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/*
* MinIO Go Library for Amazon S3 Compatible Cloud Storage
* Copyright 2015-2017 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package minio
import (
"context"
"net/http"
"time"
)
// MaxRetry is the maximum number of retries before stopping.
var MaxRetry = 10
// MaxJitter will randomize over the full exponential backoff time
const MaxJitter = 1.0
// NoJitter disables the use of jitter for randomizing the exponential backoff time
const NoJitter = 0.0
// DefaultRetryUnit - default unit multiplicative per retry.
// defaults to 200 * time.Millisecond
var DefaultRetryUnit = 200 * time.Millisecond
// DefaultRetryCap - Each retry attempt never waits no longer than
// this maximum time duration.
var DefaultRetryCap = time.Second
// newRetryTimer creates a timer with exponentially increasing
// delays until the maximum retry attempts are reached.
func (c *Client) newRetryTimer(ctx context.Context, maxRetry int, unit time.Duration, cap time.Duration, jitter float64) <-chan int {
attemptCh := make(chan int)
// computes the exponential backoff duration according to
// https://www.awsarchitectureblog.com/2015/03/backoff.html
exponentialBackoffWait := func(attempt int) time.Duration {
// normalize jitter to the range [0, 1.0]
if jitter < NoJitter {
jitter = NoJitter
}
if jitter > MaxJitter {
jitter = MaxJitter
}
// sleep = random_between(0, min(cap, base * 2 ** attempt))
sleep := unit * time.Duration(1<<uint(attempt))
if sleep > cap {
sleep = cap
}
if jitter != NoJitter {
sleep -= time.Duration(c.random.Float64() * float64(sleep) * jitter)
}
return sleep
}
go func() {
defer close(attemptCh)
for i := 0; i < maxRetry; i++ {
select {
case attemptCh <- i + 1:
case <-ctx.Done():
return
}
select {
case <-time.After(exponentialBackoffWait(i)):
case <-ctx.Done():
return
}
}
}()
return attemptCh
}
// List of AWS S3 error codes which are retryable.
var retryableS3Codes = map[string]struct{}{
"RequestError": {},
"RequestTimeout": {},
"Throttling": {},
"ThrottlingException": {},
"RequestLimitExceeded": {},
"RequestThrottled": {},
"InternalError": {},
"ExpiredToken": {},
"ExpiredTokenException": {},
"SlowDown": {},
// Add more AWS S3 codes here.
}
// isS3CodeRetryable - is s3 error code retryable.
func isS3CodeRetryable(s3Code string) (ok bool) {
_, ok = retryableS3Codes[s3Code]
return ok
}
// List of HTTP status codes which are retryable.
var retryableHTTPStatusCodes = map[int]struct{}{
429: {}, // http.StatusTooManyRequests is not part of the Go 1.5 library, yet
499: {}, // client closed request, retry. A non-standard status code introduced by nginx.
http.StatusInternalServerError: {},
http.StatusBadGateway: {},
http.StatusServiceUnavailable: {},
http.StatusGatewayTimeout: {},
// Add more HTTP status codes here.
}
// isHTTPStatusRetryable - is HTTP error code retryable.
func isHTTPStatusRetryable(httpStatusCode int) (ok bool) {
_, ok = retryableHTTPStatusCodes[httpStatusCode]
return ok
}
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