104 lines
2.6 KiB
Go
104 lines
2.6 KiB
Go
package backoff
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import (
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"time"
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)
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/*
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FibonacciBackoff 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 Fibonacci() function.
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*/
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type FibonacciBackoff 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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Slots []time.Duration
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}
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// Fibonacci creates a new instance of FibonacciBackoff.
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func Fibonacci() *FibonacciBackoff {
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return &FibonacciBackoff{
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Retries: 0,
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MaxRetries: 5,
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Delay: time.Duration(0),
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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 fibonacci backoff delay is computed as follows:
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`n = fib(c - 1) + fib(c - 2); f(0) = 0, f(1) = 1; n >= 0.` where
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`n` is the backoff delay and `c` is the retry slot.
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This method maintains a slice of time.Duration to save on fibonacci computation.
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Example, given a 1 second interval:
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Retry # Backoff delay (in seconds)
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1 0
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2 1
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3 1
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4 2
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5 3
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6 5
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7 8
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8 13
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*/
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func (fb *FibonacciBackoff) Next() bool {
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if fb.Retries >= fb.MaxRetries {
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return false
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}
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fb.Retries++
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switch fb.Retries {
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case 1:
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fb.Slots = append(fb.Slots, time.Duration(0*fb.Interval))
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fb.Delay = time.Duration(0 * fb.Interval)
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case 2:
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fb.Slots = append(fb.Slots, time.Duration(1*fb.Interval))
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fb.Delay = time.Duration(1 * fb.Interval)
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default:
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fb.Delay = fb.Slots[fb.Retries-2] + fb.Slots[fb.Retries-3]
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fb.Slots = append(fb.Slots, fb.Delay)
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}
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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 (fb *FibonacciBackoff) 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 fb.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(fb.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, the backoff delay, and backoff slots back to its initial state.
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func (fb *FibonacciBackoff) Reset() {
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fb.Retries = 0
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fb.Delay = time.Duration(0 * time.Second)
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fb.Slots = nil
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}
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