
new file mode 100644
index 000000000..fbf7b59f4
--- /dev/null
+++ b/lib/noticewrapper.php
@@ -0,0 +1,57 @@
+<?php
+/*
+ * Laconica - a distributed open-source microblogging tool
+ * Copyright (C) 2008, Controlez-Vous, Inc.
+ *
+ * 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/>.
+ */
+
+if (!defined('LACONICA')) { exit(1); }
+
+class NoticeWrapper {
+
+    public $id;                              // int(4)  primary_key not_null
+    public $profile_id;                      // int(4)   not_null
+    public $uri;                             // varchar(255)  unique_key
+    public $content;                         // varchar(140)  
+    public $rendered;                        // text()  
+    public $url;                             // varchar(255)  
+    public $created;                         // datetime()   not_null
+    public $modified;                        // timestamp()   not_null default_CURRENT_TIMESTAMP
+    public $reply_to;                        // int(4)  
+    public $is_local;                        // tinyint(1)  
+    public $source;                          // varchar(32)  
+
+	var $notices = NULL;
+	var $i = -1;
+	
+	function __construct($arr) {
+		$this->notices = $arr;
+	}
+	
+	function fetch() {
+		static $fields = array('id', 'profile_id', 'uri', 'content', 'rendered',
+							   'url', 'created', 'modified', 'reply_to', 'is_local', 'source');
+		$this->i++;
+		if ($this->i >= array_count($notices)) {
+			return false;
+		} else {
+			$n = $notices[$this->i];
+			foreach ($fields as $f) {
+				$this->$f = $n->$f;
+			}
+			return true;
+		}
+	}
+}
\ No newline at end of file