forked from TrueCloudLab/distribution
114 lines
2.4 KiB
Go
114 lines
2.4 KiB
Go
// Copyright 2021 Google LLC
|
|
//
|
|
// 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 metadata
|
|
|
|
import (
|
|
"context"
|
|
"io"
|
|
"math/rand"
|
|
"net/http"
|
|
"time"
|
|
)
|
|
|
|
const (
|
|
maxRetryAttempts = 5
|
|
)
|
|
|
|
var (
|
|
syscallRetryable = func(err error) bool { return false }
|
|
)
|
|
|
|
// defaultBackoff is basically equivalent to gax.Backoff without the need for
|
|
// the dependency.
|
|
type defaultBackoff struct {
|
|
max time.Duration
|
|
mul float64
|
|
cur time.Duration
|
|
}
|
|
|
|
func (b *defaultBackoff) Pause() time.Duration {
|
|
d := time.Duration(1 + rand.Int63n(int64(b.cur)))
|
|
b.cur = time.Duration(float64(b.cur) * b.mul)
|
|
if b.cur > b.max {
|
|
b.cur = b.max
|
|
}
|
|
return d
|
|
}
|
|
|
|
// sleep is the equivalent of gax.Sleep without the need for the dependency.
|
|
func sleep(ctx context.Context, d time.Duration) error {
|
|
t := time.NewTimer(d)
|
|
select {
|
|
case <-ctx.Done():
|
|
t.Stop()
|
|
return ctx.Err()
|
|
case <-t.C:
|
|
return nil
|
|
}
|
|
}
|
|
|
|
func newRetryer() *metadataRetryer {
|
|
return &metadataRetryer{bo: &defaultBackoff{
|
|
cur: 100 * time.Millisecond,
|
|
max: 30 * time.Second,
|
|
mul: 2,
|
|
}}
|
|
}
|
|
|
|
type backoff interface {
|
|
Pause() time.Duration
|
|
}
|
|
|
|
type metadataRetryer struct {
|
|
bo backoff
|
|
attempts int
|
|
}
|
|
|
|
func (r *metadataRetryer) Retry(status int, err error) (time.Duration, bool) {
|
|
if status == http.StatusOK {
|
|
return 0, false
|
|
}
|
|
retryOk := shouldRetry(status, err)
|
|
if !retryOk {
|
|
return 0, false
|
|
}
|
|
if r.attempts == maxRetryAttempts {
|
|
return 0, false
|
|
}
|
|
r.attempts++
|
|
return r.bo.Pause(), true
|
|
}
|
|
|
|
func shouldRetry(status int, err error) bool {
|
|
if 500 <= status && status <= 599 {
|
|
return true
|
|
}
|
|
if err == io.ErrUnexpectedEOF {
|
|
return true
|
|
}
|
|
// Transient network errors should be retried.
|
|
if syscallRetryable(err) {
|
|
return true
|
|
}
|
|
if err, ok := err.(interface{ Temporary() bool }); ok {
|
|
if err.Temporary() {
|
|
return true
|
|
}
|
|
}
|
|
if err, ok := err.(interface{ Unwrap() error }); ok {
|
|
return shouldRetry(status, err.Unwrap())
|
|
}
|
|
return false
|
|
}
|