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package retry
import (
"context"
"io"
"math"
"net"
"net/url"
"syscall"
"time"
"github.com/docker/distribution/registry/api/errcode"
errcodev2 "github.com/docker/distribution/registry/api/v2"
"github.com/hashicorp/go-multierror"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// RetryOptions defines the option to retry
type RetryOptions struct {
MaxRetry int // The number of times to possibly retry
Delay time.Duration // The delay to use between retries, if set
}
// RetryIfNecessary retries the operation in exponential backoff with the retryOptions
func RetryIfNecessary(ctx context.Context, operation func() error, retryOptions *RetryOptions) error {
err := operation()
for attempt := 0; err != nil && isRetryable(err) && attempt < retryOptions.MaxRetry; attempt++ {
delay := time.Duration(int(math.Pow(2, float64(attempt)))) * time.Second
if retryOptions.Delay != 0 {
delay = retryOptions.Delay
}
logrus.Warnf("Failed, retrying in %s ... (%d/%d). Error: %v", delay, attempt+1, retryOptions.MaxRetry, err)
select {
case <-time.After(delay):
break
case <-ctx.Done():
return err
}
err = operation()
}
return err
}
func isRetryable(err error) bool {
err = errors.Cause(err)
if err == context.Canceled || err == context.DeadlineExceeded {
return false
}
type unwrapper interface {
Unwrap() error
}
switch e := err.(type) {
case errcode.Error:
switch e.Code {
case errcode.ErrorCodeUnauthorized, errcodev2.ErrorCodeNameUnknown, errcodev2.ErrorCodeManifestUnknown:
return false
}
return true
case *net.OpError:
return isRetryable(e.Err)
case *url.Error: // This includes errors returned by the net/http client.
if e.Err == io.EOF { // Happens when a server accepts a HTTP connection and sends EOF
return true
}
return isRetryable(e.Err)
case syscall.Errno:
return isErrnoRetryable(e)
case errcode.Errors:
// if this error is a group of errors, process them all in turn
for i := range e {
if !isRetryable(e[i]) {
return false
}
}
return true
case *multierror.Error:
// if this error is a group of errors, process them all in turn
for i := range e.Errors {
if !isRetryable(e.Errors[i]) {
return false
}
}
return true
case unwrapper:
err = e.Unwrap()
return isRetryable(err)
}
return false
}
func isErrnoRetryable(e error) bool {
switch e {
case syscall.ECONNREFUSED, syscall.EINTR, syscall.EAGAIN, syscall.EBUSY, syscall.ENETDOWN, syscall.ENETUNREACH, syscall.ENETRESET, syscall.ECONNABORTED, syscall.ECONNRESET, syscall.ETIMEDOUT, syscall.EHOSTDOWN, syscall.EHOSTUNREACH:
return true
}
return isErrnoERESTART(e)
}
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