forked from TrueCloudLab/distribution
77 lines
1.7 KiB
Go
77 lines
1.7 KiB
Go
package gensupport
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import (
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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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"golang.org/x/net/context"
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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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// Retry for 5xx response codes.
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if 500 <= status && status < 600 {
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return true
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}
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// Retry on statusTooManyRequests{
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if status == statusTooManyRequests {
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return true
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}
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// Retry on unexpected EOFs and temporary network errors.
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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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