89 lines
2.1 KiB
Go
89 lines
2.1 KiB
Go
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package backoff
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import (
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"math"
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"time"
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)
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/*
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ExponentialBackoff implements the Backoff interface. It represents an
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instance that keeps track of retries, delays, and intervals for the
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fibonacci backoff algorithm. This struct is instantiated by
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the Exponential() function.
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*/
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type ExponentialBackoff struct {
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Retries int
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MaxRetries int
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Delay time.Duration
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Interval time.Duration // time.Second, time.Millisecond, etc.
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}
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// Exponential creates a new instance of ExponentialBackoff.
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func Exponential() *ExponentialBackoff {
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return &ExponentialBackoff{
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Retries: 0,
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MaxRetries: 5,
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Delay: time.Duration(0),
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Interval: time.Duration(1 * time.Second),
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}
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}
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/*
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Next gets the next backoff delay. This method will increment the retries and check
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if the maximum number of retries has been met. If this condition is satisfied, then
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the function will return. Otherwise, the next backoff delay will be computed.
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The exponential backoff delay is computed as follows:
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`n = 2^c - 1` where `n` is the backoff delay and `c` is the number of retries.
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Example, given a 1 second interval:
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Retry # Backoff delay (in seconds)
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0 0
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1 1
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2 3
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3 7
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4 15
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5 31
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*/
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func (e *ExponentialBackoff) Next() bool {
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if e.Retries >= e.MaxRetries {
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return false
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}
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e.Retries++
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e.Delay = time.Duration(math.Pow(2, float64(e.Retries))-1) * e.Interval
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return true
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}
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/*
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Retry will retry a function until the maximum number of retries is met. This method expects
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the function `f` to return an error. If the failure condition is met, this method
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will surface the error outputted from `f`, otherwise nil will be returned as normal.
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*/
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func (e *ExponentialBackoff) Retry(f func() error) error {
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err := f()
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if err == nil {
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return nil
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}
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for e.Next() {
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if err = f(); err == nil {
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return nil
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}
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time.Sleep(e.Delay)
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}
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return err
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}
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// Reset will reset the retry count and the backoff delay back to its initial state.
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func (e *ExponentialBackoff) Reset() {
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e.Retries = 0
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e.Delay = time.Duration(0 * time.Second)
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}
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