diff options
Diffstat (limited to 'vendor/github.com/segmentio/backo-go/backo.go')
-rw-r--r-- | vendor/github.com/segmentio/backo-go/backo.go | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/vendor/github.com/segmentio/backo-go/backo.go b/vendor/github.com/segmentio/backo-go/backo.go new file mode 100644 index 000000000..6f7b6d5e2 --- /dev/null +++ b/vendor/github.com/segmentio/backo-go/backo.go @@ -0,0 +1,83 @@ +package backo + +import ( + "math" + "math/rand" + "time" +) + +type Backo struct { + base time.Duration + factor uint8 + jitter float64 + cap time.Duration +} + +// Creates a backo instance with the given parameters +func NewBacko(base time.Duration, factor uint8, jitter float64, cap time.Duration) *Backo { + return &Backo{base, factor, jitter, cap} +} + +// Creates a backo instance with the following defaults: +// base: 100 milliseconds +// factor: 2 +// jitter: 0 +// cap: 10 seconds +func DefaultBacko() *Backo { + return NewBacko(time.Millisecond*100, 2, 0, time.Second*10) +} + +// Duration returns the backoff interval for the given attempt. +func (backo *Backo) Duration(attempt int) time.Duration { + duration := float64(backo.base) * math.Pow(float64(backo.factor), float64(attempt)) + + if backo.jitter != 0 { + random := rand.Float64() + deviation := math.Floor(random * backo.jitter * duration) + if (int(math.Floor(random*10)) & 1) == 0 { + duration = duration - deviation + } else { + duration = duration + deviation + } + } + + duration = math.Min(float64(duration), float64(backo.cap)) + return time.Duration(duration) +} + +// Sleep pauses the current goroutine for the backoff interval for the given attempt. +func (backo *Backo) Sleep(attempt int) { + duration := backo.Duration(attempt) + time.Sleep(duration) +} + +type Ticker struct { + done chan struct{} + C <-chan time.Time +} + +func (b *Backo) NewTicker() *Ticker { + c := make(chan time.Time, 1) + ticker := &Ticker{ + done: make(chan struct{}, 1), + C: c, + } + + go func() { + for i := 0; ; i++ { + select { + case t := <-time.After(b.Duration(i)): + c <- t + case <-ticker.done: + close(c) + return + } + } + }() + + return ticker +} + +func (t *Ticker) Stop() { + t.done <- struct{}{} +} |