rclone/fs/error.go
2016-05-14 17:11:19 +01:00

139 lines
2.9 KiB
Go

// Errors and error handling
package fs
import (
"fmt"
"io"
"net/http"
"net/url"
"strings"
)
// Retry is an optional interface for error as to whether the
// operation should be retried at a high level.
//
// This should be returned from Update or Put methods as required
type Retry interface {
error
Retry() bool
}
// retryError is a type of error
type retryError string
// Error interface
func (r retryError) Error() string {
return string(r)
}
// Retry interface
func (r retryError) Retry() bool {
return true
}
// Check interface
var _ Retry = retryError("")
// RetryErrorf makes an error which indicates it would like to be retried
func RetryErrorf(format string, a ...interface{}) error {
return retryError(fmt.Sprintf(format, a...))
}
// PlainRetryError is an error wrapped so it will retry
type plainRetryError struct {
error
}
// Retry interface
func (err plainRetryError) Retry() bool {
return true
}
// Check interface
var _ Retry = plainRetryError{(error)(nil)}
// RetryError makes an error which indicates it would like to be retried
func RetryError(err error) error {
return plainRetryError{err}
}
// IsRetryError returns true if err conforms to the Retry interface
// and calling the Retry method returns true.
func IsRetryError(err error) bool {
if r, ok := err.(Retry); ok {
return r.Retry()
}
return false
}
// isClosedConnError reports whether err is an error from use of a closed
// network connection.
//
// Code adapted from net/http
func isClosedConnError(err error) bool {
if err == nil {
return false
}
// Note that this error isn't exported so we have to do a
// string comparison :-(
str := err.Error()
if strings.Contains(str, "use of closed network connection") {
return true
}
return isClosedConnErrorPlatform(err)
}
// ShouldRetry looks at an error and tries to work out if retrying the
// operation that caused it would be a good idea. It returns true if
// the error implements Timeout() or Temporary() or if the error
// indicates a premature closing of the connection.
func ShouldRetry(err error) bool {
if err == nil {
return false
}
// Look for premature closing of connection
if err == io.EOF || err == io.ErrUnexpectedEOF || isClosedConnError(err) {
return true
}
// Unwrap url.Error
if urlErr, ok := err.(*url.Error); ok {
err = urlErr.Err
}
// Check for net error Timeout()
if x, ok := err.(interface {
Timeout() bool
}); ok && x.Timeout() {
return true
}
// Check for net error Temporary()
if x, ok := err.(interface {
Temporary() bool
}); ok && x.Temporary() {
return true
}
return false
}
// ShouldRetryHTTP returns a boolean as to whether this resp deserves.
// It checks to see if the HTTP response code is in the slice
// retryErrorCodes.
func ShouldRetryHTTP(resp *http.Response, retryErrorCodes []int) bool {
if resp == nil {
return false
}
for _, e := range retryErrorCodes {
if resp.StatusCode == e {
return true
}
}
return false
}