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(ctx context.Context, job Job, trigger Trigger) error
	// GetJobKeys returns the keys of all of the scheduled jobs.
	GetJobKeys() []int
	// GetScheduledJob returns the scheduled job with the specified key.
	GetScheduledJob(key int) (*ScheduledJob, error)
	// DeleteJob removes the job with the specified key from the Scheduler's execution queue.
	DeleteJob(key int) error
	// Clear removes all of the scheduled jobs.
	Clear()
	// Stop shutdowns the scheduler.
	Stop()
	// 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)
}

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)
	// Description returns the description of the Job.
	Description() string
	// Key returns the unique key for the Job.
	Key() int
}

Implemented Jobs

• ShellJob
• CurlJob
• FunctionJob

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-	, - * /

Examples

ctx := context.Background()
sched := quartz.NewStdScheduler()
sched.Start(ctx)
cronTrigger, _ := quartz.NewCronTrigger("1/5 * * * * *")
shellJob := quartz.NewShellJob("ls -la")
request, _ := http.NewRequest(http.MethodGet, "https://worldtimeapi.org/api/timezone/utc", nil)
curlJob, _ := quartz.NewCurlJob(request)
functionJob := quartz.NewFunctionJob(func(_ context.Context) (int, error) { return 42, nil })
sched.ScheduleJob(shellJob, cronTrigger)
sched.ScheduleJob(curlJob, quartz.NewSimpleTrigger(time.Second*7))
sched.ScheduleJob(functionJob, quartz.NewSimpleTrigger(time.Second*5))
sched.Stop()
sched.Wait(ctx)

More code samples can be found in the examples directory.

License

Licensed under the MIT License.