From 61394aa8ac3585c9b7f1e15b6c581af01854987d Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@pobox.com>
Date: Fri, 2 Apr 2010 15:39:43 -0700
Subject: [PATCH] Don't save duplicate messages into a user's packed inbox.
 We've already got the packed box loaded at insert time, so we can simply
 unpack it and check before doing the update query. Should help with dupes
 that come in when inbox distrib jobs die and get restarted, etc.

---
 classes/Inbox.php | 39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/classes/Inbox.php b/classes/Inbox.php
index 014ba3d829..2533210b73 100644
--- a/classes/Inbox.php
+++ b/classes/Inbox.php
@@ -96,12 +96,23 @@ class Inbox extends Memcached_DataObject
         $inbox = new Inbox();
 
         $inbox->user_id = $user_id;
-        $inbox->notice_ids = call_user_func_array('pack', array_merge(array('N*'), $ids));
+        $inbox->pack($ids);
         $inbox->fake = true;
 
         return $inbox;
     }
 
+    /**
+     * Append the given notice to the given user's inbox.
+     * Caching updates are managed for the inbox itself.
+     *
+     * If the notice is already in this inbox, the second
+     * add will be silently dropped.
+     *
+     * @param int @user_id
+     * @param int $notice_id
+     * @return boolean success
+     */
     static function insertNotice($user_id, $notice_id)
     {
         $inbox = DB_DataObject::staticGet('inbox', 'user_id', $user_id);
@@ -114,6 +125,13 @@ class Inbox extends Memcached_DataObject
             return false;
         }
 
+        $ids = $inbox->unpack();
+        if (in_array(intval($notice_id), $ids)) {
+            // Already in there, we probably re-ran some inbox adds
+            // due to an error. Skip the dupe silently.
+            return true;
+        }
+
         $result = $inbox->query(sprintf('UPDATE inbox '.
                                         'set notice_ids = concat(cast(0x%08x as binary(4)), '.
                                         'substr(notice_ids, 1, %d)) '.
@@ -150,7 +168,7 @@ class Inbox extends Memcached_DataObject
             }
         }
 
-        $ids = unpack('N*', $inbox->notice_ids);
+        $ids = $inbox->unpack();
 
         if (!empty($since_id)) {
             $newids = array();
@@ -229,4 +247,21 @@ class Inbox extends Memcached_DataObject
         }
         return new ArrayWrapper($items);
     }
+
+    /**
+     * Saves a list of integer notice_ids into a packed blob in this object.
+     * @param array $ids list of integer notice_ids
+     */
+    protected function pack(array $ids)
+    {
+        $this->notice_ids = call_user_func_array('pack', array_merge(array('N*'), $ids));
+    }
+
+    /**
+     * @return array of integer notice_ids
+     */
+    protected function unpack()
+    {
+        return unpack('N*', $this->notice_ids);
+    }
 }