reugn / go-quartz

Minimalist and zero-dependency scheduling library for Go

go-quartz

A minimalistic and zero-dependency scheduling library for Go.

About

Inspired by the Quartz Java scheduler.

Library building blocks

Scheduler interface

type Scheduler interface {
	// Start starts the scheduler. The scheduler will run until
	// the Stop method is called or the context is canceled. Use
	// the Wait method to block until all running jobs have completed.
	Start(context.Context)

	// IsStarted determines whether the scheduler has been started.
	IsStarted() bool

	// ScheduleJob schedules a job using a specified trigger.
	ScheduleJob(jobDetail *JobDetail, trigger Trigger) error

	// GetJobKeys returns the keys of scheduled jobs.
	// For a job key to be returned, the job must satisfy all of the
	// matchers specified.
	// Given no matchers, it returns the keys of all scheduled jobs.
	GetJobKeys(...Matcher[ScheduledJob]) []*JobKey

	// GetScheduledJob returns the scheduled job with the specified key.
	GetScheduledJob(jobKey *JobKey) (ScheduledJob, error)

	// DeleteJob removes the job with the specified key from the
	// scheduler's execution queue.
	DeleteJob(jobKey *JobKey) error

	// PauseJob suspends the job with the specified key from being
	// executed by the scheduler.
	PauseJob(jobKey *JobKey) error

	// ResumeJob restarts the suspended job with the specified key.
	ResumeJob(jobKey *JobKey) error

	// Clear removes all of the scheduled jobs.
	Clear() error

	// Wait blocks until the scheduler stops running and all jobs
	// have returned. Wait will return when the context passed to
	// it has expired. Until the context passed to start is
	// cancelled or Stop is called directly.
	Wait(context.Context)

	// Stop shutdowns the scheduler.
	Stop()
}

Implemented Schedulers

• StdScheduler

Trigger interface

type Trigger interface {
	// NextFireTime returns the next time at which the Trigger is scheduled to fire.
	NextFireTime(prev int64) (int64, error)

	// Description returns the description of the Trigger.
	Description() string
}

Implemented Triggers

• CronTrigger
• SimpleTrigger
• RunOnceTrigger

Job interface

Any type that implements it can be scheduled.

type Job interface {
	// Execute is called by a Scheduler when the Trigger associated with this job fires.
	Execute(context.Context) error

	// Description returns the description of the Job.
	Description() string
}

Several common Job implementations can be found in the job package.

Cron expression format

Field Name	Mandatory	Allowed Values	Allowed Special Characters
Seconds	YES	0-59	, - * /
Minutes	YES	0-59	, - * /
Hours	YES	0-23	, - * /
Day of month	YES	1-31	, - * ? /
Month	YES	1-12 or JAN-DEC	, - * /
Day of week	YES	1-7 or SUN-SAT	, - * ? /
Year	NO	empty, 1970-	, - * /

Distributed mode

The scheduler can use its own implementation of quartz.JobQueue to allow state sharing.
An example implementation of the job queue using the file system as a persistence layer can be found here.

Logger

To set a custom logger, use the logger.SetDefault function.
The argument must implement the logger.Logger interface.

The following example shows how to disable library logs.

import "github.com/reugn/go-quartz/logger"

logger.SetDefault(logger.NewSimpleLogger(nil, logger.LevelOff))

Examples

package main

import (
	"context"
	"net/http"
	"time"

	"github.com/reugn/go-quartz/job"
	"github.com/reugn/go-quartz/quartz"
)

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// create scheduler
	sched := quartz.NewStdScheduler()

	// async start scheduler
	sched.Start(ctx)

	// create jobs
	cronTrigger, _ := quartz.NewCronTrigger("1/5 * * * * *")
	shellJob := job.NewShellJob("ls -la")

	request, _ := http.NewRequest(http.MethodGet, "https://worldtimeapi.org/api/timezone/utc", nil)
	curlJob := job.NewCurlJob(request)

	functionJob := job.NewFunctionJob(func(_ context.Context) (int, error) { return 42, nil })

	// register jobs to scheduler
	sched.ScheduleJob(quartz.NewJobDetail(shellJob, quartz.NewJobKey("shellJob")),
		cronTrigger)
	sched.ScheduleJob(quartz.NewJobDetail(curlJob, quartz.NewJobKey("curlJob")),
		quartz.NewSimpleTrigger(time.Second*7))
	sched.ScheduleJob(quartz.NewJobDetail(functionJob, quartz.NewJobKey("functionJob")),
		quartz.NewSimpleTrigger(time.Second*5))

	// stop scheduler
	sched.Stop()

	// wait for all workers to exit
	sched.Wait(ctx)
}

More code samples can be found in the examples directory.

License

Licensed under the MIT License.