[PLUGINS] Added UnQueue, a new default plugin which does all actions immediately

plugins/UnQueue/README

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+UnQueuePlugin wraps the UnQueueManager class which is a queue manager that does all work immediately.
+
+Installation
+============
+
+This plugin is enabled by default and cannot be disabled unless another queue manager is in use.
+Disabling is not necessary but recommended in such cases.
+
+Example
+=======
+
+In config.php
+
+addPlugin('UnQueue');

plugins/UnQueue/UnQueuePlugin.php

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+<?php
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social 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.
+//
+// GNU social 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 GNU social.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Immediate action queue
+ *
+ * @package   GNUsocial
+ * @author    Miguel Dantas <biodantasgs@gmail.com>
+ * @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+
+defined('GNUSOCIAL') || die();
+
+class UnQueuePlugin extends Plugin
+{
+    const PLUGIN_VERSION = '0.0.1';
+
+    public function onStartNewQueueManager(?QueueManager &$qm)
+    {
+        $qm = new UnQueueManager();
+        return false;
+    }
+
+    public function onPluginVersion(array &$versions): bool
+    {
+        $versions[] = array('name' => 'UnQueue',
+                            'version' => self::PLUGIN_VERSION,
+                            'author' => 'Miguel Dantas',
+                            'description' =>
+                            // TRANS: Plugin description.
+                            _m('Plugin using the database as a backend for GNU social queues'));
+        return true;
+    }
+};

plugins/UnQueue/classes/UnQueueManager.php

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+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * A queue manager interface for just doing things immediately
+ *
+ * PHP version 5
+ *
+ * LICENCE: 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/>.
+ *
+ * @category  QueueManager
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @author    Sarven Capadisli <csarven@status.net>
+ * @author    Brion Vibber <brion@status.net>
+ * @copyright 2009 StatusNet, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+class UnQueueManager extends QueueManager
+{
+
+    /**
+     * Dummy queue storage manager: instead of saving events for later,
+     * we just process them immediately. This is only suitable for events
+     * that can be processed quickly and don't need polling or long-running
+     * connections to another server such as XMPP.
+     *
+     * @param Notice $object    this specific manager just handles Notice objects anyway
+     * @param string $queue
+     */
+    function enqueue($object, $transport)
+    {
+        try {
+            $handler = $this->getHandler($transport);
+            $handler->handle($object);
+        } catch (NoQueueHandlerException $e) {
+            if (Event::handle('UnqueueHandleNotice', array(&$object, $transport))) {
+                throw new ServerException("UnQueueManager: Unknown queue transport: $transport");
+            }
+        }
+    }
+}