114 lines
2.4 KiB
Go
114 lines
2.4 KiB
Go
// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package metadata
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import (
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"context"
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"io"
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"math/rand"
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"net/http"
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"time"
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)
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const (
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maxRetryAttempts = 5
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)
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var (
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syscallRetryable = func(err error) bool { return false }
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)
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// defaultBackoff is basically equivalent to gax.Backoff without the need for
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// the dependency.
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type defaultBackoff struct {
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max time.Duration
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mul float64
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cur time.Duration
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}
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func (b *defaultBackoff) Pause() time.Duration {
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d := time.Duration(1 + rand.Int63n(int64(b.cur)))
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b.cur = time.Duration(float64(b.cur) * b.mul)
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if b.cur > b.max {
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b.cur = b.max
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}
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return d
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}
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// sleep is the equivalent of gax.Sleep without the need for the dependency.
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func sleep(ctx context.Context, d time.Duration) error {
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t := time.NewTimer(d)
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select {
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case <-ctx.Done():
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t.Stop()
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return ctx.Err()
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case <-t.C:
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return nil
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}
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}
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func newRetryer() *metadataRetryer {
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return &metadataRetryer{bo: &defaultBackoff{
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cur: 100 * time.Millisecond,
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max: 30 * time.Second,
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mul: 2,
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}}
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}
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type backoff interface {
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Pause() time.Duration
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}
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type metadataRetryer struct {
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bo backoff
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attempts int
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}
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func (r *metadataRetryer) Retry(status int, err error) (time.Duration, bool) {
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if status == http.StatusOK {
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return 0, false
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}
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retryOk := shouldRetry(status, err)
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if !retryOk {
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return 0, false
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}
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if r.attempts == maxRetryAttempts {
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return 0, false
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}
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r.attempts++
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return r.bo.Pause(), true
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}
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func shouldRetry(status int, err error) bool {
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if 500 <= status && status <= 599 {
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return true
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}
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if err == io.ErrUnexpectedEOF {
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return true
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}
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// Transient network errors should be retried.
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if syscallRetryable(err) {
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return true
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}
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if err, ok := err.(interface{ Temporary() bool }); ok {
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if err.Temporary() {
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return true
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}
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}
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if err, ok := err.(interface{ Unwrap() error }); ok {
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return shouldRetry(status, err.Unwrap())
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}
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return false
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}
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