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AspNet Core上實現(xiàn)web定時任務實例

 更新時間:2019年02月11日 15:49:01   投稿:laozhang  
在本篇文章里小編給大家分享了關于AspNet Core上實現(xiàn)web定時任務的實例內(nèi)容,有興趣的朋友們學習參考下。

作為一枚后端程序狗,項目實踐常遇到定時任務的工作,最容易想到的的思路就是利用Windows計劃任務/wndows service程序/Crontab程序等主機方法在主機上部署定時任務程序/腳本。

但是很多時候,若使用的是共享主機或者受控主機,這些主機不允許你私自安裝exe程序、Windows服務程序。

碼甲會想到在web程序中做定時任務, 目前有兩個方向:

  • ①.AspNetCore自帶的HostService, 這是一個輕量級的后臺服務, 需要搭配timer完成定時任務
  • ②.老牌Quartz.Net組件,支持復雜靈活的Scheduling、支持ADO/RAM Job任務存儲、支持集群、支持監(jiān)聽、支持插件。

此處我們的項目使用稍復雜的Quartz.net實現(xiàn)web定時任務。

項目背景

最近需要做一個計數(shù)程序:采用redis計數(shù),設定每小時將當日累積數(shù)據(jù)持久化到關系型數(shù)據(jù)庫sqlite。

添加Quartz.Net Nuget 依賴包:<PackageReference Include="Quartz" Version="3.0.6" />

  • ①.定義定時任務內(nèi)容: Job
  • ②.設置觸發(fā)條件: Trigger
  • ③.將Quartz.Net集成進AspNet Core

頭腦風暴

IScheduler類包裝了上述背景需要完成的第①②點工作 ,SimpleJobFactory定義了生成指定的Job任務的過程,這個行為是利用反射機制調(diào)用無參構(gòu)造函數(shù)構(gòu)造出的Job實例。下面是源碼:

//----------------選自Quartz.Simpl.SimpleJobFactory類-------------
using System;
using Quartz.Logging;
using Quartz.Spi;
using Quartz.Util;
namespace Quartz.Simpl
{
 /// <summary> 
 /// The default JobFactory used by Quartz - simply calls 
 /// <see cref="ObjectUtils.InstantiateType{T}" /> on the job class.
 /// </summary>
 /// <seealso cref="IJobFactory" />
 /// <seealso cref="PropertySettingJobFactory" />
 /// <author>James House</author>
 /// <author>Marko Lahma (.NET)</author>
 public class SimpleJobFactory : IJobFactory
 {
  private static readonly ILog log = LogProvider.GetLogger(typeof (SimpleJobFactory));

  /// <summary>
  /// Called by the scheduler at the time of the trigger firing, in order to
  /// produce a <see cref="IJob" /> instance on which to call Execute.
  /// </summary>
  /// <remarks>
  /// It should be extremely rare for this method to throw an exception -
  /// basically only the case where there is no way at all to instantiate
  /// and prepare the Job for execution. When the exception is thrown, the
  /// Scheduler will move all triggers associated with the Job into the
  /// <see cref="TriggerState.Error" /> state, which will require human
  /// intervention (e.g. an application restart after fixing whatever
  /// configuration problem led to the issue with instantiating the Job).
  /// </remarks>
  /// <param name="bundle">The TriggerFiredBundle from which the <see cref="IJobDetail" />
  /// and other info relating to the trigger firing can be obtained.</param>
  /// <param name="scheduler"></param>
  /// <returns>the newly instantiated Job</returns>
  /// <throws> SchedulerException if there is a problem instantiating the Job. </throws>
  public virtual IJob NewJob(TriggerFiredBundle bundle, IScheduler scheduler)
  {
   IJobDetail jobDetail = bundle.JobDetail;
   Type jobType = jobDetail.JobType;
   try
   {
    if (log.IsDebugEnabled())
    {
     log.Debug($"Producing instance of Job '{jobDetail.Key}', class={jobType.FullName}");
    }

    return ObjectUtils.InstantiateType<IJob>(jobType);
   }
   catch (Exception e)
   {
    SchedulerException se = new SchedulerException($"Problem instantiating class '{jobDetail.JobType.FullName}'", e);
    throw se;
   }
  }

  /// <summary>
  /// Allows the job factory to destroy/cleanup the job if needed. 
  /// No-op when using SimpleJobFactory.
  /// </summary>
  public virtual void ReturnJob(IJob job)
  {
   var disposable = job as IDisposable;
   disposable?.Dispose();
  }
 }
}

//------------------節(jié)選自Quartz.Util.ObjectUtils類-------------------------
 public static T InstantiateType<T>(Type type)
{
  if (type == null)
  {
   throw new ArgumentNullException(nameof(type), "Cannot instantiate null");
  }
  ConstructorInfo ci = type.GetConstructor(Type.EmptyTypes);
  if (ci == null)
  {
   throw new ArgumentException("Cannot instantiate type which has no empty constructor", type.Name);
  }
  return (T) ci.Invoke(new object[0]);
}

很多時候,定義的Job任務依賴了其他組件,這時默認的SimpleJobFactory不可用, 需要考慮將Job任務作為依賴注入組件,加入依賴注入容器。

關鍵思路:

①. IScheduler 開放了JobFactory 屬性,便于你控制Job任務的實例化方式;

JobFactories may be of use to those wishing to have their application produce IJob instances via some special mechanism, such as to give the opportunity for dependency injection
②. AspNet Core的服務架構(gòu)是以依賴注入為基礎的,利用AspNet Core已有的依賴注入容器IServiceProvider管理Job 服務的創(chuàng)建過程。

編碼實踐

① 定義Job內(nèi)容:

// -------每小時將redis數(shù)據(jù)持久化到sqlite, 每日凌晨跳針,持久化昨天全天數(shù)據(jù)---------------------
public class UsageCounterSyncJob : IJob
{
  private readonly EqidDbContext _context;
  private readonly IDatabase _redisDB1;
  private readonly ILogger _logger;
  public UsageCounterSyncJob(EqidDbContext context, RedisDatabase redisCache, ILoggerFactory loggerFactory)
  {
   _context = context;
   _redisDB1 = redisCache[1];
   _logger = loggerFactory.CreateLogger<UsageCounterSyncJob>();
  }
   public async Task Execute(IJobExecutionContext context)
  {
   // 觸發(fā)時間在凌晨,則同步昨天的計數(shù)
   var _day = DateTime.Now.ToString("yyyyMMdd");
   if (context.FireTimeUtc.LocalDateTime.Hour == 0)
    _day = DateTime.Now.AddDays(-1).ToString("yyyyMMdd");

   await SyncRedisCounter(_day);
   _logger.LogInformation("[UsageCounterSyncJob] Schedule job executed.");
  }
  ......
 }

②注冊Job和Trigger:

namespace EqidManager
{
 using IOCContainer = IServiceProvider;
 // Quartz.Net啟動后注冊job和trigger
 public class QuartzStartup
 {
  public IScheduler _scheduler { get; set; }

  private readonly ILogger _logger;
  private readonly IJobFactory iocJobfactory;
  public QuartzStartup(IOCContainer IocContainer, ILoggerFactory loggerFactory)
  {
   _logger = loggerFactory.CreateLogger<QuartzStartup>();
   iocJobfactory = new IOCJobFactory(IocContainer);
   var schedulerFactory = new StdSchedulerFactory();
   _scheduler = schedulerFactory.GetScheduler().Result;
   _scheduler.JobFactory = iocJobfactory;
  }

  public void Start()
  {
   _logger.LogInformation("Schedule job load as application start.");
   _scheduler.Start().Wait();

   var UsageCounterSyncJob = JobBuilder.Create<UsageCounterSyncJob>()
    .WithIdentity("UsageCounterSyncJob")
    .Build();

   var UsageCounterSyncJobTrigger = TriggerBuilder.Create()
    .WithIdentity("UsageCounterSyncCron")
    .StartNow()
    // 每隔一小時同步一次
    .WithCronSchedule("0 0 * * * ?")  // Seconds,Minutes,Hours,Day-of-Month,Month,Day-of-Week,Year(optional field)
    .Build();
   _scheduler.ScheduleJob(UsageCounterSyncJob, UsageCounterSyncJobTrigger).Wait();

   _scheduler.TriggerJob(new JobKey("UsageCounterSyncJob"));
  }

  public void Stop()
  {
   if (_scheduler == null)
   {
    return;
   }

   if (_scheduler.Shutdown(waitForJobsToComplete: true).Wait(30000))
    _scheduler = null;
   else
   {
   }
   _logger.LogCritical("Schedule job upload as application stopped");
  }
 }

 /// <summary>
 /// IOCJobFactory :實現(xiàn)在Timer觸發(fā)的時候注入生成對應的Job組件
 /// </summary>
 public class IOCJobFactory : IJobFactory
 {
  protected readonly IOCContainer Container;

  public IOCJobFactory(IOCContainer container)
  {
   Container = container;
  }

  //Called by the scheduler at the time of the trigger firing, in order to produce
  //  a Quartz.IJob instance on which to call Execute.
  public IJob NewJob(TriggerFiredBundle bundle, IScheduler scheduler)
  {
   return Container.GetService(bundle.JobDetail.JobType) as IJob;
  }

  // Allows the job factory to destroy/cleanup the job if needed.
  public void ReturnJob(IJob job)
  {
  }
 }
}

③結(jié)合ASpNet Core 注入組件;綁定Quartz.Net

//-------------------------------截取自Startup文件------------------------
......
services.AddTransient<UsageCounterSyncJob>();  // 這里使用瞬時依賴注入
services.AddSingleton<QuartzStartup>();
......

// 綁定Quartz.Net
public void Configure(IApplicationBuilder app, Microsoft.AspNetCore.Hosting.IApplicationLifetime lifetime, ILoggerFactory loggerFactory)
{
  var quartz = app.ApplicationServices.GetRequiredService<QuartzStartup>();
  lifetime.ApplicationStarted.Register(quartz.Start);
  lifetime.ApplicationStopped.Register(quartz.Stop);
}

附:IIS 網(wǎng)站低頻訪問導致工作進程進入閑置狀態(tài)的 解決辦法

IIS為網(wǎng)站默認設定了20min閑置超時時間:20分鐘內(nèi)沒有處理請求、也沒有收到新的請求,工作進程就進入閑置狀態(tài)。

IIS上低頻web訪問會造成工作進程關閉,此時應用程序池回收,Timer等線程資源會被銷毀;當工作進程重新運作,Timer可能會重新生成起效, 但我們的設定的定時Job可能沒有按需正確執(zhí)行。

故為在IIS網(wǎng)站實現(xiàn)低頻web訪問下的定時任務:

設置了Idle TimeOut =0;同時將【應用程序池】->【正在回收】->不勾選【回收條件】

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