115 lines
3 KiB
Go
115 lines
3 KiB
Go
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// Copyright (c) 2015-2018 Jeevanandam M (jeeva@myjeeva.com), All rights reserved.
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// resty source code and usage is governed by a MIT style
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// license that can be found in the LICENSE file.
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package resty
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import (
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"math"
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"math/rand"
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"time"
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)
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const (
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defaultMaxRetries = 3
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defaultWaitTime = time.Duration(100) * time.Millisecond
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defaultMaxWaitTime = time.Duration(2000) * time.Millisecond
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)
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type (
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// Option is to create convenient retry options like wait time, max retries, etc.
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Option func(*Options)
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// RetryConditionFunc type is for retry condition function
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RetryConditionFunc func(*Response) (bool, error)
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// Options to hold go-resty retry values
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Options struct {
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maxRetries int
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waitTime time.Duration
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maxWaitTime time.Duration
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retryConditions []RetryConditionFunc
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}
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)
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// Retries sets the max number of retries
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func Retries(value int) Option {
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return func(o *Options) {
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o.maxRetries = value
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}
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}
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// WaitTime sets the default wait time to sleep between requests
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func WaitTime(value time.Duration) Option {
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return func(o *Options) {
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o.waitTime = value
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}
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}
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// MaxWaitTime sets the max wait time to sleep between requests
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func MaxWaitTime(value time.Duration) Option {
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return func(o *Options) {
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o.maxWaitTime = value
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}
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}
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// RetryConditions sets the conditions that will be checked for retry.
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func RetryConditions(conditions []RetryConditionFunc) Option {
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return func(o *Options) {
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o.retryConditions = conditions
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}
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}
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// Backoff retries with increasing timeout duration up until X amount of retries
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// (Default is 3 attempts, Override with option Retries(n))
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func Backoff(operation func() (*Response, error), options ...Option) error {
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// Defaults
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opts := Options{
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maxRetries: defaultMaxRetries,
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waitTime: defaultWaitTime,
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maxWaitTime: defaultMaxWaitTime,
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retryConditions: []RetryConditionFunc{},
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}
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for _, o := range options {
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o(&opts)
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}
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var (
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resp *Response
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err error
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)
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base := float64(opts.waitTime) // Time to wait between each attempt
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capLevel := float64(opts.maxWaitTime) // Maximum amount of wait time for the retry
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for attempt := 0; attempt < opts.maxRetries; attempt++ {
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resp, err = operation()
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var needsRetry bool
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var conditionErr error
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for _, condition := range opts.retryConditions {
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needsRetry, conditionErr = condition(resp)
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if needsRetry || conditionErr != nil {
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break
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}
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}
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// If the operation returned no error, there was no condition satisfied and
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// there was no error caused by the conditional functions.
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if err == nil && !needsRetry && conditionErr == nil {
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return nil
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}
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// Adding capped exponential backup with jitter
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// See the following article...
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// http://www.awsarchitectureblog.com/2015/03/backoff.html
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temp := math.Min(capLevel, base*math.Exp2(float64(attempt)))
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sleepDuration := time.Duration(int(temp/2) + rand.Intn(int(temp/2)))
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if sleepDuration < opts.waitTime {
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sleepDuration = opts.waitTime
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}
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time.Sleep(sleepDuration)
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}
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return err
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}
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