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, error)

	// 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

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.