425 lines
16 KiB
Go
425 lines
16 KiB
Go
package autorest
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// Copyright 2017 Microsoft Corporation
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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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import (
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"context"
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"crypto/tls"
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"fmt"
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"log"
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"math"
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"net/http"
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"net/http/cookiejar"
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"strconv"
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"time"
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"github.com/Azure/go-autorest/tracing"
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)
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// used as a key type in context.WithValue()
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type ctxSendDecorators struct{}
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// WithSendDecorators adds the specified SendDecorators to the provided context.
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// If no SendDecorators are provided the context is unchanged.
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func WithSendDecorators(ctx context.Context, sendDecorator []SendDecorator) context.Context {
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if len(sendDecorator) == 0 {
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return ctx
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}
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return context.WithValue(ctx, ctxSendDecorators{}, sendDecorator)
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}
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// GetSendDecorators returns the SendDecorators in the provided context or the provided default SendDecorators.
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func GetSendDecorators(ctx context.Context, defaultSendDecorators ...SendDecorator) []SendDecorator {
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inCtx := ctx.Value(ctxSendDecorators{})
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if sd, ok := inCtx.([]SendDecorator); ok {
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return sd
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}
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return defaultSendDecorators
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}
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// Sender is the interface that wraps the Do method to send HTTP requests.
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//
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// The standard http.Client conforms to this interface.
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type Sender interface {
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Do(*http.Request) (*http.Response, error)
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}
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// SenderFunc is a method that implements the Sender interface.
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type SenderFunc func(*http.Request) (*http.Response, error)
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// Do implements the Sender interface on SenderFunc.
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func (sf SenderFunc) Do(r *http.Request) (*http.Response, error) {
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return sf(r)
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}
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// SendDecorator takes and possibly decorates, by wrapping, a Sender. Decorators may affect the
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// http.Request and pass it along or, first, pass the http.Request along then react to the
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// http.Response result.
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type SendDecorator func(Sender) Sender
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// CreateSender creates, decorates, and returns, as a Sender, the default http.Client.
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func CreateSender(decorators ...SendDecorator) Sender {
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return DecorateSender(sender(tls.RenegotiateNever), decorators...)
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}
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// DecorateSender accepts a Sender and a, possibly empty, set of SendDecorators, which is applies to
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// the Sender. Decorators are applied in the order received, but their affect upon the request
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// depends on whether they are a pre-decorator (change the http.Request and then pass it along) or a
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// post-decorator (pass the http.Request along and react to the results in http.Response).
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func DecorateSender(s Sender, decorators ...SendDecorator) Sender {
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for _, decorate := range decorators {
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s = decorate(s)
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}
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return s
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}
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// Send sends, by means of the default http.Client, the passed http.Request, returning the
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// http.Response and possible error. It also accepts a, possibly empty, set of SendDecorators which
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// it will apply the http.Client before invoking the Do method.
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//
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// Send is a convenience method and not recommended for production. Advanced users should use
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// SendWithSender, passing and sharing their own Sender (e.g., instance of http.Client).
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//
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// Send will not poll or retry requests.
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func Send(r *http.Request, decorators ...SendDecorator) (*http.Response, error) {
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return SendWithSender(sender(tls.RenegotiateNever), r, decorators...)
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}
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// SendWithSender sends the passed http.Request, through the provided Sender, returning the
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// http.Response and possible error. It also accepts a, possibly empty, set of SendDecorators which
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// it will apply the http.Client before invoking the Do method.
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//
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// SendWithSender will not poll or retry requests.
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func SendWithSender(s Sender, r *http.Request, decorators ...SendDecorator) (*http.Response, error) {
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return DecorateSender(s, decorators...).Do(r)
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}
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func sender(renengotiation tls.RenegotiationSupport) Sender {
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// Use behaviour compatible with DefaultTransport, but require TLS minimum version.
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defaultTransport := http.DefaultTransport.(*http.Transport)
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transport := &http.Transport{
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Proxy: defaultTransport.Proxy,
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DialContext: defaultTransport.DialContext,
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MaxIdleConns: defaultTransport.MaxIdleConns,
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IdleConnTimeout: defaultTransport.IdleConnTimeout,
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TLSHandshakeTimeout: defaultTransport.TLSHandshakeTimeout,
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ExpectContinueTimeout: defaultTransport.ExpectContinueTimeout,
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TLSClientConfig: &tls.Config{
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MinVersion: tls.VersionTLS12,
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Renegotiation: renengotiation,
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},
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}
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var roundTripper http.RoundTripper = transport
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if tracing.IsEnabled() {
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roundTripper = tracing.NewTransport(transport)
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}
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j, _ := cookiejar.New(nil)
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return &http.Client{Jar: j, Transport: roundTripper}
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}
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// AfterDelay returns a SendDecorator that delays for the passed time.Duration before
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// invoking the Sender. The delay may be terminated by closing the optional channel on the
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// http.Request. If canceled, no further Senders are invoked.
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func AfterDelay(d time.Duration) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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if !DelayForBackoff(d, 0, r.Context().Done()) {
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return nil, fmt.Errorf("autorest: AfterDelay canceled before full delay")
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}
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return s.Do(r)
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})
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}
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}
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// AsIs returns a SendDecorator that invokes the passed Sender without modifying the http.Request.
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func AsIs() SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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return s.Do(r)
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})
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}
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}
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// DoCloseIfError returns a SendDecorator that first invokes the passed Sender after which
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// it closes the response if the passed Sender returns an error and the response body exists.
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func DoCloseIfError() SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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resp, err := s.Do(r)
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if err != nil {
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Respond(resp, ByDiscardingBody(), ByClosing())
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}
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return resp, err
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})
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}
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}
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// DoErrorIfStatusCode returns a SendDecorator that emits an error if the response StatusCode is
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// among the set passed. Since these are artificial errors, the response body may still require
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// closing.
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func DoErrorIfStatusCode(codes ...int) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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resp, err := s.Do(r)
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if err == nil && ResponseHasStatusCode(resp, codes...) {
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err = NewErrorWithResponse("autorest", "DoErrorIfStatusCode", resp, "%v %v failed with %s",
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resp.Request.Method,
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resp.Request.URL,
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resp.Status)
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}
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return resp, err
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})
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}
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}
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// DoErrorUnlessStatusCode returns a SendDecorator that emits an error unless the response
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// StatusCode is among the set passed. Since these are artificial errors, the response body
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// may still require closing.
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func DoErrorUnlessStatusCode(codes ...int) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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resp, err := s.Do(r)
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if err == nil && !ResponseHasStatusCode(resp, codes...) {
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err = NewErrorWithResponse("autorest", "DoErrorUnlessStatusCode", resp, "%v %v failed with %s",
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resp.Request.Method,
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resp.Request.URL,
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resp.Status)
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}
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return resp, err
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})
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}
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}
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// DoPollForStatusCodes returns a SendDecorator that polls if the http.Response contains one of the
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// passed status codes. It expects the http.Response to contain a Location header providing the
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// URL at which to poll (using GET) and will poll until the time passed is equal to or greater than
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// the supplied duration. It will delay between requests for the duration specified in the
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// RetryAfter header or, if the header is absent, the passed delay. Polling may be canceled by
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// closing the optional channel on the http.Request.
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func DoPollForStatusCodes(duration time.Duration, delay time.Duration, codes ...int) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
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resp, err = s.Do(r)
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if err == nil && ResponseHasStatusCode(resp, codes...) {
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r, err = NewPollingRequestWithContext(r.Context(), resp)
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for err == nil && ResponseHasStatusCode(resp, codes...) {
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Respond(resp,
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ByDiscardingBody(),
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ByClosing())
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resp, err = SendWithSender(s, r,
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AfterDelay(GetRetryAfter(resp, delay)))
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}
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}
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return resp, err
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})
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}
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}
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// DoRetryForAttempts returns a SendDecorator that retries a failed request for up to the specified
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// number of attempts, exponentially backing off between requests using the supplied backoff
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// time.Duration (which may be zero). Retrying may be canceled by closing the optional channel on
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// the http.Request.
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func DoRetryForAttempts(attempts int, backoff time.Duration) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
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rr := NewRetriableRequest(r)
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for attempt := 0; attempt < attempts; attempt++ {
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err = rr.Prepare()
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if err != nil {
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return resp, err
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}
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DrainResponseBody(resp)
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resp, err = s.Do(rr.Request())
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if err == nil {
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return resp, err
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}
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if !DelayForBackoff(backoff, attempt, r.Context().Done()) {
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return nil, r.Context().Err()
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}
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}
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return resp, err
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})
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}
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}
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// Count429AsRetry indicates that a 429 response should be included as a retry attempt.
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var Count429AsRetry = true
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// Max429Delay is the maximum duration to wait between retries on a 429 if no Retry-After header was received.
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var Max429Delay time.Duration
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// DoRetryForStatusCodes returns a SendDecorator that retries for specified statusCodes for up to the specified
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// number of attempts, exponentially backing off between requests using the supplied backoff
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// time.Duration (which may be zero). Retrying may be canceled by cancelling the context on the http.Request.
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// NOTE: Code http.StatusTooManyRequests (429) will *not* be counted against the number of attempts.
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func DoRetryForStatusCodes(attempts int, backoff time.Duration, codes ...int) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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return doRetryForStatusCodesImpl(s, r, Count429AsRetry, attempts, backoff, 0, codes...)
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})
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}
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}
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// DoRetryForStatusCodesWithCap returns a SendDecorator that retries for specified statusCodes for up to the
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// specified number of attempts, exponentially backing off between requests using the supplied backoff
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// time.Duration (which may be zero). To cap the maximum possible delay between iterations specify a value greater
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// than zero for cap. Retrying may be canceled by cancelling the context on the http.Request.
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func DoRetryForStatusCodesWithCap(attempts int, backoff, cap time.Duration, codes ...int) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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return doRetryForStatusCodesImpl(s, r, Count429AsRetry, attempts, backoff, cap, codes...)
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})
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}
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}
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func doRetryForStatusCodesImpl(s Sender, r *http.Request, count429 bool, attempts int, backoff, cap time.Duration, codes ...int) (resp *http.Response, err error) {
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rr := NewRetriableRequest(r)
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// Increment to add the first call (attempts denotes number of retries)
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for attempt, delayCount := 0, 0; attempt < attempts+1; {
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err = rr.Prepare()
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if err != nil {
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return
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}
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DrainResponseBody(resp)
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resp, err = s.Do(rr.Request())
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// we want to retry if err is not nil (e.g. transient network failure). note that for failed authentication
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// resp and err will both have a value, so in this case we don't want to retry as it will never succeed.
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if err == nil && !ResponseHasStatusCode(resp, codes...) || IsTokenRefreshError(err) {
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return resp, err
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}
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delayed := DelayWithRetryAfter(resp, r.Context().Done())
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// if this was a 429 set the delay cap as specified.
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// applicable only in the absence of a retry-after header.
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if resp != nil && resp.StatusCode == http.StatusTooManyRequests {
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cap = Max429Delay
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}
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if !delayed && !DelayForBackoffWithCap(backoff, cap, delayCount, r.Context().Done()) {
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return resp, r.Context().Err()
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}
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// when count429 == false don't count a 429 against the number
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// of attempts so that we continue to retry until it succeeds
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if count429 || (resp == nil || resp.StatusCode != http.StatusTooManyRequests) {
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attempt++
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}
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// delay count is tracked separately from attempts to
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// ensure that 429 participates in exponential back-off
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delayCount++
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}
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return resp, err
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}
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// DelayWithRetryAfter invokes time.After for the duration specified in the "Retry-After" header.
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// The value of Retry-After can be either the number of seconds or a date in RFC1123 format.
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// The function returns true after successfully waiting for the specified duration. If there is
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// no Retry-After header or the wait is cancelled the return value is false.
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func DelayWithRetryAfter(resp *http.Response, cancel <-chan struct{}) bool {
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if resp == nil {
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return false
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}
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var dur time.Duration
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ra := resp.Header.Get("Retry-After")
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if retryAfter, _ := strconv.Atoi(ra); retryAfter > 0 {
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dur = time.Duration(retryAfter) * time.Second
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} else if t, err := time.Parse(time.RFC1123, ra); err == nil {
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dur = t.Sub(time.Now())
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}
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if dur > 0 {
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select {
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case <-time.After(dur):
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return true
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case <-cancel:
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return false
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}
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}
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return false
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}
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// DoRetryForDuration returns a SendDecorator that retries the request until the total time is equal
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// to or greater than the specified duration, exponentially backing off between requests using the
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// supplied backoff time.Duration (which may be zero). Retrying may be canceled by closing the
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// optional channel on the http.Request.
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func DoRetryForDuration(d time.Duration, backoff time.Duration) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
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rr := NewRetriableRequest(r)
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end := time.Now().Add(d)
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for attempt := 0; time.Now().Before(end); attempt++ {
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err = rr.Prepare()
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if err != nil {
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return resp, err
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}
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DrainResponseBody(resp)
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resp, err = s.Do(rr.Request())
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if err == nil {
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return resp, err
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}
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if !DelayForBackoff(backoff, attempt, r.Context().Done()) {
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return nil, r.Context().Err()
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}
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}
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return resp, err
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})
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}
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}
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// WithLogging returns a SendDecorator that implements simple before and after logging of the
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// request.
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func WithLogging(logger *log.Logger) SendDecorator {
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return func(s Sender) Sender {
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return SenderFunc(func(r *http.Request) (*http.Response, error) {
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logger.Printf("Sending %s %s", r.Method, r.URL)
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resp, err := s.Do(r)
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if err != nil {
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logger.Printf("%s %s received error '%v'", r.Method, r.URL, err)
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} else {
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logger.Printf("%s %s received %s", r.Method, r.URL, resp.Status)
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}
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return resp, err
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})
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}
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}
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// DelayForBackoff invokes time.After for the supplied backoff duration raised to the power of
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// passed attempt (i.e., an exponential backoff delay). Backoff duration is in seconds and can set
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// to zero for no delay. The delay may be canceled by closing the passed channel. If terminated early,
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// returns false.
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// Note: Passing attempt 1 will result in doubling "backoff" duration. Treat this as a zero-based attempt
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// count.
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func DelayForBackoff(backoff time.Duration, attempt int, cancel <-chan struct{}) bool {
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return DelayForBackoffWithCap(backoff, 0, attempt, cancel)
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}
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// DelayForBackoffWithCap invokes time.After for the supplied backoff duration raised to the power of
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// passed attempt (i.e., an exponential backoff delay). Backoff duration is in seconds and can set
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// to zero for no delay. To cap the maximum possible delay specify a value greater than zero for cap.
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// The delay may be canceled by closing the passed channel. If terminated early, returns false.
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// Note: Passing attempt 1 will result in doubling "backoff" duration. Treat this as a zero-based attempt
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// count.
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func DelayForBackoffWithCap(backoff, cap time.Duration, attempt int, cancel <-chan struct{}) bool {
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d := time.Duration(backoff.Seconds()*math.Pow(2, float64(attempt))) * time.Second
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if cap > 0 && d > cap {
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d = cap
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}
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select {
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case <-time.After(d):
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return true
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case <-cancel:
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return false
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}
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}
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