distribution/storagedriver/ipc/ipc.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.
type ResponseError struct {
	Type    string
	Message string
}

// 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
	}
	return &ResponseError{
		Type:    reflect.TypeOf(err).String(),
		Message: err.Error(),
	}
}

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
}