distribution/storagedriver/ipc/ipc.go
Brian Bland a3481c5f1c Adds ability to unwrap ipc errors into their original type
This only works for a specific whitelist of error types, which is
currently all errors in the storagedriver package.

Also improves storagedriver tests to enforce proper error types are
returned
2014-11-18 17:41:48 -08:00

146 lines
3.7 KiB
Go

package ipc
import (
"fmt"
"io"
"reflect"
"github.com/docker/docker-registry/storagedriver"
"github.com/docker/libchan"
)
// StorageDriver is the interface which IPC storage drivers must implement. As external storage
// drivers may be defined to use a different version of the storagedriver.StorageDriver interface,
// we use an additional version check to determine compatiblity.
type StorageDriver interface {
// Version returns the storagedriver.StorageDriver interface version which this storage driver
// implements, which is used to determine driver compatibility
Version() (storagedriver.Version, error)
}
// IncompatibleVersionError is returned when a storage driver is using an incompatible version of
// the storagedriver.StorageDriver api
type IncompatibleVersionError struct {
version storagedriver.Version
}
func (e IncompatibleVersionError) Error() string {
return fmt.Sprintf("Incompatible storage driver version: %s", e.version)
}
// Request defines a remote method call request
// A return value struct is to be sent over the ResponseChannel
type Request struct {
Type string
Parameters map[string]interface{}
ResponseChannel libchan.Sender
}
// ResponseError is a serializable error type.
// The Type and Parameters may be used to reconstruct the same error on the
// client side, falling back to using the Type and Message if this cannot be
// done.
type ResponseError struct {
Type string
Message string
Parameters map[string]interface{}
}
// WrapError wraps an error in a serializable struct containing the error's type
// and message.
func WrapError(err error) *ResponseError {
if err == nil {
return nil
}
v := reflect.ValueOf(err)
re := ResponseError{
Type: v.Type().String(),
Message: err.Error(),
}
if v.Kind() == reflect.Struct {
re.Parameters = make(map[string]interface{})
for i := 0; i < v.NumField(); i++ {
field := v.Type().Field(i)
re.Parameters[field.Name] = v.Field(i).Interface()
}
}
return &re
}
// Unwrap returns the underlying error if it can be reconstructed, or the
// original ResponseError otherwise.
func (err *ResponseError) Unwrap() error {
var errVal reflect.Value
var zeroVal reflect.Value
switch err.Type {
case "storagedriver.PathNotFoundError":
errVal = reflect.ValueOf(&storagedriver.PathNotFoundError{})
case "storagedriver.InvalidOffsetError":
errVal = reflect.ValueOf(&storagedriver.InvalidOffsetError{})
}
if errVal == zeroVal {
return err
}
for k, v := range err.Parameters {
fieldVal := errVal.Elem().FieldByName(k)
if fieldVal == zeroVal {
return err
}
fieldVal.Set(reflect.ValueOf(v))
}
if unwrapped, ok := errVal.Elem().Interface().(error); ok {
return unwrapped
}
return err
}
func (err *ResponseError) Error() string {
return fmt.Sprintf("%s: %s", err.Type, err.Message)
}
// IPC method call response object definitions
// VersionResponse is a response for a Version request
type VersionResponse struct {
Version storagedriver.Version
Error *ResponseError
}
// ReadStreamResponse is a response for a ReadStream request
type ReadStreamResponse struct {
Reader io.ReadCloser
Error *ResponseError
}
// WriteStreamResponse is a response for a WriteStream request
type WriteStreamResponse struct {
Error *ResponseError
}
// CurrentSizeResponse is a response for a CurrentSize request
type CurrentSizeResponse struct {
Position uint64
Error *ResponseError
}
// ListResponse is a response for a List request
type ListResponse struct {
Keys []string
Error *ResponseError
}
// MoveResponse is a response for a Move request
type MoveResponse struct {
Error *ResponseError
}
// DeleteResponse is a response for a Delete request
type DeleteResponse struct {
Error *ResponseError
}