From af95005bc481d6f8f84a780bdc062426e22f3a03 Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@status.net>
Date: Mon, 4 Jan 2010 13:01:17 -0800
Subject: Ticket 2141: bugs with weighted popularity lists across year
 boundary.

Consolidated several separate implementations of the same weighting algorithm into common_sql_weight() and fixed some bugs...
For MySQL, now using timestampdiff() instead of subtraction for the comparison, so we get sane results when the year doesn't match, and utc_timestamp() rather than now() so we don't get negative ages for recent items with local server timezone.
Unknown whether the same problems affect PostgreSQL, but note that it lacks the timestampdiff() SQL function.
---
 actions/favorited.php      |  8 ++------
 actions/publictagcloud.php | 15 ++++++++-------
 2 files changed, 10 insertions(+), 13 deletions(-)

(limited to 'actions')

diff --git a/actions/favorited.php b/actions/favorited.php
index 150b67b0b..9ffa5b844 100644
--- a/actions/favorited.php
+++ b/actions/favorited.php
@@ -185,11 +185,7 @@ class FavoritedAction extends Action
 
     function showContent()
     {
-        if (common_config('db', 'type') == 'pgsql') {
-            $weightexpr='sum(exp(-extract(epoch from (now() - fave.modified)) / %s))';
-        } else {
-            $weightexpr='sum(exp(-(now() - fave.modified) / %s))';
-        }
+        $weightexpr = common_sql_weight('fave.modified', common_config('popular', 'dropoff'));
 
         $qry = 'SELECT notice.*, '.
           $weightexpr . ' as weight ' .
@@ -207,7 +203,7 @@ class FavoritedAction extends Action
         }
 
         $notice = Memcached_DataObject::cachedQuery('Notice',
-                                                    sprintf($qry, common_config('popular', 'dropoff')),
+                                                    $qry,
                                                     600);
 
         $nl = new NoticeList($notice, $this);
diff --git a/actions/publictagcloud.php b/actions/publictagcloud.php
index e7f6ee36c..9e4478dbb 100644
--- a/actions/publictagcloud.php
+++ b/actions/publictagcloud.php
@@ -105,12 +105,8 @@ class PublictagcloudAction extends Action
 
         #Add the aggregated columns...
         $tags->selectAdd('max(notice_id) as last_notice_id');
-        if(common_config('db','type')=='pgsql') {
-            $calc='sum(exp(-extract(epoch from (now()-created))/%s)) as weight';
-        } else {
-            $calc='sum(exp(-(now() - created)/%s)) as weight';
-        }
-        $tags->selectAdd(sprintf($calc, common_config('tag', 'dropoff')));
+        $calc = common_sql_weight('created', common_config('tag', 'dropoff'));
+        $tags->selectAdd($calc . ' as weight');
         $tags->groupBy('tag');
         $tags->orderBy('weight DESC');
 
@@ -136,7 +132,12 @@ class PublictagcloudAction extends Action
             $this->elementStart('dd');
             $this->elementStart('ul', 'tags xoxo tag-cloud');
             foreach ($tw as $tag => $weight) {
-                $this->showTag($tag, $weight, $weight/$sum);
+                if ($sum) {
+                    $weightedSum = $weight/$sum;
+                } else {
+                    $weightedSum = 0.5;
+                }
+                $this->showTag($tag, $weight, $weightedSum);
             }
             $this->elementEnd('ul');
             $this->elementEnd('dd');
-- 
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