/
server.go
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/
server.go
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package starlarkgrpc
import (
"context"
"fmt"
"log"
"net"
"go.starlark.net/starlark"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/status"
"google.golang.org/protobuf/reflect/protoreflect"
"google.golang.org/protobuf/reflect/protoregistry"
"google.golang.org/protobuf/types/dynamicpb"
)
// grpcServer implements starlark.Value for a grpc.Server.
type grpcServer struct {
server *grpc.Server
files *protoregistry.Files
handlers HandlerMap
}
// String implements part of the starlark.Value interface
func (s *grpcServer) String() string {
return fmt.Sprintf("<grpc.Server %v>", grpcServerServiceInfoNames(s.server))
}
// Type implements part of the starlark.Value interface
func (*grpcServer) Type() string { return "grpc.Server" }
// Freeze implements part of the starlark.Value interface
func (*grpcServer) Freeze() {} // immutable
// Truth implements part of the starlark.Value interface
func (*grpcServer) Truth() starlark.Bool { return starlark.True }
// Hash implements part of the starlark.Value interface
func (c *grpcServer) Hash() (uint32, error) {
return 0, fmt.Errorf("unhashable: %s", c.Type())
}
// AttrNames implements part of the starlark.HasAttrs interface
func (c *grpcServer) AttrNames() []string {
return []string{"register", "start", "stop"}
}
// Attr implements part of the starlark.HasAttrs interface
func (c *grpcServer) Attr(name string) (starlark.Value, error) {
switch name {
case "start":
return starlark.NewBuiltin("grpc.Server.start", c.start), nil
case "stop":
return starlark.NewBuiltin("grpc.Server.stop", c.stop), nil
case "register":
return starlark.NewBuiltin("grpc.Server.register", c.register), nil
}
return nil, nil
}
func (c *grpcServer) start(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
var listener net.Listener
if err := starlark.UnpackPositionalArgs(fn.Name(), args, kwargs, 1, &listener); err != nil {
return nil, err
}
if err := c.server.Serve(listener); err != nil {
log.Fatalln("grpc.Server error:", err)
}
return starlark.None, nil
}
func (c *grpcServer) stop(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
graceful := true
if err := starlark.UnpackArgs(fn.Name(), args, kwargs,
"graceful?", &graceful,
); err != nil {
return nil, err
}
if graceful {
c.server.GracefulStop()
} else {
c.server.Stop()
}
return starlark.None, nil
}
func (c *grpcServer) register(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
var serviceName string
var handlers *starlark.Dict
if err := starlark.UnpackArgs(fn.Name(), args, kwargs,
"service", &serviceName,
"handlers", &handlers,
); err != nil {
return nil, err
}
sd, ok := serviceDescriptorByName(c.files, serviceName)
if !ok {
return nil, fmt.Errorf("unknown service: %s (known: %v)", serviceName, serviceNames(c.files))
}
gsd := grpc.ServiceDesc{ServiceName: string(sd.FullName()), HandlerType: (*interface{})(nil)}
methods := sd.Methods()
for _, key := range handlers.Keys() {
name, ok := key.(starlark.String)
if !ok {
return nil, fmt.Errorf("%s: register error: dict key should be a fully-qualified method name (got %T)", fn.Name(), key)
}
var method protoreflect.MethodDescriptor
for i := 0; i < methods.Len(); i++ {
md := methods.Get(i)
if string(md.Name()) == name.GoString() {
method = md
break
}
}
if method == nil {
return nil, fmt.Errorf("grpc.register error: unknown method %s for service %s", name.GoString(), serviceName)
}
value, ok, err := handlers.Get(key)
if err != nil {
log.Printf("registration mapping error: get %s failed: %v", key, err)
continue
}
if !ok {
panic(fmt.Sprintf("registration mapping lookup: lookup %s failed", key))
}
callable, ok := value.(starlark.Callable)
if !ok {
return nil, fmt.Errorf("%s: register error: dict value should be function (got %s)", fn.Name(), value.Type())
}
handler := &Handler{
name: name.GoString(),
fn: callable,
reporter: thread.Print,
md: method,
}
key := fmt.Sprintf("/%s/%s", sd.FullName(), method.Name())
if method.IsStreamingServer() && method.IsStreamingClient() {
gsd.Streams = append(gsd.Streams, grpc.StreamDesc{
StreamName: string(method.Name()),
ServerStreams: true,
ClientStreams: true,
Handler: c.HandleStream,
})
} else if method.IsStreamingServer() {
gsd.Streams = append(gsd.Streams, grpc.StreamDesc{
StreamName: string(method.Name()),
ServerStreams: true,
Handler: c.HandleStream,
})
} else if method.IsStreamingClient() {
gsd.Streams = append(gsd.Streams, grpc.StreamDesc{
StreamName: string(method.Name()),
ClientStreams: true,
Handler: c.HandleStream,
})
} else {
gsd.Methods = append(gsd.Methods, grpc.MethodDesc{
MethodName: string(method.Name()),
Handler: c.HandleMethod,
})
}
c.handlers[key] = handler
}
c.server.RegisterService(&gsd, c)
return starlark.None, nil
}
// HandleStream implements grpc.StreamHandler for handling of server-streaming
// calls.
func (s *grpcServer) HandleStream(srv interface{}, ss grpc.ServerStream) error {
stream := grpc.ServerTransportStreamFromContext(ss.Context())
handler, ok := s.handlers[stream.Method()]
if !ok {
log.Println("handler not found:", stream.Method())
return status.Error(codes.Unimplemented, stream.Method())
}
var request protoreflect.ProtoMessage
if handler.md.IsStreamingServer() && !handler.md.IsStreamingClient() {
request = dynamicpb.NewMessage(handler.md.Input())
if err := ss.RecvMsg(request); err != nil {
return err
}
}
response, err := handler.handle(handler.md, request, ss.Context(), ss, nil)
if err != nil {
log.Printf("handler return value error: %v", err)
return err
}
if handler.md.IsStreamingClient() && !handler.md.IsStreamingServer() {
if err := ss.SendMsg(response); err != nil {
return err
}
}
return nil
}
// HandleStream implements grpc.methodHandler for handling of unary calls.
func (s *grpcServer) HandleMethod(srv interface{}, ctx context.Context, decode func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
sts := grpc.ServerTransportStreamFromContext(ctx)
handler, ok := s.handlers[sts.Method()]
if !ok {
log.Println("handler not found:", sts.Method())
return nil, status.Error(codes.Unimplemented, sts.Method())
}
input := dynamicpb.NewMessage(handler.md.Input())
if err := decode(input); err != nil {
return nil, err
}
response, err := handler.handle(handler.md, input, ctx, nil, sts)
if err != nil {
return nil, err
}
return response, err
}
func newServer(files *protoregistry.Files) func(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
return func(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
var credentials credentials.TransportCredentials
if err := starlark.UnpackArgs("grpc.Server", args, kwargs,
"credentials?", &credentials,
); err != nil {
return nil, err
}
var options []grpc.ServerOption
if credentials != nil {
options = append(options, grpc.Creds(credentials))
}
value := &grpcServer{
files: files,
server: grpc.NewServer(options...),
handlers: make(map[string]*Handler),
}
return value, nil
}
}
func serviceNames(files *protoregistry.Files) (names []string) {
files.RangeFiles(func(fd protoreflect.FileDescriptor) bool {
services := fd.Services()
for i := 0; i < services.Len(); i++ {
sd := services.Get(i)
names = append(names, string(sd.FullName()))
}
return true
})
return
}
func grpcServerServiceInfoNames(server *grpc.Server) (names []string) {
for name := range server.GetServiceInfo() {
names = append(names, name)
}
return
}
func serviceDescriptorByName(files *protoregistry.Files, name string) (protoreflect.ServiceDescriptor, bool) {
var sd protoreflect.ServiceDescriptor
files.RangeFiles(func(fd protoreflect.FileDescriptor) bool {
services := fd.Services()
for i := 0; i < services.Len(); i++ {
s := services.Get(i)
if string(s.FullName()) == name {
sd = s
return false
}
}
return true
})
if sd == nil {
return nil, false
}
return sd, true
}
func methodDescriptorByName(files *protoregistry.Files, serviceName, methodName string) (md protoreflect.MethodDescriptor, ok bool) {
service, ok := serviceDescriptorByName(files, serviceName)
if !ok {
return nil, false
}
methods := service.Methods()
for i := 0; i < methods.Len(); i++ {
v := methods.Get(i)
if string(v.Name()) == string(methodName) {
return v, true
}
}
return nil, false
}