registry/storagedriver/ipc/ipc.go

97 lines
2.3 KiB
Go

package ipc
import (
"errors"
"fmt"
"io"
"io/ioutil"
"reflect"
"github.com/docker/libchan"
)
// 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
}
// noWriteReadWriteCloser is a simple wrapper around an io.ReadCloser that implements the
// io.ReadWriteCloser interface
// Calls to Write are disallowed and will return an error
type noWriteReadWriteCloser struct {
io.ReadCloser
}
func (r noWriteReadWriteCloser) Write(p []byte) (n int, err error) {
return 0, errors.New("Write unsupported")
}
// WrapReader wraps an io.Reader as an io.ReadWriteCloser with a nop Close and unsupported Write
// Has no effect when an io.ReadWriteCloser is passed in
func WrapReader(reader io.Reader) io.ReadWriteCloser {
if readWriteCloser, ok := reader.(io.ReadWriteCloser); ok {
return readWriteCloser
} else if readCloser, ok := reader.(io.ReadCloser); ok {
return noWriteReadWriteCloser{readCloser}
} else {
return noWriteReadWriteCloser{ioutil.NopCloser(reader)}
}
}
type responseError struct {
Type string
Message string
}
// ResponseError wraps an error in a serializable struct containing the error's type and message
func ResponseError(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
// ReadStreamResponse is a response for a ReadStream request
type ReadStreamResponse struct {
Reader io.ReadWriteCloser
Error *responseError
}
// WriteStreamResponse is a response for a WriteStream request
type WriteStreamResponse struct {
Error *responseError
}
// ResumeWritePositionResponse is a response for a ResumeWritePosition request
type ResumeWritePositionResponse 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
}