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94 lines
2.7 KiB
94 lines
2.7 KiB
// Copyright 2019 Google LLC All Rights Reserved.
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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 retry provides methods for retrying operations. It is a thin wrapper
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// around k8s.io/apimachinery/pkg/util/wait to make certain operations easier.
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package retry
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import (
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"context"
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"errors"
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"fmt"
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"github.com/google/go-containerregistry/internal/retry/wait"
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)
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// Backoff is an alias of our own wait.Backoff to avoid name conflicts with
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// the kubernetes wait package. Typing retry.Backoff is aesier than fixing
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// the wrong import every time you use wait.Backoff.
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type Backoff = wait.Backoff
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// This is implemented by several errors in the net package as well as our
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// transport.Error.
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type temporary interface {
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Temporary() bool
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}
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// IsTemporary returns true if err implements Temporary() and it returns true.
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func IsTemporary(err error) bool {
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if errors.Is(err, context.DeadlineExceeded) {
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return false
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}
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if te, ok := err.(temporary); ok && te.Temporary() {
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return true
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}
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return false
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}
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// IsNotNil returns true if err is not nil.
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func IsNotNil(err error) bool {
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return err != nil
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}
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// Predicate determines whether an error should be retried.
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type Predicate func(error) (retry bool)
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// Retry retries a given function, f, until a predicate is satisfied, using
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// exponential backoff. If the predicate is never satisfied, it will return the
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// last error returned by f.
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func Retry(f func() error, p Predicate, backoff wait.Backoff) (err error) {
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if f == nil {
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return fmt.Errorf("nil f passed to retry")
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}
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if p == nil {
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return fmt.Errorf("nil p passed to retry")
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}
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condition := func() (bool, error) {
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err = f()
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if p(err) {
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return false, nil
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}
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return true, err
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}
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wait.ExponentialBackoff(backoff, condition)
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return
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}
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type contextKey string
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var key = contextKey("never")
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// Never returns a context that signals something should not be retried.
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// This is a hack and can be used to communicate across package boundaries
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// to avoid retry amplification.
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func Never(ctx context.Context) context.Context {
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return context.WithValue(ctx, key, true)
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}
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// Ever returns true if the context was wrapped by Never.
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func Ever(ctx context.Context) bool {
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return ctx.Value(key) == nil
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}
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