gobreakerソース分析ノート

ソニー大法オープンソースヒューズhttps://github.com/sony/gobreaker

Microsoft Circuit Breaker patternベース

3つの状態

type Settings struct {
    Name          string  //breaker 
    MaxRequests   uint32  //  ， HelfOpen 
    Interval      time.Duration  // Close ， counts 
    Timeout       time.Duration  // Open timeout ， HelfOpen
    ReadyToTrip   func(counts Counts) bool // Closed , 。 ， Open 
    OnStateChange func(name string, from State, to State) //  
}

 : Generation 

type Counts struct {
    Requests             uint32 // 
    TotalSuccesses       uint32 //  
    TotalFailures        uint32 //  
    ConsecutiveSuccesses uint32 //  
    ConsecutiveFailures  uint32 //  
}

func (cb *CircuitBreaker) Execute(req func() (interface{}, error)) (interface{}, error) {
    generation, err := cb.beforeRequest()
    if err != nil {
        return nil, err
    }

    defer func() {
        e := recover()
        if e != nil {
            cb.afterRequest(generation, false)
            panic(e)
        }
    }()

    result, err := req()
    cb.afterRequest(generation, err == nil)
    return result, err
}

func (cb *CircuitBreaker) afterRequest(before uint64, success bool) {
    cb.mutex.Lock()
    defer cb.mutex.Unlock()

    now := time.Now()
    state, generation := cb.currentState(now)
    if generation != before {
        return
    }

    if success {
        cb.onSuccess(state, now) //  counts
    } else {
        cb.onFailure(state, now) // Closed:  readyToTrip， Open。HelfOpen: Open 
    }
}