Add SoundCloud delete functionality and fixes; implement TaskManager to run background jobs

airtime_mvc/application/common/TaskManager.php

@@ -0,0 +1,160 @@
+<?php
+
+/**
+ * Class TaskManager
+ */
+final class TaskManager {
+
+    /**
+     * @var array tasks to be run
+     */
+    protected $_taskList = [
+        AirtimeTask::SOUNDCLOUD,
+        AirtimeTask::UPGRADE
+    ];
+
+    /**
+     * @var TaskManager singleton instance object
+     */
+    protected static $_instance;
+
+    /**
+     * Private constructor so class is uninstantiable
+     */
+    private function __construct() {
+    }
+
+    /**
+     * Get the singleton instance of this class
+     *
+     * @return TaskManager the TaskManager instance
+     */
+    public static function getInstance() {
+        if (!self::$_instance) {
+            self::$_instance = new TaskManager();
+        }
+        return self::$_instance;
+    }
+
+    /**
+     * Run all tasks that need to be run
+     */
+    public function runTasks() {
+        foreach ($this->_taskList as $task) {
+            $task = TaskFactory::getTask($task);
+            assert(is_subclass_of($task, 'AirtimeTask'));  // Sanity check
+            /** @var $task AirtimeTask */
+            if ($task && $task->shouldBeRun()) $task->run();
+        }
+    }
+
+}
+
+/**
+ * Interface AirtimeTask Interface for task operations - also acts as task type ENUM
+ */
+interface AirtimeTask {
+
+    /**
+     * PHP doesn't have ENUMs so declare them as interface constants
+     * Task types - values don't really matter as long as they're unique
+     */
+
+    const SOUNDCLOUD = "soundcloud";
+    const UPGRADE = "upgrade";
+
+    /**
+     * Check whether the task should be run
+     *
+     * @return bool true if the task needs to be run, otherwise false
+     */
+    public function shouldBeRun();
+
+    /**
+     * Run the task
+     *
+     * @return void
+     */
+    public function run();
+
+}
+
+/**
+ * Class TaskFactory Factory class to abstract task instantiation
+ */
+class TaskFactory {
+
+    /**
+     * Get an AirtimeTask based on a task type
+     *
+     * @param $task string the task type; uses AirtimeTask constants as an ENUM
+     *
+     * @return AirtimeTask|null return a task of the given type or null if no corresponding
+     *                          task exists or is implemented
+     */
+    public static function getTask($task) {
+        switch($task) {
+            case AirtimeTask::SOUNDCLOUD:
+                return new SoundcloudUploadTask();
+            case AirtimeTask::UPGRADE:
+                return new UpgradeTask();
+        }
+        return null;
+    }
+
+}
+
+/**
+ * Class UpgradeTask
+ */
+class UpgradeTask implements AirtimeTask {
+
+    /**
+     * Check the current Airtime schema version to see if an upgrade should be run
+     *
+     * @return bool true if an upgrade is needed
+     */
+    public function shouldBeRun() {
+        return UpgradeManager::checkIfUpgradeIsNeeded();
+    }
+
+    /**
+     * Run all upgrades above the current schema version
+     */
+    public function run() {
+        UpgradeManager::doUpgrade();
+    }
+
+}
+
+/**
+ * Class SoundcloudUploadTask
+ */
+class SoundcloudUploadTask implements AirtimeTask {
+
+    /**
+     * @var SoundcloudService
+     */
+    protected $_service;
+
+    public function __construct() {
+        $this->_service = new SoundcloudService();
+    }
+
+    /**
+     * Check the ThirdPartyTrackReferences table to see if there are any pending SoundCloud tasks
+     *
+     * @return bool true if there are pending tasks in ThirdPartyTrackReferences
+     */
+    public function shouldBeRun() {
+        return !$this->_service->isBrokerTaskQueueEmpty();
+    }
+
+    /**
+     * Poll the task queue for any completed Celery tasks
+     */
+    public function run() {
+        $this->_service->pollBrokerTaskQueue();
+    }
+
+}