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// Experimental
29//
30// Notice: This type is EXPERIMENTAL and may be changed or removed in a
31// later release.
32type PreparedMsg struct {
33	// Struct for preparing msg before sending them
34	encodedData []byte
35	hdr         []byte
36	payload     []byte
37}
38
39// Encode marshalls and compresses the message using the codec and compressor for the stream.
40func (p *PreparedMsg) Encode(s Stream, msg interface{}) error {
41	ctx := s.Context()
42	rpcInfo, ok := rpcInfoFromContext(ctx)
43	if !ok {
44		return status.Errorf(codes.Internal, "grpc: unable to get rpcInfo")
45	}
46
47	// check if the context has the relevant information to prepareMsg
48	if rpcInfo.preloaderInfo == nil {
49		return status.Errorf(codes.Internal, "grpc: rpcInfo.preloaderInfo is nil")
50	}
51	if rpcInfo.preloaderInfo.codec == nil {
52		return status.Errorf(codes.Internal, "grpc: rpcInfo.preloaderInfo.codec is nil")
53	}
54
55	// prepare the msg
56	data, err := encode(rpcInfo.preloaderInfo.codec, msg)
57	if err != nil {
58		return err
59	}
60	p.encodedData = data
61	compData, err := compress(data, rpcInfo.preloaderInfo.cp, rpcInfo.preloaderInfo.comp)
62	if err != nil {
63		return err
64	}
65	p.hdr, p.payload = msgHeader(data, compData)
66	return nil
67}
68