route/vendor/github.com/go-resty/resty/retry.go

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2017-09-30 16:47:47 +00:00
// Copyright (c) 2015-2017 Jeevanandam M (jeeva@myjeeva.com), All rights reserved.
// resty source code and usage is governed by a MIT style
// license that can be found in the LICENSE file.
package resty
import (
"math"
"math/rand"
"time"
)
const (
defaultMaxRetries = 3
defaultWaitTime = time.Duration(100) * time.Millisecond
defaultMaxWaitTime = time.Duration(2000) * time.Millisecond
)
type (
// Option is to create convenient retry options like wait time, max retries, etc.
Option func(*Options)
// RetryConditionFunc type is for retry condition function
RetryConditionFunc func(*Response) (bool, error)
// Options to hold go-resty retry values
Options struct {
maxRetries int
waitTime time.Duration
maxWaitTime time.Duration
retryConditions []RetryConditionFunc
}
)
// Retries sets the max number of retries
func Retries(value int) Option {
return func(o *Options) {
o.maxRetries = value
}
}
// WaitTime sets the default wait time to sleep between requests
func WaitTime(value time.Duration) Option {
return func(o *Options) {
o.waitTime = value
}
}
// MaxWaitTime sets the max wait time to sleep between requests
func MaxWaitTime(value time.Duration) Option {
return func(o *Options) {
o.maxWaitTime = value
}
}
// RetryConditions sets the conditions that will be checked for retry.
func RetryConditions(conditions []RetryConditionFunc) Option {
return func(o *Options) {
o.retryConditions = conditions
}
}
// Backoff retries with increasing timeout duration up until X amount of retries
// (Default is 3 attempts, Override with option Retries(n))
func Backoff(operation func() (*Response, error), options ...Option) error {
// Defaults
opts := Options{
maxRetries: defaultMaxRetries,
waitTime: defaultWaitTime,
maxWaitTime: defaultMaxWaitTime,
retryConditions: []RetryConditionFunc{},
}
for _, o := range options {
o(&opts)
}
var (
resp *Response
err error
)
base := float64(opts.waitTime) // Time to wait between each attempt
capLevel := float64(opts.maxWaitTime) // Maximum amount of wait time for the retry
for attempt := 0; attempt < opts.maxRetries; attempt++ {
resp, err = operation()
var needsRetry bool
var conditionErr error
for _, condition := range opts.retryConditions {
needsRetry, conditionErr = condition(resp)
if needsRetry || conditionErr != nil {
break
}
}
// If the operation returned no error, there was no condition satisfied and
// there was no error caused by the conditional functions.
if err == nil && !needsRetry && conditionErr == nil {
return nil
}
// Adding capped exponential backup with jitter
// See the following article...
// http://www.awsarchitectureblog.com/2015/03/backoff.html
temp := math.Min(capLevel, base*math.Exp2(float64(attempt)))
sleepDuration := time.Duration(int(temp/2) + rand.Intn(int(temp/2)))
if sleepDuration < opts.waitTime {
sleepDuration = opts.waitTime
}
time.Sleep(sleepDuration)
}
return err
}