238 lines
8.6 KiB
Go
238 lines
8.6 KiB
Go
package autorest
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import (
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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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"time"
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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 possibily 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(&http.Client{}, 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(&http.Client{}, 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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// 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, 1, r.Cancel) != nil {
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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, 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 = NewPollingRequest(resp, r.Cancel)
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for err == nil && ResponseHasStatusCode(resp, codes...) {
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Respond(resp,
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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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for attempt := 0; attempt < attempts; attempt++ {
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resp, err = s.Do(r)
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if err == nil {
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return resp, err
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}
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DelayForBackoff(backoff, attempt, r.Cancel)
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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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// 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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end := time.Now().Add(d)
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for attempt := 0; time.Now().Before(end); attempt++ {
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resp, err = s.Do(r)
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if err == nil {
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return resp, err
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}
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DelayForBackoff(backoff, attempt, r.Cancel)
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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 may be zero. The delay may be
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// canceled by closing the passed channel.
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func DelayForBackoff(backoff time.Duration, attempt int, cancel <-chan struct{}) error {
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if cancel == nil {
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cancel = make(chan struct{})
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}
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select {
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case <-time.After(time.Duration(math.Pow(float64(backoff), float64(attempt)))):
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case <-cancel:
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return fmt.Errorf("autorest: Delay canceled")
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}
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return nil
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}
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