package sync import ( "fmt" "math" "time" "github.com/micro/go-log" "github.com/micro/go-micro/sync/leader/consul" "github.com/micro/go-micro/sync/task" "github.com/micro/go-micro/sync/task/local" ) type syncCron struct { opts Options } func backoff(attempts int) time.Duration { if attempts == 0 { return time.Duration(0) } return time.Duration(math.Pow(10, float64(attempts))) * time.Millisecond } func (c *syncCron) Schedule(s task.Schedule, t task.Command) error { id := fmt.Sprintf("%s-%s", s.String(), t.String()) go func() { // run the scheduler tc := s.Run() var i int for { // leader election e, err := c.opts.Leader.Elect(id) if err != nil { log.Logf("[cron] leader election error: %v", err) time.Sleep(backoff(i)) i++ continue } i = 0 r := e.Revoked() // execute the task Tick: for { select { // schedule tick case _, ok := <-tc: // ticked once if !ok { break Tick } log.Logf("[cron] executing command %s", t.Name) if err := c.opts.Task.Run(t); err != nil { log.Logf("[cron] error executing command %s: %v", t.Name, err) } // leader revoked case <-r: break Tick } } // resign e.Resign() } }() return nil } func NewCron(opts ...Option) Cron { var options Options for _, o := range opts { o(&options) } if options.Leader == nil { options.Leader = consul.NewLeader() } if options.Task == nil { options.Task = local.NewTask() } return &syncCron{ opts: options, } }