scheduler

scheduler provides a lightning fast job scheduling library.

The ideas and design are based on the following projects:

Features

Fully support cron expressions: cron/readme
Best Performance: Benchmarks speak for themselves
Less memory allocation: Benchmarks speak for themselves
Support schedule union,minus and intersect operations
Provide a default Scheduler

Installing

Get package:
```
go get -u github.com/cnotch/scheduler
```

Import it in your code:

import "github.com/cnotch/scheduler"
import "github.com/cnotch/scheduler/cron" // when use cron expressions directly

Usage

Simple example

The following example is executed for the first time at delay 1s, and then every minute(using Scheduler):

var counter int32
mj, _ := schd.PeriodFunc(time.Second, time.Minute, func() {
	atomic.AddInt32(&counter, 1)
}, nil)
// other code
mj.Cancel()

Handle panic example

The following example cancels the job when a panic occurs

schd := scheduler.New(scheduler.WithPanicHandler(func(job *scheduler.ManagedJob, r interface{}) {
    // other handle code
	// If panic occurs, cancel the job;
	// Can also not cancel, continue to execute next time
	job.Cancel()
}))

//...
var counter int32

mj, _ := s.PeriodFunc(0, time.Millisecond*10, func() {
	atomic.AddInt32(&counter, 1)
	panic("test")
}, nil)

Compsite Schedule example

In China, many holidays are rescheduled so that people can have more time to travel. Take the May Day holiday in 2020 as an example, how do we get the work schedule? Below is the time schedule that is triggered at 8:30am every working day.

type whSchedule struct {
	times []time.Time
}

func (wh whSchedule) Next(t time.Time) time.Time {
	for _, lt := range wh.times {
		if lt.After(t) {
			return lt
		}
	}
	return time.Time{}
}

func ExampleCompsite() {
	t := time.Date(2020, 4, 25, 8, 30, 0, 0, time.Local)
	mon2fri := cron.MustParse("30 8 ? * 1-5")
	// The holiday (Saturday, Sunday) was transferred to a working day
	workday := whSchedule{[]time.Time{
		t.AddDate(0, 0, 1),  // 2020-04-26 08:30
		t.AddDate(0, 0, 14), // 2020-05-09 08:30
	}}

	// The working day (Monday - Friday) is changed into a holiday
	holiday := whSchedule{[]time.Time{
		t.AddDate(0, 0, 6), // 2020-05-01 08:30
		t.AddDate(0, 0, 9), // 2020-05-04 08:30
		t.AddDate(0, 0, 10),// 2020-05-05 08:30
	}}
	workingSchedule := Union(Minus(mon2fri, holiday), workday)

	for i := 0; i < 12; i++ {
		t = workingSchedule.Next(t)
		fmt.Println(t.Format("2006-01-02 15:04:05"))
	}
	// Output:
	// 2020-04-26 08:30:00
	// 2020-04-27 08:30:00
	// 2020-04-28 08:30:00
	// 2020-04-29 08:30:00
	// 2020-04-30 08:30:00
	// 2020-05-06 08:30:00
	// 2020-05-07 08:30:00
	// 2020-05-08 08:30:00
	// 2020-05-09 08:30:00
	// 2020-05-11 08:30:00
	// 2020-05-12 08:30:00
	// 2020-05-13 08:30:00
}

Benchmarks

gorhill/cronexpr

BenchmarkParse-8   	   64550	     18287 ns/op	    5955 B/op	      79 allocs/op
BenchmarkNext-8    	  243950	      5676 ns/op	     517 B/op	      18 allocs/op

cnotch/scheduler

BenchmarkParse-8   	 2024068	       575 ns/op	     249 B/op	       3 allocs/op
BenchmarkNext-8    	  425515	      2972 ns/op	       0 B/op	       0 allocs/op