84 lines
2.1 KiB
Go
84 lines
2.1 KiB
Go
// Copyright 2017 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 gensupport
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import (
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"context"
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"io"
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"net"
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"net/http"
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"time"
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)
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// Retry invokes the given function, retrying it multiple times if the connection failed or
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// the HTTP status response indicates the request should be attempted again. ctx may be nil.
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func Retry(ctx context.Context, f func() (*http.Response, error), backoff BackoffStrategy) (*http.Response, error) {
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for {
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resp, err := f()
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var status int
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if resp != nil {
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status = resp.StatusCode
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}
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// Return if we shouldn't retry.
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pause, retry := backoff.Pause()
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if !shouldRetry(status, err) || !retry {
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return resp, err
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}
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// Ensure the response body is closed, if any.
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if resp != nil && resp.Body != nil {
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resp.Body.Close()
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}
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// Pause, but still listen to ctx.Done if context is not nil.
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var done <-chan struct{}
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if ctx != nil {
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done = ctx.Done()
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}
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select {
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case <-done:
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return nil, ctx.Err()
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case <-time.After(pause):
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}
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}
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}
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// DefaultBackoffStrategy returns a default strategy to use for retrying failed upload requests.
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func DefaultBackoffStrategy() BackoffStrategy {
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return &ExponentialBackoff{
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Base: 250 * time.Millisecond,
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Max: 16 * time.Second,
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}
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}
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// shouldRetry returns true if the HTTP response / error indicates that the
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// request should be attempted again.
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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 status == statusTooManyRequests {
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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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if err, ok := err.(net.Error); ok {
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return err.Temporary()
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}
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return false
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}
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