Added QueueManager to process background jobs

app/Core/Queue/QueueManager.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace Kanboard\Core\Queue;
+
+use Kanboard\Core\Base;
+use Kanboard\Job\BaseJob;
+use LogicException;
+use SimpleQueue\Queue;
+
+/**
+ * Class QueueManager
+ *
+ * @package Kanboard\Core\Queue
+ * @author  Frederic Guillot
+ */
+class QueueManager extends Base
+{
+    /**
+     * @var Queue
+     */
+    protected $queue = null;
+
+    /**
+     * Set queue driver
+     *
+     * @access public
+     * @param  Queue $queue
+     * @return $this
+     */
+    public function setQueue(Queue $queue)
+    {
+        $this->queue = $queue;
+        return $this;
+    }
+
+    /**
+     * Send a new job to the queue
+     *
+     * @access public
+     * @param  BaseJob $job
+     * @return $this
+     */
+    public function push(BaseJob $job)
+    {
+        if ($this->queue !== null) {
+            $this->queue->push(JobHandler::getInstance($this->container)->serializeJob($job));
+        } else {
+            call_user_func_array(array($job, 'execute'), $job->getJobParams());
+        }
+
+        return $this;
+    }
+
+    /**
+     * Wait for new jobs
+     *
+     * @access public
+     * @throws LogicException
+     */
+    public function listen()
+    {
+        if ($this->queue === null) {
+            throw new LogicException('No Queue Driver defined!');
+        }
+
+        while ($job = $this->queue->pull()) {
+            JobHandler::getInstance($this->container)->executeJob($job);
+            $this->queue->completed($job);
+        }
+    }
+}