AspNet Core实现web定时任务

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      作为一枚后端程序狗，项目实践常遇到定时任务的工作，最容易想到的的思路就是利用Windows计划任务/wndows service程序/Crontab程序等主机方法在主机上部署定时任务程序/脚本。

但是很多时候，若使用的是共享主机或者受控主机，这些主机不允许你私自安装exe程序、Windows服务程序。

      码甲会想到在web程序中做定时任务， 目前有两个方向：

①.AspNetCore自带的HostService， 这是一个轻量级的后台服务， 需要搭配timer完成定时任务

②.老牌Quartz.Net组件，支持复杂灵活的Scheduling、支持ADO/RAM Job任务存储、支持集群、支持监听、支持插件。

 此处我们的项目使用稍复杂的Quartz.net实现web定时任务。

 

项目背景

       最近需要做一个计数程序：采用redis计数，设定每小时将当日累积数据持久化到关系型数据库sqlite。

? ? ? ?添加Quartz.Net Nuget 依赖包：<PackageReference Include="Quartz" Version="3.0.6" />

①.定义定时任务内容： Job

②.设置触发条件： Trigger

③.将Quartz.Net集成进AspNet Core

 

头脑风暴

       IScheduler类包装了上述背景需要完成的第①②点工作 ，SimpleJobFactory定义了生成指定的Job任务的过程，这个行为是利用反射机制调用无参构造函数构造出的Job实例。下面是源码：

//----------------选自Quartz.Simpl.SimpleJobFactory类-------------
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();
        }
    }
}

//------------------节选自Quartz.Util.ObjectUtils类-------------------------
 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]);
}

 

很多时候，定义的Job任务依赖了其他组件，这时默认的SimpleJobFactory不可用， 需要考虑将Job任务作为依赖注入组件，加入依赖注入容器。

关键思路：

①. IScheduler 开放了JobFactory 属性，便于你控制Job任务的实例化方式；

? ? ? ? ??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的服务架构是以依赖注入为基础的，利用AspNet Core已有的依赖注入容器IServiceProvider管理Job 服务的创建过程。

 

 编码实践

① 定义Job内容：

// -------每小时将redis数据持久化到sqlite， 每日凌晨跳针，持久化昨天全天数据---------------------
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)
        {
            // 触发时间在凌晨，则同步昨天的计数
            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注册Job和Trigger：

namespace EqidManager
{
    using IOCContainer = IServiceProvider;
    // Quartz.Net启动后注册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()
                // 每隔一小时同步一次
                .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 ：实现在Timer触发的时候注入生成对应的Job组件
    /// </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结合ASpNet Core 注入组件；绑定Quartz.Net

//-------------------------------截取自Startup文件------------------------
......
services.AddTransient<UsageCounterSyncJob>();      // 这里使用瞬时依赖注入
services.AddSingleton<QuartzStartup>();
......

// 绑定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 网站低频访问导致工作进程进入闲置状态

? ? ? ? ?IIS为网站默认设定了20min闲置超时时间：20分钟内没有处理请求、也没有收到新的请求，工作进程就进入闲置状态。

IIS上低频web访问会造成工作进程关闭，此时应用程序池回收，Timer等线程资源会被销毁；当工作进程重新运作，Timer可能会重新生成起效， 但我们的设定的定时Job可能没有按需正确执行。

 

 

故为在IIS网站实现低频web访问下的定时任务： ? ? ? ?设置了Idle TimeOut =0；同时将【应用程序池】->【正在回收】->不勾选【回收条件】 ? ? ?

 

? --------------如有问题请大胆斧正，不吝赐教；如果你觉得文章对你有价值，请点赞或者关注，蟹蟹--------------~~。。~~--------------

 

 

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