Background deletion of user accounts. Notices are deleted in chunks, then the user itself when they're all gone.

While deletion is in progress, the account is locked with the 'deleted' role, which disables all actions with rights control.

Todo:
* Pretty up the notice on the profile page about the pending delete. Show status?
* Possibly more thorough account disabling, such as disallowing all use for login and access.
* Improve error recovery; worst case is that an account gets left locked in 'deleted' state but the queue jobs have gotten dropped out. This would leave the username in use and any undeleted notices in place.

actions/deleteuser.php

@@ -162,7 +162,15 @@ class DeleteuserAction extends ProfileFormAction
     function handlePost()
     {
         if (Event::handle('StartDeleteUser', array($this, $this->user))) {
-            $this->user->delete();
+            // Mark the account as deleted and shove low-level deletion tasks
+            // to background queues. Removing a lot of posts can take a while...
+            if (!$this->user->hasRole(Profile_role::DELETED)) {
+                $this->user->grantRole(Profile_role::DELETED);
+            }
+
+            $qm = QueueManager::get();
+            $qm->enqueue($this->user, 'deluser');
+
             Event::handle('EndDeleteUser', array($this, $this->user));
         }
     }

classes/Profile.php

@@ -732,6 +732,9 @@ class Profile extends Memcached_DataObject
     function hasRight($right)
     {
         $result = false;
+        if ($this->hasRole(Profile_role::DELETED)) {
+            return false;
+        }
         if (Event::handle('UserRightsCheck', array($this, $right, &$result))) {
             switch ($right)
             {

classes/Profile_role.php

@@ -53,6 +53,7 @@ class Profile_role extends Memcached_DataObject
     const ADMINISTRATOR = 'administrator';
     const SANDBOXED     = 'sandboxed';
     const SILENCED      = 'silenced';
+    const DELETED       = 'deleted'; // Pending final deletion of notices...
 
     public static function isValid($role)
     {

lib/deluserqueuehandler.php

@@ -0,0 +1,95 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, 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/>.
+ */
+
+/**
+ * Background job to delete prolific users without disrupting front-end too much.
+ *
+ * Up to 50 messages are deleted on each run through; when all messages are gone,
+ * the actual account is deleted.
+ *
+ * @package QueueHandler
+ * @maintainer Brion Vibber <brion@status.net>
+ */
+
+class DelUserQueueHandler extends QueueHandler
+{
+    const DELETION_WINDOW = 50;
+
+    public function transport()
+    {
+        return 'deluser';
+    }
+
+    public function handle($user)
+    {
+        if (!($user instanceof User)) {
+            common_log(LOG_ERR, "Got a bogus user, not deleting");
+            return true;
+        }
+
+        $user = User::staticGet('id', $user->id);
+        if (!$user) {
+            common_log(LOG_INFO, "User {$user->nickname} was deleted before we got here.");
+            return true;
+        }
+
+        if (!$user->hasRole(Profile_role::DELETED)) {
+            common_log(LOG_INFO, "User {$user->nickname} is not pending deletion; aborting.");
+            return true;
+        }
+
+        $notice = $this->getNextBatch($user);
+        if ($notice->N) {
+            common_log(LOG_INFO, "Deleting next {$notice->N} notices by {$user->nickname}");
+            while ($notice->fetch()) {
+                $del = clone($notice);
+                $del->delete();
+            }
+
+            // @todo improve reliability in case we died during the above deletions
+            // with a fatal error. If the job is lost, we should perform some kind
+            // of garbage collection later.
+
+            // Queue up the next batch.
+            $qm = QueueManager::get();
+            $qm->enqueue($user, 'deluser');
+        } else {
+            // Out of notices? Let's finish deleting this guy!
+            $user->delete();
+            common_log(LOG_INFO, "User $user->id $user->nickname deleted.");
+            return true;
+        }
+
+        return true;
+    }
+
+    /**
+     * Fetch the next self::DELETION_WINDOW messages for this user.
+     * @return Notice
+     */
+    protected function getNextBatch(User $user)
+    {
+        $notice = new Notice();
+        $notice->profile_id = $user->id;
+        $notice->limit(self::DELETION_WINDOW);
+        $notice->find();
+        return $notice;
+    }
+
+}

lib/queuemanager.php

@@ -264,6 +264,9 @@ abstract class QueueManager extends IoManager
                 $this->connect('sms', 'SmsQueueHandler');
             }
 
+            // Background user management tasks...
+            $this->connect('deluser', 'DelUserQueueHandler');
+
             // Broadcasting profile updates to OMB remote subscribers
             $this->connect('profile', 'ProfileQueueHandler');
 

lib/userprofile.php

@@ -228,6 +228,17 @@ class UserProfile extends Widget
 
     function showEntityActions()
     {
+        if ($this->profile->hasRole(Profile_role::DELETED)) {
+            $this->out->elementStart('div', 'entity_actions');
+            $this->out->element('h2', null, _('User actions'));
+            $this->out->elementStart('ul');
+            $this->out->elementStart('p', array('class' => 'profile_deleted'));
+            $this->out->text(_('User deletion in progress...'));
+            $this->out->elementEnd('p');
+            $this->out->elementEnd('ul');
+            $this->out->elementEnd('div');
+            return;
+        }
         if (Event::handle('StartProfilePageActionsSection', array(&$this->out, $this->profile))) {
 
             $cur = common_current_user();