backoff.go (2142B)
1 // Package backoff implements backoff algorithms for retrying operations. 2 // 3 // Use Retry function for retrying operations that may fail. 4 // If Retry does not meet your needs, 5 // copy/paste the function into your project and modify as you wish. 6 // 7 // There is also Ticker type similar to time.Ticker. 8 // You can use it if you need to work with channels. 9 // 10 // See Examples section below for usage examples. 11 package backoff 12 13 import "time" 14 15 // BackOff is a backoff policy for retrying an operation. 16 type BackOff interface { 17 // NextBackOff returns the duration to wait before retrying the operation, 18 // or backoff. Stop to indicate that no more retries should be made. 19 // 20 // Example usage: 21 // 22 // duration := backoff.NextBackOff(); 23 // if (duration == backoff.Stop) { 24 // // Do not retry operation. 25 // } else { 26 // // Sleep for duration and retry operation. 27 // } 28 // 29 NextBackOff() time.Duration 30 31 // Reset to initial state. 32 Reset() 33 } 34 35 // Stop indicates that no more retries should be made for use in NextBackOff(). 36 const Stop time.Duration = -1 37 38 // ZeroBackOff is a fixed backoff policy whose backoff time is always zero, 39 // meaning that the operation is retried immediately without waiting, indefinitely. 40 type ZeroBackOff struct{} 41 42 func (b *ZeroBackOff) Reset() {} 43 44 func (b *ZeroBackOff) NextBackOff() time.Duration { return 0 } 45 46 // StopBackOff is a fixed backoff policy that always returns backoff.Stop for 47 // NextBackOff(), meaning that the operation should never be retried. 48 type StopBackOff struct{} 49 50 func (b *StopBackOff) Reset() {} 51 52 func (b *StopBackOff) NextBackOff() time.Duration { return Stop } 53 54 // ConstantBackOff is a backoff policy that always returns the same backoff delay. 55 // This is in contrast to an exponential backoff policy, 56 // which returns a delay that grows longer as you call NextBackOff() over and over again. 57 type ConstantBackOff struct { 58 Interval time.Duration 59 } 60 61 func (b *ConstantBackOff) Reset() {} 62 func (b *ConstantBackOff) NextBackOff() time.Duration { return b.Interval } 63 64 func NewConstantBackOff(d time.Duration) *ConstantBackOff { 65 return &ConstantBackOff{Interval: d} 66 }