Lazy Scheduler

Lazy Scheduler：我的轻量级任务调度框架

 

一、背景

工作中经常涉及任务调度，一直都是采用while(true) => if hitted DO => Thread.Sleep(interval)的模式。但是最近实在是感觉这种实现模式很挫。并且没有考虑到性能问题，需要撞击n次才能命中一次，使用效率不足5%（一百次while循环命中不到5次），但是单方面加大线程睡眠时间又无法保证高准确性和高精度。那有么有其它好的思路：即可以保持高准确性、高精度，又不浪费资源呢？

 二、我的思路

上述的短板在于：无目的的线程Sleep，如果我们可以每次恰到好处的Sleep，即线程被唤醒后刚好赶上下一次的任务到来，命中率就是100%了嘛。所以可以这样做：进入While后先按照Scheduler计算出下次的运行时间距离现在还有多久(Interval)，然后直接Sleep(Interval)，等待线程唤醒后就立即执行下一个既定Task就可以了。那这样做唯一的难点就在于你的Scheduler是否可计算、是否可以计算出下一次的运行时间点。

还好，我碰到的逻辑都还是满足这一点需求的：

（1）每隔一段时间执行一次的计划任务；

（2）在指定时间点必须执行的计划任务;

其他人性化设定：周六周日不运行。

三、代码实现

（1）主要有：负责调度的接口：IScheduler；Scheduler设定:ISchedulerSetting;任务接口：ITask以及一些其他的辅助类。

（2）难点:计算Interval的实现类：FixTimeSchedulerSetting.cs和IntervalSchedulerSetting.cs

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//Author:      night-king // Email:       deepleo@163.com //Home:       http://deepleo.com //Github:     https://github.com/night-king/ //Date:         2013-11-1 //Place:        Wuhan@China   using System; using System.Collections.Generic; using System.Text; using System.Collections;   namespace Deepleo.LazyScheduler.Setting {     public class FixTimeSchedulerSetting : IFixTimeSchedulerSetting, IWeekSchedulerSetting     {         public IList<DayOfWeek> ExcludeWeeks         {             get;             set;         }           public int Hour         {             get;             set;         }           public int Minutes         {             get;             set;         }           public int Second         {             get;             set;         }           public FixTimeSchedulerSetting(IList<DayOfWeek> excludeWeeks)         {             ExcludeWeeks = excludeWeeks;         }           public virtual TimeSpan CalculateNext()         {             var nowDateTime = System.DateTime.Now;             var expectNextTime = System.DateTime.Parse(string.Format("{0}-{1}-{2} {3}:{4}:{5}", nowDateTime.Year, nowDateTime.Month, nowDateTime.Day, Hour, Minutes, Second));             var todayWeek = nowDateTime.DayOfWeek;             var km = new WeekManager(ExcludeWeeks);             var delayDays = km.CalculateDelayDays(todayWeek);             if (delayDays == 0)// this day of week can do             {                 if (expectNextTime > nowDateTime) return expectNextTime - nowDateTime;                 else delayDays++;             }             return expectNextTime.AddDays(delayDays) - nowDateTime;         }     } }

　　

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using System; using System.Collections.Generic; using System.Text;   namespace Deepleo.LazyScheduler.Setting {     public class IntervalSchedulerSetting : IIntervalSchedulerSetting, IWeekSchedulerSetting     {           public TimeSpan Interval         {             get;             set;         }           public IList<DayOfWeek> ExcludeWeeks         {             get;             set;         }           public IntervalSchedulerSetting(IList<DayOfWeek> excludeWeeks)         {             ExcludeWeeks = excludeWeeks;         }           public TimeSpan CalculateNext()         {             var nowDateTime = System.DateTime.Now;             var todayWeek =nowDateTime.DayOfWeek;             var km = new WeekManager(ExcludeWeeks);             var delayDays = km.CalculateDelayDays(todayWeek);             var interval = Interval.Add(new TimeSpan(delayDays, 0, 0, 0));             if (interval.CompareTo(new TimeSpan(0, 0, 1)) <= 0) return new TimeSpan(0, 0, 1);             else return interval;         }     } }

重要的辅助类：WeekManager的实现代码：

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//Author:      night-king // Email:       deepleo@163.com //Home:       http://deepleo.com //Github:     https://github.com/night-king/ //Date:         2013-11-1 //Place:        Wuhan@China   using System; using System.Collections.Generic; using System.Text;   namespace Deepleo.LazyScheduler.Setting {        public class WeekManager     {         private Dictionary<int, DayOfWeek> _allowWeekDict;           public WeekManager(IList<DayOfWeek> notAllowWeeks)         {             _allowWeekDict = new Dictionary<int, DayOfWeek>();             if (!notAllowWeeks.Contains(DayOfWeek.Sunday))                 _allowWeekDict.Add(0, DayOfWeek.Sunday);             if (!notAllowWeeks.Contains(DayOfWeek.Monday))                 _allowWeekDict.Add(1, DayOfWeek.Monday);             if (!notAllowWeeks.Contains(DayOfWeek.Tuesday))                 _allowWeekDict.Add(2, DayOfWeek.Tuesday);             if (!notAllowWeeks.Contains(DayOfWeek.Wednesday))                 _allowWeekDict.Add(3, DayOfWeek.Wednesday);             if (!notAllowWeeks.Contains(DayOfWeek.Thursday))                 _allowWeekDict.Add(4, DayOfWeek.Thursday);             if (!notAllowWeeks.Contains(DayOfWeek.Friday))                 _allowWeekDict.Add(5, DayOfWeek.Friday);             if (!notAllowWeeks.Contains(DayOfWeek.Saturday))                 _allowWeekDict.Add(6, DayOfWeek.Saturday);         }           /// <summary>         /// Calcute how many delay days         /// </summary>         /// <param name="week">current day of week</param>         /// <returns>delay days</returns>         public int CalculateDelayDays(DayOfWeek week)         {             var weekOfDay = (int)week;             int distence = 0;             while (true)             {                 if (_allowWeekDict.ContainsKey(weekOfDay))                 {                     return distence;                 }                 else                 {                     weekOfDay = weekOfDay < 6 ? weekOfDay + 1 : 0;                     distence++;                 }             }         }     } }

四、测试

(1)5s钟时间间隔的测试结果：

（2）1s测试结果：

再看CPU占用情况：

基本上稳定在0%，内存占用也只有6.4k.

五、代码下载：

http://files.cnblogs.com/deepleo/SchedulerSolution.zip

https://github.com/night-king/LazyScheduler