聊聊dbsync的Schedulable

序

本文主要研究一下dbsync的Schedulable

Schedulable

//Schedulable represent an abstraction that can be schedule
type Schedulable struct {
    URL string
    ID  string
    *contract.Sync
    Schedule *contract.Schedule
    Status   string
    status   uint32
}

//NewSchedulableFromURL create a new scheduleable from URL
func NewSchedulableFromURL(URL string) (*Schedulable, error) {
    result := &Schedulable{}
    resource := url.NewResource(URL)
    err := resource.Decode(result)
    return result, err
}

Schedulable定義了URL、ID、*contract.Sync、Schedule、Status、status屬性；NewSchedulableFromURL方法根據URL來建立Schedulable

Clone

func (s *Schedulable) Clone() *Schedulable {
    return &Schedulable{
        URL:      s.URL,
        ID:       s.ID,
        Sync:     s.Sync.Clone(),
        Schedule: s.Schedule,
        Status:   s.Status,
    }
}

Clone方法會複製一份Schedulable

Done

//Done return true if schedulable is not running
func (s *Schedulable) Done() {
    atomic.StoreUint32(&s.status, statusScheduled)
}

Done方法更新status爲statusScheduled

IsRunning

//IsRunning return true if schedulable is running
func (s *Schedulable) IsRunning() bool {
    return atomic.LoadUint32(&s.status) == statusRunning
}

IsRunning方法更新status爲statusRunning

ScheduleNexRun

//ScheduleNexRun schedules next run
func (s *Schedulable) ScheduleNexRun(baseTime time.Time) error {
    return s.Schedule.Next(baseTime)
}

ScheduleNexRun方法執行Schedule.Next(baseTime)

Init

//Init initializes scheduleable
func (s *Schedulable) Init() error {
    if s.ID == "" {
        s.ID = uRLToID(s.URL)
    }
    now := time.Now()
    if s.Schedule == nil {
        return nil
    }

    if s.Schedule.Frequency != nil && s.Schedule.Frequency.Value == 0 {
        s.Schedule.Frequency.Value = 1
    }
    if s.Schedule.NextRun == nil {
        if s.Schedule.Frequency != nil {
            s.Schedule.NextRun = &now
        } else {
            return s.Schedule.Next(now)
        }
    }
    return nil

}

Init方法執行Schedulable的初始化

Validate

//Validate checks if Schedulable is valid
func (s *Schedulable) Validate() error {
    if s.Schedule == nil {
        return fmt.Errorf("schedule was emtpy")
    }
    if s.Schedule.Frequency == nil && s.Schedule.At == nil {
        return fmt.Errorf("schedule.Frequency and schedule.At were emtpy")
    }
    if s.ID == "" {
        return fmt.Errorf("ID were emtpy")
    }
    return nil
}

Validate方法校驗Schedule、Schedule.Frequency、Schedule.At、ID值

小結

dbsync的Schedulable定義了URL、ID、*contract.Sync、Schedule、Status、status屬性，它提供了Clone、Done、IsRunning、ScheduleNexRun、Init、Validate方法。

doc

• dbsync