NopCommerce之任务执行

NOP任务提供两种：手动执行（立即）和定时执行两种。

首先来说下手动任务执行过程，下图是NOP定时任务管理界面：

从上面可以看出，我们可以选择具体的任务来手动执行任务（立即执行），当点击【立即执行】按钮时会触发以下事件：

1、获取ScheduleTask对象（从数据库或缓存中）

2、创建Task对象，传入ScheduleTask对象作为构造参数，并为Task对象字段赋值

3、执行Task里的Execute（）方法，该方法主要负责ITask实现类的创建，并执行Execute（）方法，完成对任务的执行。

具体代码如下：

   public ActionResult RunNow(int id)

         {

             if (!_permissionService.Authorize(StandardPermissionProvider.ManageScheduleTasks))

                 return AccessDeniedView();

             try

             {

                 var scheduleTask = _scheduleTaskService.GetTaskById(id);

                 if (scheduleTask == null)

                     throw new Exception("Schedule task cannot be loaded");

                 var task = new Task(scheduleTask);

                 //ensure that the task is enabled

                 task.Enabled = true;

                 //do not dispose. otherwise, we can get exception that DbContext is disposed

                 task.Execute(true, false);

                 SuccessNotification(_localizationService.GetResource("Admin.System.ScheduleTasks.RunNow.Done"));

             }

             catch (Exception exc)

             {

                 ErrorNotification(exc);

             }

             return RedirectToAction("List");

         }

第8行：获取ScheduleTask对象（从数据库或缓存中）

第16行：、创建Task对象，传入ScheduleTask对象作为构造参数，并为Task对象字段赋值，然后我们进入到该方法体内看下

  public void Execute(bool throwException = false, bool dispose = true)

         {

             this.IsRunning = true;

             //background tasks has an issue with Autofac

             //because scope is generated each time it's requested

             //that's why we get one single scope here

             //this way we can also dispose resources once a task is completed

             var scope = EngineContext.Current.ContainerManager.Scope();

             var scheduleTaskService = EngineContext.Current.ContainerManager.Resolve<IScheduleTaskService>("", scope);

             var scheduleTask = scheduleTaskService.GetTaskByType(this.Type);

             try

             {

                 var task = this.CreateTask(scope);

                 if (task != null)

                 {

                     this.LastStartUtc = DateTime.UtcNow;

                     if (scheduleTask != null)

                     {

                         //update appropriate datetime properties

                         scheduleTask.LastStartUtc = this.LastStartUtc;

                         scheduleTaskService.UpdateTask(scheduleTask);

                     }

                     //execute task

                     task.Execute();

                     this.LastEndUtc = this.LastSuccessUtc = DateTime.UtcNow;

                 }

             }

             catch (Exception exc)

             {

                 this.Enabled = !this.StopOnError;

                 this.LastEndUtc = DateTime.UtcNow;

                 //log error

                 var logger = EngineContext.Current.ContainerManager.Resolve<ILogger>("", scope);

                 logger.Error(string.Format("Error while running the '{0}' schedule task. {1}", this.Name, exc.Message), exc);

                 if (throwException)

                     throw;

             }

             if (scheduleTask != null)

             {

                 //update appropriate datetime properties

                 scheduleTask.LastEndUtc = this.LastEndUtc;

                 scheduleTask.LastSuccessUtc = this.LastSuccessUtc;

                 scheduleTaskService.UpdateTask(scheduleTask);

             }

             //dispose all resources

             if (dispose)

             {

                 scope.Dispose();

             }

             this.IsRunning = false;

         }

第15行：ITask实现类的创建，里面可能包括反射、关联对象的一些创建

第27行：执行实现了ITask类的Execute（）方法，完成对任务的执行。最后更新字段。

二、第二种就是定时任务了，相对来说复杂点。

首先、在项目启动时的Application_Start（）方法里，我们创建了任务管理类，

     protected void Application_Start()

         {

             //start scheduled tasks

             if (databaseInstalled)

             {

                 TaskManager.Instance.Initialize();

                 TaskManager.Instance.Start();

             }

 }

该类主要负责任务的初始化，添加到线程列表，任务的开始和停止，如下：

  /// <summary>

         /// Initializes the task manager with the property values specified in the configuration file.

         /// </summary>

         public void Initialize()

         {

             this._taskThreads.Clear();

             var taskService = EngineContext.Current.Resolve<IScheduleTaskService>();

             var scheduleTasks = taskService

                 .GetAllTasks()

                 .OrderBy(x => x.Seconds)

                 .ToList();

             //group by threads with the same seconds

             foreach (var scheduleTaskGrouped in scheduleTasks.GroupBy(x => x.Seconds))

             {

                 //create a thread

                 var taskThread = new TaskThread

                                      {

                                          Seconds = scheduleTaskGrouped.Key

                                      };

                 foreach (var scheduleTask in scheduleTaskGrouped)

                 {

                     var task = new Task(scheduleTask);

                     taskThread.AddTask(task);

                 }

                 this._taskThreads.Add(taskThread);

             }

             //sometimes a task period could be set to several hours (or even days).

             //in this case a probability that it'll be run is quite small (an application could be restarted)

             //we should manually run the tasks which weren't run for a long time

             var notRunTasks = scheduleTasks

                 //find tasks with "run period" more than 30 minutes

                 .Where(x => x.Seconds >= _notRunTasksInterval)

                 .Where(x => !x.LastStartUtc.HasValue || x.LastStartUtc.Value.AddSeconds(x.Seconds) < DateTime.UtcNow)

                 .ToList();

             //create a thread for the tasks which weren't run for a long time

             if (notRunTasks.Count > )

             {

                 var taskThread = new TaskThread

                 {

                     RunOnlyOnce = true,

                     Seconds =  *  //let's run such tasks in 5 minutes after application start

                 };

                 foreach (var scheduleTask in notRunTasks)

                 {

                     var task = new Task(scheduleTask);

                     taskThread.AddTask(task);

                 }

                 this._taskThreads.Add(taskThread);

             }

         }

代码分析如下：

1、清空任务线程，

2、获取数据库内所有的任务

3、创建任务线程对象

4、创建Task对象

5、将Task对象存入 Dictionary<string, Task> 包装的集合中

6、最后将线程对象taskThread存入到由List<TaskThread>包装集合中，该集合保存了所有任务的线程，

上面执行我们将所有需要执行的任务存入到List<TaskThread>包装集合中集合，我们下面就可以针对这些任务，执行定时任务，我们看下TaskManager类中Start（）方法是如何写的：

        public void Start()

         {

             foreach (var taskThread in this._taskThreads)

             {

                 taskThread.InitTimer();

             }

         }

上面的代码可以看出，NOP是循环线程集合中所有任务，并执行定时任务的。

   public void InitTimer()

         {

             if (this._timer == null)

             {

                 this._timer = new Timer(new TimerCallback(this.TimerHandler), null, this.Interval, this.Interval);

             }

         }

上面的代码创建了Timer对象，在定时的时间内会执行TimerHandler()方法体中内容，方法体里的内容如下：

   private void TimerHandler(object state)

         {

             this._timer.Change(-, -);

             this.Run();

             if (this.RunOnlyOnce)

             {

                 this.Dispose();

             }

             else

             {

                 this._timer.Change(this.Interval, this.Interval);

             }

         }

在方法体中会有个Run()方法，该方法会执行当前任务类中的Execute（）方法，代码如下：

    private void Run()

         {

             if (Seconds <= )

                 return;

             this.StartedUtc = DateTime.UtcNow;

             this.IsRunning = true;

             foreach (Task task in this._tasks.Values)

             {

                 task.Execute();

             }

             this.IsRunning = false;

         }

这样就实现了定时执行任务功能。。。

由于很少写博客，并且功力有限。只能这样了。。。欢迎指正

巴特西

NopCommerce之任务执行

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