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//
// Copyright (c) 2015-2024 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
package madmin
import (
"context"
"math/rand"
"net/http"
"sync"
"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 1 second.
const DefaultRetryUnit = time.Second
// DefaultRetryCap - Each retry attempt never waits no longer than
// this maximum time duration.
const DefaultRetryCap = time.Second * 30
// lockedRandSource provides protected rand source, implements rand.Source interface.
type lockedRandSource struct {
lk sync.Mutex
src rand.Source
}
// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
func (r *lockedRandSource) Int63() (n int64) {
r.lk.Lock()
n = r.src.Int63()
r.lk.Unlock()
return
}
// Seed uses the provided seed value to initialize the generator to a
// deterministic state.
func (r *lockedRandSource) Seed(seed int64) {
r.lk.Lock()
r.src.Seed(seed)
r.lk.Unlock()
}
// newRetryTimer creates a timer with exponentially increasing
// delays until the maximum retry attempts are reached.
func (adm AdminClient) newRetryTimer(ctx context.Context, maxRetry int, unit time.Duration, cp 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 * 1 << uint(attempt)
if sleep > cp {
sleep = cp
}
if jitter > NoJitter {
sleep -= time.Duration(adm.random.Float64() * float64(sleep) * jitter)
}
return sleep
}
go func() {
defer close(attemptCh)
for i := 0; i < maxRetry; i++ {
// Attempts start from 1.
select {
case attemptCh <- i + 1:
case <-ctx.Done():
// Stop the routine.
return
}
select {
case <-time.After(exponentialBackoffWait(i)):
case <-ctx.Done():
// Stop the routine.
return
}
}
}()
return attemptCh
}
// List of admin error codes which are retryable.
var retryableAdminErrCodes = map[string]struct{}{
"RequestError": {},
"RequestTimeout": {},
"Throttling": {},
"ThrottlingException": {},
"RequestLimitExceeded": {},
"RequestThrottled": {},
"SlowDown": {},
// Add more admin error codes here.
}
// isAdminErrCodeRetryable - is admin error code retryable.
func isAdminErrCodeRetryable(code string) (ok bool) {
_, ok = retryableAdminErrCodes[code]
return ok
}
// List of HTTP status codes which are retryable.
var retryableHTTPStatusCodes = map[int]struct{}{
http.StatusRequestTimeout: {},
http.StatusTooManyRequests: {},
http.StatusBadGateway: {},
http.StatusServiceUnavailable: {},
// 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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