khenaidoo | a46458b | 2021-12-15 16:50:44 -0500 | [diff] [blame] | 1 | // Package grpcdynamic provides a dynamic RPC stub. It can be used to invoke RPC |
| 2 | // method where only method descriptors are known. The actual request and response |
| 3 | // messages may be dynamic messages. |
| 4 | package grpcdynamic |
| 5 | |
| 6 | import ( |
| 7 | "fmt" |
| 8 | "io" |
| 9 | |
| 10 | "github.com/golang/protobuf/proto" |
| 11 | "golang.org/x/net/context" |
| 12 | "google.golang.org/grpc" |
| 13 | "google.golang.org/grpc/metadata" |
| 14 | |
| 15 | "github.com/jhump/protoreflect/desc" |
| 16 | "github.com/jhump/protoreflect/dynamic" |
| 17 | ) |
| 18 | |
| 19 | // Stub is an RPC client stub, used for dynamically dispatching RPCs to a server. |
| 20 | type Stub struct { |
| 21 | channel Channel |
| 22 | mf *dynamic.MessageFactory |
| 23 | } |
| 24 | |
| 25 | // Channel represents the operations necessary to issue RPCs via gRPC. The |
| 26 | // *grpc.ClientConn type provides this interface and will typically the concrete |
| 27 | // type used to construct Stubs. But the use of this interface allows |
| 28 | // construction of stubs that use alternate concrete types as the transport for |
| 29 | // RPC operations. |
| 30 | type Channel interface { |
| 31 | Invoke(ctx context.Context, method string, args, reply interface{}, opts ...grpc.CallOption) error |
| 32 | NewStream(ctx context.Context, desc *grpc.StreamDesc, method string, opts ...grpc.CallOption) (grpc.ClientStream, error) |
| 33 | } |
| 34 | |
| 35 | var _ Channel = (*grpc.ClientConn)(nil) |
| 36 | |
| 37 | // NewStub creates a new RPC stub that uses the given channel for dispatching RPCs. |
| 38 | func NewStub(channel Channel) Stub { |
| 39 | return NewStubWithMessageFactory(channel, nil) |
| 40 | } |
| 41 | |
| 42 | // NewStubWithMessageFactory creates a new RPC stub that uses the given channel for |
| 43 | // dispatching RPCs and the given MessageFactory for creating response messages. |
| 44 | func NewStubWithMessageFactory(channel Channel, mf *dynamic.MessageFactory) Stub { |
| 45 | return Stub{channel: channel, mf: mf} |
| 46 | } |
| 47 | |
| 48 | func requestMethod(md *desc.MethodDescriptor) string { |
| 49 | return fmt.Sprintf("/%s/%s", md.GetService().GetFullyQualifiedName(), md.GetName()) |
| 50 | } |
| 51 | |
| 52 | // InvokeRpc sends a unary RPC and returns the response. Use this for unary methods. |
| 53 | func (s Stub) InvokeRpc(ctx context.Context, method *desc.MethodDescriptor, request proto.Message, opts ...grpc.CallOption) (proto.Message, error) { |
| 54 | if method.IsClientStreaming() || method.IsServerStreaming() { |
| 55 | return nil, fmt.Errorf("InvokeRpc is for unary methods; %q is %s", method.GetFullyQualifiedName(), methodType(method)) |
| 56 | } |
| 57 | if err := checkMessageType(method.GetInputType(), request); err != nil { |
| 58 | return nil, err |
| 59 | } |
| 60 | resp := s.mf.NewMessage(method.GetOutputType()) |
| 61 | if err := s.channel.Invoke(ctx, requestMethod(method), request, resp, opts...); err != nil { |
| 62 | return nil, err |
| 63 | } |
| 64 | return resp, nil |
| 65 | } |
| 66 | |
| 67 | // InvokeRpcServerStream sends a unary RPC and returns the response stream. Use this for server-streaming methods. |
| 68 | func (s Stub) InvokeRpcServerStream(ctx context.Context, method *desc.MethodDescriptor, request proto.Message, opts ...grpc.CallOption) (*ServerStream, error) { |
| 69 | if method.IsClientStreaming() || !method.IsServerStreaming() { |
| 70 | return nil, fmt.Errorf("InvokeRpcServerStream is for server-streaming methods; %q is %s", method.GetFullyQualifiedName(), methodType(method)) |
| 71 | } |
| 72 | if err := checkMessageType(method.GetInputType(), request); err != nil { |
| 73 | return nil, err |
| 74 | } |
| 75 | ctx, cancel := context.WithCancel(ctx) |
| 76 | sd := grpc.StreamDesc{ |
| 77 | StreamName: method.GetName(), |
| 78 | ServerStreams: method.IsServerStreaming(), |
| 79 | ClientStreams: method.IsClientStreaming(), |
| 80 | } |
| 81 | if cs, err := s.channel.NewStream(ctx, &sd, requestMethod(method), opts...); err != nil { |
| 82 | return nil, err |
| 83 | } else { |
| 84 | err = cs.SendMsg(request) |
| 85 | if err != nil { |
| 86 | cancel() |
| 87 | return nil, err |
| 88 | } |
| 89 | err = cs.CloseSend() |
| 90 | if err != nil { |
| 91 | cancel() |
| 92 | return nil, err |
| 93 | } |
| 94 | return &ServerStream{cs, method.GetOutputType(), s.mf}, nil |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | // InvokeRpcClientStream creates a new stream that is used to send request messages and, at the end, |
| 99 | // receive the response message. Use this for client-streaming methods. |
| 100 | func (s Stub) InvokeRpcClientStream(ctx context.Context, method *desc.MethodDescriptor, opts ...grpc.CallOption) (*ClientStream, error) { |
| 101 | if !method.IsClientStreaming() || method.IsServerStreaming() { |
| 102 | return nil, fmt.Errorf("InvokeRpcClientStream is for client-streaming methods; %q is %s", method.GetFullyQualifiedName(), methodType(method)) |
| 103 | } |
| 104 | ctx, cancel := context.WithCancel(ctx) |
| 105 | sd := grpc.StreamDesc{ |
| 106 | StreamName: method.GetName(), |
| 107 | ServerStreams: method.IsServerStreaming(), |
| 108 | ClientStreams: method.IsClientStreaming(), |
| 109 | } |
| 110 | if cs, err := s.channel.NewStream(ctx, &sd, requestMethod(method), opts...); err != nil { |
| 111 | return nil, err |
| 112 | } else { |
| 113 | return &ClientStream{cs, method, s.mf, cancel}, nil |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | // InvokeRpcBidiStream creates a new stream that is used to both send request messages and receive response |
| 118 | // messages. Use this for bidi-streaming methods. |
| 119 | func (s Stub) InvokeRpcBidiStream(ctx context.Context, method *desc.MethodDescriptor, opts ...grpc.CallOption) (*BidiStream, error) { |
| 120 | if !method.IsClientStreaming() || !method.IsServerStreaming() { |
| 121 | return nil, fmt.Errorf("InvokeRpcBidiStream is for bidi-streaming methods; %q is %s", method.GetFullyQualifiedName(), methodType(method)) |
| 122 | } |
| 123 | sd := grpc.StreamDesc{ |
| 124 | StreamName: method.GetName(), |
| 125 | ServerStreams: method.IsServerStreaming(), |
| 126 | ClientStreams: method.IsClientStreaming(), |
| 127 | } |
| 128 | if cs, err := s.channel.NewStream(ctx, &sd, requestMethod(method), opts...); err != nil { |
| 129 | return nil, err |
| 130 | } else { |
| 131 | return &BidiStream{cs, method.GetInputType(), method.GetOutputType(), s.mf}, nil |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | func methodType(md *desc.MethodDescriptor) string { |
| 136 | if md.IsClientStreaming() && md.IsServerStreaming() { |
| 137 | return "bidi-streaming" |
| 138 | } else if md.IsClientStreaming() { |
| 139 | return "client-streaming" |
| 140 | } else if md.IsServerStreaming() { |
| 141 | return "server-streaming" |
| 142 | } else { |
| 143 | return "unary" |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | func checkMessageType(md *desc.MessageDescriptor, msg proto.Message) error { |
| 148 | var typeName string |
| 149 | if dm, ok := msg.(*dynamic.Message); ok { |
| 150 | typeName = dm.GetMessageDescriptor().GetFullyQualifiedName() |
| 151 | } else { |
| 152 | typeName = proto.MessageName(msg) |
| 153 | } |
| 154 | if typeName != md.GetFullyQualifiedName() { |
| 155 | return fmt.Errorf("expecting message of type %s; got %s", md.GetFullyQualifiedName(), typeName) |
| 156 | } |
| 157 | return nil |
| 158 | } |
| 159 | |
| 160 | // ServerStream represents a response stream from a server. Messages in the stream can be queried |
| 161 | // as can header and trailer metadata sent by the server. |
| 162 | type ServerStream struct { |
| 163 | stream grpc.ClientStream |
| 164 | respType *desc.MessageDescriptor |
| 165 | mf *dynamic.MessageFactory |
| 166 | } |
| 167 | |
| 168 | // Header returns any header metadata sent by the server (blocks if necessary until headers are |
| 169 | // received). |
| 170 | func (s *ServerStream) Header() (metadata.MD, error) { |
| 171 | return s.stream.Header() |
| 172 | } |
| 173 | |
| 174 | // Trailer returns the trailer metadata sent by the server. It must only be called after |
| 175 | // RecvMsg returns a non-nil error (which may be EOF for normal completion of stream). |
| 176 | func (s *ServerStream) Trailer() metadata.MD { |
| 177 | return s.stream.Trailer() |
| 178 | } |
| 179 | |
| 180 | // Context returns the context associated with this streaming operation. |
| 181 | func (s *ServerStream) Context() context.Context { |
| 182 | return s.stream.Context() |
| 183 | } |
| 184 | |
| 185 | // RecvMsg returns the next message in the response stream or an error. If the stream |
| 186 | // has completed normally, the error is io.EOF. Otherwise, the error indicates the |
| 187 | // nature of the abnormal termination of the stream. |
| 188 | func (s *ServerStream) RecvMsg() (proto.Message, error) { |
| 189 | resp := s.mf.NewMessage(s.respType) |
| 190 | if err := s.stream.RecvMsg(resp); err != nil { |
| 191 | return nil, err |
| 192 | } else { |
| 193 | return resp, nil |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | // ClientStream represents a response stream from a client. Messages in the stream can be sent |
| 198 | // and, when done, the unary server message and header and trailer metadata can be queried. |
| 199 | type ClientStream struct { |
| 200 | stream grpc.ClientStream |
| 201 | method *desc.MethodDescriptor |
| 202 | mf *dynamic.MessageFactory |
| 203 | cancel context.CancelFunc |
| 204 | } |
| 205 | |
| 206 | // Header returns any header metadata sent by the server (blocks if necessary until headers are |
| 207 | // received). |
| 208 | func (s *ClientStream) Header() (metadata.MD, error) { |
| 209 | return s.stream.Header() |
| 210 | } |
| 211 | |
| 212 | // Trailer returns the trailer metadata sent by the server. It must only be called after |
| 213 | // RecvMsg returns a non-nil error (which may be EOF for normal completion of stream). |
| 214 | func (s *ClientStream) Trailer() metadata.MD { |
| 215 | return s.stream.Trailer() |
| 216 | } |
| 217 | |
| 218 | // Context returns the context associated with this streaming operation. |
| 219 | func (s *ClientStream) Context() context.Context { |
| 220 | return s.stream.Context() |
| 221 | } |
| 222 | |
| 223 | // SendMsg sends a request message to the server. |
| 224 | func (s *ClientStream) SendMsg(m proto.Message) error { |
| 225 | if err := checkMessageType(s.method.GetInputType(), m); err != nil { |
| 226 | return err |
| 227 | } |
| 228 | return s.stream.SendMsg(m) |
| 229 | } |
| 230 | |
| 231 | // CloseAndReceive closes the outgoing request stream and then blocks for the server's response. |
| 232 | func (s *ClientStream) CloseAndReceive() (proto.Message, error) { |
| 233 | if err := s.stream.CloseSend(); err != nil { |
| 234 | return nil, err |
| 235 | } |
| 236 | resp := s.mf.NewMessage(s.method.GetOutputType()) |
| 237 | if err := s.stream.RecvMsg(resp); err != nil { |
| 238 | return nil, err |
| 239 | } |
| 240 | // make sure we get EOF for a second message |
| 241 | if err := s.stream.RecvMsg(resp); err != io.EOF { |
| 242 | if err == nil { |
| 243 | s.cancel() |
| 244 | return nil, fmt.Errorf("client-streaming method %q returned more than one response message", s.method.GetFullyQualifiedName()) |
| 245 | } else { |
| 246 | return nil, err |
| 247 | } |
| 248 | } |
| 249 | return resp, nil |
| 250 | } |
| 251 | |
| 252 | // BidiStream represents a bi-directional stream for sending messages to and receiving |
| 253 | // messages from a server. The header and trailer metadata sent by the server can also be |
| 254 | // queried. |
| 255 | type BidiStream struct { |
| 256 | stream grpc.ClientStream |
| 257 | reqType *desc.MessageDescriptor |
| 258 | respType *desc.MessageDescriptor |
| 259 | mf *dynamic.MessageFactory |
| 260 | } |
| 261 | |
| 262 | // Header returns any header metadata sent by the server (blocks if necessary until headers are |
| 263 | // received). |
| 264 | func (s *BidiStream) Header() (metadata.MD, error) { |
| 265 | return s.stream.Header() |
| 266 | } |
| 267 | |
| 268 | // Trailer returns the trailer metadata sent by the server. It must only be called after |
| 269 | // RecvMsg returns a non-nil error (which may be EOF for normal completion of stream). |
| 270 | func (s *BidiStream) Trailer() metadata.MD { |
| 271 | return s.stream.Trailer() |
| 272 | } |
| 273 | |
| 274 | // Context returns the context associated with this streaming operation. |
| 275 | func (s *BidiStream) Context() context.Context { |
| 276 | return s.stream.Context() |
| 277 | } |
| 278 | |
| 279 | // SendMsg sends a request message to the server. |
| 280 | func (s *BidiStream) SendMsg(m proto.Message) error { |
| 281 | if err := checkMessageType(s.reqType, m); err != nil { |
| 282 | return err |
| 283 | } |
| 284 | return s.stream.SendMsg(m) |
| 285 | } |
| 286 | |
| 287 | // CloseSend indicates the request stream has ended. Invoke this after all request messages |
| 288 | // are sent (even if there are zero such messages). |
| 289 | func (s *BidiStream) CloseSend() error { |
| 290 | return s.stream.CloseSend() |
| 291 | } |
| 292 | |
| 293 | // RecvMsg returns the next message in the response stream or an error. If the stream |
| 294 | // has completed normally, the error is io.EOF. Otherwise, the error indicates the |
| 295 | // nature of the abnormal termination of the stream. |
| 296 | func (s *BidiStream) RecvMsg() (proto.Message, error) { |
| 297 | resp := s.mf.NewMessage(s.respType) |
| 298 | if err := s.stream.RecvMsg(resp); err != nil { |
| 299 | return nil, err |
| 300 | } else { |
| 301 | return resp, nil |
| 302 | } |
| 303 | } |