1/*
2 *
3 * Copyright 2019 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19package grpc
20
21import (
22	"google.golang.org/grpc/codes"
23	"google.golang.org/grpc/status"
24)
25
26// PreparedMsg is responsible for creating a Marshalled and Compressed object.
27//
28// This API is EXPERIMENTAL.
29type PreparedMsg struct {
30	// Struct for preparing msg before sending them
31	encodedData []byte
32	hdr         []byte
33	payload     []byte
34}
35
36// Encode marshalls and compresses the message using the codec and compressor for the stream.
37func (p *PreparedMsg) Encode(s Stream, msg interface{}) error {
38	ctx := s.Context()
39	rpcInfo, ok := rpcInfoFromContext(ctx)
40	if !ok {
41		return status.Errorf(codes.Internal, "grpc: unable to get rpcInfo")
42	}
43
44	// check if the context has the relevant information to prepareMsg
45	if rpcInfo.preloaderInfo == nil {
46		return status.Errorf(codes.Internal, "grpc: rpcInfo.preloaderInfo is nil")
47	}
48	if rpcInfo.preloaderInfo.codec == nil {
49		return status.Errorf(codes.Internal, "grpc: rpcInfo.preloaderInfo.codec is nil")
50	}
51
52	// prepare the msg
53	data, err := encode(rpcInfo.preloaderInfo.codec, msg)
54	if err != nil {
55		return err
56	}
57	p.encodedData = data
58	compData, err := compress(data, rpcInfo.preloaderInfo.cp, rpcInfo.preloaderInfo.comp)
59	if err != nil {
60		return err
61	}
62	p.hdr, p.payload = msgHeader(data, compData)
63	return nil
64}
65