AspNet Core上實現web定時任務

專案背景

最近需要做一個計數程式：採用redis計數，設定 每小時 將 當日累積資料 持久化到關係型資料庫sqlite。

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

①.定義定時任務內容： Job

②.設定觸發條件： Trigger

③.將Quartz.Net整合進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 呼叫 無參建構函式構 造出的Job例項。下面是原始碼：

//----------------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]);
}

關鍵思路：

①. IScheduler 開放了JobFactory 屬性，便於你控制Job任務的例項化方式；

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 服務的建立過程。

編碼實踐

① 定義Job內容：

// -------每小時將redis資料持久化到sqlite， 每日凌晨跳針，持久化昨天全天資料---------------------
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)
{
// 觸發時間在凌晨，則同步昨天的計數
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註冊Job和Trigger：

namespace EqidManager
{
using IOCContainer = IServiceProvider;
// Quartz.Net啟動後註冊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 ：實現在Timer觸發的時候注入生成對應的Job元件
/// </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結合ASpNet Core 注入元件；繫結Quartz.Net

//-------------------------------擷取自Startup檔案------------------------
......
services.AddTransient<UsageCounterSyncJob>();// 這裡使用瞬時依賴注入
services.AddSingleton<QuartzStartup>();
......

// 繫結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 網站低頻訪問導致工作程序進入閒置狀態

IIS為網站預設設定了 20min閒置超時 時間：20分鐘內沒有處理請求、也沒有收到新的請求，工作程序就進入閒置狀態。

IIS上低頻web訪問會造成工作程序關閉，此時應用程式池回收，Timer等執行緒資源會被銷燬；當工作程序重新運作，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行。

故為在IIS網站實現低頻web訪問下的定時任務：

設定了Idle TimeOut =0；同時將【應用程式池】->【正在回收】-> 不勾選 【回收條件】      

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