captron

An 'apt' cron job service in golang.

Improved version of roylee0704/gron.

Goals

• Minimalist APIs for scheduling jobs.
• Thread safety.
• Customizable Job Type.
• Customizable Schedule.

Installation

$ go get github.com/pravj/captron

Usage

Create schedule.go

package main

import (
	"fmt"
	"time"
	"github.com/pravj/captron"
)

func main() {
	c := captron.New()
	c.AddFunc(captron.Every(1*time.Hour), func() {
		fmt.Println("runs every hour.")
	})
	c.Start()
}

Schedule Parameters

All scheduling is done in the machine's local time zone (as provided by the Go time package).

Setup basic periodic schedule with captron.Every().

captron.Every(1*time.Second)
captron.Every(1*time.Minute)
captron.Every(1*time.Hour)

Also support Day, Week by importing captron/xtime:

import "github.com/pravj/captron/xtime"

captron.Every(1 * xtime.Day)
captron.Every(1 * xtime.Week)

Schedule to run at specific time with .At(hh:mm)

captron.Every(30 * xtime.Day).At("00:00")
captron.Every(1 * xtime.Week).At("23:59")

Custom Job Type

You may define custom job types by implementing captron.Job interface: Run().

For example:

type Reminder struct {
	Msg string
}

func (r Reminder) Run() {
  fmt.Println(r.Msg)
}

After job has defined, instantiate it and schedule to run in captron.

c := captron.New()
r := Reminder{ "Feed the baby!" }
c.Add(captron.Every(8*time.Hour), r)
c.Start()

Custom Job Func

You may register Funcs to be executed on a given schedule. captron will run them in their own goroutines, asynchronously.

c := captron.New()
c.AddFunc(captron.Every(1*time.Second), func() {
	fmt.Println("runs every second")
})
c.Start()

Custom Schedule

Schedule is the interface that wraps the basic Next method: Next(p time.Duration) time.Time

In captron, the interface value Schedule has the following concrete types:

• periodicSchedule. adds time instant t to underlying period p.
• atSchedule. reoccurs every period p, at time components(hh:mm).

For more info, checkout schedule.go.

Full Example

package main

import (
	"fmt"
	"github.com/pravj/captron"
	"github.com/pravj/captron/xtime"
)

type PrintJob struct{ Msg string }

func (p PrintJob) Run() {
	fmt.Println(p.Msg)
}

func main() {

	var (
		// schedules
		daily     = captron.Every(1 * xtime.Day)
		weekly    = captron.Every(1 * xtime.Week)
		monthly   = captron.Every(30 * xtime.Day)
		yearly    = captron.Every(365 * xtime.Day)

		// contrived jobs
		purgeTask = func() { fmt.Println("purge aged records") }
		printFoo  = printJob{"Foo"}
		printBar  = printJob{"Bar"}
	)

	c := captron.New()

	c.Add(daily.At("12:30"), printFoo)
	c.AddFunc(weekly, func() { fmt.Println("Every week") })
	c.Start()

	// Jobs may also be added to a running captron
	c.Add(monthly, printBar)
	c.AddFunc(yearly, purgeTask)

	// Stop captron (running jobs are not halted).
	c.Stop()
}