A distributed cron framework.
First of all, you should implement a distributed atomic operation:
type Atomic interface {
SetIfNotExists(key, value string) bool
}You can implement it any way you like, for example, via Redis SetNX:
type RedisAtomic struct {
client *redis.Client
}
func (m *RedisAtomic) SetIfNotExists(key, value string) bool {
ret := m.client.SetNX(key, value, time.Hour)
return ret.Err() == nil && ret.Val()
}Now we can create a cron with that:
ra := &RedisAtomic{
// init redis client
}
cron := dcron.NewCron(dcron.WithKey("TestCron"), dcron.WithAtomic(ra))There are many ways to create jobs:
- use
dcron.NewJob; - use
dcron.NewJobWithAutoKey; - implement interface
dcron.Job.
func main {
job1 := dcron.NewJob("Job1", "*/15 * * * * *", func(ctx context.Context) error {
if task, ok := dcron.TaskFromContext(ctx); ok {
log.Println("run:", task.Job.Spec(), task.Key)
}
// do something
return nil
})
job2 := dcron.NewJobWithAutoKey("*/20 * * * * *", Job2)
job3 := Job3{}
}
func Job2(ctx context.Context) error {
if task, ok := dcron.TaskFromContext(ctx); ok {
log.Println("run:", task.Job.Spec(), task.Key)
}
// do something
return nil
}
type Job3 struct {
}
func (j Job3) Key() string {
return "Job3"
}
func (j Job3) Spec() string {
return "*/30 * * * * *"
}
func (j Job3) Run(ctx context.Context) error {
if task, ok := dcron.TaskFromContext(ctx); ok {
log.Println("run:", task.Job.Spec(), task.Key)
}
// do something
return nil
}
func (j Job3) Options() []dcron.JobOption {
return nil
}Finally, add the jobs to the cron, and start it:
if err := cron.AddJobs(job1, job2, job3); err != nil {
panic(err)
}
cron.Start()
log.Println("cron started")
time.Sleep(time.Minute)
<-cron.Stop().Done()
log.Println("cron stopped")You will see logging:
2020/03/11 15:28:04 cron started
2020/03/11 15:28:15 run: */15 * * * * * dcron:TestCron.Job1@1583911695
2020/03/11 15:28:20 run: */20 * * * * * dcron:TestCron.Job2@1583911700
2020/03/11 15:28:30 run: */30 * * * * * dcron:TestCron.Job3@1583911710
2020/03/11 15:28:30 run: */15 * * * * * dcron:TestCron.Job1@1583911710
2020/03/11 15:28:40 run: */20 * * * * * dcron:TestCron.Job2@1583911720
2020/03/11 15:28:45 run: */15 * * * * * dcron:TestCron.Job1@1583911725
2020/03/11 15:29:00 run: */30 * * * * * dcron:TestCron.Job3@1583911740
2020/03/11 15:29:00 run: */15 * * * * * dcron:TestCron.Job1@1583911740
2020/03/11 15:29:00 run: */20 * * * * * dcron:TestCron.Job2@1583911740
2020/03/11 15:29:04 cron stopped
There is the complete example: _example/main.go.