retry.go

package req

import (
	"math"
	"math/rand"
	"time"
)

func defaultGetRetryInterval(resp *Response, attempt int) time.Duration {
	return 100 * time.Millisecond
}

// RetryConditionFunc is a retry condition, which determines
// whether the request should retry.
type RetryConditionFunc func(resp *Response, err error) bool

// RetryHookFunc is a retry hook which will be executed before a retry.
type RetryHookFunc func(resp *Response, err error)

// GetRetryIntervalFunc is a function that determines how long should
// sleep between retry attempts.
type GetRetryIntervalFunc func(resp *Response, attempt int) time.Duration

func backoffInterval(min, max time.Duration) GetRetryIntervalFunc {
	base := float64(min)
	capLevel := float64(max)
	return func(resp *Response, attempt int) time.Duration {
		temp := math.Min(capLevel, base*math.Exp2(float64(attempt)))
		halfTemp := int64(temp / 2)
		sleep := halfTemp + rand.Int63n(halfTemp)
		return time.Duration(sleep)
	}
}

func newDefaultRetryOption() *RetryOption {
	return &RetryOption{
		GetRetryInterval: defaultGetRetryInterval,
	}
}

// RetryOption controls the retry behavior of a request.
// It is typically configured via Client.SetCommonRetry* or Request.SetRetry*
// methods and can be read from middleware with Request.GetRetryOption.
//
// MaxRetries is the maximum number of retries (not including the initial
// attempt). A negative value means retry infinitely. Zero means no retries.
// GetRetryOption may still return a non-nil option if only non-count setters
// (interval, condition, or hook) were used while leaving MaxRetries at zero.
type RetryOption struct {
	MaxRetries       int
	GetRetryInterval GetRetryIntervalFunc
	RetryConditions  []RetryConditionFunc
	RetryHooks       []RetryHookFunc
}

// Clone returns a deep copy of RetryOption.
func (ro *RetryOption) Clone() *RetryOption {
	if ro == nil {
		return nil
	}
	o := &RetryOption{
		MaxRetries:       ro.MaxRetries,
		GetRetryInterval: ro.GetRetryInterval,
	}
	o.RetryConditions = append(o.RetryConditions, ro.RetryConditions...)
	o.RetryHooks = append(o.RetryHooks, ro.RetryHooks...)
	return o
}