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moby--moby/vendor/github.com/stevvooe/ttrpc/services.go

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package ttrpc
import (
"context"
"io"
"os"
"path"
"github.com/gogo/protobuf/proto"
"github.com/pkg/errors"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
)
type Method func(ctx context.Context, unmarshal func(interface{}) error) (interface{}, error)
type ServiceDesc struct {
Methods map[string]Method
// TODO(stevvooe): Add stream support.
}
type serviceSet struct {
services map[string]ServiceDesc
}
func newServiceSet() *serviceSet {
return &serviceSet{
services: make(map[string]ServiceDesc),
}
}
func (s *serviceSet) register(name string, methods map[string]Method) {
if _, ok := s.services[name]; ok {
panic(errors.Errorf("duplicate service %v registered", name))
}
s.services[name] = ServiceDesc{
Methods: methods,
}
}
func (s *serviceSet) call(ctx context.Context, serviceName, methodName string, p []byte) ([]byte, *status.Status) {
p, err := s.dispatch(ctx, serviceName, methodName, p)
st, ok := status.FromError(err)
if !ok {
st = status.New(convertCode(err), err.Error())
}
return p, st
}
func (s *serviceSet) dispatch(ctx context.Context, serviceName, methodName string, p []byte) ([]byte, error) {
method, err := s.resolve(serviceName, methodName)
if err != nil {
return nil, err
}
unmarshal := func(obj interface{}) error {
switch v := obj.(type) {
case proto.Message:
if err := proto.Unmarshal(p, v); err != nil {
return status.Errorf(codes.Internal, "ttrpc: error unmarshaling payload: %v", err.Error())
}
default:
return status.Errorf(codes.Internal, "ttrpc: error unsupported request type: %T", v)
}
return nil
}
resp, err := method(ctx, unmarshal)
if err != nil {
return nil, err
}
switch v := resp.(type) {
case proto.Message:
r, err := proto.Marshal(v)
if err != nil {
return nil, status.Errorf(codes.Internal, "ttrpc: error marshaling payload: %v", err.Error())
}
return r, nil
default:
return nil, status.Errorf(codes.Internal, "ttrpc: error unsupported response type: %T", v)
}
}
func (s *serviceSet) resolve(service, method string) (Method, error) {
srv, ok := s.services[service]
if !ok {
return nil, status.Errorf(codes.NotFound, "service %v", service)
}
mthd, ok := srv.Methods[method]
if !ok {
return nil, status.Errorf(codes.NotFound, "method %v", method)
}
return mthd, nil
}
// convertCode maps stdlib go errors into grpc space.
//
// This is ripped from the grpc-go code base.
func convertCode(err error) codes.Code {
switch err {
case nil:
return codes.OK
case io.EOF:
return codes.OutOfRange
case io.ErrClosedPipe, io.ErrNoProgress, io.ErrShortBuffer, io.ErrShortWrite, io.ErrUnexpectedEOF:
return codes.FailedPrecondition
case os.ErrInvalid:
return codes.InvalidArgument
case context.Canceled:
return codes.Canceled
case context.DeadlineExceeded:
return codes.DeadlineExceeded
}
switch {
case os.IsExist(err):
return codes.AlreadyExists
case os.IsNotExist(err):
return codes.NotFound
case os.IsPermission(err):
return codes.PermissionDenied
}
return codes.Unknown
}
func fullPath(service, method string) string {
return "/" + path.Join("/", service, method)
}